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- Biomedical Optics
Biomedical Optics
The effects of LED rectal irradiation on the experimental ulcerative colitis in rats
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We evaluated the effects of light emitting diode(LED λ 632.8nm; power 4.0mw)applied directly to the colon on the experimental ulcerative colitis. 34 rats were divided into 3 groups, which was LED treatment group (n=12), model group (n=12), and normal control group (n=10). Given glacial acetic acid (5%) intra-anally so as to be replicated the rat model of ulcerative colitis. LED irradiation was used to curative group, with 30min each time, once per day. The period of treatment was one week. Then the activity of superoxide dismutase (SOD) and content of malondi-aldehyde (MDA) in the blood plasma were detected and the histopathological study in Colonic tissue was performed. The degree of the Colonic tissue injury in curative group was not as significant as that in the model group. Comparing with model group, the Content of MDA in LED curative group was reductive and the activity of SOD was increased significantly. We concluded that the LED irradiation can protect colonic mucosa from acetic acid induced damage in rats and the effects may be related to the photobiomodulation of LED.
Affecting factors on optical clearing of bio-tissues: tissue anatomical structures and permeation property of hyperosmotic agents
Xianqun Xu,
Liu Wu
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With an effort to understand the impacting factors on optical clearing of tissues and to look for effective clearing, two types of tissues i. e. muscle tissue (porcine skeletal muscle) and epithelial tissue (porcine stomach mucosa) treated with glycerol are investigated by the use of optical coherence tomography (OCT) and near infrared spectroscopy. Stomach mucosa applied with mixed solutions of glycerol and dimethyl sulfoxide (DMSO) is furthermore studied. The improved contrast among different layers in the both tissues is visualised with the OCT assessment. The overall increase in light transmittance in the muscle and the mucosal tissue at 30 min. after the application of 80% glycerol are approximate 21% and 16%, decrease in diffuse reflectance are 33% and 21%, respectively. The different anatomical structures of muscle and mucosal tissue probably account for the difference in clearing effect between the two tissues. For stomach mocusa, 50% glycerol with 30% DMSO shows significantly stronger clearing effect than 80% glycerol. High permeability and enhancer activity of DMSO are thought to aid in the synergistic clearing effect. It is concluded that the optical clearing accomplished by the hyperosmotic agents is strongly dependent on anatomical structure of tissue and permeation property of clearing agents, which must be taken into account for effective clearing.
Experimental study and numerical simulation of laser ablation in the nasopharyngeal tissue of rabbit
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The purpose of this study was to determine the ablation threshold of 1341nm Nd:YAP laser radiation on the nasopharyngeal tissue of rabbit. The laser power of irradiation on the tissue surface was varied from 5 to 12W, while the duration of the irradiation was from 1.0 to 2.5s in 0.5s by increments. With the Nd:YAP laser, the ablation threshold was found in the energy density range among 8.0x103-9.5x103 J/cm2 and the average diameter of ablation groove was about 0.3mm. Based on the experimental results, a heat transfer model including a phase change process is fitted with the structure of the nasopharyngeal tissue of rabbit. By the photothermal parameters of the nasopharyngeal tissue of rabbit, the energy distribution induced by laser irradiation in tissue is mapped by numerical simulation method and compared with the experimental results.
Photorejuvenation: still not a fully established clinical tool for cosmetic treatment
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Several methods have been used to improve the esthetic appearance of photodamaged skin including dermabrasion, chemical peels and laser resurfacing using CO2 and Er:YAG laser. These procedures sacrifice epidermis, resulting in a long recuperation period and potential complications including persistent scarring, infection, hyperpigmentation, etc. Compared to ablative CO2 or Er:YAG laser resurfacing, non-ablative photorejuvenation technologies are playing an increasing role in the treatment of photodamaged skin. The clinical objective of which is to maximize thermal damage to upper dermis while minimizing injury to overlying skin. A variety of laser and non-laser systems have been used in the initial stage for this treatment. In our review, different treatment modalities have resulted in varying degrees of clinical effects. The basic mechanisms relate to improvement in employing non-ablative technologies are also discussed. Photorejuvenation is still not a fully established clinical tool for cosmetic treatment according to our review, therefore more research on basic mechanisms should be made.
Laser light propagation in adipose tissue and laser effects on adipose cell membranes
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Recently Neira et al. have presented a new liposuction technique that demonstrated the movement of fat from inside to outside of the cell, using a low-level laser device during a liposuction procedure with Ultrawet solution. The clinical observations, allowed this new surgical development, started a set of physical, histological and pharmacological studies aimed to determine the mechanisms involved in the observed fat mobilization concomitant to external laser application in liposuction procedures. Scanning and Transmission Electron Microscopy, studies show that the cellular arrangement of normal adipose tissue changes when laser light from a diode laser: 10 mW, 635 nm is applied. Laser exposures longer than 6 minutes cause the total destruction of the adipocyte panicles. Detailed observation of the adipose cells show that by short irradiation times (less than four minutes) the cell membrane exhibits dark zones, that collapse by longer laser exposures. Optical measurements show that effective penetration length depends on the laser intensity. Moreover, the light scattering is enhanced by diffraction and subsequent interference effects, and the tumescent solution produces a clearing of the tissue optical medium. Finally, isolate adipose cell observation show that fat release from adipocytes is a concomitant effect between the tumescent solution (adrenaline) and laser light, revealing a synergism which conduces to the aperture, and maybe the disruption, of the cell membrane. All these studies were consistent with a laser induced cellular process, which causes fat release from inside the adipocytes into the intercellular space, besides a strong modification of the cellular membranes.
Near-infrared spectroscopy probe with position sensor for obtaining spatial metabolism on human tissue
Shuji Taue,
Yoko Fujimoto,
Mayumi Fukuda,
et al.
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We propose a scanning probe for near-infrared spectroscopy. The scanning probe has a red light emitting diode for indicating its position in addition to a set of two near-infrared light emitting diodes and a photodetector for near-infrared spectroscopy measurement. The red light is detected by a camera and the probe position is obtained by processing the captured images. There are two usages of the probe: In one usage, the user scans the probe on the body surface to obtain a spatial distribution of metabolic status; in the other usage, the probe is fixed on the body and simultaneously measures metabolic status and movement of the body to investigate their relationship.
Hemodynamic responses to functional activation accessed by optical imaging
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A multi-wavelength light-emitting diode (LED) and laser diode (LD) based optical imaging system was developed to visualize the changes in cerebral blood flow, oxygenation following functional activation simultaneously in rodent cortex. The 2-D blood flow image was accessed by laser speckle contrast imaging, and the spectroscopic imaging of intrinsic signal was used for the calculation of oxyhemoglobin (HbO), deoxyhemoglobin (Hb) and total hemoglobin (HbT) concentration. The combination of spectroscopic imaging and laser speckle contrast imaging provides the capability to simultaneously investigate the spatial and temporal blood flow and hemoglobin concentration changes with high resolution, which may lead to a better understanding of the coupling between neuronal activation and vascular responses. The optical imaging system been built is compact and convenient to investigators. And it is reliable to acquire raw data. In present study, the hemodynamic responses to cortical spreading depression (CSD) in parietal cortex of ∝-chloralose/urethan anesthetized rats were demonstrated.
Generalized diffusion approximation for highly absorbing media and small source-detector separations
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The diffusion approximation to the transport equation is commonly used in biomedical optical diagnostic techniques, but constrains its applicability to highly scattering system. The generalized diffusion approximation was developed by Venugopalan can be used to quantify optical properties of turbid media using small source detector separations and allow the measurement of media with highly absorption. Unfortunately, the simulated result from this theory was larger than the real value because δ-Eddington phase function contained too much forward scattering. Here a new independent control parameter is introduced to δ-Eddington phase function so as to modify the generalized diffusion approximation presented. The solution is presented in the stationary case for infinite media with a collimated source of finite size exhibiting spherical symmetry. The solution is compared to results given by the conventional diffusion theory, the generalized diffusion approximation as well as to the Monte-Carlo simulation in steady state diffusion equation for slab boundary condition. The simulation results show that the modified generalized diffusion approximation with an appropriate control parameter is more closed to Monte-Carlo simulation. The modified generalized formulation of diffusion theory presented here may enable the quantitative application of present optical diagnostic techniques to turbid systems which are more highly absorbing and allow these systems to be probed using smaller source-detector separations.
Mechanism of endogenetic chromophore mediated photo-damage and its applications
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Photobiomodulation is an effect of low intensity monochromatic light or laser irradiation on biological systems, which stimulates or inhibits biological functions but does not results in irreducible damage. However, many cellular experiments, animal experiments or clinic studies with monochromatic light or laser irradiation which intensity is not so high that it directly destroys cells have found no photobiomodulation but cell compartment damage, apoptosis or necrosis so that a new concept, a moderate intensity laser or monochromatic light, should be defined if its intensity is so high that no photobiomodulation can be observed, but is so low that it can not directly destroy cells. There might be two pathways mediated the effects of a moderate intensity laser or monochromatic light: one is mediated by the photodynamic effects of endogenetic photosensitizers to induce apoptosis or necrosis, one is mediated by laser or monochromatic light induced stress wave through endogenetic chromophore to induce apoptosis. These effects can be used to understand laser or monochromatic light induced cell compartment damage, apoptosis or necrosis. They are beneficial in phototherapy of cancer and scar, but deleterious in phototherapy of delayed onset of muscular soreness.
Photobiomodulation on the proliferation and collagen synthesis of normal human skin fibroblast cells
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Background and Objective: Cultured normal human skin fibroblast cells (HSFs) were once used to study the mechanism of the effects of low intensity He-Ne laser irradiation (LHNL) on wound healing. The proliferation and collagen synthesis of HFSs were modulated by LHNL in different papers, respectively, and both of them are studied in this paper. Study Design/Materials and Methods: The dosage was studied for the same radiation time 300s. The proliferation and collagen synthesis were measured by 3-[4,5-Dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT) assay and the spectrophotometric method for the determination of hydroxyproline, respectively. Results: The dose zones were called dose 1, dose 2 and dose 3 from low dose on so that HSF proliferation was inhibited in dose 1 (16, 24 mJ/cm2), and promoted in dose 2 (298, 503, 597mJ/cm2), and the collagen synthesis was inhibited in dose 2 (401, 526 mJ/cm2), and promoted in dose 3 (714, 926, 1539, 1727mJ/cm2), which supports our biological model of photobiomodulation. It was found there is the linear relationship of the effect with dose with dose in each dose zone. Conclusions: The photobiomodulation on the proliferation and collagen synthesis of HSFs might be linearly dose-dependent in limited dosage with radiation time kept constant, which provides a foundation to discuss photobiomodulation on wound healing.
Monitoring thermally induced blood flow change of rat mesentery by laser speckle imaging
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Blood perfusion depends on blood flow and vessel in local tissue, which plays important role during hyperthermia. Laser speckle imaging technique was developed to obtain the regional blood flow distribution with high spatio-temporal resolution. Through LSI method, the velocity and diameter change of microvessels can be acquired simultaneously. In this paper, the spatiotemporal characteristics of local mesentery blood flow in anesthetized rats during thermal therapy (43°C, 45°C, 47°C, 49°C, 60min) were monitored in vivo and real time by laser speckle imaging method. The blood flow distribution image of microvessels diameters in 10-50μm was obtained and analyzed to get the information of the response of the diameter of blood vessel, the velocity of blood flood and the perfusion to hyperthermia. The results showed that the diameter of microvessels increased firstly, then decrease appeared if heated continuously while heated at 43°C, 45°C. The same trend could be found for changes in blood velocity and blood perfusion. While heated at a higher temperature, for example, at 47°C, 49°C, the diameter and blood velocity of microvessels decreased soon. This indicated that the microvessels underwent thermal damage. The thermal damage exhibitions were obvious when heated at higher temperature, and the blood flow blanking even may appear. In general, the blood flow of branch stops early more than the blood flow on the backbone. The analysis of the damage rate showed that the higher the heating temperature, the quicker the damage rate.
Photobiomodulation in laser surgery
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Laser surgery provides good exposure with clear operating fields and satisfactory preliminary functional results. In contrast to conventional excision, it was found that matrix metalloproteinases and the tissue inhibitors of metalloproteinases -1 mRNA expression is higher, myofibroblasts appeared and disappeared slower in laser excision wounds. It has been suggested that the better anatomical and functional results achieved following laser cordectomy may be explained by the fact that such procedures result in better, more rapid healing processes to recover vocal cord for early glottic tumors and better. In this paper, the role of photobiomodulation in laser surgery will be discussed by the cultured monolayer normal human skin fibroblast model of the photobiomodulation of marginal irradiation of high intensity laser beam, the photobiomodulation related to the irradiated tissue, the biological information model of photobiomodulation and the animal models of laser surgery. Although high intensity laser beam is so intense that it destroys the irradiated cells or tissue, its marginal irradiation intensity is so low that there is photobiomodulation on non-damage cells to modulate the regeneration of partly damaged tissue so that the surgery of laser of different parameters results in different post-surgical recovery. It was concluded that photobiomodulation might play an important role in the long-term effects of laser surgery, which might be used to design laser surgery.
Studies of light-emitting diode sources for photobiomodulation on cells
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Light-emitting diode (LED), smaller and less expensive, requires less power than laser does, is more and more popular in studying photobiomodulation. Three new LED systems with different intensity have been designed in this paper. The three LED systems consist of a set of lens to expand the beam of light or/and to focus the rays of light, and an array of LEDs set in the sphere connected with Fresnel lens. The intensity of the three LED systems ranges from: 0.002 to 1.465 W/m2 with the spot diameter 40 mm; 0.358 to 11.229 W/m2 with the spot diameter 60 mm; 17.626 to 115.371 W/m2 with the spot diameter 80 mm. Their experimental formulae for calculating intensity were obtained by SPSS.
Photobiomodulation on tumor cells in vitro and tumor tissue in vivo
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Background and Objective: There are many kinds of photobiomodulation (PBM) on tumor cells whereas PBM induced oncogenic transformation has not been found. These will be discussed in view of the anti-cancer efficacy of PBM. Study Design/Materials and Methods: The biological information model of PBM (BIMP) will be used to study PBM on tumor cells. Results: The PBM on tumor cells includes cell proliferation, cell cycle modulation, cell adhesion, cell differentiation and so on. The PBM on small tumor tissue in vivo may include the inhibition or promotion of tumor growth. The PBM can be designed to play an important role in anti-cancer treatments in terms of BIMP. Conclusions and discussion: PBM on tumor cells may develop into a novel anti-cancer therapeutic approach.
Latitude distribution of track and field elite athletes in China mainland
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The civilization theories prevailed among people are the theories paying attention to the geographical factors. In this
paper, the latitude distribution of track and field elite athletes in China mainland has been studied in terms of the biological effects of sunlight. The China mainland is divided into seven latitude zones according to the absolute latitude value so that the larger the zone number is, the larger the distance from the Equator. The elite athletes are classified into speed-type, jump-type, strength-type and endurance-type so that the latitude distribution can be discussed in terms of exercise physiology. The latitude distribution shows that the elite athletes of speed-type or jump-type prefer to the zones of low latitude, and the elite athletes of strength-type or endurance-type prefer to the zones of high latitude. These phenomena can be understood by the effects of sunlight on exercise physiological index such as skeletal muscle fibre types.
Photothermal effect in the tissue during photodynamic therapy
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Based on the Pennes' bio-heat transfer equation, temperature distribution in the tissue during PDT is analyzed in theory. The study indicates that laser heat source could be formed in tissue during laser irradiation, which results in the temperature rising in one-dimensional space. The rising of tissue temperature increases in exponent with time and decreases in exponent with the distance from laser irradiation position.. There exists a minimal light dosage threshold during the photothermal interaction between laser and bio-tissue. When the light dosage is lower than the critical threshold, the laser irradiation will not produce thermal effect. The threshold dosage, which depends on the optical and thermal properties of bio-tissue, increases in exponent with the distance from laser irradiating point along the direction of incident light.
Fourier transform infrared spectroscopic study of truffles
Dezhang Zhao,
Gang Liu,
Dingshan Song,
et al.
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Truffles are rare wild growing edible mushrooms belonging to Ascomycetes. In this paper, Fourier transform infrared (FTIR) spectroscopy was used to obtain vibrational spectra of truffles. The results show that the mushrooms exhibit characteristic spectra. The two strongest absorption bands appear at about 1077cm-1 and 1040 cm-1, which were described as C-O stretching in carbohydrate. The vibrational spectra indicate that the main compositions of the truffles are polysaccharide and protein. According to the characteristics bands and absorption ratios of spectra, different species of truffles can be discriminated. It is also found the great changes between moldy and healthy truffles, which the major differences are observed in the bands of protein. In addition, FTIR spectral differences are observed between the same species of truffles from different producing areas. It is showed that the FTIR spectroscopic method is valuable tool for rapid and nondestructive analysis of truffles prior to any extraction method used.
A study of the mushrooms of Boletes by Fourier transform infrared spectroscopy
Gang Liu,
Dingshan Song,
Dezhang Zhao,
et al.
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In this paper, Fourier transform infrared spectroscopy (FTIR) was used to study the fruiting bodies of six species of wild growing edible mushrooms belonging to Boletes of Basidiomycetes. The results show that each mushroom has its characteristic infrared spectrum, in which the major peaks are attributed to proteins and polysaccharides. The spectra indicate that both α-glucans and β-glucans exist in the polysaccharides of mushrooms. According to the differences of their characteristic spectra peaks and absorbance ratios, the different species of Boletes can be identified. The region between 750 and 1200 cm-1 could serve as fingerprints to discriminate mushrooms. A new identification method of mushrooms may be based on the characteristic vibrational spectra and chemical information provided by FTIR.
Analysis of human breast tissues with Raman microspectroscopy
Gang Liu,
Lin Zhang,
Jianhong Liu,
et al.
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Raman microspectroscopy was used to study normal, benign and malignant human breast tissues. The Raman spectrum of normal breast tissue recorded with 514.5 nm line of Ar+ laser excitation contains features attributed to carotenoids and lipids. The CH2 bending mode near 1447 cm-1 in normal tissue shifts up to 1454 cm-1 in diseased tissues (benign and malignant). The band near 1660 cm-1 in normal tissue is narrow and sharp; whereas the band is broaden in the diseased tissues. In the region of C-H stretching mode, the 2902-/2860-cm-1 intensity ratio shows differences among normal, benign and malignant breast tissues. The ratio is the smallest in carcinoma tissue. The observed spectra differences may be used to probe breast lesion. The results show that Raman spectroscopic technique may have clinical applications.
Pulse oximeter using a gain-modulated avalanche photodiode operated in a pseudo lock-in light detection mode
Tsuyoshi Miyata,
Tetsuo Iwata,
Tsutomu Araki
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We propose a reflection-type pulse oximeter, which employs two pairs of a light-emitting diode (LED) and a gated avalanche photodiode (APD). One LED is a red one with an emission wavelength λ = 635 nm and the other is a near-infrared one with that λ = 945 nm, which are both driven with a pulse mode at a frequency f (=10 kHz). Superposition of a transistor-transistor-logic (TTL) gate pulse on a direct-current (dc) bias, which is set so as not exceeding the breakdown voltage of each APD, makes the APD work in a gain-enhanced operation mode. Each APD is gated at a frequency 2f (=20 kHz) and its output signal is fed into a laboratory-made lock-in amplifier that works in synchronous with the pulse modulation signal of each LED at a frequency f (=10 kHz). A combination of the gated APD and the lock-in like signal detection scheme is useful for the reflection-type pulse oximeter thanks to the capability of detecting a weak signal against a large background (BG) light.
Research on the 3D image restoration of the wide-field microscope based on the MPMAP
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A new method is proposed for the 3D (three-dimensional) image restoration of the wide-field microscope based on the MPMAP algorithm (Poisson-MAP Super-resolution image restoration algorithm with Markov constraint) according to the 3D features of the microscopic image. The neighborhood of the Markov random field in MPMAP algorithm is extended to 3D, and the regularization parameter α of the bound term in MPMAP is simplified. As a result, the restoration of 3D image of wide-field microscope is achieved, and the more perfect effect of the image restoration is got. When images within noise are restored by different value α, different attainable resolution and signal-to-noise ratio (SNR) in the restored image. Experiment results show that it is necessary to select appropriately value of α, and take tradeoff between resolution and SNR in the restored image so that the more perfect effect of the image restoration is got.
The simulation study on point spread function and thick specimen imaging of optical microscope imaging system
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Optical microscope is a common tool in histology and microanatomy, but it is difficult for traditional optical microscope to analyze a three-dimensional specimen. Adopting optical slices will overcome the three-dimensional effect. Optical slices are a series of two-dimensional images by moving the specimen along the focal plane axis. Managing every image with deblurring algorithms to weaken or wipe off the out-of-focus information of the neighbor slices. In this paper, a optical microscope imaging system is analyzed. The relations of defocus error, optical transfer function(OTF) and point spread function(PSF) with defocus distance of specimen-space ▵z are educed. And thick specimen imaging of this system is simulated, which is consistent with the real imaging process of this system. The results are useful for the study of deblurring algorithms.
Design of endoscopic optical coherence tomography system
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Optical coherence tomography (OCT), which bases on the principle of low-coherence interferometry, is an emerging cross-sectional imaging technology. With ultrahigh resolution, OCT is sensitive enough to detect early-stage tissue abnormalities associated with diseases such as early carcinoma. To detect pathologic change in gastrointestinal tract, we combine OCT with endoscopic technique. Later we call this technique as endoscopic optical coherence tomography (EOCT). Compared with time-domain OCT imaging technique, spectral OCT eliminates depth scan in the reference arm so increases the imaging speed. Basing on spectral OCT, EOCT can realize real-time imaging. The EOCT unit is comprised of an endoscopically compatible radially scanning probe as the sample arm. In this paper the principle of spectral OCT is introduced and the crucial parameters of experimental system are discussed. Also the design of a novel probe is presented. In our experiment, a mirror is used as a sample to test the validity of this
method.
Evaluation of the reconstruction algorithms for a phase-stepped full-field optical coherence tomography
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We report on the implementation of a phase-stepped full-field Optical Coherence Tomography which is realized with a superluminescent diode for illuminating the sample, voice coil and piezo-electric translators for controlling the optical path length of the reference channel, and a scientific-grade CCD array for recording 2-D sample interferograms. Evaluation results of several amplitude reconstruction algorithms for this phase-stepped OCT is presented, including 3-, 4-, and 5-step as well as a derived amplitude-based version of the Carre method, a 4-step algorithm that requires equal but arbitrary step sizes that need not be known. Using a planar mirror as the sample and different phase stepping protocols, sensitivity for the four reconstruction algorithms were measured at 85, 87, 95, and 90dB, respectively. Reconstruction results of in vitro bovine retina and a piece of plastic tape show that the performance of the system depends on whether the full dynamic range of the CCD camera is utilized.
Dispersion phenomenon and a compensation method in optical coherence tomography
Tao Tao,
Ran Liao,
Jun Lu,
et al.
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The resolution of optical coherence tomography (OCT) depends on the spectral properties of the light sources used in OCT systems. The minimum distance that can be resolved by this technique is inversely proportional to the spectral width of the light source. Using broadband light sources, ultrahigh-resolution OCT can achieve axial image resolutions on the few micron scale. However, dispersion is known to increase the width of the envelope of the OCT signal and to reduce the resolution of OCT because different wavelengths of a broadband light source have different velocities in dispersive media. In the present paper, a super-luminescent diode (SLD) source is used to characterize the dispersion of different samples. The center wavelength of the light source is 845nm and spectral width is 26nm. A 30mm thick BK7 glass slab is tested. Based on the measured source spectrum, the broadened signals are calculated with the specific dispersion coefficients of different materials. The calculated signals are compared with the results measured in the experiments. A general numerical dispersion compensation method is present, which can both be applied in time domain and in frequency domain. Using this automatic iterative optimization method, the unbroadened signal can be regenerated with high resolution.
Laminar flow velocity estimation by the use of narrow-band electronics with optical coherence tomography
Liu Wu,
Xiangqun Xu,
Xiaomeng Guo
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Doppler optical coherence tomography (DOCT) technique is a new extension to the current OCT developments, that is capable of determining the frequency shift due to the moving scatterers, making it possible to map out the localised blood flows and vessels beneath tissue surface. Doppler OCT system, being employed with a broadband detection electronics to measure frequency shift, is more complex than a narrowband OCT system, because a follow up filter is needed to overcome its low signal-to-noise ratio (SNR) for structure imaging. We describe a simple technique to estimate accurately the laminar flow velocity by the use of narrowband OCT system that is simpler and has a high SNR. It utilises the limited band of electronics to reconstruct the whole laminar velocity profile across target by the use of the least square curve fitting technique. The experimental results demonstrate that the estimated velocity profile by using this method correlate very well with the theoretical predictions. It may, therefore, allow the simpler OCT system to determine the flow velocity functionally in a simple and economic way for monitoring blood flow in vivo.
Study on the combination of confocal scanning microscopy and defocusing imaging
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The combination of the confocal scanning microscopy and the defocusing imaging in the plane of imaging system was proposed. A switch lens and a pinhole with fine focusing aid are used to switch between the confocal scanning imaging mode and defocusing imaging mode. Objectives of different magnification can be used to get different field of vision. The complementary images can offer more information than any single one. Image blur or distortion caused by scanning, such as the displacement of the target and the excursion of scanning stage, can be corrected according to the comparison of two images. Location and adjustment of the target can be achieved easily and the accuracy of scanning image will be improved obviously. Some samples were tested on a home-built system.
Analysis of the effect on tissue autofluorescence detection from off-focus of linear-array pinholes in LP-laser scanning confocal fluorescence microscopical imaging spectrometer
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The research of antofluorescence of the live tissue starts to be used in the disease diagnoses and prevention in recent years. The laser scanning confocal microscope has always played a great role in the autofluorescence research in biomedical field. As the technology of imaging spectrometer got successfully used in the remote sensing fields, microscopical imaging spectrometer for biomedical analyses emerged after the integration of imaging spectrometer and laser scanning confocal microscope. It can get the autofluorescence image and the spectral information of the sample simultaneously, this will supply more information to the diagnoses for difficult diseases. In this paper the principle of a Linear-array Pinholes Laser Scanning Confocal Microscopical Imaging Spectrometer (LP-LSCMIS) developed by the authors is proposed. It can be widely used in the autofluorescence detection of the live tissue in the body, such as the gastric, kidney, etc. The effect of off-focus of linear-array pinholes on microscopical imaging spectrometer subsystem in this device is mainly analyzed. The spatially resolution of fluorescence imaging and the modulation depth of autofluorescence spectrum in the live tissue is affected by the off-focus according to our research. We analyse the modulation depth of the interferogram thinking of the factor of off-focus.
DAPI-fluorescent fading: a problem in microscopy or a way to measure nuclear DNA content?
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In observation by confocal or conventional fluorescence microscopy, the retardation of the lost in fluorescence, from highest signal of fluorescence to lowest intensity are important factors in order to obtain accurate images. This problem is very common in fluorochromes for nuclear DNA and especially for DAPI stain. The fluorescence of DAPI is rapidly lost when it is exposure to excitation by ultra violet (UV) light, and especially under optimal condition of observation. Although the fading process could be retardate by using of mounting medium with antifading solutions, the photochemical process underlying the fluorescence decay has not yet been fully explained. In addiction, neither relationship has been tested between the fluorescence fading and nuclear DNA content. However, the capacity of the DNA to absorb UV light is knows. In order to test this relationship we measured by means of image analysis the fluorescence intensity in several nuclei types during a fading period. The analysis was performed by an algorithm specifically built in MATLAB software. The relationship between nuclear DNA content and DAPI-fluorescence fading was found equal to 99%. This study demonstrates the feasibility for estimates genome size by quantification of fluorescence fading. In this context, the present method allows to measure nuclear DNA content in several medical applications (cancer, HIV, organ transplants, etc). Nowadays, for measuring DNA content, flow cytometry is widely used; however, with the flow cytometry method it is not possible to select a specific group of cells, such as from a specific region of a tumor. Moreover, the using of image analysis allows automatizing diagnostics procedures.
Real-time detecting gelatinases activity in living cells by FRET imaging
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Degradation of the extracellular matrix by Matrix metalloproteinases (MMPs) not only enhances tumor invasion, but also affects tumor cell behaviour and leads to cancer progression. To monitor gelatinases (contain MMP2 and MMP9) activity in living cells, we constructed a vector that encoded a gelatinases recognition site (GRS) between citrine (mutation of EYFP Q69M) in N terminal and ECFP in C terminal. Because Gelatinases are secretory proteins and act outside of cell, an expressing vector displayed the fusion protein on cellular surface was used for this FRET gene probe. On expression of YFP-GRS-ECFP in MCF-7 cells that expressed no gelatinases, we were able to observe the efficient transfer of energy from excited ECFP to YFP within the YFP-GRS-ECFP molecule. However, the fusion protein YFP-GRS-ECFP was expressed in MDA-MB 453s cell line with high secretory gelatinases, so YFP-GRS-ECFP was cleaved by gelatinases, no such transfer of energy was detected and fluorescence signal disappeared in YFP channel since YFP protein was cut down. Moreover, Doxycycline, a MMP inhibitor, could make FRET signal increase and fluorescence signal appeared in YFP channel. Thus, the FRET probe YFP-GRS-ECFP can sensitively and reliably monitor gelatinases activation in living cells and can be used for screening MMP inhibitors.
Imaging of caspase-3 activation by a novel FRET probe composed of CFP and DsRed
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Caspases-3 is a kind of cysteine proteases and plays an important role in cell apoptosis. It has been reported that caspase-3 activation can be real-time detected in living cells by fluorescence resonance energy transfer (FRET) between an enhanced cyan fluorescent protein and enhanced yellow fluorescent protein. However, the large spectral overlap between cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP) emission and the highly sensitivity to pH of YFP restricted their detecting sensitivity and reliability. CFP and red fluorescent protein (DsRed) possess superb wavelength separation of donor and acceptor emission spectra and DsRed was insensitive to pH, so the FRET probe composed of CFP and DsRed would be more suitable for imaging caspase-3 activation than the FRET probe composed of CFP and YFP. We constructed a vector that encoded CRS (caspase-3 recognition site) fused with CFP and DsRed (CFP-CRS-DsRed). In CFP-CRS-DsRed expressing tumor cells, FRET from CFP to DsRed could be detected. In the Clinical applications of cancer chemotherapy, cisplatin is one of the most broadly used drugs. It was already confirmed that caspase-3 was activated in HeLa cell treated by cisplatin. When the cells were stimulated with cisplatin, we found that the FRET efficient was remarkably decreased and then disappeared. It indicated that actived caspase-3 cleaved the CFP-CRS-DsRed fusion protein at CRS site. Thus, the FRET probe of CFP-CRS-DsRed could sensitively and reliably monitor caspase-3 activation in living cell. This probe will be highly useful for rapid-screening potential drugs that may target the apoptotic process and for imaging tumors in vivo.
Optical researches of structural organization axisymmetrical polycrystallic biofibres
V. M. Zolotarev,
A. N. Bekhterev
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In a radial approaching the simulation of optical property of composite systems by the way of fascicles consisting of anisotropic fibres with axisymmetrical packing is made. Is rotined, that at such observation of composite systems is interferential - polarization method for a case of the crossed nicols the figures by the way systems of concentric light and dark rings will be derivated. In center of an interference pattern there is a dark cross.
The outcomes of model calculations made with reference to microsections of dens of the person have shown good qualitative conformity of calculation and experiment for observed pictures in case of separate is model (molar tooth, premolar tooth).
The influence of the complex refractive index of tissues on the image contrast of phase-contrast microscopy
Rong Wang,
Nai Zhou Xu,
Ming Jie Wang
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Most of the materials in nature have complex refractive indexes, especially for biological tissues. The real and imaginary components of the complex refractive index are respectively responsible for the phase delay and absorption of light traveled in the tissues. Taking the complex refractive index into consideration, we modified the imaging theory of phase contrast microscopy. A relationship between the distributions of complex refractive index in measured samples and the intensity distributions of phase contrast micrographs is obtained. Based on this relationship, the influences of the refractive index and thickness of biological slices on the image contrast of phase contrast micrographs are analyzed in detail.
Opto-numerical procedures supporting dynamic lower limbs monitoring and their medical diagnosis
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New optical full-field shape measurement systems allow transient shape capture at rates between 15 and 30 Hz. These frequency rates are enough to monitor controlled movements used e.g. for medical examination purposes. In this paper we present a set of algorithms which may be applied for processing of data gathered by fringe projection method implemented for lower limbs shape measurement. The purpose of presented algorithms is to locate anatomical structures based on the limb shape and its deformation in time. The algorithms are based on local surface curvature calculation and analysis of curvature maps changes during the measurement sequence. One of anatomical structure of high medical interest that is possible to scan and analyze, is patella. Tracking of patella position and orientation under dynamic conditions may lead to detect pathological patella movements and help in knee joint disease diagnosis. Therefore the usefulness of the algorithms developed was proven at examples of patella localization and monitoring.
Phase retrieval for in-line hard x-ray phase-contrast imaging with the Yang-Gu algorithm
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X-ray phase-contrast imaging is an important diagnostic tool in medicine, biology and materials science. In-line hard x-ray phase-contrast imaging is based on Fresnel diffraction of x-ray, therefore we propose to make phase retrieval calculations between arbitrary planes interrelated through the Fresnel domain. A new approach to the numerical reconstruction of object phase by the diffraction intensity for in-line x-ray phase-contrast imaging is presented. The new method is tested on simulated image and the results demonstrate the validity of this new approach.
Soft x-ray cathode and its application in Lixiscope
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In this text the photoelectric emission principle of X-ray cathode was introduced at first. Then we provided the manufacture method of CsI/MCP X-ray cathode, analyzed the quantum efficiency and noise characteristic of reflection type and transmission type X-ray cathode, proposed the improved process, provided the output characteristic and front and sectional stereoscan photograph of CsI/MCP and pointed out the development of Lixiscope and application prospect in biomedicine.
A new method to acquire 3-D images of a dental cast
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This paper introduced our newly developed method to acquire three-dimensional images of a dental cast. A rotatable table, a laser-knife, a mirror, a CCD camera and a personal computer made up of a three-dimensional data acquiring system. A dental cast is placed on the table; the mirror is installed beside the table; a linear laser is projected to the dental cast; the CCD camera is put up above the dental cast, it can take picture of the dental cast and the shadow in the mirror; while the table rotating, the camera records the shape of the laser streak projected on the dental cast, and transmit the data to the computer. After the table rotated one circuit, the computer processes the data, calculates the three-dimensional coordinates of the dental cast's surface. In data processing procedure, artificial neural networks are enrolled to calibrate the lens distortion, map coordinates form screen coordinate system to world coordinate system. According to the three-dimensional coordinates, the computer reconstructs the stereo image of the dental cast. It is essential for computer-aided diagnosis and treatment planning in orthodontics. In comparison with other systems in service, for example, laser beam three-dimensional scanning system, the characteristic of this three-dimensional data acquiring system: a. celerity, it casts only 1 minute to scan a dental cast; b. compact, the machinery is simple and compact; c. no blind zone, a mirror is introduced ably to reduce blind zone.
Improvements to magnetic tracking system for virtual reality
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Magnetic tracking system is widely used in a Virtual or Augmented Reality system to track the orientation and position of an object in space. When being applied in medical applications such as surgical navigation or medical image registration, accurate 6 DOF (Degree-of-Freedom) tracking is especially important. In order to compensate the influence of metal object and magnetic fields in the surrounding environments on the accuracy of the measurements, an AC magnetic tracking system whose orientation is obtained with the output of 3-axis orthogonal magnetic sensors and 2-axis accelerometers is designed. On the basis of analyzing the influence of environmental magnetic fields on the measurement accuracy of heading, a compensation algorithm is presented, which fits the outputs of the magnetic sensors to an ellipse with the principle of least square and rotation invariant and calibrates the heading with the parameters of the ellipse to rotate and scale the measurement results. Compared with the existing approach, the proposed method can effectively compensate the influence of environmental interference when the magnetic tracking system moves in horizontal plane and can also be applied in the applications with continuous movements. Experimental results show that the proposed method can effectively compensate environmental interference and improve the tracking accuracy.
Digital in-line holography: 4-D imaging and tracking of micro-structures and organisms in microfluidics and biology
J. Garcia-Sucerquia,
W. Xu,
S. K. Jericho,
et al.
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In recent years, in-line holography as originally proposed by Gabor, supplemented with numerical reconstruction, has been perfected to the point at which wavelength resolution both laterally and in depth is routinely achieved with light by using digital in-line holographic microscopy (DIHM). The advantages of DIHM are: (1) simplicity of the hardware (laser- pinhole-CCD camera), (2) magnification is obtained in the numerical reconstruction, (3) maximum information of the 3-D structure with a depth of field of millimeters, (4) changes in the specimen and the simultaneous motion of many species, can be followed in 4-D at the camera frame rate. We present results obtained with DIHM in biological and microfluidic applications. By taking advantage of the large depth of field and the plane-to-plane reconstruction capability of DIHM, we can produce 3D representations of the paths followed by micron-sized objects such as suspensions of microspheres and biological samples (cells, algae, protozoa, bacteria). Examples from biology include a study of the motion of bacteria in a diatom and the track of algae and paramecium. In microfluidic applications we observe micro-channel flow, motion of bubbles in water and evolution in electrolysis. The paper finishes with new results from an underwater version of DIHM.
Application of three-dimensional fluoroscopic navigation in neural surgical operation
Changzheng Liu,
Qian Ding,
Changhong Liu
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The major shortcoming of image-guided navigational systems is the use of presurgically acquired image data, which does not account for intraoperative changes in brain morphology. The occurrence of these surgically induced volumetric deformations, or "brain shift", has been well established. Maximum measurements for surface and midline shifts were reported. There is no detailed analysis, however, of the changes occurring throughout the entire surgery. Intraoperative MRI provides a unique opportunity to obtain serial imaging data and characterize the time course of brain deformations during surgery. Methods: The vertically open-configuration intraoperative fluoroscope system permits access to the operative field and allows multiple intraoperative image updates without the need of moving the patient. We developed volumetric display software, the "3D Slicer", which allows quantitative analysis of degree and direction of brain shift. On twenty-five patients, four or more volumetric intraoperative image acquisitions were extensively evaluated. Results: Serial acquisitions allow a comprehensive sequential description of the direction and magnitude of intraoperative deformations. Brain shift occurs at various surgical stages and at different regions. Surface shift occurs throughout surgery and is mainly due to gravity. Subsurface shift occurs during resection involving collapse of the resection cavity and intraparenchymal changes that are difficult to model. Conclusions: Brain shift is a continuous dynamic process, which evolves differently in distinct brain regions. Therefore only serial imaging or continuous data acquisition provide consistently accurate image guidance. Furthermore only serial intraoperative fluoroscope provides an accurate basis for the computational analysis of brain deformations, which might lead to an understanding, and eventually simulation of "brain shift" for intraoperative guidance.
High-sensitivity detection of PSA by time-resolved fluorometry with europium chelate
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Prostate-specific antigen (PSA) is an androgen-dependent glycoprotein protease (M.W. 33 kDa) and a member of kallikrein super-family of serine protease, and has chymotrypsin-like enzymatic activity. It is synthesized by the prostate epithelial cells and found in the prostate gland and seminal plasma as a major protein. It is widely used as a clinical marker for diagnosis, screening, monitoring and prognosis of prostate cancer. In normal male adults, the concentration of PSA in the blood is below 4 ng/ml and this value increases in patients with the prostate cancer or the benign prostatic hyperplasia (BPH) due to its leakage into the circulatory system. As such, systematic monitoring of the PSA level in the blood can provide critical information about the progress of the prostatic disease. We have fabricated a bread-board time resolved fluorescence system that could detect a concentration of Prostate Specific Antigen t-PSA) at clinically meaningful level in plasma as well as in whole blood sample. We chose Europium chelates as the fluorescence markers to attach to the PSA for its long decay lifetime and relative photostability. We have simplified the electronic circuits considerably by employing a MCS. With this setup, we have successfully proved that PSA concentration of 4pg/mL can be detected with acceptable reliability.
New technology of functional infrared imaging and its clinical applications
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With improvements in infrared camera technology, the promise of reduced costs and noninvasive character, infrared thermal imaging resurges in medicine. The paper introduces a new technology of functional infrared imaging, thermal texture maps (TTM), which is not only an apparatus for thermal radiation imaging but also a new method for revealing the relationship between the temperature distribution of the skin surface and the emission field inside body. The skin temperature distribution of a healthy human body exhibits a contralateral symmetry. Any disease in the body is associated with an alteration of the thermal distribution of human body. Infrared thermography is noninvasive, so it is the best choice for studying the physiology of thermoregulation and the thermal dysfunction associated with diseases. Reading and extracting information from the thermograms is a complex and subjective task that can be greatly facilitated by computerized techniques. Through image processing and measurement technology, surface or internal radiation sources can be non-invasively distinguished through extrapolation. We discuss the principle, the evaluation procedure and the effectiveness of TTM technology in the clinical detection and diagnosis of cancers, especially in their early stages and other diseases by comparing with other imaging technologies, such as ultrasound. Several study cases are given to show the effectiveness of this method. At last, we point out the applications of TTM technology in the research field of traditional medicine.
An inexpensive x-ray imaging system of big visual field
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In this paper, a new kind of x-ray imaging system designed by our laboratory is introduced in detail. Different from the traditional x-ray imaging system, its image intensifier is a combined one. The system's main components are the intensifying screen and the brightness intensifier and they are coupled by lens. Compared with the traditional x-ray imaging system, it has the advantages of low cost, big visual field and convenient installation. At the very beginning of this paper, the structure and the imaging principle of the new kind of x-ray imaging system are described, then requirements for the key components of this system are discussed and put forward. At the end of this paper, we give the images of the foot and the bag, which are the imaging results of the system. It indicates that the x-ray imaging system is satisfied and just for its low price, the usual users such as the middle and small hospitals can afford the system. As for the imaging performance of the system as concerned, it can be applied to security checking, medical treatment, nondestructive testing and many other fields of the science and technology.
Research of the performance of the measuring aberrations in human eye with Hartmann-Shack sensor
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In this paper the performance of Hartmann-Shack wave-front sensor in the aberration measurements of human eyes is investigated and the accuracy and repeatability of measurements are presented qualitatively and quantitatively.
Medical x-ray coherent scatter images processing based on the MRF model
Taihui Liu,
Junxi Sun,
Jingxin Liu,
et al.
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X-ray coherent scatter imaging is a novel imaging technique. A clinical X-ray coherent scatter imaging equipment based on image processing method is introduced, adopting CR and IP plate instead of the diffractometers. The scatter images obtained are made of some circles with the same center. According to our equipment, it is vital to calculate the energy template to classify the different samples. However, it is difficult to separate them using the traditional threshold method due to noise and overlapped shadow. Markov Random Field (MRF) is employed to segment the scatter image, which takes spatial information into account to deal with the noise and overlapped shadow. The experiment results show our method is reasonable and feasible.
The classical electrodynamics approach to explain the photoelectric effect and the photoelectric emission
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By re-analyzing the photoelectric effect, the limitations of Einstein's photon hypothesis are identified and the relation
between the photoelectron's kinetic energy and the circular frequency of the incident light is reinterpreted using classical
electrodynamics. And it is realized that photoelectric emission is dependent on the incident light's circular frequency ω
and the photon density of the incident light.
Video stereo-laparoscopy system
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Minimally invasive surgery (MIS) has contributed significantly to patient care by reducing the morbidity associated with more invasive procedures. MIS procedures have become standard treatment for gallbladder disease and some abdominal malignancies. The imaging system has played a major role in the evolving field of minimally invasive surgery (MIS). The image need to have good resolution, large magnification, especially, the image need to have depth cue at the same time the image have no flicker and suit brightness. The video stereo-laparoscopy system can meet the demand of the doctors. This paper introduces the 3d video laparoscopy has those characteristic, field frequency: 100Hz, the depth space: 150mm, resolution: 10pl/mm. The work principle of the system is introduced in detail, and the optical system and time-division stereo-display system are described briefly in this paper. The system has focusing image lens, it can image on the CCD chip, the optical signal can change the video signal, and through A/D switch of the image processing system become the digital signal, then display the polarized image on the screen of the monitor through the liquid crystal shutters. The doctors with the polarized glasses can watch the 3D image without flicker of the tissue or organ. The 3D video laparoscope system has apply in the MIS field and praised by doctors. Contrast to the traditional 2D video laparoscopy system, it has some merit such as reducing the time of surgery, reducing the problem of surgery and the trained time.
Fast determination of total ginsenosides content in ginseng powder by near infrared reflectance spectroscopy
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Near infrared (NIR) reflectance spectroscopy was used to develop a fast determination method for total ginsenosides in Ginseng (Panax Ginseng) powder. The spectra were analyzed with multiplicative signal correction (MSC) correlation method. The best correlative spectra region with the total ginsenosides content was 1660 nm~1880 nm and 2230nm~2380 nm. The NIR calibration models of ginsenosides were built with multiple linear regression (MLR), principle component regression (PCR) and partial least squares (PLS) regression respectively. The results showed that the calibration model built with PLS combined with MSC and the optimal spectrum region was the best one. The correlation coefficient and the root mean square error of correction validation (RMSEC) of the best calibration model were 0.98 and 0.15% respectively. The optimal spectrum region for calibration was 1204nm~2014nm. The result suggested that using NIR to rapidly determinate the total ginsenosides content in ginseng powder were feasible.
FTIR study on the normal and malignant gastric tissues
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By experimenting with Fourier transform infrared spectroscopy (FTIR), it was found that FTIR yielded much better results and faster determination of normal and malignant gastric tissues when accompanied with OMNI-sampler. The results showed that there were obvious and regularity differences between FTIR spectra of them in spectral parameters such as frequency, intensity and shape of the bands etc. They indicated significant differences of content, structure and conformation of proteins, nucleic acids and lipids in normal and malignant gastric tissues. The probability found by the results of goodness-of-fit tests of frequency of the bands in the second derivative FTIR, between each of the normal and malignant gastric tissues was less than 0.01. This result was found to be significant. The present results suggested that FTIR could show the properties of normal and malignant gastric tissues in the molecular level. It contains the ability to supply rich and reliable information to investigation of normal and malignant gastric tissues and can be used as a convenient and reliable diagnostic tool for tumors.
3D measurement of human face by stereophotogrammetry
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The following article describes a stereophotogrammetry based technique for 3D measurement of human faces. The method was developed for function orientated diagnostics and therapy in dentistry to provide prognoses for jaw-growth or surgical procedures. The main aim of our activities was to realize both -- a rapid measurement and a dense point cloud.
The setup consists of two digital cameras in a convergent arrangement and a digital projector. During the measurement a rapid sequence of about 20 statistical generated patterns were projected onto the face and synchronously captured by the two cameras. Therefore, every single pixel of the two cameras is encoded by a characteristically stack of intensity values. To find corresponding points into the image sequences a correlation technique is used. At least, the 3D
reconstruction is done by triangulation.
The advantages of the shown method are the possible short measurement time (< 1 second) and - in comparison to gray code and phase shift techniques - the low quality requirements of the projection unit. At present the reached accuracy is +/- 0.1mm (rms), which is sufficient for medical applications. But the demonstrated method is not restricted to evaluate the shape of human faces. Also technical objects could be measured.
Three-dimensional fluorescence spectra of human blood
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The absorption spectroscopy and three-dimensional fluorescence spectra of human blood were measured and an attempt was made to exploit the endogenous fluorophores of major peaks in the UV and visible light. Fluorescence excitation wavelength range 260-540 nm were used to induce the fluorescence spectra of human blood, and the corresponding emission spectra were acquired from a range starting 20 nm above the excitation wavelength and extending to 780 nm. Fluorescence excitation-emission matrix was used to exploit endogenous fluorophores. The results indicate that the absorption peaks for human blood appear at 274, 345, 415, 541 and 576 nm, and the remarkable emission peaks occur at excitation-emission wavelength pairs of 260-630, 280-340, 340-460, 450-520 nm. According to the previous referenced studies, these fluorescence peaks were attributed to endogenous porphyrins, tryptophan, NAD(P)H, and FAD, respectively. The results obtained can be used to evaluate the distorting effect of blood on the autofluorescence signals of human tissues for optical biopsy.
Influence of different magnetic composites carriers on the immobilization of laccase
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Laccase (E.C.1.10.3.2) has been used in various fields and enzyme immobilization technology is an effective means to perform enzyme reuse and to improve its stability. Carrier materials play an important role in the application of an immobilized enzyme. Magnetic carriers have been widely used in the field of protein and enzyme immobilization. The most important parameters of magnetic carriers are size, structure, density of reactive surface groups and the superparamagnetic property. The copper tetraaminophthalocyanine (CuTAPc)- Fe3O4 nano particle composite and chitosan-Fe3O4 microspheres composite were successfully synthesized and characterized by FTIR spectra, XRD and SEM micrograph. Active amino groups of two magnetic carriers could be used to bind laccase via glutaraldehyde. The optimal pH of the two immobilized laccases were the same at pH 3.0. The optimal temperature of laccase immobilized on CuTAPc-Fe3O4 nano particle was 45°C and that of the chitosan-Fe3O4 microspheres was 55°C. The immobilization yields of the two immobilized laccases were 5mg/g and 16mg/g, respectively. The Km value of the laccase immobilized on CuTAPc-Fe3O4 nano particles was 23.8μM, lower than that of the laccase immobilized on chitosan-Fe3O4 microspheres, 171.1μM. The laccase immobilized on magnetic composites could be used as biological sensing materials for biosensor.
Optical characterization of bare CdSe and CdSe/CdS core/shell nanocrystals
L. M. An,
P. N. Sun,
L. Liu,
et al.
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Thiol-capped CdSe/CdS core/shell nanocrystals (NCs) which show high luminescence quantum yield are synthesized in an aqueous solution. UV-Vis absorption spectroscopy and photoluminescence (PL) spectroscopy are employed to analyze optical characters and stabilities of NCs. Furthermore, PL properties are studied in a temperature range between 77K and 300K. The PL peak position of bare CdSe NCs shifts toward shorter wavelengths and the band becomes sharper with decreasing temperature. On the same condition, the PL peak position of CdSe/CdS core/shell NCs keeps unconverted nearly with the variation of temperature. Photostability of bare CdSe NCs and CdSe/CdS core/shell NCs are compared under the 325nm laser irradiation. It takes 78 seconds that the PL intensity declines to the half for CdSe NCs, but 442 seconds for CdSe/CdS core/shell NCs. The fluorescence decay lifetime increases about six times after overcoating. The results indicate that the CdS shell can improve the low temperature PL stability and photostability of CdSe NCs effectively.
Synthesis and properties of quantum dots optical probes for bio-imaging
Tian-Cai Liu,
Zhen-Li Huang,
Hai-Qiao Wang,
et al.
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A novel green synthesis of semiconductor nanoparticles was introduced and it was used as optical probes for bio-imaging. Quantum dots are known as <10nm scaled semiconductor nanoparticles, which could dramatically improve fluorescent imaging. Since these nanocrystals act as robust broadly tunable nano-emitters that can be excited by a single light source, they could pride significant advantages over current labels (e.g. traditional organic dyes, isotope and fluorescent proteins) in vitro and in vivo. As for a novel green synthesis, the usage of dangerous organic composites under rigorously air-free conditions was avoided, and ZnS-capped CdSe semiconductor nanoparticles was prepared economically. And the surface of as- synthesized nanoparticle would be modified by hydrophilic molecules for optical bio-probes. Moreover, such optical probes under aqueous biological conditions could maintain many characters: economy, photostability, colloidal stability, efficient fluorescence, low non-specific adsorption, biological compatibility and validity for multiplex assays.
Quantitative doping of commercial polystyrene microbeads with quantum dots
Hai-Qiao Wang,
Zhen-Li Huang,
Tian-Cai Liu,
et al.
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Microbeads with embedded encode characteristics are of considerable interest due to their potential use in multiplexed bioassays, high-throughput screening and combinatorial chemistry. Lots of encoding strategies for tagging or labeling microbeads have arisen in the past couple of years. Compared with the organic dye counterparts, the ideal optical properties of quantum dots (QDs) (e.g. characteristic narrow and symmetric spectra, size-tunable emission and simultaneous excitation) make it possible to tag microbeads in a quantitative way. In this paper, quantitative doping of commercial polystyrene microbeads with single color quantum dots was reported. A detailed analysis of the optical characteristics of the QD-tagged microbeads was presented based on the combination of fluorescent spectroscopy and microscope imaging.
Biomedical measurement using the levitation mass method
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The mechanical response of a palm of a human hand against impact force is accurately determined by means of a practical method, a variation of the Levitation Mass Method. In the method, a mass that is levitated with a pneumatic linear bearing, and hence encounters negligible friction, is made to collide with a material under test. During the collision the Doppler frequency shift of a laser beam reflecting from the mass is accurately measured using an optical interferometer. The velocity, position, acceleration and inertial force of the mass are calculated from the measured time-varying Doppler shift. The method is characterized by the fact that preparation of the test specimen is very easy, the testing time is very short and the measurement accuracy is very high. The possibility of using the method for biomedical engineering is discussed.
Determination of radical species generated in hexyl-5-aminolevulinate-based photodynamic therapy using electron spin resonance spectroscopy
Lu Xin,
Yoshitaka Ohya,
Toshiyuki Kosobe,
et al.
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Generation of radical species in hexyl-5-aminolevulinate (h-ALA)- based photodynamic therapy (PDT) was determined in terms of electron spin resonance (ESR) spectroscopy with N-tert-buthyl-α-phenylnitrone (PBN) as a spin trapping agent. Hexyl-5-aminolevulinate and PBN were administered into murine thymic lymphoma (EL-4) cells, and the ESR spectra of the EL-4 cell dispersions were measured with irradiating light (400-410 nm). There were no ESR signals in the EL-4 dispersion without the irradiation. At 30 min light irradiation we found the specific ESR signals, of which the intensity increased with an irradiation time. The ESR spectra of EL-4 cell dispersion with only PBN (without h-ALA) and of the culture medium with h-ALA and PBN were determined with the same method. The ESR signals in the both systems was similar to that in the system of EL-4 cell dispersion with h-ALA and PBN. Nevertheless, the signal intensity of the ESR signals in the formers was obviously lower than that in the latter. There results indicate, therefore, that some radical species occur in the cell dispersion by h-ALA-based PDT. In addition, the generation of radical species is considered to be related to the release of singlet oxygen by irradiating the light.
Novel grinding stone used for polishing 3D plastic replica with rapid prototyping technology
Wang Feng,
Yoshihiro Niikura,
Toshio Sato,
et al.
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Rapid prototyping (RP) apparatus accepts a specific format translated from CAD data (patient's CT) and "slices" it into two-dimensional cross sections for laser photo curing. Surgeon can conduct safer surgery by reappearing on an actual model using 3D plastic replica in the preoperative. Polishing has to be used to eliminate the marks after removal of supports and the build layer pitches. Complicated and narrow areas of the 3D replica are difficult to be polished with the conventional grinding stone.
This study proposes a novel grinding stone and introduces its producing process and characteristics. The novel grinding stone has many advantages as follows; (1) Preparation is possible of grinding stone that follows the complicated shape. (2) Grinding stone with uniformly dispersed abrasive grains can be prepared using magnetic particles and magnetic field. (3) Reshaping of grinding stone by heating is possible since the binder is made of a thermoplastic resin. (4) Every process can easily be carried out. We could polish to eliminate the marks after removal of supports and the build layer pitches on 3D plastic replica surface with the grinding stone.