Proceedings Volume 8596

Reporters, Markers, Dyes, Nanoparticles, and Molecular Probes for Biomedical Applications V

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Proceedings Volume 8596

Reporters, Markers, Dyes, Nanoparticles, and Molecular Probes for Biomedical Applications V

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Volume Details

Date Published: 26 March 2013
Contents: 10 Sessions, 26 Papers, 0 Presentations
Conference: SPIE BiOS 2013
Volume Number: 8596

Table of Contents

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Table of Contents

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  • Molecular Probes for Targeted Imaging and Therapy
  • NIR Fluorescent Molecular Probes for Biological Imaging
  • Imaging Molecular Processes with Fluorescent Reporters
  • Nonbleaching and Ultrasmall Fluorescent Tags II: Joint Session with Conferences 8596 and 8635
  • Nanoparticles for Biological Applications
  • Soft Nanoparticles for Biomedical Applications
  • Hybrid Technologies for Molecular Imaging Applications
  • Molecular Approaches and Methods
  • Poster Session
  • Front Matter: Volume 8596
Molecular Probes for Targeted Imaging and Therapy
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ICG-loaded polymeric nanocapsules functionalized with anti-HER2 for targeted fluorescence imaging and photodestruction of ovarian cancer cells
Baharak Bahmani, Yadir Guerrero, Valentine Vullev, et al.
Optical nano-materials present a promising platform for targeted molecular imaging of cancer biomarkers and its photodestruction. Our group is investigating the use of polymeric nanoparticles, loaded with indocyanine green, an FDA-approved chromophore, as a theranostic agent for targeted intraoperative optical imaging and laser-mediated destruction of ovarian cancer. These ICG-loaded nanocapsules (ICG-NCs) can be functionalized by covalent attachment of targeting moieties onto their surface. Here, we investigate ICG-NCs functionalized with anti-HER2 for targeted fluorescence imaging and laser-mediated destruction of ovarian cancer cells in vitro. ICG-NCs are formed through ionic cross-linking between polyallylamine hydrochloride chains and sodium phosphate ions followed by diffusion-mediated loading with ICG. Before functionalization with antibodies, the surface of ICG-NCs is coated with single and double aldehyde terminated polyethylene glycol (PEG). The monoclonal anti-HER2 is covalently coupled to the PEGylated ICG-NCs using reductive amination to target the HER2 receptor, a biomarker whose over-expression is associated with increased risk of cancer progression. We quantify uptake of anti-HER2 conjugated ICG-NCs by ovarian cancer cells using flow cytometery. The in-vitro laser-mediated destruction of SKOV3 cells incubated with anti-HER2 functionalized ICG-NCs is performed using an 808 nm diode laser. Cell viability is characterized using the Calcein and Ethidium homodimer-1 assays following laser irradiation. Our results indicate that anti-HER2 functionalized ICG-NCs can be used as theranostic agents for optical molecular imaging and photodestruction of ovarian cancers in-vitro.
In vivo imaging of tumor vascular endothelial cells
Dawen Zhao, Jason H. Stafford, Heling Zhou, et al.
Phosphatidylserine (PS), normally restricted to the inner leaflet of the plasma membrane, becomes exposed on the outer surface of viable (non-apoptotic) endothelial cells in tumor blood vessels, probably in response to oxidative stresses present in the tumor microenvironment. In the present study, we optically imaged exposed PS on tumor vasculature in vivo using PGN635, a novel human monoclonal antibody that targets PS. PGN635 F(ab’)2 was labeled with the near infrared (NIR) dye, IRDye 800CW. Human glioma U87 cells or breast cancer MDA-MB-231 cells were implanted subcutaneously or orthotopically into nude mice. When the tumors reached ~5 mm in diameter, 800CW- PGN635 was injected via a tail vein and in vivo dynamic NIR imaging was performed. For U87 gliomas, NIR imaging allowed clear detection of tumors as early as 4 h later, which improved over time to give a maximal tumor/normal ratio (TNR = 2.9 ± 0.5) 24 h later. Similar results were observed for orthotopic MDA-MB-231 breast tumors. Localization of 800CW-PGN635 to tumors was antigen specific since 800CW-Aurexis, a control probe of irrelevant specificity, did not localize to the tumors, and pre-administration of unlabeled PGN635 blocked the uptake of 800CW-PGN635. Fluorescence microscopy confirmed that 800CW-PGN635 was binding to PS-positive tumor vascular endothelium. Our studies suggest that tumor vasculature can be successfully imaged in vivo to provide sensitive tumor detection.
NIR Fluorescent Molecular Probes for Biological Imaging
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NIR fluorescent dyes: versatile vehicles for marker and probe applications
Gabor Patonay, Gala Chapman, Garfield Beckford, et al.
The use of the NIR spectral region (650-900 nm) is advantageous due to the inherently lower background interference and the high molar absorptivities of NIR chromophores. Near-Infrared (NIR) dyes are increasingly used in the biological and medical field. The binding characteristics of NIR dyes to biomolecules are possibly controlled by several factors, including hydrophobicity, size and charge just to mention a few parameters. Binding characteristics of symmetric carbocyanines and found that the hydrophobic nature of the NIR dye is only partially responsible for the binding strength. Upon binding to biomolecules significant fluorescence enhancement can be observed for symmetrical carbocyanines. This fluorescence amplification facilitates the detection of the NIR dye and enhances its utility as NIR reporter. This manuscript discusses some probe and marker applications of such NIR fluorescent dyes. One application discussed here is the use of NIR dyes as markers. For labeling applications the fluorescence intensity of the NIR fluorescent label can significantly be increased by enclosing several dye molecules in nanoparticles. To decrease self quenching dyes that have relatively large Stokes’ shift needs to be used. This is achieved by substituting meso position halogens with amino moiety. This substitution can also serve as a linker to covalently attach the dye molecule to the nanoparticle backbone. We report here on the preparation of NIR fluorescent silica nanoparticles. Silica nanoparticles that are modified with aminoreactive moieties can be used as bright fluorescent labels in bioanalytical applications. A new bioanalytical technique to detect and monitor the catalytic activity of the sulfur assimilating enzyme using NIR dyes is reported as well. In this spectroscopic bioanalytical assay a family of Fischer based n-butyl sulfonate substituted dyes that exhibit distinct variation in absorbance and fluorescence properties and strong binding to serum albumin as its sulfonic acid moiety is modified to less water soluble moiety was identified. In polar solvents, these water soluble compounds are strongly fluorescent, however form the less soluble aggregated species with virtual loss of fluorescence when the sulfonate groups are cleaved by enzymatic activity to form the corresponding straight chain alkyl aldehyde derivatives. To achieve this conversion in vitro photo-reduced riboflavin mononucleotide (FMN) with a glucose/ glucose-oxygenase oxygen scavenging system was utilized. The reduced FMN serves as a key substrate in the enzymatic desulfonation. Once the FMNH2 was produced the desulfonation reaction was characterized by using Laser Induced Fluorescence Capillary Zone Electropheresis (LIF-CZE). This method can be utilized as an assay to detect the enzyme activity in vitro with the possibilities of in vivo applications.
Covalent IR820-PEG diamine conjugates: characterization and in vivo biodistribution
Alicia Fernandez-Fernandez, Romila Manchanda, Denny A. Carvajal, et al.
Introduction: IR820 is a near-infrared probe with potential applications in optical imaging and hyperthermia. Its chlorosubstituted cyclohexene makes it amenable to forming conjugates as multifunctional probes. We prepared a novel covalent IR820/PEG-diamine (IRPDcov) nanoconjugate. Methods: IRPDcov was prepared using IR820 and 6kDa PEG-diamine, characterized by SEM, H-NMR, spectrophotometry, and spectrofluorometry; and studied in vitro and in vivo. Mice (n=36) were used to explore the biodistribution of IRPDcov compared to IR820 and indocyanine green (ICG) after i.v. injection of a 0.24 mg/kg dose of dye, with plasma samples collected at 15-30-60 minutes and 24 hours. The plasma concentrations were fit to a biexponential curve following a two compartment model. Organ samples were collected after 24 hours. Results and Discussion: IRPDcov retained the ability to fluoresce for in vivo optical imaging and also to generate heat, and was significantly more stable than IR820 in aqueous solution over a period of 72 hours. IRPDcov and IR820 demonstrated significantly longer (p<0.05) plasma half-lives, elimination half-lives, and area-under-the-curve values compared to ICG. This could pose an advantage in therapeutic probe applications such as hyperthermia or drug delivery. Both IR820 and IRPDcov showed a very strong signal in the liver and lower-intensity signal in the kidneys 24 hours after injection, whereas the predominant signal for ICG was weak and located in the intestines, demonstrating a much more rapid GI elimination. IR820 showed signal in the lungs, which was not present in IRPDcov subjects indicating that IRPDcov may have been able to escape detection by alveolar macrophages.
Near-infrared light-triggered dissociation of block copolymer micelles for controlled drug release
Jie Cao, Shanshan Huang, Yuqi Chen, et al.
In this manuscript, a new near-infrared (NIR) light-breakable amphiphilic block copolymer containing light-sensitive triggering group on the hydrophobic block was developed. By encapsulating NIR dye cypate inside micelles of poly (N-succinyl-N'-4- (2-nitrobenzyloxy)-succinyl chitosan) and exposing the micellar solution to 765.9 nm light, the photo-cleavage reaction was activated and leading to the dissociation of micelles and release of co-loaded hydrophobic species. The UV-vis absorption spectra, fourier transform infrared (FTIR) spectra and 1H nuclear magnetic resonance (1H NMR) spectra of micelles were characterized. Triggered burst release of the payload upon NIR irradiation and subsequent degradation of the micelles were observed by transmission electron microscopy (TEM). This system represents a general and efficient method to circumvent the need for UV or visible light excitation that is a common drawback for light-responsive polymeric systems developed for potential biomedical applications.
Near-infrared imaging loaded polymeric nanoparticles: In vitro and In vivo studies
Tingjun Lei, Romila Manchanda, Yen-Chih Huang, et al.
Introduction: Recent research has focused on developing new biomaterials for delivery of imaging agents and drugs. In our study, we report a new biocompatible and biodegradable polymer, termed poly(glycerol-co-malic-dodecanoate) (PGMD), which was then used for synthesis of nanoparticles (NPs) and loading of NIR dyes. Methods: The PGMD polymer was synthesized via thermal condensation method and was characterized by FTIR. The NPs were synthesized via o/w single emulsion technique. IR820 was chosen as the NIR dye. The loading efficiency of IR820 in PGMD NPs was measured by spectrophotometer. The release of IR820 was estimated with a spectrofluorometer in different pH phosphate buffered saline. The cytotoxicity of NPs was estimated through a Sulforhodamine B colorimetric assay. A biodistribution and pharmacokinetics study of the NPs versus free IR820 was performed in a murine model (n=12) after i.v. injection. Plasma samples were collected at time points 15-30-60 minutes and 24 hours. Organ samples were also collected and measured at the 24-hour time point. Results and Discussion: Void PGMD NPs and IR820-PGMD NPs had mean sizes around 90 nm and 110 nm, respectively. FTIR showed that polyester bonds were forming in the PGMD polymer. The release of IR820 was increased in acidic buffer (pH=5.0) as compared to neutral buffer (pH=7.4), indicating that the release of IR820 is controllable. Cellular uptake studies showed comparable fluorescence of IR820-PGMD NPs to free IR820 (5 μM) after 24-hour exposure. IR820-PGMD NPs induced significant cancer cell killing after laser exposure due to the photothermal effect of the dye. In vivo studies showed that the IR820 in NPs formulation has a longer plasma half-life than free IR820, providing longer imaging collection times for cancer diagnostics, and potentially widening the window for hyperthermia applications. Conclusion: We expect that ease of synthesis and good biocompatibility make PGMD a good candidate for numerous imaging agent and drug delivery applications. The IR820-PGMD NPs have the ability to be used for both imaging and hyperthermia purposes.
Imaging Molecular Processes with Fluorescent Reporters
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Fluorescent proteins as singlet oxygen photosensitizers: mechanistic studies in photodynamic inactivation of bacteria
Rubén Ruiz-González, John H. White, Aitziber L. Cortajarena, et al.
Antimicrobial photodynamic therapy (aPDT) combines a photosensitizer, light and oxygen to produce reactive oxygen species (ROS), mainly singlet oxygen (1O2), to photo-oxidize important biomolecules and induce cell death. aPDT is a promising alternative to standard antimicrobial strategies, but its mechanisms of action are not well understood. One of the reasons for that is the lack of control of the photosensitizing drugs location. Here we report the use of geneticallyencoded fluorescent proteins that are also 1O2 photosensitizers to address the latter issue. First, we have chosen the red fluorescent protein TagRFP as a photosensitizer, which unlike other fluorescent proteins such as KillerRed, is able to produce 1O2 but not other ROS. TagRFP photosensitizes 1O2 with a small, but not negligible, quantum yield. In addition, we have used miniSOG, a more efficient 1O2 photosensitizing fluorescent flavoprotein that has been recently engineered from phototropin 2. We have genetically incorporated these two photosensitizers into the cytosol of E. coli and demonstrated that intracellular 1O2 is sufficient to kill bacteria. Additional assays have provided further insight into the mechanism of cell death. Photodamage seems to occur primarily in the inner membrane, and extends to the outer membrane if the photosensitizer’s efficiency is high enough. These observations are markedly different to those reported for external photosensitizers, suggesting that the site where 1O2 is primarily generated proves crucial for inflicting different types of cell damage.
Investigating real-time activation of adenosine receptors by bioluminescence resonance energy transfer technique
Adenosine receptors play important roles in many physiological and pathological processes, for example regulating myocardial oxygen consumption and the release of neurotransmitters. The activations of adenosine receptors have been studied by some kinds of techniques, such as western blot, immunohistochemistry, etc. However, these techniques cannot reveal the dynamical response of adenosine receptors under stimulation. In this paper, bioluminescence resonance energy transfer technique was introduced to study the real-time activation of adenosine receptors by monitoring the dynamics of cyclic adenosine monophosphate (cAMP) level. The results showed that there were significant differences between adenosine receptors on real-time responses under stimulation. Moreover, the dynamics of cAMP level demonstrated that competition between adenosine receptors existed. Taken together, our study indicates that monitoring the dynamics of cAMP level using bioluminescence resonance energy transfer technique could be one potential approach to investigate the mechanism of competitions between adenosine receptors.
Nonbleaching and Ultrasmall Fluorescent Tags II: Joint Session with Conferences 8596 and 8635
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Probing intra-cellular drug release event using activatable (OFF/ON) CdS:Mn/ZnS quantum dots (Qdots): spectroscopic studies to investigate interaction of Qdots with quencher
Jeremy Tharkur, Andrew Teblum, Srijita Basumallick, et al.
In recent years, activatable Quantum Dots (AQdots) are gaining popularity in a number of chemical and biological sensing applications. A basic design of AQdot probes involves a suitable quencher which is capable of altering optical properties of the Qdots. In our previous studies we have shown that CdS:Mn/ZnS fluorescence can be effectively quenched using small molecule quenchers (such as dopamine, chemotherapeutic drug) as well as iron oxide nanoparticle via electron/energy transfer process. We have also shown that the quenched Qdot fluorescence can be restored when the Qdots are separated from the quencher. Using Qdot based activatable probes, we detected intracellular drug release event. Qdot fluorescence was restored upon interaction with the intracellular glutathione (GSH). In this paper, we report a GSH induced quenching of water-soluble N-Acetyl Cysteine (NAC) surface-conjugated Cds:Mn/ZnS Qdots. Quenching of NAC-Qdots was due to aggregation of Qdots in solution. This aggregation induced fluorescence quenching phenomenon resembles with the self-quenching phenomenon of traditional organic fluorescence dyes at high concentrations. UV-VIS and fluorescence emission spectroscopy data support the interaction and binding of GSH with the NAC-Qdots. Increase in particle size due to GSH induced aggregation of NAC-Qdots was confirmed by the Dynamic Light Scattering (DLS) data.
Lanthanide-doped nanoparticles for hybrid x-ray/optical imaging
L. Sudheendra, Gautom K. Das, C. Li, et al.
Some lanthanide-doped nanoparticles can absorb X-ray radiation and emit in the visible to near infrared spectrum via a down-conversion mechanism, making them a potentially valuable agent for in vivo imaging studies. We have studied a series of Gd3+ and Eu3+compositions in lanthanide fluorides to optimize the emission from Eu3+ upon X-ray excitation. The optimum concentration of Eu3+ that produced the most intense emission in NaGdF4 was found to be 15% molar concentration. The impact of the crystallographic phases (i.e. cubic or hexagonal) on the optical emission was investigated. Furthermore, an attempt to include a sensitizer (i.e Ce3+) in NaGdF4:Eu resulted in a reduction in the emission following X-ray excitation. A surface coating of NaGdF4:Eu nanoparticles with a gold shell showed a similar decrease in luminescence intensity by a factor of two although the gold shell offers other advantages in biomedical applications.
Nanoparticles for Biological Applications
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Molecular thermometers for potential applications in thermal ablation procedures
Natalia G. Zhegalova, Alex Aydt, Steven T. Wang, et al.
Thermal ablation is a promising minimally invasive method for treating tumors without surgical intervention. Thermal ablation uses thermal sources such as lasers, radiowaves or focused ultrasound to increase the temperature of the tumor to levels lethal to cancer cells. This treatment based on heat therapy may be problematic as the temperature of the operation site is unknown. To address this problem, we developed optical molecular thermometers that can potentially measure the temperature on a molecular scale and be compatible with in vivo measurements. The thermometers are centered on a combination of two fluorophores emitting in two distinct spectral ranges and having different temperature-dependent emission properties. In this design, a fluorophore with relatively insensitive temperature-dependent fluorescence serves as a reference while another sensitive fluorophore serves as a sensor. We have demonstrated the feasibility of this approach using a coumarin-rhodamine conjugate. The sensitivity of the construct to the clinically relevant ablation temperatures (20-85 °C) was demonstrated in vitro.
Soft Nanoparticles for Biomedical Applications
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Suppressing inflammation from inside out with novel NIR visible perfluorocarbon nanotheranostics
Jelena M. Janjic, Sravan K. Patel, Michael J. Patrick, et al.
Highly innovative multimodal perfluorocarbon (PFC) nanoemulsions are presented. They serve simultaneously as dual-mode imaging reagents (NIR and 19F MRI), and drug delivery vehicles for water insoluble cyclooxgenase-2 (COX-2) inhibitors. These features qualify them as theranostic. Cancer progression and metastasis are highly influenced by tumor microenvironment and inflammation. Infiltration of primary tumors with inflammation-promoting cells (e.g. macrophages) is a negative prognostic factor for cancer patient survival. We postulate that the suppression of COX-2 enzyme in macrophages by theranostic PFC nanoemulsions will result in changes in macrophage levels of accumulation in tumors and/or their phenotype, which can suppress tumor- promoting activity. The presented theranostic nanoemulsions are designed to label immune cells such as macrophages, and deliver celecoxib, a COX-2 inhibitor. The designed theranostic incorporates two fluorescent reporters: a near-infrared (NIR) fluorescent dye for improved optical in vivo imaging, and a distinct fluorescent dye for histological analysis of excised tissues. A high content of PFC in the theranostic allows 19F MRI to quantitatively assess the distribution of the injected nanomedicine in the peritumoral area, and measure tumor-associated inflammation, while 1H MRI provides anatomical context. NIR imaging is used as a complementary in vivo technique to assess biodistribution of the theranostic. We report preparation and characterization of the nanoemulsions’ colloidal and optical stability, in vitro toxicity, and imaging capabilities. This theranostic offers flexibility for in vitro and in vivo inflammation imaging and histological analysis using three different imaging functionalities (fluorescence, NIR and 19F MRI), advancing the monitoring and modulating of tumor-infiltrating immune cells in vivo.
Hybrid Technologies for Molecular Imaging Applications
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Engineering a lifetime-based activatable probe for photoacoustic imaging
Ekaterina Morgounova, Qi Shao, Benjamin Hackel, et al.
High-resolution, high-penetration depth activatable probes are needed for in-vivo imaging of enzyme activity. In this paper, we will describe the contrast mechanism of a new photoacoustic activatable probe that changes its excitation lifetime upon activation. The excitation decay of methylene blue (MB), a chromophore commonly used in therapeutic and diagnostic applications, is probed by photoacoustic lifetime contrast imaging (PLCI). The monomer of the dye presents a high-quantum yield of intersystem-crossing and long lifetime (70 μs) whereas the dimer is statically quenched with a short lifetime (a few ns). This forms the basis of a highly sensitive contrast mechanism between monomers and dimers. Two dimerization models - one using sodium sulfate, the other using sodium dodecyl sulfate - were applied to control the monomer-to-dimer ratio in MB solutions. Preliminary results show that the photoacoustic signal of a dimer solution is efficiently suppressed (< 20 dB) due to their short lifetime compared to the monomer sample. Flash-photolysis of the same solutions reveals a 99% decrease in transient absorption confirming PLCI results. This contrast mechanism can be applied to design a MB dual-labeled activatable probe bound by an enzyme-specific cleavable peptide linker. When the probe is cleaved by its target, MB molecules will separate by molecular diffusion and recover their long excitation lifetime enabling their detection by PLCI. Our long-term goal is to investigate enzyme-specific imaging in small animals and establish pre-clinical data for translational research and implementation of the technology in clinical applications.
Polyacrylamide based ICG nanocarriers for enhanced fluorescence and photoacoustic imaging
Aniruddha Ray, Hyung Ki Yoon, HeeJu Ryu, et al.
Indocyanine green (ICG) is an FDA approved tricarbocyanine dye. This dye, with a strong absorbance in the near infrared (NIR) region, has been extensively used for fluorescence and photoacoustic imaging in vivo. ICG in its free form, however, has a few drawbacks that limit its in vivo applications, such as non-targetability, tendency to form aggregates which changes its optical properties, fast degradation, short plasma lifetime and reduced fluorescence at body temperature. In order to bypass these inherent drawbacks, we demonstrate a polyacrylamide based nanocarrier that was particularly designed to carry the negatively charged ICG molecules. These nanocarriers are biodegradable, biocompatible and can be specifically targeted to any cell or tissue. Using these nanocarriers we avoid all the problems associated with free ICG, such as degradation, aggregation and short plasma lifetime, and also enhance demonstrate its ability towards photoacoustics and fluorescence imaging.
Photothermal detection of the contrast properties of polypyrrole nanoparticles using optical coherence tomography
Deepa Kasaragod, Kin Man Au, Zenghai Lu, et al.
We report on a photothermal modulation detection scheme developed using a swept source-based optical coherence tomography (OCT) system centred at 1300nm. Photothermal detection is an improved technique for studying the contrast properties of exogenous contrast agents such as highly absorbing polypyrrole (PPy) nanoparticles used for OCT imaging. The swept source based OCT system has a wavelength sweep rate of 10 kHz which is used for the phase modulation detection of various concentrations of PPy nanoparticles. PPy nanoparticles have been recently reported to be a promising candidate for OCT imaging owing to their strong NIR absorption from 700–1300nm. Phase-sensitive detection of the photothermal modulation signal is achieved using a pumped 975 nm laser beam at 80Hz and 160Hz for varying concentrations of PPy nanoparticles dispersed in 2% Intralipid phantom. A phase-sensitive detection system is realised by carrying out the phase calibration using the back reflections obtained from the coverslip used with the sample. This study provides quantitative support for the use of PPy nanoparticles as a potential biocompatible contrast agent in OCT imaging.
Molecular Approaches and Methods
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Predicting errors from spectral overlap in multi-probe and multi-laser flow cytometry
In flow cytometry a group of cells labeled with a fluorescent probe molecule or dye is focused into a single cell stream passing through a laser light source. The fluorescent light is filtered and sampled by an array of detectors. In many cases a single light source and one probe/dye molecule have been used. But additional information can be obtained if several different laser wavelengths and multiple probes fluorescing at other wavelengths are used. We consider four lasers at 488nm, 532nm, 640nm and 785nm which occur near the peak absorptions of common fluorescent probes, Alexa488, Alexa532, Alexa647 and Alexa750, respectively. In some cases overlapping of the various fluorescent spectra occur. This effect can be mitigated by checking the emitted signals in individual wavelength channels and subtracting them, a practice known as compensation. But residual amounts of fluorescence as well as phosphorescence may not be completely taken into account because of the photodetector sensitivity. Using our unique numerical we calculated both the fluorescence and phosphorescence intensities in a multi-laser and multi-probe configuration. The total intensities of the fluorescent state and phosphorescent state are calculated for a range of laser powers from 5mW to 100mW. We found that there can be significant overlap between fluorescence and phosphorescence emission from multiple dyes.
Intracellular delivery of molecular beacons by PMMA nanoparticles and carbon nanotubes for mRNA sensing
We describe here the use of carbon nanotubes (CNTs) and polymeric nanoparticles made of a core of polymethylmethacrylate (PMMA) surrounded by a shell bearing cationic groups, as intracellular delivery tools of molecular beacons (MBs), particular fluorescent DNA probes, for the detection and localization of a specific mRNA. Survivin mRNA targeting MBs have been used with Atto647N and Blackberry 650 as fluorophore/quencher pair. The MB was anchored to the surface of CNTs and PMMA nanoparticles via a commercial sulfhydryl-reactive heterobifunctional crosslinker and the achieved nanomaterials were then characterized in vitro.
Poster Session
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Single molecule interactions studied by using a modified DNA sequencer: a comparison with surface plasmon resonance
Jens Sobek, Stefan Schauer, Hubert Rehrauer, et al.
In this study we established the principles for using a commercial off-the-shelf DNA sequencer (RS, Pacific Biosciences) to measure biomolecular interactions. Binding between single oligonucleotides immobilized at the bottom of a nanowell to a complementary DNA strand was used as a model system. The influence of the labeling dye on the hybridization of a 7mer oligonucleotide was investigated. The resulting association and dissociation rate constants (kon and koff) and the calculated dissociation constants (Kd) were compared to data obtained from surface plasmon resonance (SPR) measurements. In the present study we identified a good agreement of the determined kinetic constants by the two methods investigated.
Real-time point-of-care measurement of impaired renal function in a rat acute injury model employing exogenous fluorescent tracer agents
Richard B. Dorshow, Richard M. Fitch, Karen P. Galen, et al.
Renal function assessment is needed for the detection of acute kidney injury and chronic kidney disease. Glomerular filtration rate (GFR) is now widely accepted as the best indicator of renal function, and current clinical guidelines advocate its use in the staging of kidney disease. The optimum measure of GFR is by the use of exogenous tracer agents. However current clinically employed agents lack sensitivity or are cumbersome to use. An exogenous GFR fluorescent tracer agent, whose elimination rate could be monitored noninvasively through skin would provide a substantial improvement over currently available methods. We developed a series of novel aminopyrazine analogs for use as exogenous fluorescent GFR tracer agents that emit light in the visible region for monitoring GFR noninvasively over skin. In rats, these compounds are eliminated by the kidney with urine recovery greater than 90% of injected dose, are not broken down or metabolized in vivo, are not secreted by the renal tubules, and have clearance values similar to a GFR reference compound, iothalamate. In addition, biological half-life of these compounds measured in rats by noninvasive optical methods correlated with plasma derived methods. In this study, we show that this noninvasive methodology with our novel fluorescent tracer agents can detect impaired renal function. A 5/6th nephrectomy rat model is employed.
Molecular dynamics study of phospholipid biomacromolecules using a coarse-grained model
Olga E. Glukhova, Elena L. Kossovich, Anna S. Kolesnikova, et al.
We studied the phospholipid molecule structure, rigidity, rotary mobility and micelle aggregation process using a coarse-grained (CG) model. It was found that the phospholipid structure can be presented as a spring with a rigidity of 27.68 kN/m. The rotational frequency of such molecule equals to 0.9 GHz at the temperature of 293 K and increases up to 1.2 GHz at 309K. At the constant temperature the micelle aggregation time does not depend on number of interacting molecules. Along with the temperature increase, the aggregation time decreases. At lower temperatures the assembly process depends on distance between the adjacent molecules.
Development of the terahertz emitter model based on nanopeapod in terms of biomedical applications
Olga E. Glukhova, Igor S. Nefedov, Anna S. Kolesnikova, et al.
Model of terahertz radiation sources was developed in this work. This model based on the nanopeapod: carbon nanotube (10, 10) with incapsulated chains of the fullerene C60. Simulation of the nanoemitter action was carried out by means of the molecular-mechanical model. The length of the considered nanotube is equals to 10.3 nm, and radius of this tube is equals to 1.35 nm. It was found that to generate the radiation in terahertz range it is necessary to apply the external field with strength of 1⋅106 V / cm to our system. The moving fullerene C60 has a charge of +3е, and the nanotube has a charge of -3е. It was established that the field emission process from the surface of the nanotube is not observed in this case. The submitter model of nanoemitter works with a frequency 0.36 THz at a field strength of 1⋅106 V / cm.
Carbon nanotube+graphene quantum dots complex for biomedical applications
Olga E. Glukhova, Igor N. Saliy, Anna S. Kolesnikova, et al.
Different types of carbon nanotube + graphene quantum dot composites were investigated. Stable configuration of carbon nanotube + graphene quantum dot composites with the van der Waals and the chemical interactions were established. It was shown that a peapod + graphene quantum dot (GQD) composite is a stable configuration at the chemical interaction. Investigation of the stability were performed by means of the empirical method based on Brenner's potential. The ionization potential of the peapod + GQD composite decreases by 0.5% in comparison with the ionization potential of the hollow nanotubes.
Docosahexaenoic acid conjugated near infrared flourescence probe for in vivo early tumor diagnosis
Siwen Li, Jie Cao, Jingyi Qin, et al.
Docosahexaenoic acid(DHA) is an omega-3 C22 natural fatty acid with six cis double bonds and as a constituent of membranes used as a precursor for metabolic and biochemical path ways. In this manuscript,we describe the synthesis of near-infrared(NIR) flourescence ICG-Der-01 labeled DHA for in vitro and vivo tumor targeting.The structure of the probe was intensively characterized by UV and MS. The in vitro and vivo tumor targeting abilities of the DHA-based NIR probes were investigeted in MCF-7 cells and MCF-7 xenograft mice model differently by confocal microscopy and CCD camera. The cell cytotoxicity were tested in tumor cells MCF-7 .The results shows that the DHA-based NIR probes have high affinity with the tumor both in vitro and vivo.In addition ,we also found that the DHA-based NIR probes have the apparent cytotoxicity on MCF-7 cells .which demonstrated that DHA was conjugated with other antitumor drug could increase the abilities of antirumor efficacy .So DHA-ICG-Der-01 is a promising optical agent for diagnosis of tumors especially in their early stage.
MUC1 aptamer based near infrared fluorescence probes for tumor diagnosis
Juan Zhao, Yuxiang Ma, Sisi Cui, et al.
Mucin 1 (MUC1) is a cell surface mucin broadly expressed in mucosal tissues. The aberrant expression of MUC1 under-glycosylated forms has been reported in various carcinomas of the epithelium, such as breast, pancreatic and ovarian cancers. Using the Systematic Evolution of Ligands by Exponential Enrichment (SELEX) methodology, aptamers previously selected against MUC1 glycoprotein with high affinities and specificities. In this study, we developed two targeted near-infrared fluorescent probes for tumor in-vivo diagnostics using a MUC1 aptamer(APT) as targeted ligand and near-infrared fluorescent dye (ICG-Der-02) as labelling. MUC1 aptamer conjugated ICG-Der-02 (APT-ICG-Der-02) displayed a great selectivity to MUC1 positive cell line MCF7 and MCF7 xenograft-bearing nude mice. To improve the high targeting of the probe to the tumor cells, PEG, with high biocompatibility, non immunogenicity and long circulation, was conjugated to the probe .The new probe (APT-PEG-ICG-Der-02) showed better tumour uptake and clearance, and also displayed a great selectivity to MCF7 tumor-bearing nude mice. Data obtained demonstrate a high potential of the targeted near-infrared fluorescent probes in cancer early diagnosis.
Thermal-lens study of semiconductor nanoparticles embedded in restorative dental resin
Leandro P. Alves, Viviane Pilla, Adalberto N. Iwazaki, et al.
Thermal Lens (TL) and spectroscopic characterizations were performed in CdSe/ZnS core-shell quantum dots (QDs) embedded into two commercial dental resin composites. The thermal-optical studies were performed in CdSe/ZnS QDs (core size Φ= 4.1 nm) and PMMA-encapsulated CdSe/ZnS (Φ= 3.7 nm) embedded in restorative dental resins at concentration of 0.025 and 0.42 % in mass, respectively. The thermal diffusivity (D) results are characteristics of the dental resin composites studied. Photoacoustic (PA) technique results for the dental resin composites support the TL results.
Front Matter: Volume 8596
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Front Matter: Volume 8596
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