Cell-based assays and organ-like substrates gather increasing attention due to their potentials in diagnostic and drug development. The use of these cell-based systems will allow to better understand in-vivo processes and to test for the direct influence of different substances on cell viability or metabolic activity e.g. in drug development and in addition to identify the influence of generated metabolites or different cell types. In this paper we present a respective technical platform, which enables the use of such cell-based assays. The platform is based on a microfluidic cell-assay toolbox, designed in a fashion allowing to minimize manual steps for cell culture on chip. Elements being essential for this work include membrane elements integrated into a microfluidic device for the separation of liquid stream together with a targeted supply of reagents and a three dimensional feeding of embedded cells. The influence of the metabolism from one cell type on the other can be evaluated due to the arrangement of cell compartments as interacting networks. A respective Lab-on-a-chip handling platform allows for the direct manipulation on a microscope stage and an incubator-free cell culture. Furthermore, luminescent sensors represent promising tools to be embedded into the microfluidic system to monitor the on-chip conditions or to provide information on cell viability and metabolic activity. Finally, examples for implemented assays on chip will be presented, ranging from cell culture showing the cell behavior in respect to surface functionalization and different growth conditions to finally embedding organ-on-chip structures of cultured cell lines.

Nucleic amplification using quantitative polymeric chain reaction (qPCR) has become the gold standard of molecular testing. These systems offer both amplification and simultaneous fluorescence detection. An ultrafast microfluidic module (allowing 30 PCR cycles in 6 minutes) based on the oscillating fluid plug concept was previously developed ^[1,2] allowing the amplification of native genomic deoxyribonucleic acid (DNA) molecules. This abstract presents the actual status of the advanced system. The upgraded system generates high quality qPCR amplification plots and additional sensitive melting point analysis comparable to data obtained from commercial real-time cyclers. These features provide the user with all information needed to analyze PCR products. The system uses light emitting diodes (LED) for illumination and a low cost Charge-coupled Device (CCD) camera for optical detection. Image data processing allows the automated process control of the overall system components. The system enables the performance of rapid and robust nucleic acid amplifications together with the integration of real time measurement technology. This allows the amplification and simultaneous quantification of the targeted pathogens. The integration of duplex amplification performance allows the incorporation of the necessary controls into the device to validate the PCR performance. This demonstrator can be run either as fully autonomously working device or as OEM part of a sample-to-answer platform.

Foodborne outbreaks caused by Listeria monocytogenes continue to raise major public health concerns worldwide. In the United States alone, the centers for disease control and prevention have confirmed the occurrence of 183 cases of listeriosis with 39 fatalities within the last 3 years. Standard methods for the detection of pathogenic strains require up to 7 days to yield results, thus faster techniques with the same level of reliability for bacteria detection are desirable. This study reports on the development of a rapid, accurate, and sensitive electrochemical biosensor for rapid testing of Listeria spp. based on the selective binding of InlA aptamers to internalins in the cell membrane of the target bacteria. Hybrid nanomaterial platforms based on reduced graphene oxide and nanoplatinum were deposited onto Pt/Ir electrodes for enhancing electrochemical transduction during the recognition events. InlA aptamers were immobilized onto the nanomaterial platforms via metal-thiol adsorption. Aptamer loading onto different platform nanostructures was investigated through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The detection mechanism was evaluated by recording the electrochemical response to several bacterial dilutions in PBS buffer using the non-pathogenic species Listeria innocua. These preliminary results show that the aptasensor can be tuned for detection of Listeria concentrations as low as 100 CFU/ml in less than 3 hours (including incubation time and data analysis). The developed aptasensor opens a promising direction for rapid testing of Listeria monocytogenes in food products.

Solution procedures were proposed to analyze nonlinear mass transport through an optical biosensor. A generalized collocation technique was applied to predict the dynamic behavior of an analyte along the flow chamber as a result of convection, diffusion and chemical reaction. The method estimated the effective time constants for reaching average steady-state concentrations of the free and bound analytes in the cell. When diffusion in the direction of flow was neglected, a closed-form solution, based on double Laplace transforms, was obtained after linearizing the original system. In both models, an increase in the sample diffusion coefficient lowered the effective time constant. This approach may help researchers evaluate the performance of biosensors and meet specific design criteria.

In this paper, we describe a narrow-bandwidth generation and detection of photoacoustic (PA) signals in biological specimens using frequency-domain photoacoustics. An intensity-modulated laser was used for PA generation, and a homodyne Michelson interferometer coupled to a lock-in amplifier was used for optical PA detection. The amplitude and phase of the PA signal were measured at the modulation frequency as the frequency was swept over the bandwidth of interest. A synthesized pulse response was obtained using time-domain reconstruction and the absorber map was estimated using k-space reconstruction methods. Experimental results obtained from 500-μm graphite rods embedded in tissue-mimicking phantoms and slide-mounted tissue samples are presented along with their respective time-domain and time-reversal reconstruction maps.

Globally, cancer is a major health issue as advances in modern medicine continue to extend the human life span. Breast cancer ranks second as a cause of cancer death in women in the United States. Photoacoustic (PA) imaging (PAI) provides high molecular contrast at greater depths in tissue without the use of ionizing radiation. In this work, we describe the development of a PA tomography (PAT) system and a rapid wavelength-cycling Alexandrite laser designed for clinical PAI applications. The laser produces 450 mJ/pulse at 25 Hz to illuminate the entire breast, which eliminates the need to scan the laser source. Wavelength cycling provides a pulse sequence in which the output wavelength repeatedly alternates between 755 nm and 797 nm rapidly within milliseconds. We present imaging results of breast phantoms with inclusions of different sizes at varying depths, obtained with this laser source, a 5-MHz 128-element transducer and a 128-channel Verasonics system. Results include PA images and 3D reconstruction of the breast phantom at 755 and 797 nm, delineating the inclusions that mimic tumors in the breast.

Generally the fabrication, assembly and evaluation of plasmonic nanostructures for surface enhanced Raman scattering (SERS) substrates has focused on static rigid substrates such as glass and silicon. However, these static substrates severely limit the application of plasmonic nanostructures as (i) they provide no means to alter the state of assembly of the nanostructures once they are formed or anchored on the surface i.e., not reconfigurable; and (ii) preclude applications which demand non-planar, flexible or conformal surfaces. The above considerations has led to the development of a novel class of SERS substrates based on flexible substrates such paper, polymer membranes and electrospun fibers. These flexible SERS media based on unconventional substrates such as paper offer distinct advantages compared to the conventional SERS substrates in that (i) flexible nature of the substrate enables conformal contact with the surfaces under investigation leading to efficient sample collection; (ii) porous nature of the SERS substrate (interstices between the fibers) provides efficient access to the analytes; (iii) high surface area of the 3D paper substrate results in large dynamic range of the chemical sensors; (iv) intricate network of fibers decorated with metal nanoparticles can provide potentially high density of electromagnetic hotspots; (v) intense light scattering caused by the fibrous structure of the substrate (e.g., paper) enables efficient light-metal interaction; and (vi) facile fabrication leads to efficient, robust, reliable, reusable and cost-effective SERS substrates. In this presentation, we will focus on the Army need for a more flexible (substrate surface and application) SERS substrate for universal sensing. This presentation will leverage from material presented at a flexible SERS (May 2014) workshop hosted by Dr. Srikanth Singamaneni at Washington University.

There is an ongoing effort to obtain molecular level information from living cells using surface-enhanced Raman scattering (SERS) not only to understand changes of cellular processes upon exposure to external stimuli but also to decide the status of cells; whether they are healthy or abnormal. In our research effort, we investigate how much information can be obtained from living cells to use for decision making about the cellular processes using SERS. The undertaken studies include cytotoxicity assessment of the nanomaterials and differentiation of the healthy and cancer cells. In the first case, A549 (lung cancer) and HDF (human dermal fibroblast) cells were incubated with 50 nm gold nanoparticles (AuNP) and exposed to three different nanoparticles (Zinc oxide nanoparticles (ZnO NPs), titanium dioxide nanoparticles (TiO2) and single walled carbon nanotubes (SWCNTs)) to perform SERS analysis and track the cellular response to these nanomaterials (NMs). After the principal component analysis on the spectral data, it was shown that the NPs exposed samples could be differentiated through SERS. In the second case, SERS spectra obtained from human kidney adenocarcinoma (ACHN), human kidney carcinoma (A-498) and non-cancerous human kidney embryonic cells (HEK 293) were used to diagnose metastatic, primary and non-cancerous cell lines. Linear discriminant analysis (LDA) based on principal component analysis (PCA) was applied to collected multidimensional SERS spectral data set to differentiate three different cell lines.

Surface enhanced Raman spectroscopy (SERS) requires the analyte molecule to be close to the plasmonic surface in order to generate SERS enhancement. This limitation restricts the practical application of SERS to molecules that possess functional groups that interact strongly with gold or silver surfaces. Moreover, the identification of target analytes in a complex sample matrix is made even more difficult when interferents compete with the target for binding to the plasmonic surface, resulting in overlapping spectral signatures. In this work, we report a strategy to functionalize inkjet printed P-SERS substrates by strategically placing supramolecular structures (such as nucleic acid aptamers) onto the gold nanoparticles. This promotes the selective interaction of target molecules with the plasmonic surface, leading to improved sensor performance.

Super-resolution chemical imaging via Raman spectroscopy provides a significant ability to simultaneously or pseudosimultaneously monitor numerous label-free analytes while elucidating their spatial distribution on the surface of the sample. However, spontaneous Raman is an inherently weak phenomenon making trace detection and thus superresolution imaging extremely difficult, if not impossible. To circumvent this and allow for trace detection of the few chemical species present in any sub-diffraction limited resolution element of an image, we have developed a surface enhanced Raman scattering (SERS) coherent fiber-optic imaging bundle probe consisting of 30,000 individual fiber elements. When the probes are tapered, etched and coated with metal, they provide circular Raman chemical images of a sample with a field of view of approximately 20μm (i.e. diameter) via the array of 30,000 individual 50 nm fiber elements. An acousto-optic tunable filter is used to rapidly scan or select discrete frequencies for multi- or hyperspectral analysis. Although the 50nm fiber element dimensions of this probe inherently provide spatial resolutions of approximately 100nm, further increases in the spatial resolution can be achieved by using a rapid dithering process. Using this process, additional images are obtained one-half fiber diameter translations in the x- and y- planes. A piezostage drives the movement, providing the accurate and reproducible shifts required for dithering. Optimal probability algorithms are then used to deconvolute the related images producing a final image with a three-fold increase in spatial resolution. This paper describes super-resolution chemical imaging using these probes and the dithering method as well as its potential applications in label-free imaging of lipid rafts and other applications within biology and forensics.

Surface enhanced Raman spectroscopy (SERS) has several advantages as a transduction method for many types of optical sensors, due to its sensitivity and potential for multiplexed detection. Over the years, SERS probes have been developed to be capable of extreme sensitivities, with single molecule SERS having been achieved in randomly located hot-spots of colloidal aggregates. However, these structures suffer from significant irreproducibility, due to the randomness of the aggregation. Alternatively, strategies such as ordered 2D arrays or enhancement based on single probes (e.g. immunno-nanosensors, nanostars) have high reproducibilities but limited enhancement factors. In our laboratory a widely applicable enhancing geometry based on metal thin films interleaved with dielectric spacers that takes advantage of interaction into the volume of the probe (perpendicularly to the surface) to enhance the signal independently from the underlying structure has been developed. Preliminary evidence into the mechanism of this enhancement suggests that the dielectric spacer material and thickness play a key role in the magnitude of the resulting enhancement. In this paper we investigate the thickness dependence of the multilayer enhancement using substrates fabricated using ultrathin oxide deposited by atomic layer deposition as spacers. The SERS enhancement measured for substrates based on semiconductor and dielectric materials have been characterized in order to understand the origin of this dependence. In addition a model to describe the mechanism by which the spacer properties influence the multilayer enhancement will also be discussed.

Nanosensors employing quantum dots (QDs) with appended biofunctional moieties offer tremendous promise for disease surveillance/diagnostics and chemical/biological threat activity. Their small size permits cell penetration and their inherent photochemical properties are well-suited for rapid, optical measurement. The effectiveness of enzymes immobilized on QDs, however, are not completely understood, hindering development of chemical/biological sensors and remediation materials. Here, we analyze enzyme effectiveness for the neutralization of a simulant nerve agent when attached to two distinctly-sized QDs. Two sizes of QDs, 525 or 625 nm, were appended with DHLA ligands to improve aqueous stability and prevent aggregation. Various molar ratios of de novo phosphotriesterase trimer (PTE₃) were rapidly self-assembled via spontaneous metal coordination of the PTE oligohistidine tag onto the Zn²⁺-rich QD surface. PTE catalyzes the detoxification of organophosphate pesticides (e.g, paraoxon, an analog of sarin) to p-nitrophenol whose absorbance can be measured at 405 nm. The optimal ratio of PTE₃ to 525 nm and 625 nm QD’s was determined to be 12 and 24, respectively. The enhanced enzyme performance in both cases is most likely due to increased enzyme-substrate interactions from improvements in enzyme orientation, enzyme density, and substrate diffusion on or near the QD. Development of these nansosensors as optical-based biosensors (e.g., within compact microfluidic devices) may greatly improve the sensitivity of conventional biological/chemical detection schemes.

The aim of this study is calculation of bifurcation carotid angle by detection of vessel boundaries to assist the medical doctors if this angle is a risk factor about formation of carotid plaques.Carotid ct angiography images are clustered automatically by ISODATA unsupervised classification algorithm. Since the spectral digital numbers (DN) of vessel pixels are bigger than the other part of the images, the cluster which has the biggest median value of DN among all other classes gives the vessel class. The cluster image in raster format is converted into the vector format which allows working on the vessel geometry. The converted vector vessel cluster dataset has been simplified using Douglas-Peucker algorithm to eliminate the zigzag effects of pixel data which are remained on the vector form dataset. Then the cluster polygon is converted to lines and the vertices which will be used for the calculation of bifurcation carotid angle. For sorting the vertex points to calculate the angle on each vertex, alpha-shapes algorithm is applied along the boundary. Then all the angles on each vertex point along the boundary of vessels are calculated. It is also visually clear that the angle which has the minimum value among all the calculated angles, gives the bifurcation carotid angle for one projected plane. The final carotid angle has calculated and 18 sample datasets are used to test the method.

Bistable illusion reflects two different kinds of interpretations for a single image, which is currently known as a competition between two groups of antagonism of neurons. Recent research indicates that these two groups of antagonism of neurons express different comprehension, while one group is emitting a pulse, the other group will be restrained. On the other hand, when this inhibition mechanism becomes weaker, the other antagonism neurons group will take over the interpretation. Since attention plays key roles controlling cognition, is highly interesting to find the location and frequency band used by brain (with either top-down or bottom-up control) to reach deterministic visual perceptions. In our study, we used a 16-channel EEG system to record brain signals from subjects while conducting bistable illusion testing. An extra channel of the EEG system was used for temporal marking. The moment when subjects reach a perception switch, they click the channel and mark the time. The recorded data were presented in form of brain electrical activity map (BEAM) with different frequency bands for analysis. It was found that the visual cortex in the on the right side between parietal and occipital areas was controlling the switching of perception. In the periods with stable perception, we can constantly observe all the delta, theta, alpha and beta waves. While the period perception is switching, almost all theta, alpha, and beta waves were suppressed by delta waves. This result suggests that delta wave may control the processing of perception switching.

Transcranial magnetic stimulation (TMS) has become one of the most widely used noninvasive method for brain tissue stimulation and has been used as a treatment tool for various neurological and psychiatric disorders including migraine, stroke, Parkinson's disease, dystonia, tinnitus and depression. In the process of developing advanced TMS deep brain stimulation tools, we need first to develop field measurement devices like sensory probes and brain phantoms, which can be used to calibrate the TMS systems. Currently there are commercially available DC magnetic or electric filed measurement sensors, but there is no instrument to measure transient fields. In our study, we used a commercial figure-8 shaped TMS coil to generate transient magnetic field and followed induced field and current. The coil was driven by power amplified signal from a pulse generator with tunable pulse rate, amplitude, and duration. In order to obtain a 3D plot of induced vector electric field, many types of probes were designed to detect single component of electric-field vectors along x, y and z axis in the space around TMS coil. We found that resistor probes has an optimized signal-to-noise ratio (SNR) near 3k ohm but it signal output is too weak compared with other techniques. We also found that inductor probes can have very high output for Curl E measurement, but it is not the E-field distribution we are interested in. Probes with electrical wire wrapped around iron coil can directly measure induced E-field with high sensitivity, which matched computer simulation results.

A low-cost, high resolution 3D scanning system has been developed at the University of North Dakota that creates 3D models (complete with color and texture data) using hardware and software with a cost of approximately $5,000. This paper presents the design, testing and initial uses for this scanning hardware; it also discusses the efficacy of this technology for a variety of applications and the utility of being able to capture high-quality scans at low cost. A discussion of the required operating conditions and the limitations that this places on the applications the scanner is suitable for is also included.

Chikungunya fever is a global concern due to the occurrence of large outbreaks, the presence of persistent arthropathy and its rapid expansion throughout various continents. Globalization and climate change have contributed to the expansion of the geographical areas where mosquitoes Aedes aegypti and Aedes albopictus (Stegomyia) remain. It is necessary to improve the techniques of vector control in the presence of large outbreaks in The American Region. We derive measures of disease control, using a mathematical model of mosquito-human interaction, by means of three scenarios: a) a single vector b) two vectors, c) two vectors and human and non-human reservoirs. The basic reproductive number and critical control measures were deduced by using computer algebra with Maple (Maplesoft Inc, Ontario Canada). Control measures were simulated with parameter values obtained from published data. According to the number of households in high risk areas, the goals of effective vector control to reduce the likelihood of mosquito-human transmission would be established. Besides the two vectors, if presence of other non-human reservoirs were reported, the monthly target of effective elimination of the vector would be approximately double compared to the presence of a single vector. The model shows the need to periodically evaluate the effectiveness of vector control measures.

We address an optical imaging method that allows imaging, which owing to the “memory-effect” for speckle correlations, through highly scattering turbid media with “Error Reduction - Hybid Input Ouput (ER-HIO)” algorithm. When light propagates through the opaque materials, such as white paint, paper or biological tissues, it will be scattered away due to the inhomogeneity of the refractive index. Multiple scattering of light in highly scattering media forms speckle field, which will greatly reduce the imaging depth and degrade the imaging quality. Some methods have been developed to solve this problem in recent years, including wavefront modulation method (WMM), transmission matrix method (TMM) and speckle correlations method (SCM). A novel approach is proposed to image through a highly scattering turbid medium, which combines speckle correlations method (SCM) with phase retrieval algorithm (PRA). Here, we show that, owing to the “optical memory effect” for speckle correlations, a single frame image of the speckle field, captured with a high performance detector, encodes sufficient information to image through highly scattering turbid media. Theoretical and experimental results show that, neither the light source, nor wave-front shaping is required in this method, and that the imaging can be easily realized here using just a simple optical system with the help of optical memory effect. Our method does not require coherent light source, which can be achieved with LED illumination, unlike previous approaches, and therefore is potentially suitable for more and more areas. Consequently, it will be beneficial to achieve imaging in currently inaccessible scenarios.

The incident light will be scattered away due to the inhomogeneity of the refractive index in many materials which will greatly reduce the imaging depth and degrade the imaging quality. Many exciting methods have been presented in recent years for solving this problem and realizing imaging through a highly scattering medium, such as the wavefront modulation technique and reconstruction technique. The imaging method based on compressed sensing (CS) theory can decrease the computational complexity because it doesn't require the whole speckle pattern to realize reconstruction. One of the key premises of this method is that the object is sparse or can be sparse representation. However, choosing a proper projection matrix is very important to the imaging quality. In this paper, we analyzed that the transmission matrix (TM) of a scattering medium obeys circular Gaussian distribution, which makes it possible that a scattering medium can be used as the measurement matrix in the CS theory. In order to verify the performance of this method, a whole optical system is simulated. Various projection matrices are introduced to make the object sparse, including the fast Fourier transform (FFT) basis, the discrete cosine transform (DCT) basis and the discrete wavelet transform (DWT) basis, the imaging performances of each of which are compared comprehensively. Simulation results show that for most targets, applying the discrete wavelet transform basis will obtain an image in good quality. This work can be applied to biomedical imaging and used to develop real-time imaging through highly scattering media.

Leptospirosis is a bacterial zoonosis with world distribution and multiform clinical spectrum in men and animals. The etiology of this disease is the pathogenic species of Leptospira, which cause diverse manifestations of the disease, from mild to serious, such as the Weil disease and the lung hemorrhagic syndrome with lethal proportions of 10% - 50%. This is an emerging problem of urban health due to the growth of marginal neighborhoods without basic sanitary conditions and an increased number of rodents. The presence of rodents and the probability of having contact with their urine determine the likelihood for humans to get infected. In this paper, we simulate the spatial distribution of risk infection of human leptospirosis according to the proximity to rodent burrows considered as potential source of infection. The Bessel function K₀ with an r distance from the potential point source, and the scale parameter α in meters was used. Simulation inputs were published data of leptospirosis incidence rate (range of 5 to 79 x 10 000), and a distance of 100 to 5000 meters from the source of infection. We obtained an adequate adjustment between the function and the simulated data. The risk of infection increases with the proximity of the potential source. This estimation can become a guide to propose effective measures of control and prevention.