Search

Surface plasmon resonance devices typically rely on the use of gold-coated surfaces, but the use of more abundant metals is desirable for the long-term development of plasmonic biochips. As a substitute for gold, thin copper films have been deposited on glass coverslips by thermal evaporation. As expected, these films immersed in a water solution initially exhibit an intense plasmonic resonance comparable to gold. However, without protection, an angle-resolved optical analysis shows a rapid degradation of the copper, characterized by a continuous angular shift of the plasmonic resonance curve. We show that copper films protected with a thin layer of aluminum oxide of a few nanometers can limit the oxidation rate for a sufficient time to perform some standard measurements. As the process is simple and compatible with the current biochip production technique, such an approach could pave the way for the production of alternative and more sustainable biochips. [ABSTRACT FROM AUTHOR]

Biochips are engineered substrates that have different spots that change colour according to biochemical reactions. These spots can be read together to detect different analytes (such as different types of antibiotic, pathogens, or biological agents). While some chips are designed so that each spot on its own can detect a particular analyte, chip designs that use a combination of spots to detect different analytes can be more efficient and detect a larger number of analytes with a smaller number of spots. These types of chip can, however, be more difficult to design, as an efficient and effective combination of biosensors needs to be selected for the chip. These need to be able to differentiate between a range of different analytes so the values can be combined in a way that demonstrates the confidence that a particular analyte is present or not. The study described in this paper examines the potential for information visualisation to support the process of designing and reading biochips by developing and evaluating applications that allow biologists to analyse the results of experiments aimed at detecting candidate bio-sensors (to be used as biochip spots) and examining how biosensors can combine to identify different analytes. Our results demonstrate the potential of information visualisation and machine learning techniques to improve the design of biochips. [ABSTRACT FROM AUTHOR]

With the increasing demand for fast, accurate, and reliable biological sensor systems, miniaturized systems have been aimed at droplet-based sensor systems and have been promising. A micro-electrode dot array (MEDA) biochip, which is one kind of the miniaturized systems for biochemical protocols such as dispensing, dilutions, mixing, and so on, has become widespread due to enabling dynamical control of the droplets in microfluidic manipulations. In MEDA biochips, the electrowetting-on-dielectric (EWOD) technique stands out since it can actuate droplets with nano/picoliter volumes. Microelectrode cells on MEDA actuate multiple droplets simultaneously to route locations for the purpose of the biochemical operations. Taking advantage of the feature, droplets are often routed in parallel to achieve high-throughput outcomes. Regarding parallel manipulation of multiple droplets, however, the droplets are known to be initially placed at a distant position to avoid undesirable mixing. The droplets thus result in traveling a long way for a manipulation, and the required biochip size for routing is also enlarged. This paper proposes a routing method for droplets to reduce the biochip size on a MEDA biochip with the allowance of splitting during routing operations. We mathematically derive the routing problem, and the experiments demonstrate that our proposal can significantly reduce the biochip size by 70.8% on average, compared to the state-of-the-art method. [ABSTRACT FROM AUTHOR]

The development of high-resolution molecular printing allows the engineering of analytical platforms enabling applications at the interface between chemistry and biology, i.e. in biosensing, electronics, single-cell biology, and point-of-care diagnostics. Their successful implementation stems from the combination of large area printing at resolutions from sub-100 nm up to macroscale, whilst controlling the composition and volume of the ink, and reconfiguring the deposition features in due course. Similar to handwriting pens, the engineering of continuous writing systems tackles the issue of the tedious ink replenishment between different printing steps. To this aim, this review article provides an unprecedented analysis of the latest continuous printing methods for bioanalytical chemistry, focusing on ink deposition systems based on specific sets of technologies that have been developed to this aim, namely nanofountain probes, microcantilever spotting, capillary-based polymer pens and continuous 3D printing. Each approach will be discussed revealing the most important applications in the fields of biosensors, lab-on-chips and diagnostics. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance devices typically rely on the use of gold-coated surfaces, but the use of more abundant metals is desirable for the long-term development of plasmonic biochips. As a substitute for gold, thin copper films have been deposited on glass coverslips by thermal evaporation. As expected, these films immersed in a water solution initially exhibit an intense plasmonic resonance comparable to gold. However, without protection, an angle-resolved optical analysis shows a rapid degradation of the copper, characterized by a continuous angular shift of the plasmonic resonance curve. We show that copper films protected with a thin layer of aluminum oxide of a few nanometers can limit the oxidation rate for a sufficient time to perform some standard measurements. As the process is simple and compatible with the current biochip production technique, such an approach could pave the way for the production of alternative and more sustainable biochips.

The article describes the non-genetic roles of DNA molecule and its applications in diagnostic and therapeutic fields such as in biosensors, barcodes, nanomachines, biochips, probes, and DNA scaffolds. [ABSTRACT FROM AUTHOR]

A biosensor capable of differentiating cells or other microparticles based on morphology finds significant biomedical applications. Examples may include morphological determination in the cellular division process, differentiation of bacterial cells, and cellular morphological variation in inflammation and cancer etc. Here, we present a novel integrated multi-planar microelectrodes geometry design that can distinguish a non-spherical individual particle flowing along a microchannel based on its electrical signature. We simulated multi-planar electrodes design in COMSOL Multiphysics and have shown that the changes in electrical field intensity corresponding to multiple particle morphologies can be distinguished. Our initial investigation has shown that top–bottom electrodes configuration produces significantly enhanced signal strength for a spherical particle as compared to co-planar configuration. Next, we integrated the co-planar and top–bottom configurations to develop a multi-planar microelectrode design capable of electrical impedance measurement at different spatial planes inside a microchannel by collecting multiple output signatures. We tested our integrated multi-planar electrode design with particles of different elliptical morphologies by gradually changing spherical particle dimensions to the non-spherical. The computed electrical signal ratio of non-spherical to spherical particle shows a very good correlation to predict the particle morphology. The biochip sensitivity is also found be independent of orientation of the particle flowing in the microchannel. Our integrated design will help develop the technology that will allow morphological analysis of various bioparticles in a microfluidic channel in the future. [ABSTRACT FROM AUTHOR]

This article discusses a system for the molecular diagnosis of diseases at the early stages based on biochips using field effect nanotransistors. Practical questions relating to data processing to avoid signal distortion are addressed, as well as problems of signal visualization. [ABSTRACT FROM AUTHOR]

Abstract An immunosensing biochip for simultaneous detection of three biomarkers related to acute myocardial infarction (AMI) was developed based on anionic soybean peroxidase (SBP) functionalized nanoprobe and chemiluminescent imaging. The nanoprobes (Ab2-SiO 2 -SBP) were fabricated by co-immobilization of SBP and one of the detection polyclonal antibodies, anti-cardiac troponin I antigen (anti-cTnI), anti-creatine kinase-MB (anti-CK-MB) and anti-myoglobin (anti-Myo), on the silica nanoparticle surface. The detection sensitivity was enhanced since the large surface area of silica carriers increased the loading of SBP for per sandwiched immunoreaction. The immunosensing biochip designed as 3 × 8 wells array was constructed by simultaneously immobilizing three capture monoclonal antibodies on the same one microtiter well with 2 × 3 active spots. In the presence of target protein, the nanoprobes will be attached onto the spots with high specificity through the sandwiched immunoreactions, which triggered the chemiluminescence (CL) signals on each sensing site of the microtiter plates and allowed to CL imaging of three biomarkers in one well at the same time. Therefore, the proposed biochip was a promising convenient strategy for simultaneous detection of cTnI, CK-MB and Myo, which showed potential application for multianalyte determination in clinical diagnostics. Highlights • Simultaneous detection of three biomarkers related to acute myocardial infarction. • SBP functionalized nanoprobes is used for improving the detection sensitivity. • The proposed biochip shows high sensitivity, good specificity and stability. • The biochip shows potential application in clinical diagnostics. [ABSTRACT FROM AUTHOR]

This paper proposed a fully integrated 4-channel GMR biochip for biomedical detection assays, including the acquisition analog frontend for small signal extraction, 180° phase shifter, resistor ladder and control circuits for carrier cancellation, and amplifiers. Besides, the overall system was evaluated comprehensively by experiment, and the output noise is as low as 321.7nV/Hz, which is lower than the signal produced by one single 500nm magnetic particle during the detection. [ABSTRACT FROM AUTHOR]

Most cancer patients do not die from the primary tumor but from its metastasis. Current in vitro and in vivo cancer models are incapable of satisfactorily predicting the outcome of various clinical treatments on patients. This is seen as a serious limitation and efforts are underway to develop a new generation of highly predictive cancer models with advanced capabilities. In this regard, organ-on-chip models of cancer metastasis emerge as powerful predictors of disease progression. They offer physiological-like conditions where the (hypothesized) mechanistic determinants of the disease can be assessed with ease. Combined with high-throughput characteristics, the employment of organ-on-chip technology would allow pharmaceutical companies and clinicians to test new therapeutic compounds and therapies. This will permit the screening of a large battery of new drugs in a fast and economic manner, to accelerate the diagnosis of the disease in the near future, and to test personalized treatments using cells from patients. In this review, we describe the latest advances in the field of organ-on-chip models of cancer metastasis and their integration with advanced imaging, screening and biosensing technologies for future precision medicine applications. We focus on their clinical applicability and market opportunities to drive us forward to the next generation of tumor models for improved cancer patient theranostics. [ABSTRACT FROM AUTHOR]

In this article, a surface-enhanced Raman scattering ( SERS) substrate of silver nanocap arrays was reported. With increasing the size of nanocaps, the localized surface plasmon resonance ( LSPR) of the arrays exhibited tunable ability in the visible spectral region. The optical response of the nanocap arrays stimulated their use in SERS experiments. The assessment of SERS activity of the nanocap arrays was performed by using the 514.5 nm excitation line, and different average enhancement factor ( EF) values were obtained. The good tunability of LSPR, relatively high average EF values and long-range order of these substrates suggest that the silver nanocap arrays have promising applications as functional components in spectroscopy, immunoassay, biosensors, and biochips. [ABSTRACT FROM AUTHOR]

A planar three electrodes system (PTES) chip which is consisted of planar Au, Ag/AgCl, and Pt electrodes on ITO (Indium-Tin Oxide) glass is fabricated using state of the art inkjet printing technology to serve as biosensor for electrochemical detection of biomolecules. The electrochemical detection of melamine and dopamine is successfully performed with this PTES chip and established higher sensitivity in comparison with traditional commercial three electrode system, indicating this PTES chip has great potential in practical applications as electrochemical sensor for biomolecules. [ABSTRACT FROM AUTHOR]

Integrated optical system-on-chip in silicon operating in the visible range can have a tremendous impact on enabling new applications in sensing and imaging through the ultra-miniaturization of complex optical instrumentation. CMOS technology has allowed an integration of optical detection circuitry for image sensors with massively large number of pixels. In this paper, we focus on techniques to realize complex optical-field processing elements inside CMOS by exploiting optical interaction with sub-wavelength metal nanostructures realized in the electrical interconnects layers, whose feature sizes are now in the sub-100-nm range. In particular, we present a fully integrated fluorescence-based bio-molecular sensor in 65-nm CMOS with integrated nanoplasmonic waveguide-based filters capable of more than 50 dB of rejection ratio across a wide range of incident angles. Co-designed with the integrated photo-detection circuitry, capacitive TIAs, and correlated double-sampling circuitry, the sensor is capable of detecting 48 zeptomoles of quantum dots on the surface with 52 fA of photodetector current with a fluorescence/excitation ratio of nearly −62 dB without any post-fabrication, external optical filters, lenses, or collimators. The ability to integrate complex nanoplasmonic metal structures with unique optical properties in CMOS with no post-processing creates the opportunity to enable large multiplexed assays on a single chip and a wide variety of applications, from in vitro to in vivo. [ABSTRACT FROM PUBLISHER]

Tethered lipid bilayer membranes (tBLMs) have been used in many applications, including biosensing and membrane protein structure studies. This report describes a biosensor for anthrax toxins that was fabricated through the self-assembly of a tBLM with B. anthracis protective antigen ion channels that are both the recognition element and electrochemical transducer. We characterize the sensor and its properties with electrochemical impedance spectroscopy and surface plasmon resonance. The sensor shows a sensitivity similar to ELISA and can also be used to rapidly screen for molecules that bind to the toxins and potentially inhibit their lethal effects. [ABSTRACT FROM AUTHOR]

Goal: The objective of this study is to design and develop a portable tool consisting of a disposable biochip for measuring electrothermomechanical (ETM) properties of breast tissue. Methods: A biochip integrated with a microheater, force sensors, and electrical sensors is fabricated using microtechnology. The sensor covers the area of 2 mm and the biochip is 10 mm in diameter. A portable tool capable of holding tissue and biochip is fabricated using 3-D printing. Invasive ductal carcinoma and normal tissue blocks are selected from cancer tissue bank in Biospecimen Repository Service at Rutgers Cancer Institute of New Jersey. The ETM properties of the normal and cancerous breast tissues (3-mm thickness and 2-mm diameter) are measured by indenting the tissue placed on the biochip integrated inside the 3-D printed tool. Results: Integrating microengineered biochip and 3-D printing, we have developed a portable cancer diagnosis device. Using this device, we have shown a statistically significant difference between cancerous and normal breast tissues in mechanical stiffness, electrical resistivity, and thermal conductivity. Conclusion: The developed cancer diagnosis device is capable of simultaneous ETM measurements of breast tissue specimens and can be a potential candidate for delineating normal and cancerous breast tissue cores. Significance: The portable cancer diagnosis tool could potentially provide a deterministic and quantitative information about the breast tissue characteristics, as well as the onset and disease progression of the tissues. The tool can be potentially used for other tissue-related cancers. [ABSTRACT FROM AUTHOR]

Screen printing technology provides a cheap and easy means to fabricate disposable electrochemical devices in bulk quantities which are used for rapid, low-cost, on-site, real-time and recurrent industrial, pharmaceutical or environmental analyses. Recent developments in micro-fabrication and nano-characterization made it possible to screen print reproducible feature on materials including plastics, ceramics and metals. The processed features forms screen-printed disposable biochip (SPDB) upon the application of suitable bio-chemical recognition receptors following appropriate methods. Adequacy of biological and non-biological materials is the key to successful biochip development. We can further improve recognition ability of SPDBs by adopting new screen printed electrode (SPE) configurations. This review covers screen-printing theory with special emphasis on the technical impacts of SPE architectures, surface treatments, operational stability and signal sensitivity. The application of SPE in different areas has also been summarized. The article aims to highlight the state-of-the-art of SPDB at the laboratory scale to enable us in envisaging the deployment of emerging SPDB technology on the commercial scale. [ABSTRACT FROM PUBLISHER]

Living bacteria or yeast cells are frequently used as bioreporters for the detection of specific chemical analytes or conditions of sample toxicity. In particular, bacteria or yeast equipped with synthetic gene circuitry that allows the production of a reliable non-cognate signal (e.g., fluorescent protein or bioluminescence) in response to a defined target make robust and flexible analytical platforms. We report here how bacterial cells expressing a fluorescence reporter (“bactosensors”), which are mostly used for batch sample analysis, can be deployed for automated semi-continuous target analysis in a single concise biochip. Escherichia coli-based bactosensor cells were continuously grown in a 13 or 50 nanoliter-volume reactor on a two-layered polydimethylsiloxane-on-glass microfluidic chip. Physiologically active cells were directed from the nl-reactor to a dedicated sample exposure area, where they were concentrated and reacted in 40 minutes with the target chemical by localized emission of the fluorescent reporter signal. We demonstrate the functioning of the bactosensor-chip by the automated detection of 50 μgarsenite-As l−1 in water on consecutive days and after a one-week constant operation. Best induction of the bactosensors of 6–9-fold to 50 μg l−1 was found at an apparent dilution rate of 0.12 h−1 in the 50 nl microreactor. The bactosensor chip principle could be widely applicable to construct automated monitoring devices for a variety of targets in different environments. [ABSTRACT FROM AUTHOR]

Point-of-care detection is a widely studied area that attracts effort and interest from a large number of fields and companies. However, there is also increased interest from the general public in this type of device, which has driven enormous changes in the design and conception of these developments and the way data is handled. Therefore, future point-of-care detection has to include communication with front-end technology, such as smartphones and networks, automation of manufacture, and the incorporation of concepts like the Internet of Things (IoT) and cloud computing. Three key examples, based on different sensing technology, are analyzed in detail on the basis of these items to highlight a route for the future design and development of point-of-care detection devices and their data capture and handling. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

This study describes the development of a novel electrochemical biosensor for meat species identification using DNA-redox electrostatic interactions and the nonspecific adsorption of these molecules on graphene biochips. The ruthenium hexamine molecule [Ru(NH 3 ) 6 ] 3+ , or RuHex, was observed to form complexes with free DNA in solution that adsorbed onto graphene surfaces, enabling the development of a rapid, high-sensitivity DNA biosensor. Reproducible cathodic current signals were generated from these low-cost graphene biochips, both in the presence and absence of dsDNA and loop-mediated isothermal amplification (LAMP) amplicons. The combination of the DNA-redox molecule complexes and the graphene surface therefore provided a novel detection strategy. This new biosensor was able to identify different meat species based on the isothermal amplification of target genes followed by electrochemical detection with square wave voltammetry. To optimize the specificity and sensitivity of the biosensor, the LAMP parameters were investigated under varying isothermal conditions using varying concentrations of reagents and target DNA, and with different combinations of newly designed loop primers. Using these novel biomarkers along with the new on-chip detection strategy, we observed limits of detection of target DNA of 1 pg/μL and 100 pg/μL for chicken and pork species, respectively. [ABSTRACT FROM AUTHOR]

We propose a method and optical design for direct visualization of label-free detection. The system, similar to a tiny spectral analyzer, is composed of a nanostructure-based surface plasmon resonance chip, linear polarizer and 532 nm laser light source. The full-width-at-half-maximum bandwidths of the enhanced surface plasmon resonances are about 5 nm. The distribution of the transmitted light from these arrays comprises a spectral image on the chip. The qualitative and quantitative analyses of the analyte can be conducted by observing the spot shift on the chip. We tested the sensing capability of the chip. The detectable surface mass density with the naked eye is about 0.476 μg cm−2. In addition, antigen–antibody interaction experiments are conducted to verify the surface binding measurements. A monolayer protein attached on the chip can be directly observed and the concentration levels of the analyte can be estimated with the naked eye. Such plasmonic biochips can benefit sensing applications in point-of-care diagnostics. [ABSTRACT FROM AUTHOR]

Introduction: Surface plasmon resonance biosensors are high sensitive analytical instruments that normally employ glass materials at the optical substrate layer. However, the use of polymer-based substrates is increasing in the last years due to favorable features, like: disposability, ease to construction and low-cost design. Review: Recently, a polymer-based SPR biochip was proposed by using monochromatic and polychromatic input sources. Its construction and experimental considerations are detailed here. Experimental considerations and results, aspects from performance characteristics (resonance parameters, sensitivity and full width at half maximum – FWHM – calculations) are presented for hydrophilic and hydrophobic solutions. It is included also a brief description of the state of the art of polymer-based SPR biosensors. [ABSTRACT FROM AUTHOR]

Immobilization of proteins on a solid support is critical with respect to the fabrication and performance of biosensors and biochips. Protein attachment with a preferable orientation can effectively avoid its denaturation and keeps its active sites fully exposed to solution, thus maximally preserving the bioaffinity or bioactivity. This review (with 140 refs.) summarises the recent advances in oriented immobilization of proteins with a particular focus on antibodies and enzymes. Following an introduction that describes reasons for oriented immobilization on (nano)surfaces, we summarize (a) methods for (bio)chemical affinity-mediated oriented immobilization (with sections on immunoglobulin G (IgG)-binding protein as the capture ligand, DNA-directed immobilization, aptamer- and peptide-mediated immobilization, affinity ligand and fusion tag-mediated immobilization, material-binding peptide-assisted immobilization); (b) methods for covalent oriented immobilization (with sections on immobilization via cysteine residues or cysteine tags, via carbohydrate moieties; via enzyme fusion or enzymatic catalysis, and via nucleotide binding sites of antibodies); (c) methods based on molecular imprinting techniques; (d) methods for characterization of oriented immobilized proteins; and then make conclusions and give perspectives. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The self-made fluorescence detection system was integrated to detect the biological signal of DNA sample. And the portable fluorescence detection system with four channels microfluidic biochip was finished for DNA hybridization. In the biochip preparation, the PDMS cast-forming process was used to fabricate microfluidic biochip with width 150 μm and height 200 μm. In the fluorescence detection system, four sets of independent 532 nm green lasers were adopted to illuminate the four detection areas of the microfluidic biochip for fluorescence sample excitation, then the voltage of excitation fluorescence signal was obtained. Then the PSOC embedded system was utilized synchronously to display the four voltage values on LCD, in the meantime, the voltage value was transferred to the computer for recording. From the experimental result of DNA hybridization, it can be seen that portable fluorescence detection system can be utilized to measure four fluorescence signals of DNA samples at the same time. Moreover, due to the hybridization specificity of fluorescence probe ET996-Hex, the DNA hybridization of Edwardsiella tarda BCRC 16711 and Edwardsiella tarda BCRC 16702 can be judged successfully for fluorescence probe ET996-Hex. The portable fluorescence detection system had the capability to distinguish disease source. [ABSTRACT FROM AUTHOR]

Conjugation of biomolecules on gold nanorod (GNR) surfaces is the basis for successful applications in biosensing, imaging, and drug delivery. Current functionalization methods are often problematic, involving multi-step nanoparticle modification to replace surfactant bilayer, delicate nanoparticle protection during surfactant exchange, and material loss due to inevitable aggregation. Instead of intensive surface modification of GNRs, we describe herein a facile method to functionalize gold nanorod surfaces via covalent Au–S bonds by thiolating receptors. The resulting GNR-bioconjugates showed superior dispersion and stability in buffer for months without morphology change and aggregation. ELISA tests confirmed the high biofunctionality of the thiolated anti-IgG moieties immobilized on the GNR surfaces. Furthermore, this simple method facilitated a straightforward functionalization of GNR assembly on glass substrate to construct a specific biochip, which can detect human IgG targets in a label-free fashion with high sensitivity and specificity. Compared to electropolymeric coating to functionalize the GNR, our method exhibited a five-fold enhancement in the spectral sensitivity to refractive index change caused by the target binding. This universal GNR bioconjugation method can be extended to bind different proteins and antibodies for development of biosensors or drug delivery. [ABSTRACT FROM AUTHOR]

In the field of blood transfusion, there is a need to improve the bedside pre-transfusion ABO compatibility test. In France, this test is mandatory for each red cell concentrates transfusion. It is performed manually and serious transfusion accidents still occur, principally due to human errors. Therefore, an automated ABO compatibility test is required. Works concerning objective interpretation of ABO compatibility test have been reported but the proposed techniques cannot be easily translated to the patient's bedside. We propose a prototype device which demonstrates the easy use of biochip technology to perform this test: it contains a fluidic system, biochips (two to test the patient and two to test the red cell concentrates) and an optical absorbance detection module. When blood is applied to the biochips, red blood cells are trapped onto the surface if antigens and antibodies are complementary (positive chips). If they are not complementary, very little red blood cells are adsorbed (negative chips). Percentages of surface covered with red blood cells in negative biochips are 2% ± 2 (red cell concentrates) and 1% ± 1 (whole blood). This proves that the fluidic configuration leads to an optimum control of fluids flows with little retention of red blood cells in the circuitry. These percentages increase to 96% ± 3 and 82% ± 8 for red cell concentrates and whole blood respectively. This demonstrates a strong and specific immunocapture of red blood cells on positive chips. Furthermore, optical detection proves to be efficient at critical red blood cells concentrations (10 8 C/mL) and absorbance strongly correlates to the percentage of red blood cells captured by antibodies. [ABSTRACT FROM AUTHOR]

Abstract: A selective fluorescent-free detection method of biomolecules on nanoarray biochips was developed based on wavelength-dependent single plasmonic nanoparticles by differential interference contrast (DIC) microscopy. As a model target protein molecule, human cardiac troponin I (cTnI) was bound between primary anti-cTnI oriented on gold-nanopatterned chips (GNCs) and secondary silver nanoparticle (SNP) anti-cTnI. SNPs were employed as non-fluorescent probes to determine the immuno-reaction. Gold and silver exhibited clear peaks with DIC contrast at different wavelengths because plasmonic noble metals display extraordinarily large apparent refractive indices near their plasmon resonance wavelengths. Therefore, when the SNPs-cTnI antibody was bound to GNC, the normalized maximum intensity of the DIC contrast was blue-shifted. A linear relationship of the calibration curve was obtained between the DIC intensity and cTnI concentration in the range of 85aM–10fM without spectroscopic interference. This combination method of wavelength-dependent DIC microscopy and plasmonic nanoparticles could overcome the limitations of the potential for nonspecific labeling by promiscuous antibodies and the lack of reagents or biomarkers for disease-specific applications. [Copyright &y& Elsevier]

Highlights: [•] TMBP from hyperthermophilic bacteria T. litoralis is extremely stable protein. [•] The unfolding of TMBP and TMBP–glucose is an “all or nothing” transition. [•] TMBP/C182S/A14C–BADAN is a potential basis for glucose biosensor system development. [Copyright &y& Elsevier]

Highlights: [•] Optical SPR experiment as an important part of patulin detection is presented. [•] Conjugation of a new derivative of patulin to BSA is described. [•] Innovative immune-assay for detection of patulin is presented. [Copyright &y& Elsevier]

A reusable and mediator-free cholesterol biosensor based on cholesterol oxidase (ChOx) was fabricated based on self-assembled monolayer (SAM) of thioglycolic acid (TGA) (covalent enzyme immobilization by dropping method) using bio-chips. Cholesterol was detected with modified bio-chip (Gold/Thioglycolic-acid/Cholesterol-oxidase i.e., Au/TGA/ChOx) by reliable cyclic voltammetric (CV) technique at room conditions. The Au/TGA/ChOx modified bio-chip sensor demonstrates good linearity (1.0 nM to 1.0 mM; R = 0.9935), low-detection limit (∼0.42 nM, SNR∼3), and higher sensitivity (∼74.3 µAµM−1cm−2), lowest-small sample volume (50.0 μL), good stability, and reproducibility. To the best of our knowledge, this is the first statement with a very high sensitivity, low-detection limit, and low-sample volumes are required for cholesterol biosensor using Au/TGA/ChOx-chips assembly. The result of this facile approach was investigated for the biomedical applications for real samples at room conditions with significant assembly (Au/TGA/ChOx) towards the development of selected cholesterol biosensors, which can offer analytical access to a large group of enzymes for wide range of biomedical applications in health-care fields. [ABSTRACT FROM AUTHOR]

Here, we present a silicon microfluidic system for the purification and extraction of nucleic acids from human body fluid samples utilizing a dimethyl adipimidate (DMA)-based solid-phase extraction method. We propose DMA, which has been used as an amino-reactive cross-linking agent within cells and proteins, as a non-chaotropic reagent for the capture of nucleic acids to overcome the limitations of existing chaotropic and non-chaotropic techniques such as low binding efficiency, PCR inhibition and so on. DMA contains bi-functional imidoesters that form reversible cross-linking structures with DNA therefore providing a high surface-area to volume ratio for capturing DNA without structurally modifying microfluidic channels. In this work, we have first demonstrated highly efficient capture and purification of genomic DNA (T24 cell line) with DMA using a label-free silicon microring resonator sensor device. In addition, we observed the improvement of the DNA amplification efficiency by using the proposed technique for both the genetic (HRAS) and epigenetic (RARβ) analysis of DNA biomarkers. Particularly, we confirmed that the DMA-based solid-phase extraction technique can be applied for the extraction of genomic DNA with higher purity (p ＜ 0.001) using human body fluids (blood and urine) in silicon microfluidic devices compared to other chaotropic methods. Therefore, the proposed technique would be able to harmonize with a micro-total analysis system platform for the analysis of genetic and epigenetic DNA biomarkers related to human diseases in the field of point-of-care (POC) diagnostic applications. [ABSTRACT FROM AUTHOR]

The physical separation of individual cells from cell populations for single-cell analysis and proliferation is of wide interest in biology and medicine. Today, single-cell isolation is routinely applied to non-adherent cells, though its application to cells grown on a substrate remains challenging. In this report, a versatile approach for isolating single HeLa cells directly from their culture dish is presented. Fluidic force microscopy is first used to detach the targeted cell(s) via the tunable delivery of trypsin, thereby achieving cellular detachment with single-cell resolution. The cell is then trapped by the microfluidic probe via gentle aspiration, displaced with micrometric precision and either transferred onto a new substrate or deposited into a microwell. An optimised non-fouling coating ensures fully reversible cell capture and the potential for serial isolation of multiple cells with 100% successful transfer rate (n = 130) and a survival rate of greater than 95%. By providing an efficient means for isolating targeted adherent cells, the described approach offers exciting possibilities for biomedical research. [ABSTRACT FROM AUTHOR]

We introduce the use of correlation analysis to extend the dynamic range of suspended micro- and nanochannel resonator (SMR/SNR) mass sensors by over five orders of magnitude. This method can analyze populations of particles flowing through an embedded channel micromechanical resonator, even when the individual particle masses are far below the noise floor. To characterize the method, we measured the mass of polystyrene nanoparticles with 300 zg resolution. As an application, we monitored the time course of insulin amyloid formation from pre-fibrillar aggregates to mature fibrils of 15 MDa average mass. Results were compared with thioflavin-T (ThT) assays and electron microscopy (EM). Mass measurements offer additional information over ThT during the fluorescent inaccessible lag period, and the average fibril dimensions calculated from the mass signal are in good accordance with EM. In the future, we envision that more detailed modeling will allow the computational deconvolution of multicomponent samples, enabling the mass spectrometric characterization of a variety of biomolecular complexes, small organelles, and nanoparticles in solution. [ABSTRACT FROM AUTHOR]

Gradients of biochemical molecules play a key role in many physiological processes such as axon growth, tissue morphogenesis, and trans-epithelium nutrient transport, as well as in pathophysiological phenomena such as wound healing, immune response, bacterial invasion, and cancer metastasis. In this paper, we report a microfluidic transwell insert for generating quantifiable concentration gradients in a user-friendly and modular format that is compatible with conventional cell cultures and with tissue explant cultures. The device is simply inserted into a standard 6-well plate, where it hangs self-supported at a distance of ~250 μm above the cell culture surface. The gradient is created by small microflows from the device, through an integrated track-etched porous membrane, into the cell culture well. The microfluidic transwell can deliver stable, quantifiable gradients over a large area with extremely low fluid shear stress to dissociated cells or tissue explants cultured independently on the surface of a 6-well plate. We used finite-element modeling to describe the porous membrane flow and molecular transport and to predict gradients generated by the device. Using the device, we applied a gradient of the chemotactic peptide N-formyl-met-leu-phe (fMLP) to a large population of HL-60 cells (a neutrophil cell line) and directly observed the migration with time-lapse microscopy. On quantification of the chemotactic response with an automated tracking algorithm, we found 74% of the cells moving towards the gradient. Additionally, the modular design and low fluid shear stress made it possible to apply gradients of growth factors and second messengers to mouse retinal explant cultures. With a simplified interface and well-defined gradients, the microfluidic transwell device has potential for broad applications to gradient-sensing biology. [ABSTRACT FROM AUTHOR]

Abstract: At present, 33 blood groups representing over 300 antigens are listed by the International Society of Blood Transfusion (ISBT). Most of them result from a single nucleotide polymorphism (SNP) in the corresponding DNA sequence, i.e. approx. 200 SNPs. In immunohematology laboratories, blood group determination is classically carried out by serological tests, but these have some limitations, mostly in term of multiplexing and throughput. Yet, there is a growing need of extended blood group typing to prevent alloimmunization in transfused patients and transfusion accidents. The knowledge of the molecular bases of blood groups allows the use of molecular biology methods within immunohematology laboratories. Numerous assays focused on blood group genotyping were developed and described during the last 10years. Some of them were real biochips or biosensors while others were more characterized by the particular molecular biology techniques they used, but all were intending to produce multiplex analysis. PCR techniques are most of the time used followed by an analytical step involving a DNA biosensor, biochip or analysis system (capillary electrophoresis, mass spectrometry). According to the method used, the test can then be classified as low-, medium- or high-throughput. There are several companies which developed platforms dedicated to blood group genotyping able to analyze simultaneously various SNPs or variants associated with blood group systems. This review summarizes the characteristics of each molecular biology method and medium-/high-throughput platforms dedicated to the blood group genotyping. [Copyright &y& Elsevier]

We report a simple but efficient method to fabricate versatile graphene nanonet (GNN)-devices. In this method, networks of V2O5 nanowires (NWs) were prepared in specific regions of single-layer graphene, and the graphene layer was selectively etched via a reactive ion etching method using the V2O5 NWs as a shadow mask. The process allowed us to prepare large scale patterns of GNN structures which were comprised of continuous networks of graphene nanoribbons (GNRs) with chemical functional groups on their edges. The GNN can be easily functionalized with biomolecules for fluorescent biochip applications. Furthermore, electrical channels based on GNN exhibited a rather high mobility and low noise compared with other network structures based on nanostructures such as carbon nanotubes, which was attributed to the continuous connection of nanoribbons in GNN structures. As a proof of concept, we built DNA sensors based on GNN channels and demonstrated the selective detection of DNA. Since our method allows us to prepare high-performance networks of GNRs over a large surface area, it should open up various practical biosensing applications. [ABSTRACT FROM AUTHOR]

Abstract: Aptamer-based biochips for selective cell detection and quantitation in combination of the recent biochip technology and the conventional cell staining methods are described. Using a model system comprising HER2- or PSMA-positive cells as the analytes and single-stranded RNA aptamers specific for HER2 or PSMA as immobilized ligands on chips, we could demonstrate that aptamers were equivalent or superior to antibodies in terms of specificity and sensitivity, respectively. In particular, our PSMA-specific sensor was found to have the characteristics of good stability, reproducibility and reusability, with detection limit as low as 103 LNCaP cells. In conclusion, we could show the suitability of nucleic acid aptamers as low molecular weight receptors on biochips for sensitive and specific cell detection and quantitation for future diagnostics development. [Copyright &y& Elsevier]