Biosensor Chip Research Articles

Real-Time Monitoring of Post-Surgical and Post-Traumatic Eye Injuries Using Multilayered Electrical Biosensor Chip.

Lack of current techniques for the early monitoring of bleb leaks and other post-traumatic or post-surgical ocular injury has posed an unmet clinical need for the development of new techniques. Present evaluation techniques use either subjective or nonquantitative approaches. At present, there are no FDA approved ocular devices that can directly measure ascorbic acid (AA) concentration levels for both tear film (TF) and aqueous humor (AH) at point-of-care (POC) level. Toward this aim, we present a novel POC quantitative assay, called the ocular biosensor device, which can be used to evaluate the integrity of the anterior surface of the eye by measuring the concentration of AA in TF and AH. Herein, we utilize a novel scientific engineering approach for the development of a disposable paper based POC ocular biosensor strip. A grafted poly(styrene)-block-poly(acrylic acid) (PS-b-PAA) and graphene platelet composite with contour based μ-electrodes design (CBμE) exhibit a highly sensitive platform to perform electrochemical immunosensing technique to study clinical samples that have small volumes like tear fluid. Samples used in this study were collected clinically from subjects undergoing therapeutic anterior chamber paracentesis. The proposed biosensor reports the level of AA concentration on an electronic screen, making the results easy to read, efficient, and reliable.

Biochip Spray: Simplified Coupling of Surface Plasmon Resonance Biosensing and Mass Spectrometry.

A simplified coupling of surface plasmon resonance (SPR) immuno-biosensing with ambient ionization mass spectrometry (MS) was developed. It combines two orthogonal analysis techniques: the biosensing capability of SPR and the chemical identification power of high resolution MS. As a proof-of-principle, deoxynivalenol (DON), an important mycotoxin, was captured using an SPR gold chip containing an antifouling layer and monoclonal antibodies against the toxin and, after washing, the chip could be taken out and analyzed by direct spray MS of the biosensor chip to confirm the identity of DON. Furthermore, cross-reacting conjugates of DON present in a naturally contaminated beer could be successfully identified, thus showing the potential of rapid identification of (un)expected cross-reacting molecules.

Paper-Based Analytical Biosensor Chip Designed from Graphene-Nanoplatelet-Amphiphilic-diblock-co-Polymer Composite for Cortisol Detection in Human Saliva.

Cortisol has been identified as a biomarker in saliva to monitor psychological stress. In this work, we report a label-free paper-based electrical biosensor chip to quantify salivary cortisol at a point-of-care (POC) level. A high specificity of the sensor chip to detect cortisol with a detection limit of 3 pg/mL was achieved by conjugating anticortisol antibody (anti-CAB) on top of gold (Au) microelectrodes using 3,3'-dithiodipropionic acid di(N-hydroxysuccinimide ester (DTSP) as a self-assembled monolayer (SAM) agent. The electrode design utilized poly(styrene)-block-poly(acrylic acid) (PS67-b-PAA27) polymer and graphene nanoplatelets (GP) suspension coated on filter paper to increase the sensitivity of the immune response. A biosensor chip was then integrated with a lab-built low-cost miniaturized printed circuit board (PCB) to provide an electrical connection and to wirelessly transmit/receive electrical signals using MATLAB. This fully integrated proposed hand-held device successfully exhibited a wide cortisol-detection range from 3 pg/mL to 10 μg/mL, with a sensitivity of 50 Ω (pg mL-1)-1. The performance of the proposed cortisol sensor chip was validated using an enzyme-linked immunosorbent assay (ELISA) technique with a regression value of 0.9951. The advantages of the newly developed cortisol immune biosensor over previously reported chips include an improved limit of detection, no need for additional redox medium for electron exchange, faster response to achieve stable data, excellent shelf life, and its economical production.

Multiplexed efficient on-chip sample preparation and sensitive amplification-free detection of Ebola virus

An automated microfluidic sample preparation multiplexer (SPM) has been developed and evaluated for Ebola virus detection. Metered air bubbles controlled by microvalves are used to improve bead-solution mixing thereby enhancing the hybridization of the target Ebola virus RNA with capture probes bound to the beads. The method uses thermally stable 4-formyl benzamide functionalized (4FB) magnetic beads rather than streptavidin coated beads with a high density of capture probes to improve the target capture efficiency. Exploiting an on-chip concentration protocol in the SPM and the single molecule detection capability of the antiresonant reflecting optical waveguide (ARROW) biosensor chip, a detection limit of 0.021pfu/mL for clinical samples is achieved without target amplification. This RNA target capture efficiency is two orders of magnitude higher than previous results using streptavidin beads and the limit of detection (LOD) improves 10×. The wide dynamic range of this technique covers the whole clinically applicable concentration range. In addition, the current sample preparation time is ~1h which is eight times faster than previous work. This multiplexed, miniaturized sample preparation microdevice establishes a key technology that intended to develop next generation point-of-care (POC) detection system.

Surface Modification Procedure for Biosensor Chips Made of Chemically Sensitive Polymers

Polymers are common housing materials in biosensor chips, but are often chemically less resistant than the biosensor components. Hence, modification procedures optimized for biosensor surfaces may affect potential chip materials. Still, it might be more economic to re-adapt a surface modification procedure than to re-establish a chip fabrication process with a chemically more stable polymer. In the following, potential means to deal with chemically less stable polymers are shown.

The effect of isatin on protein-protein interactions between cytochrome b5 and cytochromes P450

Cytochromes P450 (CYP) are involved in numerous biochemical processes including metabolism of xenobiotics, biosynthesis of cholesterol, steroid hormones etc. Since some CYP catalyze indol oxidation to isatin, we have hypothesized that isatin can regulate protein-protein interactions (PPI) between components of the CYP system thus representing a (negative?) feedback mechanism. The aim of this study was to investigate a possible effect of isatin on interaction of human CYP with cytochrome b5 (CYB5A). Using the optical biosensor test system employing surface plasmon resonance (SPR) we have investigated interaction of immobilized CYB5A with various CYP in the absence and in the presence of isatin. The SPR-based experiments have shown that a high concentration of isatin (270 mM) increases Kd values for complexes CYB5A/CYP3А5 and CYB5A/CYP3A4 (twofold and threefold, respectively), but has no influence on complex formation between CYB5A and other CYP (including indol-metabolizing CYP2C19 and CYP2E1). Isatin injection to the optical biosensor chip with the preformed molecular complex CYB5A/CYP3A4 caused a 30%-increase in its dissociation rate. Molecular docking manipulations have shown that isatin can influence interaction of CYP3А5 or CYP3A4 with CYB5A acting at the contact region of CYB5A/CYP.

바이오센서용 CMOS 이미지 센서를 위한 DC-DC Converter 설계

바이오센서용 CMOS 이미지 센서를 위한 DC-DC Converter 설계

Detection of alprazolam with a lab on paper economical device integrated with urchin like Ag@ Pd shell nano-hybrids

We present results of the studies relating to fabrication of a microfluidic biosensor chip based on urchin like Ag@ Pd shell nano-hybrids that is capable of sensing alprazolam through electrochemical detection. Using this chip we demonstrate, with high reliability and in a time efficient manner, the detection of alprazolam present in buffer solutions at clinically relevant concentrations. Methylene blue (MB) was also doped as redox transition substance for sensing alprazolam. Nano-hybrids modified EμPAD showed wide linear range 1–300ng/ml and low detection limit of 0.025ng/l. Low detection limit can further enhance its suitability for forensic application. Nano-hybrids modified EμPAD was also employed for determination of drug in real samples such as human urine. Reported facile lab paper approach integrated with urchin like Ag@ Pd shell nano-hybrids could be well applied for the determination of serum metabolites.

Pressure free nanoimprinting lithography using ladder-type HSQ material for LSPR biosensor chip

We present an ingenious pressure free NIL (Nanoimprint lithography) method by simply employing a very thin PDMS mold along with a Spin-on-Glass HSQ material. Fabricating nano-patterns (i.e. nano-gratings and 2 D nano-arrays) via NIL is advantageous for LSPR based biosensors for producing large working area with high-throughput. Unlike conventional NIL and other fabrication methods, no complicated equipment is required in this work; only a simple heating plate (at 100°C) was utilized for curing time reduction. Nano-pillar structure with definition down to 50–100nm has been successfully fabricated using this method. After Au-deposition, mushroom like Au-capped nano-pillar chip has been successfully validated as a LSPR bio-sensor chip for IgA detection. In addition, this method provides promising features for higher dimensional structures fabrication which is considered as a beneficial tool for LSPR based biosensor sensitivity enhancement.

A fluorescent porous silicon-based biosensor for small molecule detection

Fluorescent porous silicon was prepared as a stable biosensor chip substrate. The aminopropyltriethoxysilane (APTES) molecules are attached in the pores of the porous silicon with a crosslink method, and when the molecules are added into the chip, the fluorescence intensity is reduced according to the concentration of the APTES. Controlled experiments are also presented with the small molecule that cannot be covalently coupled, and the results show that this kind of sensor chip has better specificity. Compared with other conventional methods, this method is simple, quick and label-free.

Fabrication of a Nanogold-Dot Array for Rapid and Sensitive Detection of Vascular Endothelial Growth Factor in Human Serum

A simple and accurate device for early detection of malignancies is paramount for prompt treatment and prevention of metastases. In this study, we describe a novel fabrication method for producing an ordered nanogold-dot array with strong localized surface plasmon resonance (LSPR) and narrow bandwidth. The array was used as an optical biosensing chip for the detection of vascular endothelial growth factor 165 (VEGF165) in human serum. The biochip was constructed by conjugating an anti-VEGF antibody, a specific biorecognition element for VEGF165, onto the array via the fragment crystallizable (Fc) region of the antibody, ultimately increasing the efficiency of VEGF165 detection. The resulting biochip was sensitive, had a wide linear detection range (0.01-100 ng/mL), was specific for VEGF165 (showing no interference when challenged with glucose and ascorbic acid), and characterized by an excellent stability (allowing storage and transportation at room temperature). Owing to the good correlations of VEGF165 measurements obtained with ELISA, we believe that our chip holds promise as a tool for early diagnosis of cancer.

Paper-based magnetic nanoparticle-peptide probe for rapid and quantitative colorimetric detection of Escherichia coli O157:H7

There is a critical and urgent demand for a simple, rapid and specific qualitative and quantitative colorimetric biosensor for the detection of the food contaminant Escherichia coli O157:H7 (E. coli O157:H7) in complex food products due to the recent outbreaks of food-borne diseases. Traditional detection techniques are time-consuming, require expensive instrumentation and are labour-intensive. To overcome these limitations, a novel, ultra-rapid visual biosensor was developed based on the ability of E. coli O157:H7 proteases to change the optical response of a surface-modified, magnetic nanoparticle-specific (MNP-specific) peptide probe. Upon proteolysis, a gradual increase in the golden color of the sensor surface was visually observed. The intensification of color was correlated with the E. coli O157:H7 concentration. The color change resulting from the dissociation of the self-assembled monolayer (SAM) was detected by the naked eye and analysed using an image analysis software (ImageJ) for the purpose of quantitative detection. This biosensor demonstrated high sensitivity and applicability, with lower limits of detection of 12CFUmL−1 in broth samples and 30–300CFUmL−1 in spiked complex food matrices. In conclusion, this approach permits the use of a disposable biosensor chip that can be mass-produced at low cost and can be used not only by food manufacturers but also by regulatory agencies for better control of potential health risks associated with the consumption of contaminated foods.

Facile synthesis of Prussian blue nanocubes/silver nanowires network as a water-based ink for the direct screen-printed flexible biosensor chips

The large-scale fabrication of nanocomposite based biosensors is always a challenge in the technology commercialization from laboratory to industry. In order to address this issue, we have designed a facile chemical method of fabricated nanocomposite ink applied to the screen-printed biosensor chip. This ink can be derived in the water through the in-situ growth of Prussian blue nanocubes (PBNCs) on the silver nanowires (AgNWs) to construct a composite nanostructure by a facile chemical method. Then a miniature flexible biosensor chip was screen-printed by using the prepared nanocomposite ink. Due to the synergic effects of the large specific surface area, high conductivity and electrocatalytic activity from AgNWs and PBNCs, the as-prepared biosensor chip exhibited a fast response (<3s)， a wider linear response from 0.01 to 1.3mM with an ultralow LOD=5µm, and the ultrahigh sensitivities of 131.31 and 481.20µAmM−1cm−2 for the detections of glucose and hydrogen peroxide (H2O2), respectively. Furthermore, the biosensor chip exhibited excellent stability, good reproducibility and high anti-interference ability towards physiological substances under a very low working potential of −0.05. Hence, the proposed biosensor chip also showed a promising potential for the application in practical analysis.

Rapid and label-free bioanalytical method of alpha fetoprotein detection using LSPR chip

Alpha fetoprotein (AFP) is a cancer marker, particularly for hepatocellular carcinoma. Normal levels of AFP are less than 20ng/mL; however, its levels can reach more than 400ng/mL in patients with HCC. Enzyme linked immunosorbent assay (ELISA) and radioimmunoassay (RIA) have been employed for clinical diagnosis of AFP; however, these methods are time consuming and labor intensive. In this study, we developed a localized surface plasmon resonance (LSPR) based biosensor for simple and rapid detection of AFP. This biosensor consists of a UV–Vis spectrometer, a cuvette cell, and a biosensor chip nanopatterned with gold nanoparticles (AuNPs). In our LSPR biosensor, binding of AFP to the surface of the sensor chip led to an increasing magnitude of the LSPR signals, which was measured by an ultraviolet-visible (UV–Vis) spectrometer. Our LSPR biosensor showed sufficient detectability of AFP at concentrations of 1ng/mL to 1μg/mL. Moreover, the overall procedure for detection of AFP was completed within 20min. This biosensor could also be utilized for a point of care test (POCT) by employing a portable UV–Vis spectrometer. Owing to the simplicity and rapidity of the detection process, our LSPR biosensor is expected to replace traditional diagnostic methods for the early detection of diseases.

Hypermetabolism in B-lymphocytes from malignant hyperthermia susceptible individuals.

Malignant hyperthermia (MH) is a pharmacogenetic disorder of skeletal muscle metabolism which is characterized by generalized muscle rigidity, increased body temperature, rhabdomyolysis, and severe metabolic acidosis. The underlying mechanism of MH involves excessive Ca2+ release in myotubes via the ryanodine receptor type 1 (RyR1). As RyR1 is also expressed in B–lymphocytes, this study investigated whether cellular metabolism of native B–lymphocytes was also altered in MH susceptible (MHS) individuals. A potent activator of RyR1, 4–chloro–m–cresol (4-CmC) was used to challenge native B-lymphocytes in a real–time, metabolic assay based on a pH–sensitive silicon biosensor chip. At the cellular level, a dose–dependent, phasic acidification occurred with 4–CmC. The acidification rate, an indicator of metabolic activation, was significantly higher in B–lymphocytes from MHS patients and required 3 to 5 fold lower concentrations of 4–CmC to evoke similar acidification rates to MHN. Native B–lymphocytes from MHS individuals are more sensitive to 4–CmC than those from MHN, reflecting a greater Ca2+ turnover. The acidification response, however, was less pronounced than in muscle cells, presumably reflecting the lower expression of RyR1 in B–lymphocytes.

A novel enzyme based SPR-biosensor to detect bromocriptine as an ergoline derivative drug

In the modern biomedical and therapeutic drug monitoring technology, development of high performance sensing methods for ergoline derivative drug, bromocriptine (BC), is a critical issue due to its plasma low concentration and important function in Parkinson’s disease. The results of the protein-ligand docking simulation consistent with competitive inhibition experimental study strongly support the binding of BC to the laccase active site. Therefore, a new biosensor for direct label-free detection of BC is presented based on surface plasmon resonance (SPR) using laccase from Bacillus sp. HR03 as a recognition element. The biosensor chip surface was constructed by covalent immobilization of the laccase on a SPR carboxymethyl dextran surface. The calculated kinetic affinity (KD) was 5.4nM, which indicated the high affinity between BC and the immobilized laccase. The biosensor could determine BC in a linear detection range from 0.001ng/ml to 1000ng/ml with a lower detection limit of 0.001ng/ml. The biosensor provided acceptable specificity with suitable recovery in simulated blood samples. This new biosensor represents a novel, fast, sensitive, economic cost effective and accurate method for the therapeutic monitoring and detection of the BC.

Hemocompatibility of EpoCore/EpoClad photoresists on COC substrate for optofluidic integrated Bragg sensors

We report on the hemocompatibility properties of EpoCore/EpoClad UV-structurable epoxy resins in combination with a TOPAS® cyclic olefin copolymer substrate for potential application as an optofluidic biosensor chip. For comprehensive hemocompatibility tests human blood is directly exposed to layers of the different chip materials up to 3h. Counts in white blood cells, red blood cells and platelets as well as hemolysis and concentration of thrombin/antithrombin complex (TAT), of complement fragment (C5a) and heparin are determined. Our results attest TOPAS and the epoxy resins high hemocompatibility properties. Subsequently, an optofluidic chip fabrication concept with integrated Bragg grating sensors is suggested. Bragg gratings are directly inscribed into rectangular EpoCore waveguides on TOPAS 6017 substrate by coherent phase mask illumination. UV-structured EpoClad resist serves both as waveguide cladding and microfluidic channel network. In evanescent field refractive index sensing experiments sensitivities up to 76.9nm/RIU and a maximum refractive index resolution of 1.3·10−5 are achieved by detecting multimode Bragg reflections.

Fabrication of gold-deposited plasmonic crystal based on nanoimprint lithography for label-free biosensing application

Here, we developed a highly sensitive label-free plasmonic crystal (PC). The PC is composed of two types of nanoperiodic metal structures, nanodiscs and nanohole arrays, fabricated simultaneously by nanoimprint lithography using a nanostructured polymer mold. The PC absorbed light at specific wavelengths based on localized surface plasmon resonance (LSPR). The strongly enhanced electric field was excited by the combined structures of nanodiscs and nanohole arrays; thus, highly sensitive biosensing was possible. The LSPR-based optical characteristics of the PC were analyzed by finite-difference time-domain simulation; the structure (metal layer thickness) was optimized to respond to changes in the surrounding refractive index with high sensitivity. PC-based biosensor chips were prepared by immobilizing anti-human immunoglobulin G, which was successfully detected in the 200 pg/mL to 200 ng/mL range. Our approach introduces an easy and rapid process allowing large-area fabrication of PCs, resulting in a highly sensitive label-free biosensor device.

Sensor chip design for increasing surface-plasmon-assisted fluorescence enhancement of the V-trench biosensor

A sensor chip design for the V-trench biosensor, which is an instrument for highly sensitive fluorescence assay, was investigated to increase its sensitivity. A simulation based on the transfer matrix method revealed that the vertex angle and electric field enhancements of the V-trench biosensor chip are increased by employing a high-refractive-index material for the chip. It was proved that a chip made of high-refractive-index glass for press molding exhibited a 1.4-fold larger electric field enhancement than that made of polystyrene. Influenza virus detection was also demonstrated using glass chips, and a detection limit of 104 pfu/mL was obtained with a sample volume of 15 µL.

Multiplexed electrochemical immunosensor for label-free detection of cardiac markers using a carbon nanofiber array chip

We present an electrochemical multianalyte or multiplexed immunosensor for simultaneous label free detection of cardiac markers panel, comprising of C-reactive protein, cardiac troponin-I and myoglobin. The multi-electrode biosensor chip contains nine identical but electrically isolated microelectrodes arranged in a 3×3 array configuration. Each electrode contains carbon nanofiber nanoelectrodes grown vertically using plasma enhanced chemical vapor deposition. A hydrophobic photoresist layer, lithographically etched on the chip, exposes the electrodes and helps to selectively immobilize the antibody probes for the three target cardiac biomarkers using carbodiimide chemistry. The real-time label free detection of the three cardiac markers from a mixture is demonstrated with high sensitivity and selectivity. Detection in complex protein mixtures in human blood serum does not show any false positives from non-specific protein adsorption. The results show that the present sensor can serve as a miniaturized, low cost lab-on-a-chip system for the detection of various biomarkers in healthcare, environmental monitoring and security applications.