Cell-based Biosensors Research Articles

Toxicity studies of agarwood essential oil in vero cells using electrical impedance sensor

Natural products have traditionally been used for medicinal purposes in Asian communities. Toxicity studies typically use animal testing to predict the harmfulness of a particular substance to human health. For this study, in lieu of animal testing, we utilize cell-based biosensors to evaluate the toxicity of natural products. The cell-based biosensors are fabricated on a printed circuit board with copper electrodes and are equipped with PDMS cell culture chambers. Two different electrodes (interdigitated and circular) were designed. Vero cells were used to represent normal healthy cells. The cells are first cultured on biosensors and then are inoculated with natural products, Taxol (chemo drug – positive control) and DMSO (negative control). Impedances of these biosensors were then recorded at six-hour intervals for 80 hours to determine the growth of the cells. It was found that compared to Taxol, natural products has a very low toxicant values.

Enhancing the copper-sensing capability of Escherichia coli-based whole-cell bioreporters by genetic engineering.

Metals are essential to all organisms; accordingly, cells employ numerous genes to maintain metal homeostasis as high levels can be toxic. In the present study, the gene operons responsive to metal(loid)s were employed to generate bacterial cell-based biosensors to detect target metal(loid)s. The cluster of genes related to copper transport known as the cop-operon is regulated by the interaction between the copA promoter region (copAp) and CueR, turning on and off gene expression upon copper ion binding. Therefore, the detection of copper ions could be achieved by inserting a plasmid harboring the fusion of copAp and reporter genes, such as enzymes and fluorescent genes. However, copAp is not as strong a promoter as other metal-inducible promoters, such as znt-, mer-, and ars-operons; thereby, its sensitivity toward copper ions was not sufficient for quantification. To overcome this problem, we engineered Escherichia coli with a deletion of copA to interfere with copper export from cells. The engineered E. coli whole-cell bioreporter was able to detect copper ions at 0 to 10μM in an aqueous solution. Most importantly, it was specific to copper among several tested heavy metal(loid)s. Therefore, it will likely be useful to detect copper in diverse environmental systems. Although additional improvements are still required to optimize the E. coli-based copper-sensing whole-cell bioreporters presented in this study, our results suggest that there is huge potential to generate whole-cell bioreporters for additional targets by molecular engineering.

Content Cytotoxicity Studies of Colorectal Carcinoma Cells Using Printed Impedance Sensors

Monitoring the effectiveness of drugs on cancer cells is crucial for chemotherapeutics studies. In-vitro cell-based biosensors can be used as an alternative for characteristic studies of cells’ response to drugs. Cell-based sensors provide real-time measurements and require smaller sample volumes compared to conventional T-flask measurement methods. This paper presents a biosensor that detects in real-time, impedance variations of human colon cancer, HCT-116 cells when treated with anti-cancer agent, 5-Fluorouracil (5-FU). Two different extracellular matrix (ECM); polyaniline and gelatin were tested and evaluated in terms of attachment quality. Polyaniline was found to provide the best attachment for HCT-116 cells and was used for cytotoxicity studies. Cytokinetic behavior indicated that 5-FU inhibited HCT-116 cells at IC50 of 6.8 µg/mL. Trypan blue exclusion method for testing cell viability was used to validate the impedance measurements, where the cancer cell concentrations were reduced to ~35% when treated with 2.5 µg/mL, and 50% when treated with 6.8 µg/mL. The results generated by the microfabricated impedance biosensor are comparable to the Trypan blue method since both gave similar cell growth trend. It can be concluded that the impedance biosensor has potential to be used as an alternative method in drug testing applications.

Synthetic biology for microbial heavy metal biosensors.

Using recombinant DNA technology, various whole-cell biosensors have been developed for detection of environmental pollutants, including heavy metal ions. Whole-cell biosensors have several advantages: easy and inexpensive cultivation, multiple assays, and no requirement of any special techniques for analysis. In the era of synthetic biology, cutting-edge DNA sequencing and gene synthesis technologies have accelerated the development of cell-based biosensors. Here, we summarize current technological advances in whole-cell heavy metal biosensors, including the synthetic biological components (bioparts), sensing and reporter modules, genetic circuits, and chassis cells. We discuss several opportunities for improvement of synthetic cell-based biosensors. First, new functional modules must be discovered in genome databases, and this knowledge must be used to upgrade specific bioparts through molecular engineering. Second, modules must be assembled into functional biosystems in chassis cells. Third, heterogeneity of individual cells in the microbial population must be eliminated. In the perspectives, the development of whole-cell biosensors is also discussed in the aspects of cultivation methods and synthetic cells.

Graphene Oxide as a Novel Signal Enhancer for Cell-Based Impedimetric Biosensors

Graphene Oxide as a Novel Signal Enhancer for Cell-Based Impedimetric Biosensors

Generation of an immortalized mesenchymal stem cell line producing a secreted biosensor protein for glucose monitoring.

Diabetes is a chronic disease characterized by high levels of blood glucose. Diabetic patients should normalize these levels in order to avoid short and long term clinical complications. Presently, blood glucose monitoring is dependent on frequent finger pricking and enzyme based systems that analyze the drawn blood. Continuous blood glucose monitors are already on market but suffer from technical problems, inaccuracy and short operation time. A novel approach for continuous glucose monitoring is the development of implantable cell-based biosensors that emit light signals corresponding to glucose concentrations. Such devices use genetically modified cells expressing chimeric genes with glucose binding properties. MSCs are good candidates as carrier cells, as they can be genetically engineered and expanded into large numbers. They also possess immunomodulatory properties that, by reducing local inflammation, may assist long operation time.Here, we generated a novel immortalized human MSC line co-expressing hTERT and a secreted glucose biosensor transgene using the Sleeping Beauty transposon technology. Genetically modified hMSCs retained their mesenchymal characteristics. Stable transgene expression was validated biochemically. Increased activity of hTERT was accompanied by elevated and constant level of stem cell pluripotency markers and subsequently, by MSC immortalization. Furthermore, these cells efficiently suppressed PBMC proliferation in MLR transwell assays, indicating that they possess immunomodulatory properties. Finally, biosensor protein produced by MSCs was used to quantify glucose in cell-free assays. Our results indicate that our immortalized MSCs are suitable for measuring glucose concentrations in a physiological range. Thus, they are appropriate for incorporation into a cell-based, immune-privileged, glucose-monitoring medical device.

Development of a bacterial propionate-biosensor for anaerobic digestion monitoring.

Monitoring anaerobic digestion (AD) leachate for changes in acetate and propionate concentrations is essential for effective AD operation. In this paper the development of a novel propionate cell-based biosensor is described. A previously designed E. coli mutant (IMD Wldgy) that could selectively determine acetate concentrations in synthetic leachates, based on oxygen uptake measurements, was used as a starting point in the development of a propionate biosensor. However, the propionate-grown IMD Wldgy cells exhibited extremely low propionate:acetate O2 consumption ratios (1:2.4). Screening for alternative propionate-grown E. coli strains naturally possessing a more favourable propionate:acetate O2 consumption ratio identified strain IMD 1, which exhibited a positive ratio (1.6:1). To improve the selectivity of the strain, successive gene knockouts were performed generating the IMD 1 hldgyep mutant. However, propionate-grown IMD 1hdlgyep's O2 consumption ratio was deemed too low to be considered as a propionate detecting bio-element. It was reasoned that the mechanisms by which E. coli activates acetate had to be removed. Deleting acs (acetyl-CoA synthesase) and ackA (acetate kinase) from IMD Wldgyep, resulted in an E. coli IMD Wldgyepak knockout mutant that, when grown on propionate, produced a mean propionate:acetate O2 consumption ratio of approx. 13:1. The resulting IMD Wldgyep and IMD Wldgyepak strains, which formed the acetate- and propionate-biosensor, respectively, were capable of detecting acetate and propionate concentrations ranging from 0.05mM to 4.5mM within two-phase AD synthetic leachates.

Real-Time Bioimpedance Sensing of Antifibrotic Drug Action in Primary Human Cells

Fibrotic diseases are among the most serious health issues with severe burdens due to their chronic nature and a large number of patients suffering from the debilitating effects and long-term sequelae. Collagenase treatment is a nonsurgical option but has limited results. To date, there is no potent noninvasive solution for fibrosis. Part of the reason for this is the lack of appropriate in vitro live cell screening tools to assess the efficacy of new therapeutical agents. Here, we demonstrate the utility of a cell-based electrochemical impedance biosensor platform to screen the efficacy of potential antifibrotic compounds. The platform employs a label-free and noninvasive strategy to detect the progression of fibrosis and the potency of the antifibrotic molecules in real-time. The fundamental principle that governs thisnovel system is that dynamic changes in cell shape and adhesion during fibrosis can be measured accurately by monitoring the changes in the impedance. This is achieved by growing the cells on a transparent interdigitated indium tin oxide (ITO) electrodes. It was demonstrated by monitoring the efficacy of a model antifibrotic compound, PXS64, on cells collected from patients with Dupuytren's contracture. We confirmed the validity of the developed biochemical impedance biosensor as an tool for in vitro screening of antifibrotic compounds and provided quantitative information on subcellular influences of the examined chemical molecules using correlative microscopy analyses that monitor the average cell area, cell morphology, and the amount and directionality of the deposited extracellular matrix protein collagen and measurement of cytosolic Ca2+ changes.

Love mode surface acoustic wave and impedance sensors for water toxicity sensing

Clean water supply systems and infrastructure require periodic testing of water samples to maintain water quality. To enable this, toxicity tests need to be rapid, accurate, portable, and low cost to provide affordable water security especially in developing countries. Qualitative and quantitative measurement of contaminants in water is classically done by standard analytic chemical methods, which are time‐consuming, labor‐intensive, expensive, and cannot be performed easily outside the laboratory. An alternative to these methods is cell‐based sensors, which can detect the presence of a wide range of toxicants by monitoring the cell states.Although electric cell‐substrate impedance sensing (ECIS) has been demonstrated to be an effective method for water toxicity sensing, the use of ECIS only is not sensitive enough to detect many toxicants at low concentrations. Merging a sensor platform with multiparametric measurement capabilities could increase the security of detection. Love mode surface acoustic wave (SAW) device is considered as one of the powerful candidates for cell‐based toxicity biosensors. In this study, a hybrid Love mode SAW/ECIS sensor was developed. Theoretical analysis and experiments were performed to demonstrate the capability of two sensing techniques (i.e., SAW and ECIS) for toxicity sensing. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 172–179, 2018

A novel and simple cell-based electrochemical biosensor for evaluating the antioxidant capacity of Lactobacillus plantarum strains isolated from Chinese dry-cured ham

The analysis of antioxidants in foodstuffs has become an active area of research, leading to the recent development of numerous methods for assessing antioxidant capacity. Here we described the fabrication and validation of a novel and simple cell-based electrochemical biosensor for this purpose. The biosensor is used to assess the antioxidant capacity of cell-free extracts from Lactobacillus plantarum strains isolated from Chinese dry-cured ham. The biosensor relies on the determination of cellular reactive oxygen species (ROS) (the flux of H2O2 released from RAW 264.7 macrophage cells) to indirectly assess changes in intracellular oxidative stress level as influenced by L. plantarum strains. A one-step acidified manganese dioxide (a-MnO2) modified gold electrode (GE) was used to immobilize RAW 264.7 macrophage cells, which were then encapsulated in a 3D cell culture system consisting of alginate/ graphene oxide (NaAlg/GO). The biosensor exhibited a rapid and sensitive response for the detection of H2O2 released from RAW264.7 cells. The detection limit was 0.02μM with a linear response from 0.05μM to 0.85μM and the biosensor was shown to have good stability and outstanding repeatability. This technique was then used for evaluating the antioxidant ability of extracts from L. plantarum NJAU-01. According to the electrochemical investigations and assays of SEM, TEM, and ROS, these cell-free extracts effectively reduced the oxidative stress levels in RAW264.7 cells under external stimulation. Extracts from L. plantarum strains at a dose of 1010CFU/mL showed the highest antioxidant activities with a relative antioxidant capacity (RAC) rate of 88.94%. Hence, this work provides a simple and efficient electrochemical biosensing platform based on RAW264.7 cells for fast, sensitive and quantitative assessment of antioxidant capacity of L. plantarum strains. The method demonstrates its potential for rapid screening for evaluating antioxidant properties of samples.

Micromachining on and of Transparent Polymers for Patterning Electrodes and Growing Electrically Active Cells for Biosensor Applications.

We report on microfabrication and assembly process development on transparent, biocompatible polymers for patterning electrodes and growing electrically active cells for in vitro cell-based biosensor applications. Such biosensors are typically fabricated on silicon or glass wafers with traditional microelectronic processes that can be cost-prohibitive without imparting necessary biological traits on the devices, such as transparency and compatibility for the measurement of electrical activity of electrogenic cells and other biological functions. We have developed and optimized several methods that utilize traditional micromachining and non-traditional approaches such as printed circuit board (PCB) processing for fabrication of electrodes and growing cells on the transparent polymers polyethylene naphthalate (PEN) and polyethylene terephthalate (PET). PEN-based biosensors are fabricated utilizing lithography, metal lift-off, electroplating, wire bonding, inkjet printing, conformal polymer deposition and laser micromachining, while PET-based biosensors are fabricated utilizing post-processing technologies on modified PCBs. The PEN-based biosensors demonstrate 85–100% yield of microelectrodes, and 1-kHz impedance of 59.6 kOhms in a manner comparable to other traditional approaches, with excellent biofunctionality established with an ATP assay. Additional process characterization of the microelectrodes depicts expected metal integrity and trace widths and thicknesses. PET-based biosensors are optimized for a membrane bow of 6.9 to 15.75 µm and 92% electrode yield on a large area. Additional qualitative optical assay for biomaterial recognition with transmitted light microscopy and growth of rat cortical cells for 7 days in vitro (DIV) targeted at biological functionalities such as electrophysiology measurements are demonstrated in this paper.

The Application of Whole Cell-Based Biosensors for Use in Environmental Analysis and in Medical Diagnostics.

Various whole cell-based biosensors have been reported in the literature for the last 20 years and these reports have shown great potential for their use in the areas of pollution detection in environmental and in biomedical diagnostics. Unlike other reviews of this growing field, this mini-review argues that: (1) the selection of reporter genes and their regulatory proteins are directly linked to the performance of celllular biosensors; (2) broad enhancements in microelectronics and information technologies have also led to improvements in the performance of these sensors; (3) their future potential is most apparent in their use in the areas of medical diagnostics and in environmental monitoring; and (4) currently the most promising work is focused on the better integration of cellular sensors with nano and micro scaled integrated chips. With better integration it may become practical to see these cells used as (5) real-time portable devices for diagnostics at the bedside and for remote environmental toxin detection and this in situ application will make the technology commonplace and thus as unremarkable as other ubiquitous technologies.

Development of a simple and convenient cell-based electrochemical biosensor for evaluating the individual and combined toxicity of DON, ZEN, and AFB1

A simple and convenient cell-based electrochemical biosensor was developed to assess the individual and combined toxicity of deoxynivalenol (DON), zearalenone (ZEN), and Aflatoxin B1 (AFB1) on Hep G2 cells. The sensor was modified in succession with AuNPs (gold nanoparticles), cysteamine, and laminin. The cells interacting with laminin formed tight cell-to-electrode contacts, and collagen was used to maintain cell adhesion and viability. Electrochemical impedance spectroscopy (EIS) was developed to evaluate mycotoxin toxicity. Experimental results show that DON, ZEN, and AFB1 caused a significant decrease in cell viability in a dose dependent manner. The EIS value decreased with concentrations of DON, ZEN, and AFB1 in the range of 0.01–20, 0.1–50, and 0.1–3.5μg/mL, and IC50 obtained using the developed method was 48.5, 59.0, and 3.10μg/mL, respectively. A synergistic effect was observed between DON and ZEN, an additive effect was observed between DON and AFB1, and an antagonism effect was found in the binary mixtures of ZEN and AFB1 and ternary mixtures. These results were confirmed via CCK-8 assay. Utilizing SEM, we found that cells treated with mycotoxins caused significant changes in cell morphology, thus lessening cell adsorption and impedance reduction. Biological assay indicated that EIS patterns correlated with [Ca2+]i concentrations and apoptosis and necrotic cells ratios, thus effecting electrochemical signals. This method is simpler, more convenient, sensitive, and has a quicker response rate than most conventional cytotoxicity evaluation methods.

Cell Microarray Technologies for High-Throughput Cell-Based Biosensors.

Due to the recent demand for high-throughput cellular assays, a lot of efforts have been made on miniaturization of cell-based biosensors by preparing cell microarrays. Various microfabrication technologies have been used to generate cell microarrays, where cells of different phenotypes are immobilized either on a flat substrate (positional array) or on particles (solution or suspension array) to achieve multiplexed and high-throughput cell-based biosensing. After introducing the fabrication methods for preparation of the positional and suspension cell microarrays, this review discusses the applications of the cell microarray including toxicology, drug discovery and detection of toxic agents.

Optimizing the Performance of Supported Lipid Bilayers as Cell Culture Platforms Based on Extracellular Matrix Functionalization.

Strategies to fabricate biofunctionalized surfaces are essential for many biotechnological applications. Zwitterionic lipid bilayer coatings doped with lipids with chemically selective headgroups provide a robust platform for immobilization of biomolecules in an antifouling, protein resistant background. Herein, we assess the biological activity of two important components of the extracellular matrix (ECM), collagen type I (Col I) and fibronectin (FN), which are covalently attached to a supported lipid bilayer (SLB), and compare their activity with the same proteins, nonspecifically adsorbed onto a SiO2 surface. The characterization of protein coatings by quartz crystal microbalance with dissipation revealed that Col I and FN attached to SLB are less dense and have higher structural flexibility than when adsorbed onto SiO2. Cell adhesion, proliferation, and function, as well as Col I–FN interactions, were more efficient on the ECM-functionalized SLB, making it a promising platform for cell-based diagnostics, tissue engineering, medical implants, and biosensor development.

Label-Free Dynamic Mass Redistribution and Bio-Impedance Methods for Drug Discovery.

Label-free biosensors are increasingly employed in drug discovery. Cell-based biosensors provide valuable insights into the biological consequences of exposing cells and tissues to chemical agents and the underlying molecular mechanisms associated with these effects. Optical biosensors based on the detection of dynamic mass redistribution (DMR) and impedance biosensors using cellular dielectric spectroscopy (CDS) capture changes of the cytoskeleton of living cells in real time. Because signal transduction correlates with changes in cell morphology, DMR and CDS biosensors are exquisitely suited for recording integrated cell responses in an unbiased, yet pathway-specific manner without the use of labels that may interfere with cell function. Described in this unit are several experimental approaches utilizing optical label-free system capturing dynamic mass redistribution (DMR) in living cells (Epic System) and an impedance-based CDS technology (CellKey). In addition, potential pitfalls associated with these assays and alternative approaches for overcoming such technical challenges are discussed. © 2017 by John Wiley & Sons, Inc.

Detection of toxic substances in microbial fuel cells

Microbial fuel cells (MFCs) is a highly promising bioelectrochemical technology and uses microorganisms as catalyst to convert chemical energy directly to electrical energy. Microorganisms in the anodic chamber of MFC oxidize the substrate and generate electrons. The electrons are absorbed by the anode and transported through an external circuit to the cathode for corresponding reduction. The flow of electrons is measured as current. This current is a linear measure of the activity of microorganisms. If a toxic event occurs, microbial activity will change, most likely decrease. Hence, fewer electrons are transported and current decreases as well. In this way, a microbial fuel cell-based biosensor provides a direct measure to detect toxicity for samples. This paper introduces the detection of antibiotics, heavy metals, organic pollutants and acid in MFCs. The existing problems and future application of MFCs are also analyzed.

A localized chemical pulse generator for the development of a microfluidic cell-based biosensor

Cell-based biosensor (CBB) has shown potential to provide a rapid and sensitive measurement means for monitoring specific biological substances. However, the detecting frequency and reusability remain a challenge for further application of CBB. In this paper, a microfluidic cell-based biosensor (μCBB) was developed, which consisted of a localized millisecond chemical pulse as sample introduction for pulsing individual cells without interfering with adjacent cells and single HeLa cells expressing endogenous P2Y receptors as the sensing elements. Gated injection of pinched flow was used to generate millisecond ATP pulses with predefined width. By integrating localized ATP pulse with predefined width, multiple sensing elements could be used to detect ATP pulses without impact on their functionality. Thus, the detecting frequency of the developed μCBB is multiplied by the number of available cells in comparison to that reported previously. We expect the developed method to be potentially useful to enhance the usability of CBB for biological and biomedical analysis.

Precision Plating of Electrogenic Cells on Microelectrodes Enhanced with Nano-Porous Platinum for Cell-Based Biosensing Applications

Microelectrode Array (MEA) devices are well established platforms for biosensing applications, however, limitations in electrode materials and cell coupling to electrodes still exist. Signal-to-noise ratio (SNR), a fabrication limitation, can be improved by reducing the impedance of the microelectrodes without increasing their physical size using conductive nanomaterials. Platinum is a well-studied conductive material that has been determined to be compatible with MEA devices, contains high electronic conductivity, is non-toxic to cells and has excellent catalytic activity. Nano-porous platinum, as compared to pure platinum, has larger surface area enabled by nano-scale definition, and as a result can lower the impedance of microelectrodes. Therefore, in this study nano-porous platinum was electroplated onto thin film gold electrodes to increase SNR in a single-well MEA device. Numerous commercial and research grade MEAs are available and have been subject to for various applications such as disease modeling and pharmaceutical screening. Although high densities of cells can increase the probability of cell-electrode coupling, only signals near electrodes will be detected. Our approach introduces a method of precise patterning of cells on electrodes to increase the probability of cell-electrode coupling and reducing inaccuracies and expenses associated with cell plating. The single-well MEA glass die was designed and fabricated to contain 64 microelectrodes (30 µm diameter with a pitch of 200 µm) and 4 internal on-chip reference electrodes. The MEA glass die fabrication was performed on a 4-inch, 500 µm thick glass wafer. First, metal traces composed of titanium and gold were deposited using lift-off lithography. Subsequently, 5 µm of SU-8 was spin coated and defined as an insulation layer. A separate printed circuit board (PCB) was designed and fabricated to contain 72 contact pads and routing traces. The biocompatible epoxy 353ND was used to package the glass die and PCB in specific orientations determined by alignment markers. Ball bonding with 20 µm diameter gold wire was used to wirebond the glass die to the PCB. A packaging technique was developed that would allow the characterization of key properties of the MEA. This technique involved using copper wire, 100 µm in diameter, and attaching it to the contact pads on the backside of PCBs using a conductive epoxy. Finally, a polystyrene culture well and lid were attached to the MEA using the epoxy, 353ND. Nano-Porous platinum electroplating solution was prepared with a combination of chloroplantinic acid, HCl and lead acetate, all diluted in DI water. Fully packaged devices containing approximately 3 mL of electrolyte were placed within the Axion BioSystems Muse for nano-porous platinum electrodeposition, utilizing the custom Application Specific Integrated Circuit (ASIC) in the system at room temperature. The nano-porous platinum electroplated devices were subsequently characterized using electrical impedance spectroscopy and cyclic voltammetry against the control devices, which contained gold electrodes. The impedance of each device was measured across a scanned frequency range of 10 Hz-100 kHz between the microelectrode, the internal reference electrode and cellular conductive media. The impedance of the nano-porous platinum devices is an order of magnitude lower than the devices with gold electrodes. Cyclic voltammograms were obtained at a scan rate of 20 mV/s in the range from -0.28 to 1.2 V vs. Ag/AgCl. RMS noise comparison between nano-porous platinum electroplated devices and control devices (gold electrodes) was determined using the Muse system and Axion’s Integrated Studio (AxIS) software. Biosensing applications for the devices were explored using electrogenic cells in combination with a precise plating technique. As depicted in Figure 1, cells were positioned in a pattern on and around electrodes to increase the probability of cell-electrode coupling. The electrical response was obtained and analyzed using the Muse system and AxIS software. SNR of action potentials recorded from cells growing on devices enhanced with nano-porous platinum electrodeposition and cells on control devices with gold electrodes were compared. Activity within neuronal networks / beat frequencies of cell patches on electrodes were monitored over the course of 2-3 weeks. The methods explored in this study not only decreases impedance of microelectrodes to increase SNR but also increases cell-electrode coupling by warranting the placement of cells next or on the electrodes by precision patterning. Future studies will aim to optimize electrode sensitivity using novel electrode materials, the porosity of different materials, and characterization using emerging analytical methods. Eventually these devices will provide in vitro systems to monitor both acute and chronic effects of drugs and toxins as well as to perform functional studies under physiological or induced pathophysiological conditions that mimic in vivo damages. Figure 1: Electrogenic cells patterned near nano-porous platinum electrode Figure 1

Smartphone-based portable biosensing system using cell viability biosensor for okadaic acid detection

Okadaic acid (OA), as a diarrheic shellfish poisoning toxin, had wide distribution and frequent occurrence. Therefore, low-cost, high-throughput, wide-range and portable detection of OA was in high demand for food safety and environmental monitoring. In this study, a novel and portable smartphone-based system using cell viability biosensor (CVBS) was developed for label-free, non-invasive and long-term monitoring of cell viability. The variation of cell viability reflected the changes of cell morphology, cell count and cell proliferation indirectly. And this system applied the combination of image analysis and cell counting kit-8 assay (CCK-8) to monitor the reflection. The biosensing system chose HepG2 cells as sensing elements to build CVBS and used it in OA detection. Results showed this system could synchronously detect OA in 96 channels. And this biosensor presented a good performance to various OA concentrations, with a wide linear detection range (10–800μg/L). Moreover, the point-in-time having best detection performance could be located by the traversal algorithm in the monitoring duration. Thus, this cell-based biosensor system provided a convenient and efficient approach in seafood safety testing such as OA screening.