Fabrication Of Biosensors Research Articles

Ti3C2Tx MXene -facilitated non-selective trapping effect: Efficient SERS detection of exosomal PD-L1

Biosensors developed through a sandwich approach have demonstrated favorable detection performance for exosomal programmed cell death 1 ligand 1 (ExoPD-L1) detection. However, the reported PD-L1 antibodies, peptides, and aptamers utilized in these biosensors typically bind to the extracellular region, with overlapping binding sites that severely constrain the fabrication of biosensors. In this study, we present a simple approach to specifically identify and analyze ExoPD-L1 through the non-selective trapping effect of Ti3C2TX (X=-O, -F, -OH) MXene on exosomes via the formation of Ti–O–P complexation, and the selective capture of peptide-functionalized Au@MPBA (4-Mercaptophenylboronic acid) @SiO2 surface enhanced Raman scattering (SERS) tags on ExoPD-L1. The biosensor delivered a both hypersensitive and reliable performance in exosome detection with a low limit of detection (20.74 particles/mL) in the linear range of 102 to 5×106 particles/mL. Furthermore, the biosensor demonstrated excellent stability and interference resistance in detecting ExoPD-L1 in clinical serum samples, enabling the easy differentiation of breast cancer patients from healthy controls. This work provides new insights into the design of biosensors for exosome detection and can serve as a replicable template for sandwich immunoassay detection for other types of sensors, including but not limited to SERS.

Applications of Nanomaterials for Biosensor Fabrication Based on Redox Enzyme and Protein: A Short Review

Redox enzyme and protein modified biosensors are commercially triumphant bioelectronic devices used in the point-of-care analysis. The use of nanotechnology derived nanomaterials during enzyme immobilization creates a synergistic effect by integrating enzyme’s recognition and catalytic properties with the electronic properties of nanomaterials. This synergy improves the biosensor’s sensitivity, conductivity stability, surface-to-volume ratio, selectivity, detection limit and other analytical features. This critical review focuses on the redox enzymes and proteins most frequently used in glucose and hydrogen peroxide sensing, such as horseradish peroxidase (HRP), glucose oxidase (GOx), hemoglobin (HB), and cytochrome C (Cyt c). Besides, we evaluate the state of art of this approach, selection of nanomaterials, preparation and immobilization mechanisms, their role and sensing applications. Besides advantages, the discussions have discussed on the pressing challenges of developing these sensors. This review will guide the research community to develop rational and highly efficient nanomaterial immobilized biosensors.

Nanomaterials with Plant or Animal Origin for Greener Biodelivery and Biosensor Applications: A Review

Nanomaterials are now used in almost every field of science; as conductors and electrodes in electronics, as nanodelivery systems in health screenings and drug delivery, as nanofibrils in filtering and textile industry, as nanoparticles in biosensor fabrication for toxin and pathogen detection, and in packaging materials in the food industry. Synthetic materials and plastics accumulate in the environment causing increasing health concerns for their use in food and pharmaceutical products. Therefore, researchers now try to find new greener fabrication methods for nanomaterials. In this review, some of the most recent studies were summarized and discussed where novel green nanomaterials were synthesized from plant or animal-based polymers. The focus has been given on the synthesis of 1) nanodelivery systems for bioactive and drug delivery in the form of nanoparticles, nanotubes and nanofibers, 2) nanophotonic film or nanofiber-based biosensors for food toxin and pathogen detection, and 3) functional nanocomposite films. The studies summarized here give the reader a clear understanding of the science behind creating green nanomaterial-based systems and how they are used in various applications.

Amperometric bienzymatic biosensor in flow injection analysis system for determination of aspartame in foods.

An amperometric bienzymatic biosensor was developed for the determination of aspartame in a flow injection analysis (FIA) system, consisting of two enzyme reactor columns packed with immobilized α-chymotrypsin (CHY) and alcohol oxidase (AOX) beads and a hydrogen peroxide electrode, connected in series. The CHY and AOX were separately immobilized on glutaraldehyde (GA)-activated beads through covalent bonding. The biosensor fabrication and operational conditions were optimized. The optimal fabrication conditions were: 2% GA with 120min activation time; and 250 U/mL CHY and 100 U/mL AOX, with 180min enzyme immobilization time. The optimal operational conditions were a flow rate of 0.5mL/min and pH 8.0 at room temperature. The developed biosensor showed linearity over the aspartame concentration range 0.01-1.2mM, with a detection limit of 0.005mM. The developed biosensor was satisfactorily applied for detecting aspartame in beverage samples without any excessive pretreatments.

Recent Advances in Conjugated Polymer-Based Biosensors for Virus Detection

Nowadays, virus pandemics have become a major burden seriously affecting human health and social and economic development. Thus, the design and fabrication of effective and low-cost techniques for early and accurate virus detection have been given priority for prevention and control of such pandemics. Biosensors and bioelectronic devices have been demonstrated as promising technology to resolve the major drawbacks and problems of the current detection methods. Discovering and applying advanced materials have offered opportunities to develop and commercialize biosensor devices for effectively controlling pandemics. Along with various well-known materials such as gold and silver nanoparticles, carbon-based materials, metal oxide-based materials, and graphene, conjugated polymer (CPs) have become one of the most promising candidates for preparation and construction of excellent biosensors with high sensitivity and specificity to different virus analytes owing to their unique π orbital structure and chain conformation alterations, solution processability, and flexibility. Therefore, CP-based biosensors have been regarded as innovative technologies attracting great interest from the community for early diagnosis of COVID-19 as well as other virus pandemics. For providing precious scientific evidence of CP-based biosensor technologies in virus detection, this review aims to give a critical overview of the recent research related to use of CPs in fabrication of virus biosensors. We emphasize structures and interesting characteristics of different CPs and discuss the state-of-the-art applications of CP-based biosensors as well. In addition, different types of biosensors such as optical biosensors, organic thin film transistors (OTFT), and conjugated polymer hydrogels (CPHs) based on CPs are also summarized and presented.

Hollow cage-like PtCu nanozyme-regulated photo-activity of porous CdIn2S4/SnO2 heterojunctions for ultrasensitive PEC sensing of streptomycin

Streptomycin (STR) is extensively employed for preventive and curative purposes in animals, which is accumulated in human body through food chain and induces serious health problems. Herein, highly photoactive type II heterojunctions of porous CdIn2S4/SnO2 microspheres were initially prepared, which can effectively inhibit the recombination of the charge-hole pairs. Besides, the peroxidase-mimicking catalytic property of the hollow PtCu nanocages (PtCu NCs) was carefully investigated by UV–vis spectroscopy, where catalytic oxidation of tetramethylbenzidine behaved as the benchmarked reaction. On such basis, a highly selective photoelectrochemical (PEC) aptasensor was established with the CdIn2S4/SnO2 heterojunctions for bioanalysis of streptomycin, coupled by the PtCu NCs nanozyme-catalyzed biocatalytic precipitation to achieve signal magnification. Specifically, the home-made nanozyme was applied for catalytic oxidation of 3,3’-diaminobenzidine to generate insulating precipitate in aqueous H2O2 system and thereby block the light harvesting on the photoanode, showing steeply declined PEC responses. The as-built aptasensor showed a broad linear range of 0.01–200 nM with a low limit of detection of 7.50 pM (S/N = 3) for such analysis, combined by exploring its practical detection in milk samples. This work shows excellent nanozyme-catalyzed signal amplification for fabrication of ultrasensitive PEC biosensors towards other antibiotics detection.

Multi-signal amplification electrochemiluminescence biosensor based on GO-CDTPA-AuNPs composites and PET-RAFT for ultrasensitive detection of KRAS G12C mutation

The detection of the Kirsten Rat Sarcoma (KRAS) G12C point mutation plays an important role in the early diagnosis and individualized treatment of non-small cell lung cancer (NSCLC). Herein, a novel electrochemiluminescence (ECL) biosensor for the detection of KRAS G12C mutation via GO-CDTPA-AuNPs composites and photo-induced electron/energy transfer reversible addition-fragment chain transfer (PET-RAFT) multi-signal amplification strategy was fabricated for the first time. In this work, gold nanoparticles (AuNPs) were loaded onto the graphene oxide (GO) surface to form a luminol electrochemiluminescence enhanced composite by simple amide reaction and electrostatic adsorption. Specifically, in the presence of KRAS G12C mutation DNA, i.e. target DNA (tDNA), self-assembled hairpin DNA (hDNA) on the biosensor electrode surface was activated after hybridization with the tDNA to expose a 3′-terminal amino group, that could be further linked to GO-CDTPA-AuNPs composites. To increase luminol-based ECL, GO-CDTPA-AuNPs composites contained a lot of photo-induced electron/energy transfer reversible addition-fragment chain transfer (PET-RAFT) agent loaded onto GO surface. PET-RAFT polymerization of N-acryloxysuccinimide (NAS) monomer was initiated to form polymer chains containing multiple binding sites for luminol. Due to the amplification of luminol attachment sites, very high quantities of luminol could be introduced onto the biosensor electrode surface, resulting in significantly amplified ECL signal intensity. Under optimal biosensor fabrication conditions, a good linear relationship between ECL signal intensity and the logarithm of tDNA concentration was observed over the range of 1 fM to 10 nM with a 0.12 fM limit of detection. Moreover, this strategy exhibited high selectivity and excellent applicability for KRAS G12C mutation detection in the clinical human serum samples. Thus, the fabricated biosensor has great potential for application in the clinical diagnosis.

Synthesis and electrochemical study of enzymatic graphene oxide-based nanocomposite as stable biosensor for determination of bevacizumab as a medicine in colorectal cancer in human serum and wastewater fluids

This work's goal was the fabrication of a graphene oxide-based nanocomposite biosensor for the determination of bevacizumab (BVZ) as a medicine for colorectal cancer in human serum and wastewater fluids. For the fabrication electrode, graphene oxide was electrodeposited on GCE (GO/GCE), and then DNA and monoclonal anti-bevacizumab antibodies were immobilized on the GO/GCE surface, respectively (Ab/DNA/GO/GCE). Structural characterization using XRD, SEM, and Raman spectroscopy confirmed the binding of DNA to GO nanosheets and the interaction of Ab with the DNA/GO array. Electrochemical characterization of Ab/DNA/GO/GCE using CV and DPV indicated immobilization of antibodies on DNA/GO/GCE and sensitive and selective behavior of modified electrodes for determination of BVZ. The linear range was obtained 10–1100 μg/mL, and the sensitivity and detection limit values were determined to be 0.14575 μA/μg.mL−1 and 0.02 μg/mL, respectively. To verify the applicability of the planned sensor for determination of BVZ in human serum and wastewater fluid specimens, the outcomes of DPV measurements using Ab, DNA, GO, and GCE and the results of the Bevacizumab ELISA Kit for determination of BVZ in prepared real specimens showed good conformity between the outcomes of both analyses. Moreover, the proposed sensor showed considerable assay precision with recoveries ranging from 96.00% to 98.90% and acceptable relative standard deviations (RSDs) below 5.11%, illustrating sufficiently good sensor accuracy and validity in the determination of BVZ in prepared real specimens of human serum and wastewater fluids. These outcomes demonstrated the feasibility of the proposed BVZ sensor in clinical and environmental assay applications.

An unique DNA junction scaffold-based electrochemical sensing platform achieving multilevel signal responses for amplified multiplexed nucleic acid analysis and logic operation

Herein, a DNA junction scaffold structure was exploited as the only immobilization probe to construct a simple and multifunctional electrochemical sensing platform. The programmable operation of a catalytic DNA circuit reaction on it afforded the amplified and well-controllable signal responses for the individual and simultaneous analysis of two nucleic acid targets. Also, it could be flexibly harnessed for each target assay based on multilevel signal response behaviours including single-signal, dual-signal and ratiometric signal responses. Then, its application for the operation of two logic devices of “AND” and “OR” gates toward different target inputs was demonstrated. Interestingly, the “OR” gate could be in-situ evolved from the “AND” status by simply controlling signal output. The low detection limit could reach 10 fM whether for the simultaneous or individual analysis of two targets in buffer or serum. Current sensing platform by only a DNA junction scaffold probe features in facile biosensor fabrication and operation, sensitive and selective analysis of multiplexed targets, well-controllable and multilevel signal response behaviours, and expandable logic operation. It thus may open a promising avenue toward the development of advanced biosensors or logic devices applied for molecular diagnosis or information processing.

Development of disposable electrode for the detection of mosquito-borne viruses.

Development of disposable, rapid, and convenient biosensor with high sensitivity and reliability is the most desired method of viral disease prevention. To achieve this goal, in this work, a practical impedimetric biosensor has been implemented into a disposable electrode on a screen-printed carbon electrode (SPCE) for the detection of two mosquito-borne viruses. The biosensor fabrication has step-wisely carried out on the disposable electrode surface at room temperature: starting from conductive film formation, physical binding of the gold nanoparticles (AuNPs)-polyaniline (PAni) into the conductive film, and biofunctionalization. To get the maximum efficiency of the antibody, biotinylated antibody has been conjugated on the surface of AuNP-PAni/PAni-SPCE via the streptavidin-biotin conjugation method which is a critical factor for the high sensitivity. Using the antibody-antigen interaction, this disposable electrode has designed to detect mosquito-borne infectious viruses, Chikungunya virus (CHIKV), and Zika virus (ZIKV) separately in a wide linear range of 100fgmL-1 to 1ngmL-1 with a low detection limit of 1.33 and 12.31fgmL-1 , respectively.

Enhancing effect of black phosphorus quantum dots on electrochemiluminescence of Ir(dF(CF3)ppy)2(bpy) in ionic liquid medium and its sensing application

Room temperature ionic liquids are increasingly used in electrochemical measurement because of their excellent properties. In the present work, a strong anodic electrochemiluminescence (ECL) of one kind of water insoluble iridium complex (Ir(dF(CF3)ppy)2(bpy)) was obtained in ionic liquid medium through immobilizing it onto the electrode via solvent evaporation method. Black phosphorus quantum dots (BPQDs) could not only enhance the anodic ECL, but also generate a new anodic ECL at lower potential. The spectral investigation indicated that BPQDs could interact with Ir(dF(CF3)ppy)2(bpy) to enhance ECL signal and induce new ECL. Dopamine could compete with Ir complex to interact with BPQDs, which exhibited apparent inhibiting effect on ECL emission. As a result, dopamine was sensitively detected in the range of 0.1 nM to 0.1 μM with a detection limit of 3.76 × 10−11 mol L−1. The present work revealed that iridium complex ECL could be obtained in ionic liquids, which provided new avenue for the fabrication of ECL biosensor.

Damage-free remote SF6 plasma-treated CNTs for facile fabrication of electrochemical enzyme biosensors

Remote SF6 plasma treatment of CNTs is performed to graft hydrophobic fluorine on the surface of CNTs. Fluorinated CNTs (F-CNTs) allow for the facile adsorption of enzyme molecules via hydrophobic interaction between F-CNTs and the hydrophobic patches of enzyme molecules. The loading of glucose oxidase (GOx) on F-CNTs correlates well with plasma treatment time. Interestingly, the Rct value of GOx/F-CNTs decreases when CNTs are treated with plasma for a short time such as 1 and 5 min, which is due to weakly-bound chemisorbed fluorine molecules on F-CNTs (semi-ionic C-F). As an example, the Rct value of GOx/F-CNT electrode with 1 min plasma treatment is 0.57 times lower than that of GOx/CNTs, while increasing its sensitivity by 2.5 times. Upon extending the treatment time such as 30, 45 and 60 min, the XPS results reveal the dominance of covalently-attached fluorine, leading to marginally-increased resistance and sensitivity. It is worthy of noting this work is the first report of simple enzyme adsorption on remote-plasma treated CNT surfaces together with its detailed mechanism studies, especially for the binding of enzyme molecules semi-ionic fluorine.

MicroRNA Detection via Nanostructured Biochips for Early Cancer Diagnostics.

MicroRNA (miRNA) are constituted of approximately 22 nucleotides and play an important role in the regulation of many physiological functions and diseases. In the last 10 years, an increasing interest has been recorded in studying the expression profile of miRNAs in cancer. Real time-quantitative polymerase chain reaction (RT-qPCR), microarrays, and small RNA sequencing represent the gold standard techniques used in the last 30 years as detection methods. The advent of nanotechnology has allowed the fabrication of nanostructured biosensors which are widely exploited in the diagnostic field. Nanostructured biosensors offer many advantages: (i) their small size allows the construction of portable, wearable, and low-cost products; (ii) the large surface-volume ratio enables the loading of a great number of biorecognition elements (e.g., probes, receptors); and (iii) direct contact of the recognition element with the analyte increases the sensitivity and specificity inducing low limits of detection (LOD). In this review, the role of nanostructured biosensors in miRNA detection is explored, focusing on electrochemical and optical sensing. In particular, four types of nanomaterials (metallic nanoparticles, graphene oxide, quantum dots, and nanostructured polymers) are reported for both detection strategies with the aim to show their distinct properties and applications.

MoS2-ZnO Nanocomposite Mediated Immunosensor for Non-Invasive Electrochemical Detection of IL8 Oral Tumor Biomarker

In order to support biomolecule attachment, an effective electrochemical transducer matrix for biosensing devices needs to have many specialized properties, including quick electron transfer, stability, high surface area, biocompatibility, and the presence of particular functional groups. Enzyme-linked immunosorbent assays, gel electrophoresis, mass spectrometry, fluorescence spectroscopy, and surface-enhanced Raman spectroscopy are common techniques used to assess biomarkers. Even though these techniques provide precise and trustworthy results, they cannot replace clinical applications because of factors such as detection time, sample amount, sensitivity, equipment expense, and the need for highly skilled individuals. For the very sensitive and targeted electrochemical detection of the salivary oral cancer biomarker IL8, we have created a flower-structured molybdenum disulfide-decorated zinc oxide composite on GCE (interleu-kin-8). This immunosensor shows very fast detection; the limit of detection (LOD) for interleukin-8 (IL8) detection in a 0.1 M phosphate buffer solution (PBS) was discovered to be 11.6 fM, while the MoS2/ZnO nanocomposite modified glassy carbon electrode (GCE) demonstrated a high catalytic current linearly from 500 pg to 4500 pg mL-1 interleukin-8 (IL8). Therefore, the proposed biosensor exhibits excellent stability, high accuracy sensitivity, repeatability, and reproducibility and shows the acceptable fabrication of the electrochemical biosensors to detect the ACh in real sample analysis.

Carbonic Anhydrase Enhanced UV-Crosslinked PEG-DA/PEO Extruded Hydrogel Flexible Filaments and Durable Grids for CO2 Capture.

In this study, poly (ethylene glycol) diacrylate/poly (ethylene oxide) (PEG-DA/PEO) interpenetrating polymer network hydrogels (IPNH) were extruded into 1D filaments and 2D grids. The suitability of this system for enzyme immobilization and CO2 capture application was validated. IPNH chemical composition was verified spectroscopically using FTIR. The extruded filament had an average tensile strength of 6.5 MPa and elongation at break of 80%. IPNH filament can be twisted and bent and therefore is suitable for further processing using conventional textile fabrication methods. Initial activity recovery of the entrapped carbonic anhydrase (CA) calculated from esterase activity, showed a decrease with an increase in enzyme dose, while activity retention of high enzyme dose samples was over 87% after 150 days of repeated washing and testing. IPNH 2D grids that were assembled into spiral roll structured packings exhibited increased CO2 capture efficiency with increasing enzyme dose. Long-term CO2 capture performance of the CA immobilized IPNH structured packing was tested in a continuous solvent recirculation experiment for 1032 h, where 52% of the initial CO2 capture performance and 34% of the enzyme contribution were retained. These results demonstrate the feasibility of using rapid UV-crosslinking to form enzyme-immobilized hydrogels by a geometrically-controllable extrusion process that uses analogous linear polymers for both viscosity enhancement and chain entanglement purposes, and achieves high activity retention and performance stability of the immobilized CA. Potential uses for this system extend to 3D printing inks and enzyme immobilization matrices for such diverse applications as biocatalytic reactors and biosensor fabrication.

Biocompatible epoxysilane substituted polymer-based nano biosensing platform for label-free detection of cancer biomarker SP17 in patient serum samples

Herein, we report the results of the studies relating to developing a simple, sensitive, cost-effective, and disposable electrochemical-based label-free immunosensor for real-time detection of a new cancer biomarker, sperm protein-17 (SP17), in complex serum samples. An indium tin oxide (ITO) coated glass substrate modified with self-assembled monolayers (SAMs) of 3-glycidoxypropyltrimethoxysilane (GPTMS) was functionalized via covalent immobilization of monoclonal anti-SP17 antibodies using EDC(1-(3-(dimethylamine)-propyl)-3-ethylcarbodiimide hydrochloride) - NHS (N-hydroxy succinimide) chemistry. The developed immunosensor platform (BSA/anti-SP17/GPTMS@SAMs/ITO) was characterized via scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle (CA), Fourier transform infrared (FT-IR) spectroscopic, and electrochemical techniques such as cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) techniques. The fabricated BSA/anti-SP17/GPTMS@SAMs/ITO immunoelectrode platform was used to measure changes in the magnitude of the current of the electrodes through an electrochemical CV and DPV technique. A calibration curve between current and SP17 concentrations exhibited a broad linear detection range of (100–6000 & 50–5500 pg mL−1), with enhanced sensitivity (0.047 & 0.024 μA pg mL−1 cm−2), limit of detection (LOD) and limit of quantification (LOQ) of 47.57 & 142.9 pg mL−1 and 158.58 & 476.3 pg mL−1, by CV and DPV technique, respectively with a rapid response time of 15 min. It possessed exceptional repeatability, outstanding reproducibility, five-time reusability, and high stability. The biosensor's performance was evaluated in human serum samples, giving satisfactory findings obtained via the commercially available enzyme-linked immunosorbent assay (ELISA) technique, proving the clinical applicability for early diagnosis of cancer patients. Moreover, various in vitro studies in murine fibroblast cell line L929 have been performed to assess the cytotoxicity of GPTMS. The results demonstrated that GPTMS has excellent biocompatibility and can be used for biosensor fabrication.

Craft-and-Stick Xurographic Manufacturing of Integrated Microfluidic Electrochemical Sensing Platform

An innovative modular approach for facile design and construction of flexible microfluidic biosensor platforms based on a dry manufacturing "craft-and-stick" approach is developed. The design and fabrication of the flexible graphene paper electrode (GPE) unit and polyethylene tetraphthalate sheet (PET)6/adhesive fluidic unit are completed by an economic and generic xurographic craft approach. The GPE widths and the microfluidic channels can be constructed down to 300 μm and 200 μm, respectively. Both units were assembled by simple double-sided adhesive tapes into a microfluidic integrated GPE (MF-iGPE) that are flexible, thin (<0.5 mm), and lightweight (0.4 g). We further functionalized the iGPE with Prussian blue and glucose oxidase for the fabrication of MF-iGPE glucose biosensors. With a closed-channel PET fluidic pattern, the MF-iGPE glucose biosensors were packaged and sealed to protect the integrated device from moisture for storage and could easily open with scissors for sample loading. Our glucose biosensors showed 2 linear dynamic regions of 0.05-1.0 and 1.0-5.5 mmol L-1 glucose. The MF-iGPE showed good reproducibility for glucose detection (RSD < 6.1%, n = 6) and required only 10 μL of the analyte. This modular craft-and-stick manufacturing approach could potentially further develop along the concept of paper-crafted model assembly kits suitable for low-resource laboratories or classroom settings.

Heavy metal‐free electrochemical detection of pyrophosphate ions by Nafion/carbon dots decorated screen printed carbon electrodes

AbstractWe employ Nafion‐mixed carbon dots (CDs) and low‐cost screen‐printed carbon electrodes (SPCEs) as foundation matrices for the fabrication of electrochemical biosensors. The NH2 and COOH functional groups present on the SPCE surface after Nafion/CDs deposition allow for pyrophosphate ions (PPis) collection. Using Fe(CN)63− as the electrochemical mediator, the SPCE‐Nafion/CDs are applied to the detection of aqueous PPi by square wave voltammetry. Between 50 and 1 μM, a linear connection is established between the square wave voltammetry current and the PPi concentration. The limit of detection is determined to be 1.01 μM, and recoveries of 113% (±1.9%) and 108% (±3.9%) are achieved for human urine samples spiked with 6 and 3 μM of PPi, respectively. Furthermore, this PPi assay is suitable for the usage of complicated urine matrices without the inclusion of heavy metals. We anticipate that this unique approach will be beneficial for PPi level monitoring in urine during therapeutic treatments of illnesses and malignancies.

Recent Developments in the Design and Fabrication of Electrochemical Biosensors Using Functional Materials and Molecules.

Electrochemical biosensors are superior technologies that are used to detect or sense biologically and environmentally significant analytes in a laboratory environment, or even in the form of portable handheld or wearable electronics. Recently, imprinted and implantable biosensors are emerging as point-of-care devices, which monitor the target analytes in a continuous environment and alert the intended users to anomalies. The stability and performance of the developed biosensor depend on the nature and properties of the electrode material or the platform on which the biosensor is constructed. Therefore, the biosensor platform plays an integral role in the effectiveness of the developed biosensor. Enormous effort has been dedicated to the rational design of the electrode material and to fabrication strategies for improving the performance of developed biosensors. Every year, in the search for multifarious electrode materials, thousands of new biosensor platforms are reported. Moreover, in order to construct an effectual biosensor, the researcher should familiarize themself with the sensible strategies behind electrode fabrication. Thus, we intend to shed light on various strategies and methodologies utilized in the design and fabrication of electrochemical biosensors that facilitate sensitive and selective detection of significant analytes. Furthermore, this review highlights the advantages of various electrode materials and the correlation between immobilized biomolecules and modified surfaces.

Fabrication of Rapid Electrical Pulse-Based Biosensor Consisting of Truncated DNA Aptamer for Zika Virus Envelope Protein Detection in Clinical Samples

Zika virus (ZV) infection causes fatal hemorrhagic fever. Most patients are unaware of their symptoms; therefore, a rapid diagnostic tool is required to detect ZV infection. To solve this problem, we developed a rapid electrical biosensor composed of a truncated DNA aptamer immobilized on an interdigitated gold micro-gap electrode and alternating current electrothermal flow (ACEF) technique. The truncated ZV aptamer (T-ZV apt) was prepared to reduce the manufacturing cost for biosensor fabrication, and it showed binding affinity similar to that of the original ZV aptamer. This pulse-voltammetry-based biosensor was composed of a T-ZV apt immobilized on an interdigitated micro-gap electrode. Atomic force microscopy was used to confirm the biosensor fabrication. In addition, the optimal biosensor performance conditions were investigated using pulse voltammetry. ACEF promoted aptamer-target binding, and the target virus envelope protein was detected in the diluted serum within 10 min. The biosensor waveform increased linearly as the concentration of the Zika envelope in the serum increased, and the detection limit was 90.1 pM. Our results suggest that the fabricated biosensor is a significant milestone for rapid virus detection.