The development of a cost-effective and environmentally friendly nano-heterostructure electrochemical sensing material for analyzing hazardous substances is a critical and challenging task. ...Variations in Fermi levels (Ef) create a driving force for electron flow at the metal/semiconductor interfaces, leading to the formation of a built-in electric field that enhances charge transfer within the electrochemical sensing layer. In this study, a hierarchical nanoflower-shaped Co3O4/SnO2/polyaniline (Co3O4/SnO2/PANI) heterostructure with a built-in electric field was successfully synthesized using a hydrothermal method and chemical oxidative polymerization. The electrochemical biosensing platform based on Co3O4/SnO2/PANI nanoflowers for detecting dichlorvos through enzyme inhibition principle exhibited excellent analytical performance, including a wide detection range (4.53×10−13 M ∼ 4.53×10−7 M), a low detection limit (12.6 fM), good anti-interference capability, acceptable reproducibility, and recoveries ranging from 92.4 % to 105.7 %. These results were attributed to the exceptional physicochemical properties of the heterostructure, such as excellent electronic conductivity, enhanced charge transfer, a large electrochemical active area due to its unique morphology, and high electrocatalytic property of the heterojunction. This research serves as a valuable reference for designing advanced electrochemical biosensing platforms for hazardous substances in the realms of food safety and environmental monitoring.
•A hierarchical nanoflower-shaped Co3O4/SnO2/PANI heterostructure was controllably synthesized.•The Co3O4/SnO2/PANI nanoflowers largely enhance the electrochemical sensing interlayer charge transfer.•The fabricated electrochemical biosensor exhibits high sensitivity and a low detection limit.
Graphene is an intriguing two-dimensional honeycomb-like carbon material with a unique basal plane structure, charge carrier mobility, thermal conductivity, wide electrochemical spectrum, and unusual ...physicochemical properties. Therefore, it has attracted considerable scientific interest in the field of nanoscience and bionanotechnology. The high specific surface area of graphene allows it to support high biomolecule loading for good detection sensitivity. As such, graphene, graphene oxide (GO), and reduced GO are excellent materials for the fabrication of new nanocomposites and electrochemical sensors. Graphene has been widely used as a chemical building block and/or scaffold with various materials to create highly sensitive and selective electrochemical sensing microdevices. Over the past decade, significant advancements have been made by utilizing graphene and graphene-based nanocomposites to design electrochemical sensors with enhanced analytical performance. This review focus on the synthetic strategies, as well as the structure-to-function studies of graphene, electrochemistry, novel multi nanocomposites combining graphene, limit of detection, stability, sensitivity, assay time. Finally, the review describes the challenges, strategies and outlook on the future development of graphene sensors technology that would be usable for the internet of things are also highlighted.
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•Several synthetic strategies for graphene-based nanocomposites and electrochemical applications are reviewed.•Current limitations and insights of the analytical systems for biosensing are provided.•Electrochemical detection performance in graphene-based sensor are summarized.•The global research trends, need for on-site detection and future availability of the technologies are discussed.
Precisely detecting organophosphorus pesticides (OPs) is paramount in upholding human safety and environmental preservation, especially in food safety. Herein, an electrochemical acetylcholinesterase ...(AChE) sensing platform entrapped in chitosan (Chit) on the glassy carbon electrodes (GCEs) decorated with Pt/MoS2/Ti3C2 MXene (Pt/MoS2/TM) was constructed for the detection of chlorpyrifos. It is worth noting that Pt/MoS2/TM possesses good biocompatibility, remarkable electrical conductivity, environmental stability and large specific surface area. Besides, the heterostructure formed by the composite of TM and MoS2 improves the conductivity and maintains the original structure, which is conducive to improving the electrochemical property. The coordination effect between the individual components enables the even distribution of functional components and enhances the electrochemical performance of the biosensor (AChE-Chit/Pt/MoS2/TM). Under optimal efficiency and sensitivity, the AChE-Chit/Pt/MoS2/TM/GCE sensing platform exerts comparable analytical performance and a wide concentration range of chlorpyrifos from 10−12 to 10−6 M as well as a low limit of detection (4.71 × 10−13 M). Furthermore, the biosensor is utilized to detect OPs concerning three kinds of fruits and vegetables with good feasibility and recoveries (94.81% to 104.0%). This work would provide a new scheme to develop high-sensitivity sensors based on the two-dimensional nanosheet/laminar hybrid structure for practical applications in environmental monitoring and agricultural product detection.
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•An electrochemical sensor was fabricated to detect organophosphorus pesticides (OPs).•Pt/MoS2/Ti3C2 MXene possesses remarkable electrical conductivity and good biocompatibility.•The sensor has environmental stability, abundant active sites and large specific surface area.•The sensor is utilized to measure OPs with low limit of detection (4.71 × 10−13 M).•OPs from three kinds of fruits and vegetables was quantified with good feasibility and recoveries.
Nonspecific adsorption occurring on the surface of electrochemical sensors seriously affects the sensitivity and accuracy of sensing and is particularly prominent when applied to complex food ...matrices. Construction of antifouling sensing surfaces by modifying antifouling materials is a promising approach to address surface biofouling. In this study, a biomimetic phosphorylcholine (PC-SH) was synthesized by a simple Michael addition reaction with a hydrophilic zwitterion group and a thiol group. Poly(sodium-p-styrene sulfonate) (PSS)-doped poly(3,4-ethylenedioxythiophene) (PEDOT) and Au NPs were used as the conductive substrate. As a result, PC-SH effectively enhanced the hydrophilicity of the sensing surfaces, and the biomimetic phosphorylcholine-based antifouling surface showed excellent antifouling ability both in three single protein solutions (signal suppression as low as 0.9 %) and milk samples (signal suppression as low as 0.5 %). The constructed antifouling biosensor was able to sensitively detect TC with a low limit of detection of 8.8 pg mL−1. More importantly, the biomimetic phosphorylcholine-based antifouling biosensor achieved satisfactory recoveries (96.9–107.6 %) in milk with dilution treatment only, which effectively avoided cumbersome sample pre-treatment and proved its promising application for antibiotic monitoring in complex food matrices.
•Biomimetic phosphorylcholine synthesized via a Michael addition reaction.•An antifouling sensing surface prepared by biomimetic phosphorylcholine.•An antifouling electrochemical biosensor with a low limit of detection for TC.•Sensitive detection of TC in milk only by dilution without other pre-treatments.
•MoS2 nanoflowers are prepared by hydrothermal synthesis using (NH4)6Mo7O24•4H2O and CN2H4S.•MoS2 nanoflowers-graphene/ITO electrode can simultaneously detect DA and UA without obvious ...interference.•MoS2 nanoflowers-graphene/ITO electrode exhibits a high sensitivity of 2.29 μA μM−1 for dopamine (DA) and 1.88 μA μM−1 for uric acid (UA) and the limit of detection is 0.12 μM for DA and 0.14 μM for UA, respectively.
MoS2 nanoflowers (NFs) prepared by hydrothermal synthesis were mixed with graphene oxide (GO) suspension prepared by Hummers method. Then, the mixture was spray coated on indium tin oxide (ITO) glass. After heatment, MoS2 NFs-reduced GO/ITO (MoS2 NFs-rGO/ITO) was obtained and used as a working electrode to electrochemically detect dopamine and uric acid simultaneously. The results are as follows: MoS2 NFs with the diameter of ~ 1 μm are composed by nanosheets and the graphene with a high transparence and large number of folds is coated on the surface of MoS2 NFs. A large number of holes form in the electrode so that bioactive molecules can easily enter and contact with the hybrid. The electrode exhibits a high sensitivity (2.29 and 1.88 μA μM−1) for the determination of dopamine and uric acid. The electrode also shows a low detection of limit, good anti-interference and stability. And it can be used for detecting real biomolecules.
Aflatoxin B1 (AFB1), known for its high toxicity, poses a serious threat to the agriculture and food chain, thereby impacting human health. Herein, a facile electrochemical aptasensor was developed ...based on alternating current electrokinetic enrichment for rapid and sensitive detection of AFB1. Alternating electric fields on the interdigital electrode array was introduced to improve the sensitivity and time, because the target could be manipulated for migrating from the solution to the sensing interface instead of aimless random motion, leading to the enrichment of the target. The biosensor achieved the trace detection of AFB1, demonstrating a remarkable detection limit of 9.55 × 10−6 ng/mL, and the linear range of 10−3–102 ng/mL. Furthermore, the biosensor was successfully employed for the detection of AFB1 in actual peanuts and peanut oil, demonstrating its great application potential in food analysis.
•A electrochemical aptasensor was developed based on alternating current electrokinetic enrichment for detection of AFB1.•Alternating electric fields on the interdigital electrode array was introduced to improve the sensitivity and time.•The biosensor response is quantitative from 10−3 to 102 ng/mL, and reaches a limit of detection of 9.55 × 10−6 ng/mL.
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•A multi-functional zwitterionic polymer was prepared via free radical copolymerization.•Dip coating the polymer creates a thin, hydrophilic, and ionically conductive biosensor ...coating.•Improved charge transfer, direct attachment to the electrode, and effective anti-fouling are achieved.•Redox-labeled DNA and COVID-19 can be quantified in unprocessed plasma and unfiltered 50% saliva.•The platform avoids or reduces the need for backfilling/blocking agents and sample pre-processing.
Most electrochemical biosensors require sample processing to reduce biofouling induced by the complex composition of biological samples that typically causes a decrease in the target-to-blank signal. Herein, we report a zwitterionic copolymer bearing sulfobetaine, carboxylic, aldehyde, and thiol groups as a thin (∼16 nm) anti-fouling coating for electrochemical biosensing platforms. The resulting polymer-coated electrodes reduced protein adsorption by ∼ 67 % compared to the bare-gold surface when incubated with radiolabeled human serum albumin (HSA) protein-spiked human plasma, while cyclic voltammetry yielded a 5 % increase in anodic current signal after incubation in 1 % HSA for 1 h compared to the 83 % decrease in anodic current observed with bare gold electrodes. The polymer-coated electrode facilitated the detection of redox-labeled DNA in buffer, as well as in unprocessed and undiluted plasma with detection limits of 23 nM and 21 nM, respectively; detection of 104 cp mL−1 lentivirus pseudotyped with the Omicron spike protein of SARS-CoV-2 in unfiltered 50 % saliva was also achieved within 5 min with improved target-to-blank ratios and reproducibility relative to the well-established PEG-based biosensing platform for detecting COVID-19. On this basis, the Zwitter-repel coating offers potential to sensitively detect other disease biomarkers/analytes while eliminating or reducing the need for sample pre-processing and/or the use of additional backfilling/blocking agents.
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•Adsorption-controlled electrochemical system of TMB on PtNP-modified LIG surface.•TMB electrochemical reaction with reversible dimerization: voltammetric response.•TMB ...electrochemical reaction coupled to preceding oxidation: impedimetric response.•Adsorption-associated phasance as a function of affinity-bound protein concentration.•Capacitive immunosensing of rheumatoid factor; LOD = 0.515 U mL−1 in spiked serum.
Electrokinetic modelling and experimental studies are conducted on an adsorption system, with a model redox-active adsorbate 3,3′,5,5′-tetramethylbenzidine (TMB), strongly adsorbed to a platinum nanoparticle (PtNP)-modified porous laser induced graphene (LIG) surface. The adsorption-assisted system defined here involves an electrochemical reaction coupled to a preceding, surface-bound, chemical oxidation of the adsorbate. TMB is also known to undergo intermediate reversible dimerization during oxidation. A shift in the general expressions governing the voltammetric trends due to this reversible dimerization step, and the associated impact on the electrokinetic parameters is presented here for the first time. Impedance analysis reveals a modified Randles circuit, with the faradaic contribution of the adsorbate represented by a CPE circuit component. The adsorption-associated phasance, Qads, is expressed as a function of the surface concentrations, ΓO and ΓR, of the oxidised and reduced forms. Changes in the total surface concentration of the adsorbate, Γm, as a result of the presence of localised non-conductive entities, such as proteins, can be correlated to Qads, and subsequently, this capacitive change can be utilised for affinity sensing of an antigen on a specific immunosurface. Proof of concept is carried out with the immunosensing of a model protein, rheumatoid factor, on a PtNP-modified LIG surface biofunctionalised with the specific capture probe, the Fc fragment of IgG. The relationship between the antigenic concentration CRF, Qads and Γm is established. This label-free, adsorption-assisted, capacitive biosensing mechanism has not be reported previously, to the best of our knowledge, with a linear range of 0–300 U mL−1 and an LOD of 0.515 U mL−1 in spiked serum samples, comparable to the gold standard, ELISA.
Aflatoxin contamination causes tremendous economic losses and seriously threatens human health due to its prevalence in agricultural products and foods coupled with the severe toxicity of aflatoxins. ...Thus, sensitive, reliable, and rapid methods for aflatoxin analysis are urgently required. In recent years, electrochemical biosensors have emerged as a suitable alternative to gold standard methods that rely on sophisticated instruments (e.g. HPLC-MS). This review aims to describe recent advances (2016–2019) in electrochemical biosensors for aflatoxins detection in novel sensing strategies, recognition reporters, and integrated platforms. Particular emphasis is placed on the utilization of novel sensing strategies including dual-mode detection and ratiometric sensing in the fabrication of biosensors based on electrochemistry, photoelectrochemistry, and electrochemiluminescence. Meanwhile, a comprehensive discussion is provided on the challenges and perspectives related to electrochemical biosensing of aflatoxins.
•This review aims to provide the recent advances of electrochemical biosensors for aflatoxins.•Particular emphasis is given to the ratiometric electrochemical biosensing and dual-mode detection.•Challenges and perspectives related to electrochemical biosensing of aflatoxin are discussed.
Antioxidants play an important role in human health and provide a defense against many diseases. Electrochemical biosensors are considered promising tools for antioxidant research due to their high ...sensitivity, fast response time, and ease of miniaturization and have penetrated a variety of markets, including food analysis, drug screening, and toxicity research. In this review, recent advances in current state-of-the-art electrochemical biosensors and antioxidant assessment strategies are discussed with a focus on the use of several biosensors, and their advantages and limitations for the rapid and precise analysis of antioxidants in foods. It is concluded that there is widespread applications of electrochaemical biosensors in food quality analysis, the functional evaluation of active factors, and effective components screening. The challenges associated with electrochemical biosensor technology and future directions in this field are also presented.
•Electrochemical biosensor strategies are discussed and they have vast potential applications in antioxidant analysis.•Short review on DNA-based electrochemical biosensor used in antioxidant assessment.•Enzyme-based electrochemical biosensors for antioxidants quantification and evaluation were depicted.•The potential of cell-based electrochemical biosensor in antioxidant analysis were demonstrated.
