Carcinoembryonic Antigen (CEA), an acidic glycoprotein with human embryonic antigen properties, is found on the surface of cancer cells that have differentiated from endodermal cells. This paper ...presents a label-free electrochemical immunoassay for the dual amplification detection of CEA using gold nanoparticles loaded with polypyrrole polydopamine (Au/PPy-PDA) and polymerized polycaprolactone (Ng-PCL) prepared by ring-opening polymerization (ROP). First, the composite Au/PPy-PDA was adhered to the electrode surface. Then, gold nanoparticles form a Au–S bond with the sulfhydryl group in Apt1 to secure it on the electrode surface. Subsequently, the non-specific binding sites on the electrodes surface are closed by bovine serum albumin (BSA). Next, CEA is dropped onto the electrode surface, which is immobilized by antigen-antibody specific recognition, and the carboxyl-functionalized Apt2 forms a "sandwich structure" of antibody-antigen-antibody by specific recognition. Polymeric Ng-PCL is adhered to the electrode surface, leading to an increase in the electrochemical impedance signal, resulting in a complete chain of signal analysis. Finally, the response signal is detected by electrochemical impedance spectroscopy (EIS). Under optimal experimental conditions, the method has the advantages of high sensitivity and wide linear range (1 pg mL−1∼100 ng mL−1), and the lower limit of detection (LOD) is 0.234 pg mL−1. And it has the same high sensitivity, selectivity and interference resistance for the real samples detection. Thus, it provides a new way of thinking about biomedical and clinical diagnosis.
Construction principle of label-free electrochemical biosensor based on dual amplification of gold nanoparticles and polycaprolactones for CEA detection. Display omitted
•The method utilizes Au/PPy-PDA nanocomposites and Ng-PCL polymers as dual signal amplification for CEA detection.•Label-free electrochemical biosensors have the advantages of simple instrumentation, fast response and high sensitivity.•This electrochemical biosensor showed good performance in actual sample detection of CEA.•The proposed sensor has high sensitivity, strong selectivity, good stability and low cost.
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.
Circulating tumor cell (CTC) has been a valuable biomarker for the diagnosis of breast cancer, while folate receptor is a kind of cell surface receptor glycoprotein which is overexpressed in breast ...cancer. In this work, we have designed and fabricated an electrochemical biosensor for sensitive detection of folate receptor-positive CTCs based on mild reduction assisted CRISPR/Cas system. Specifically, folate functionalized magnetic beads are firstly prepared to capture CTCs owing to the strong affinity between folate and the folate receptors on the surface of cells. Then, the cell membranes are treated by mild reduction so as to expose a large number of free sulfhydryl groups, which can be coupled with maleimide-DNA to introduce the signal amplified CRISPR/Cas12a system. After the trans-cleavage activity of CRISPR/Cas12a is activated, the long chain DNA modified with electroactive molecules methylene blue can be randomly cleaved into short DNA fragments, which are then captured on the graphite electrode through the host-guest recognition with cucurbit 7uril, generating highly amplified electrochemical signal corresponding to the number of CTCs. The electrochemical biosensor not only demonstrates the sensitivity with a low detection limit of 2 cells/mL, but also highlights its excellent selectivity and stability in complex environment. Therefore, our biosensor may provide an alternative tool for the analysis of CTCs.
•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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•Developing a novel biosensor to detect miRNA-21 based on PET-RAFT signal amplification.•PET-RAFT catalyzed by erythrosin B was first applied to biosensor.•The biosensor has highly ...sensitive to miRNA-21 with a detection limit of 12.4 aM.•The biosensor exhibits an excellent anti-interference ability in serum samples.
Quantitative detection of the cancer-associated biomarker miRNA-21 is essential for the prevention and treatment of early-stage cancer patients. In the early diagnosis of cancer, due to the low concentration of miRNA in the organism, it is necessary to develop a fast, simple, highly sensitive and specific method using signal amplification techniques. Herein, a photo-induced electron/energy transfer reversible addition-fragmentation chain transfer polymerization signal amplification electrochemical biosensor was developed. Peptide nucleic acid was used as the recognition probe for miRNA-21 and the chain transfer agent (4-cyano-4-(dodecylsulfonylsulfanylthiocarbonyl)sulfonylpentanoic acid) bearing a carboxylic acid group was successfully conjugated with a phosphate group in the presence of ZrOCl2 to form the phosphate-Zr(IV)-carboxylic acid complex. Subsequently, the polymerization of the monomer (ferrocenylmethyl methacrylate) was achieved by blue light irradiation in the presence of erythrosin B (higher triple quantum yield) and triethanolamine (increases electron transfer rate). With this sophisticated signal amplification biosensing platform, low detection limit of 12.4 aM was achieved for miRNA-21. The biosensor reduces costs and simplifies experimentation while ensuring high sensitivity and selectivity. Meanwhile, the biosensor exhibits excellent anti-interference ability in serum samples and has great potential for practical applications in the early prevention of cancer.
Detection of urea has garnered considerable attention due to its critical relevance in clinical health assessment and environmental analysis. Fluctuations in urea concentrations within the human body ...can signify diverse disorders, accentuating the need for timely detection for early intervention. Biosensing methods provide a convenient, rapid, selective, and remarkably sensitive approach to the detection of urea. Enzymatic electrochemical biosensors have emerged as pivotal tools in the field of biosensing, owing to their remarkable attributes, including high sensitivity, great specificity, rapid response, and their adaptability to a diverse spectrum of applications. The scope of this review encompasses enzymatic electrochemical urea biosensors documented in the literature, providing a comprehensive summary of the various materials employed for the modification of the working electrode surface, including nanoparticles, carbon-based materials, polymers, and magnetic nanomaterials. Furthermore, this review evaluates the unique structural features and performance parameters of the biosensors, such as their detection limit, detection range, and response time. Through the integration of these critical components, the review emphasizes the strides made in the field, the promising possibilities, and the flexibility of enzymatic electrochemical biosensors in achieving accurate urea detection.
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•An overview on enzymatic electrochemical urea biosensors is provided.•Several materials employed for the modification of working electrode surface are discussed.•Performance parameters of the biosensors including detection limit, detection range, and response time were investigated.
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.
