Electrochemical Biosensing Strategy Research Articles

Bioreceptor modified electrochemical biosensors for the detection of life threating pathogenic bacteria: a review.

The lack of reliable and efficient techniques for early monitoring to stop long-term effects on human health is an increasing problem as the pathogenesis effect of infectious bacteria is growing continuously. Therefore, developing an effective early detection technique coupled with efficient and continuous monitoring of pathogenic bacteria is increasingly becoming a global public health prime target. Electrochemical biosensors are among the strategies that can be utilized for accomplishing that goal with promising potential. In recent years, identifying target biological analytes by interacting with bioreceptors modified electrodes is among the most commonly used detection techniques in electrochemical biosensing strategies. The commonly employed bioreceptors are nucleic acid molecules (DNA or RNA), proteins, antibodies, enzymes, organisms, tissues, and biomimetic components such as molecularly imprinted polymers. Despite the advancement in electrochemical biosensing, developing a reliable and effective biosensor for detecting pathogenic bacteria is still in the infancy stage with so much room for growth. A major milestone in addressing some of the issues and improving the detection pathway is the investigation of specific bacterial detection techniques. The present study covers the fundamental concepts of electrochemical biosensors, human PB illnesses, and the latest electrochemical biosensors based on bioreceptor elements that are designed to detect specific pathogenic bacteria. This study aims to assist researchers with the most up-to-date research work in the field of bio-electrochemical pathogenic bacteria detection and monitoring.

A Clinically Feasible Diagnostic Typing of Breast Cancer Built on a Homogeneous Electrochemical Biosensor for Simultaneous Multiplex Detection.

Simultaneous detection of multiple tumor markers is of great significance for an accurate diagnosis and early treatment of cancer. Electrochemical homogeneous biosensing strategies have been shown to have advantages, such as high sensitivity and no electrode modification, but they are still a challenge in the field of simultaneous detection of multiple tumor markers. The ER, PR, HER2, and Ki67 proteins are the standard biomarkers for the clinical molecular typing of breast cancer. Precise, sensitive, and simultaneous detection of these four biomarkers is of great importance in the molecular typing of breast cancer, which helps in the creation of personalized treatment plans. In the present study, we developed an electrochemical homogeneous electrochemical bioplatform based on metal ions/SiO2NPs/magnetic beads for detection of the four biomarkers and simultaneous diagnosis of the 10 types of breast cancer directly in human serum at one system by a single electrode. The electrochemical bioplatform has a short detection time of 140 min; however, the current clinical tissue testing time takes about 1 week. Also, the electrochemical bioplatform selectively detects HER2, ER, Ki67, and PR in a range of 0-1000 pg/mL with detection limits of 2, 1.8, 10.36, and 1.33 pg/mL, respectively.

An electrochemical aptasensor for zearalenone detection based on the Co3O4/MoS2/Au nanocomposites and hybrid chain reaction.

Anelectrochemical aptasensor was used for the fast and sensitive detection of zearalenone (ZEN) based on the combination of Co3O4/MoS2/Au nanocomposites and the hybrid chain reaction (HCR). The glassy carbon electrode was coated with Co3O4/MoS2/Au nanomaterials to immobilize the ZEN-cDNA that had been bound with ZEN-Apt by the principle of base complementary pairing. In the absence of ZEN, the HCR could not be triggered because the ZEN-cDNA could not be exposed. After ZEN was added to the surface of the electrode, a complex structure was produced on the modified electrode by the combination of ZEN and ZEN-Apt. Therefore, the ZEN-cDNA can raise the HCR to produce the long-strand dsDNA structure. Due to the formation of dsDNA, the methylene blue (MB) could be inserted into the superstructure of branched DNA and the peak currents of the MB redox signal dramatically increased. So the concentration of ZEN could be detected by the change of signal intensity. Under optimized conditions, the developed electrochemical biosensing strategy showed an outstanding linear detection range of 1.0×10-10 mol/L to 1.0×10-6 mol/L, a low detection limit (LOD) of 8.5×10-11 mol/L with desirable selectivity and stability. Therefore, the fabricated platform possessed a great application potential in fields of food safety, medical detection, and drug analysis.

Electrochemical detection strategies for cardiovascular disease biomarkers: Applications in troponin I and troponin T assays

Electrochemical biosensors have emerged as promising tools for the sensitive and rapid detection of cardiac troponin I (cTnI) and troponin T (cTnT), essential biomarkers for the diagnosis and management of cardiovascular diseases (CVD). This comprehensive review explores the recent advancements in electrochemical biosensing strategies for cTnI and cTnT detection, focusing on antibody-based immunosensors, aptamer-based biosensors, and the integration of nanomaterials and microfluidic platforms. The biological aspects, diagnostic and prognostic value, and evolution of troponin assays are discussed in detail. The review highlights the remarkable performance of electrochemical biosensors, achieving femtomolar to attomolar detection limits and clinically relevant linear ranges. Signal amplification strategies and the potential for non-invasive monitoring using alternative biofluids are also explored. Although challenges persist in clinical validation and commercialization, the opportunities for multiplexed analysis, integration with digital health technologies, and personalized CVD management are promising.

Microfluidic-Based Non-Invasive Wearable Biosensors for Real-Time Monitoring of Sweat Biomarkers.

Wearable biosensors are attracting great interest thanks to their high potential for providing clinical-diagnostic information in real time, exploiting non-invasive sampling of biofluids. In this context, sweat has been demonstrated to contain physiologically relevant biomarkers, even if it has not been exhaustively exploited till now. This biofluid has started to gain attention thanks to the applications offered by wearable biosensors, as it is easily collectable and can be used for continuous monitoring of some parameters. Several studies have reported electrochemical and optical biosensing strategies integrated with flexible, biocompatible, and innovative materials as platforms for biospecific recognition reactions. Furthermore, sampling systems as well as the transport of fluids by microfluidics have been implemented into portable and compact biosensors to improve the wearability of the overall analytical device. In this review, we report and discuss recent pioneering works about the development of sweat sensing technologies, focusing on opportunities and open issues that can be decisive for their applications in routine-personalized healthcare practices.

Recent advances in nonenzymatic electrochemical biosensors for sports biomarkers: focusing on antibodies, aptamers and molecularly imprinted polymers.

Nonenzymatic electrochemical biosensors, renowned for their high sensitivity, multi-target analysis capabilities, and miniaturized integration, align well with the requirements of non-invasive, multi-index integrated, continuous monitoring, and user-friendly wearable biosensors in sports science. In the past three years, novel strategies targeting specific responses to sports biomarkers have opened new avenues for applications in sports science. However, these advancements also pose challenges in achieving adequate sensitivity and specificity for online analysis of complex sweat bio-samples. Our article focuses on three key nonenzymatic electrochemical biosensing strategies: antigen-antibody reactions, nucleic acid aptamer recognition, and molecular imprinting capture. We delve into strategies to enhance specificity and sensitivity in the application of biosensors in sports science, including shortening signal transduction paths through built-in signal probes, increasing reaction sites through increased surface area and the introduction of nanostructures, multi-target analyses, and microfluidic techniques.

High-sensitive and rapid electrochemical detection of miRNA-31 in saliva using Cas12a-based 3D nano-harvester with improved trans-cleavage efficiency

Salivary miRNA-31 is a reliable diagnostic marker for early-stage oral squamous cell carcinoma (OSCC), but accurate detection of miRNA-31 in saliva samples is a challenge because of its low level and high sequence homology. The CRISPR/Cas12a system has the exceptional potential to enable simple nucleic acid analysis but suffers from low speed and sensitivity. To achieve rapid and high-sensitive detection of miRNA-31 using the CRISPR/Cas12a system, a Cas12a-based nano-harvester activated by a polymerase-driven DNA walker, named as dual 3D nanorobots, was developed. The target walked rapidly on the surface of DNA hairpin-modified magnetic nanoparticles driven by DNA polymerase, generating numerous double-strand DNA (dsDNA). Then, the Cas12a bound to the generated dsDNA for activating its trans-cleavage activity, forming 3D nano-harvester. Subsequently, the harvester cut and released methylene blue-labeled DNA hairpins immobilized on the sensing interface, leading to the change in electrochemical signal. We found that the trans-cleavage activity of the harvester was higher than the conventional CRISPR/Cas12a system. The developed dual 3D nanorobots could enable rapid (detection time within 60 min), high-sensitive (detection limit of femtomolar), and specific analysis of miRNA-31 in saliva samples. Thus, our established electrochemical biosensing strategy has great potential for early diagnosis of OSCC.

DNA-functionalized carbon quantum dots for electrochemical detection of pyocyanin: A quorum sensing molecule in Pseudomonas aeruginosa

The electrochemical biosensing strategy for pyocyanin (PYO), a virulent quorum-sensing molecule responsible for Pseudomonas aeruginosa infections, was developed by mimicking its extracellular DNA interaction. Calf thymus DNA (ct-DNA) functionalized amine-containing carbon quantum dots (CQDs) were used as a biomimetic receptor for electrochemical sensing of PYO as low as 37 nM in real urine sample. The ct-DNA-based biosensor enabled the selective measurement of PYO in the presence of other interfering species. Calibration and validation of the PYO sensor platform were demonstrated in buffer solution (0–100 μM), microbial culture media (0–100 μM), artificial urine (0–400 μM), and real urine sample (0–250 μM). The sensor capability was successfully implemented for point-of-care (POC) detection of PYO release from Pseudomonas aeruginosa strains during lag and stationary phases. Cross-reactivity of the sensing platform was also tested in other bacterial species such as Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, Shigella dysenteriae, Staphylococcus aureus, and Streptococcus pneumoniae. Potential clinical implementation of the ct-DNA-based sensor was manifested in detecting the PYO in P. aeruginosa cultured baby diaper and sanitary napkin. Our results highlight that the newly developed ct-DNA-based sensing platform can be used as a potential candidate for real-time POC diagnosis of Pseudomonas aeruginosa infection in clinical samples.

An enzyme-free electrochemical biosensor based on NiCoP@PtCu nanozyme and multi-MNAzyme junctions for ultrasensitive Uracil-DNA glycosylase detection

Abnormal expressions of uracil-DNA glycosylase (UDG) have been associated with various diseases. We proposed a novel electrochemical biosensing platform-based strategy for UDG detection. This method combined NiCoP@PtCu nanozyme with multi-MNAzyme junctions. The U base was deleted in the presence of UDG, resulting in self-assembly of multi-MNAzyme junctions with the ability to continually cleave DNA hairpins and release various products. The products could bind the protective probes, exposing capture probes on the electrode’s surface. Moreover, the exposed probes hybridized with the sDNAs-labeled NiCoP@PtCu nanozyme, yielding a significant electrochemical signal. The established biosensor was enzyme-free and with an ultrahigh sensitivity. Benefiting from the twofold amplification of multi-MNAzyme junctions and nanozyme, the sensing technique exhibited a large dynamic range, from 0.001 to 1.0 U mL −1 and a low detection of 6.6 × 10−4 U mL −1. In addition, the method was effectively used for UDG detection in lysed cells. Therefore, the biosensor we established has broad prospects in clinical diagnosis and biomedical research.

A universal distance-independent ratiometric electrochemical biosensing strategy based on competitive host-guest interactions for matrix metalloproteinase-2 detection

A versatile and universal distance-independent ratiometric electrochemical biosensing strategy was developed for accurate and sensitive determination of matrix metalloproteinase-2 (MMP-2). The universal ratiometric biosensing surface with excellent electrocatalytic activity and dual signal output mode was successfully constructed through the electrodeposition of β-CD on PtGa nanorods decorated graphene oxide modified electrode surface and using bisphenol A (BPA) and rhodamine B (RhB) as ratiometric probes. The target MMP-2 could trigger the release of phospholipase A2 from the as prepared multi-functionalized magnetic bead to release a large amount of BPA encapsulated with liposome and realize “one-to-many” amplification. Based on the competitive host-guest interactions, the released BPA could replace RhB, which results in the peak current of RhB (IRhB) decreased and the peak current of BPA (IBPA) appeared correspondingly. As a result, the IBPA/IRhB can be used to accurately reflect the original level of MMP-2. Accordingly, the biosensor exhibited a wide linear detection range from 0.1 fg/mL to 0.1 ng/mL with a detection limit of 36.57 ag/mL for MMP-2. This work opens a promising avenue to develop the distance-independent ratiometric biosensing system and provide favorable expansibility for the universal detection of biomolecules.

An Electrochemical Immunoassay System for Measuring Circulating Protein Biomarkers of Pediatric Soft Tissue Sarcoma

The combination of simple, inexpensive 3D-printed flow cells with electrochemical biosensors has recently emerged a promising strategy for detecting molecular biomarkers of disease. In this study, we report a multiplex electrochemical immunoassay based on pencil graphite electrode arrays, 3D-printed flow cells and magnetic bead bioconjugates for simultaneous detection of three biomarker proteins (cancer antigen 125 (CA-125), midkine (MK) and osteopontin (OPN)) linked to pediatric soft tissue sarcoma (PSTS). Magnetic bead bioconjugates are functionalized with large amounts of antibody and enzyme labels according to a previously reported strategy,1 pencil graphite electrodes are modified with gold nanoparticles and antibodies for specific capture of bioconjugate-labeled biomarkers, and 3D-printed flow cells to facilitate amperometric detection. Using this immunoassay platform, detection limits for CA-125, MK and OPN that are 100 times lower than those obtained using commercial enzyme-linked immunosorbent assay (ELISA) can be achieved. The combination of low-cost pencil graphite electrode arrays with the convenience of multi-labeled magnetic bead bioconjugates and simplicity of 3D-printed flow-cells results in a promising electrochemical biosensing strategy for biomarker proteins CA-125, MK, and OPN in human serum samples.Reference(1) Malhotra, R.; Patel, V.; Chikkaveeraiah, B. v.; Munge, B. S.; Cheong, S. C.; Zain, R. B.; Abraham, M. T.; Dey, D. K.; Gutkind, J. S.; Rusling, J. F. Ultrasensitive Detection of Cancer Biomarkers in the Clinic by Use of a Nanostructured Microfluidic Array. Analytical Chemistry 2012, 84 (14), 6249–6255. https://doi.org/10.1021/ac301392g.

Taking glucose as intermediate bridge-signal-molecule for on-site and convenient detection of ochratoxin A in rice with portable glucose meter

On-site screening of biotoxins is of great importance for food safety. A new electrochemical-biosensing strategy was constructed for ochratoxin A (OTA) detection by direct using ready-made commercial portable-glucose-meter (PGM). Aptamer against OTA was adopted as the recognition probe and pre-immobilized onto the sensing interface. The complementary biotin-modified probe was further decorated by hybridization. Biotinylated invertase was further introduced onto the sensing system with streptavidin, which also acted as the signal amplification unit. The invertase, which was depended on the amount of OTA, produced the glucose from sucrose in the sensing solution. The glucose could be directly and conveniently measured with PGM. Quantitative analysis of OTA was achieved with a linear range from 0.5 ng/mL to 10 ng/mL and detection limit of 0.45 ng/mL. Of significance, it has been successfully applied for OTA analysis in rice with satisfied recoveries. This unique PGM-based electrochemical platform reveals prospective potential in food safety monitoring.

Designing Triangular Silver Nanoplates with GSH/GSSG Surface Mixed States as Novel Nanoparticle-based Redox Mediators for Electrochemical Biosensing.

Herein, a dual signal-quenched electrochemical (EC) biosensing strategy utilizing surface-engineered trisodium citrate (TSC)-glutathione (GSH)/oxidized glutathione (GSSG)-capped triangular silver nanoplates (Tri-Ag NPsTSC-GSH/GSSG) as a novel nanoparticle-based redox mediator was explored for biomarker determination. In contrast with conventional redox mediators, Tri-Ag NPsTSC-GSH/GSSG provided more admirable EC performance along with a lower oxidation potential (∼0.14 V). Taking advantage of the split-type mode, the immune response in a 96-well microplate was independent from EC detection, which could effectively eliminate the biological interference and thereby greatly enhance the sensitivity. As for the surface engineering process of Tri-Ag NPs, it was composed of partial GSH replacement and the formation of the GSH/GSSG surface mixed state. Primarily, the signal response of Ag NPsTSC-GSH decreased due to the hindrance of GSH on electron transfer. Moreover, varying proportions of GSH/GSSG could further impede the oxidation process of Tri-Ag NPsTSC-GSH/GSSG and eventually realize efficient dual signal quenching of this system. Notably, the ZIF-67@MIL-88B-GOx nanocomposite as the label was applied for a cascade reaction system with GSH peroxidase-like activities to form the optimal GSH/GSSG proportion, causing sensitive changes in signal response with a range of different antigen concentrations. On this basis, the fabricated biosensor provided measurable outputs of aflatoxin B1 concentrations in a linear range of 0.0005-50 ng/mL with a low detection limit of 0.61 pg/mL (S/N = 3). All of the results indicated that the novel biosensor could be a promising analytical tool for future biomarker detection.

Recent advances on the electrochemical and optical biosensing strategies for monitoring microRNA-21: a review.

The small non-coding RNA, microRNA-21 (miR-21), is dysregulated in various cancers and can be considered an appropriate target for therapeutic approaches. Therefore, the detection of miR-21 concentration is important in the diagnosis of diseases. Low specificity and the cost of materials are two necessary limitations in the traditional diagnosis method such as RT-PCR, northern blotting and microarray analysis. Biosensor technology can play an effective role in improving the quality of human life due to its capacity of rapid diagnosis, monitoring different markers, suitable sensitivity, and specificity. Moreover, bioanalytical systems have an essential role in the detection of biomolecules or miRNAs due to their critical features, including easy usage, portability, low cost and real-time analysis. Electrochemical biosensors based on novel nanomaterials and oligonucleotides can hybridize with miR-21 in different ranges. Moreover, optical biosensors and piezoelectric devices have been developed for miR-21 detection. In this study, we have evaluated different materials used in bioanalytical systems for miR-21 detection as well as various nanomaterials that offer improved electrodes for its detection.

Two-stage nicking enzyme signal amplification (NESA)-based biosensing platform for the ultrasensitive electrochemical detection of pathogenic bacteria.

The sensitive and selective detection of pathogenic bacteria represents an essential approach in food safety analysis and clinical diagnostics. We report the development of a simple, rapid, and low-cost electrochemical biosensing strategy for the detection of pathogenic bacteria with ultrasensitivity and high specificity. The biosensor relies on the target and aptamer binding-triggered two-stage nicking enzyme signal amplification (NESA) and three-way junction probe-mediated electrochemical signal transduction. In the presence of the target S. typhimurium, the specific binding of S. typhimurium and aptamer results in the release of a primer, which hybridizes with HAP1 and initiates an extension reaction with the aid of polymerase and dNTPs. A specific recognition site for Nt.BsmaI is generated in the DNA duplex; thus, the produced DNA is nicked and the secondary primer is released (named recycle I). Subsequently, the reaction solution supplemented with a helper DNA is dropped on the electrode surface, and a three-way junction probe containing a specific recognition site for Nt.BsmaI is thus formed. The MB-labeled probe is nicked with the help of Nt.BsmaI and the dissociated primer-helper DNA duplex combines with another HAP2 (named recycle II). Thus, a remarkably decreased electrochemical signal is generated because the electroactive MB is far away from the electrode surface. As far as we know, this work is the first time that NESA and three-way junction probe-mediated electrochemical signal transduction has been used for pathogenic bacteria detection. Under optimal conditions, the results reveal that the calibration plot obtained for S. typhimurium is approximately linear from 9.6 to 9.6 × 105 cfu mL-1 with the limit of detection of 8 cfu mL-1. Additionally, the proposed strategy has been successfully applied to the quantitative assay of S. typhimurium in the real samples. Therefore, the NESA-based biosensing strategy might create a useful and practical platform for pathogenic bacteria identification, and the related food safety analysis and clinical diagnosis.

Sandwich-type microRNA biosensor based on graphene oxide incorporated 3D-flower-like MoS2 and AuNPs coupling with HRP enzyme signal amplification.

A sandwich electrochemical biosensing strategy for ultrasensitive detection of miRNA-21 was developed by using graphene oxide incorporated 3D-flower-like MoS2 (3D MoS2-rGO) nanocomposites as the substrate and horseradish peroxidase (HRP)-functionalized DNA strand 1 (S1)-gold nanoparticles (S1-AuNPs-HRP) as signal amplification probes. Herein, 3D MoS2-rGO nanocomposites not only had a large specific surface area and excellent conductivity, but also provided more attachment sites for electrodepositing AuNPs. In the presence of target miRNA, a sandwich structure was formed, and the determination of the miRNA-21 was carried out by measuring the DPV response of H2O2 mediated by hydroquinone (HQ) at a potential of + 0.052V (vs AgCl reference electrode). Under the optimal experimental conditions, the as-prepared biosensor enabledthe ultrasensitive detection of miRNA-21 from 5 fM to 0.5μM with the low detection limit of 0.54 fM (S/N = 3), comparable or lower than previous reported methods for miRNA-21 detection, which benefited from the synergistic amplification of 3D MoS2-rGO and AuNPs-HRP. Theprepared biosensor showed satisfactory selectivity, reproducibility, and stability towards miRNA-21 detection. Thebiosensor was feasible for accurate and quantitative detection of miRNA-21 in normal human serum samples with RSD below 5.86%, which showed a great potential in clinical analysis and disease diagnosis.

Electrochemical biosensing of DENV nucleic acid amplified with triplet nanostructure-mediated dendritic hybridization chain reaction

A universal and highly sensitive electrochemical biosensing strategy was developed by using a triplet nanostructure-mediated dendritic hybridization chain reaction (HCR) for the analysis of Dengue virus (DENV) nucleic acid. A locked dsDNA was firstly recognized by the target DENV nucleic acid fragment to release the initiator, which was then captured by a capture DNA modified gold electrode to initiate the HCR in the presence of biotin labeled substrates A and B, and two helpers. After the recognition reactions of the captured initiator with substrate A and then helper 1, one DNA structure was formed to react with substrate B, which produced a triplet nanostructure to trigger the dendritic HCR by the toehold of the hybridization structure. After the dendritic product was bound with avidin labeled horseradish peroxidase (avidin-HRP), an amperometric signal could be obtained to achieve ultrasensitive electrochemical detection of DENV. The non-enzymatic isothermal amplification was driven only by entropy. The stable three-dimensional dendritic nanostructure with rigid double helix could assure the excellent performance of the designed electrochemical biosensing strategy. The proposed method showed a detection range of 1.6–1000 pM with a detection limit of 188 fM and ability to distinguish single-base mutation. By changing the recognition sequence of the initiator, the detection of different DENV nucleic acid fragments could be achieved with the same performance. Thus, this method had good extendability for other nucleic acids, providing a promising candidate for nucleic acid detection in early clinical diagnosis.

Novel electrochemical biosensor based on Exo III-assisted digestion of dsDNA polymer from hybridization chain reaction in homogeneous solution for CYFRA 21-1 DNA assay

A novel electrochemical biosensing strategy was proposed to detect cytokeratin fragment antigen 21-1 (CYFRA 21-1) DNA based on Exo III-assisted digestion of dsDNA polymer (EADDP) from hybridization chain reaction (HCR). Primarily, the presence of target can drive a catalytic hairpin assembly (CHA) reaction, which was aimed to achieve target recognition and circulation. Then the HCR can be triggered for further signal amplification and generate long dsDNA polymer with signal tags. Subsequently, the introduction of Exo III can digest the long dsDNA polymer to produce large amounts of double signal fragments (DSFs). The above experiments were all carried out in homogeneous solution. Finally, the released DSF can be captured onto the electrode directly by capture probe (CP) and a highly amplified electrochemical signal can be detected. The EADDP in homogeneous solution circumvented complex solid-liquid interface reaction and tedious operation steps on electrode. Besides, one target can be converted into abundant DSFs, which greatly improved the sensitivity. This biosensor exhibited a low detection limit (0.0348 fM) and wide linear range (5 fM ∼ 50 nM) for CYFRA 21-1 DNA biosensing with reliable specificity and stability.

A novel ratiometric electrochemical biosensing strategy based on T7 exonuclease-assisted homogenous target recycling coupling hairpin assembly-triggered double-signal output for the multiple amplified detection of miRNA.

A novel ratiometric electrochemical biosensing strategy based on T7 exonuclease (T7 Exo)-assisted homogenous target recycling coupling hairpin assembly triggered dual-signal output was proposed for the accurate and sensitive detection of microRNA-141 (miRNA-141). Concretely, in the presence of target miRNA, abundant signal transduction probes were released via the T7 Exo-assisted homogenous target recycling amplification, which could be captured by the specially designed ferrocene-labeled hairpin probe (Fc-H1) on -electrode interface and triggered the nonenzymatic catalytic hairpin assembly (Fc-H1 + MB-H2) to realize the cascade signal amplification and dual-signal output. Through such a conformational change process, the electrochemical signal of Fc (IFc) and MB (IMB) is proportionally and substantially decreased and increased. Therefore, the signal ratio of IMB/IFc can be employed to accurately reflect the true level of original miRNA. Benefiting from the efficient integration of the T7 Exo-assisted target recycle, nonenzymatic hairpin assembly and dual-signal output mode, the proposed sensor could realize the amplified detection of miRNA-141 effectively with a wide detection range from 1 fM to 100 pM, and a detection limit of 200 aM. Furthermore, it exhibits outstanding sequence specificity to discriminate mismatched RNA, acceptable reproducibility and feasibility for real sample. This strategy effectively integrated the advantages of multiple amplification and ratiometric output modes, which could provide an accurate and efficient method in biosensing and clinical diagnosis.

Revisiting Electrochemical Biosensing in the 21st Century Society for Inflammatory Cytokines Involved in Autoimmune, Neurodegenerative, Cardiac, Viral and Cancer Diseases.

The multifaceted key roles of cytokines in immunity and inflammatory processes have led to a high clinical interest for the determination of these biomolecules to be used as a tool in the diagnosis, prognosis, monitoring and treatment of several diseases of great current relevance (autoimmune, neurodegenerative, cardiac, viral and cancer diseases, hypercholesterolemia and diabetes). Therefore, the rapid and accurate determination of cytokine biomarkers in body fluids, cells and tissues has attracted considerable attention. However, many currently available techniques used for this purpose, although sensitive and selective, require expensive equipment and advanced human skills and do not meet the demands of today’s clinic in terms of test time, simplicity and point-of-care applicability. In the course of ongoing pursuit of new analytical methodologies, electrochemical biosensing is steadily gaining ground as a strategy suitable to develop simple, low-cost methods, with the ability for multiplexed and multiomics determinations in a short time and requiring a small amount of sample. This review article puts forward electrochemical biosensing methods reported in the last five years for the determination of cytokines, summarizes recent developments and trends through a comprehensive discussion of selected strategies, and highlights the challenges to solve in this field. Considering the key role demonstrated in the last years by different materials (with nano or micrometric size and with or without magnetic properties), in the design of analytical performance-enhanced electrochemical biosensing strategies, special attention is paid to the methods exploiting these approaches.