Electrochemical Biosensing Platform Research Articles

Sandwich-type supersensitive electrochemical aptasensor of glypican-3 based on PrGO-Hemin-PdNP and AuNP@PoPD.

Anew sandwich-type electrochemical biosensing platform was developed by gold @polyphthalenediamine nanohybrids (AuNP@PoPD) as the sensing platform and phosphorus doped reduced graphene oxide-hemin-palladium nanoparticles (PrGO-Hemin-PdNP) as the signal amplifierfor phosphatidylinositol proteoglycan 3 (GPC3).AuNP@PoPD, co-electrodeposited into the screen printed electrode with high conductivity and stability, is dedicated to assembling the primary GPC3 aptamer (GPC3Apt). The second GPC3Apt immobilized on the high conductivity and large surface area of PrGO-Hemin-PdNP was utilized as an electrochemical signal reporter by hemin oxidation (PrGO-Hemin-PdNP-GPC3Apt). In the range 0.001-10.0ng/mL, the hemin oxidation current signal of the electrochemical aptasensor increased log-linearly with the concentration of GPC3, the lowest detection limit was 0.13pg/mL, and the sensitivity was 2.073 μA/μM/cm2. Theaptasensor exhibited good sensing performance in a human serum samplewith the relative error of 4.31-8.07%. The sandwich sensor showed good selectivity and stability for detection GPC3 in human serum samples, providing a new efficient and sensitive method for detecting HCC markers.

First DFT-supported point of care and novel electrochemical biosensing: Determination of yellow fever NS1 antibody in human plasma

In our study, we developed a point of care electrochemical biosensing platform based on the functionalized cysteine-positioned gold electrode to diagnose yellow fever disease from human plasma samples. The developed platform underwent characterization through diverse methods encompassing cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and density-functional theory. The capacitive interaction between yellow fever virus non-structural antigen and antibody gave a cathodic signal at approximately −260 mV, and increased in proportion to the amount of non-structural antibody. The created electrochemical biosensor has an ability to detect 96 ag/mL of the yellow fever non-structural antibody with an extensive analytical range varied from 0.1 fg/mL to 1 μg/mL. The interference effects of various substances that could be found in human plasma, and the performance of the method were examined from the point of recovery and relative standard deviation for human plasma samples; hereby, the results confirmed the unprecedented selectivity and accuracy of the proposed method.

Distinguishable Magnetic Reporter Coordination with Buoyancy-Magnetism Separation for Immobilization-Free Dual-Target Electrochemical Immunosensing.

Simultaneous sensitive and precise determination of multibiomarkers is of great significance for improving detection efficiency, reducing diagnosis and treatment expenses, and elevating survival rates. However, the development of simple and portable biosensors for simultaneous determination of multiplexed targets in biological fluids still faces challenges. Herein, a unique and versatile immobilization-free dual-target electrochemical biosensing platform, which combines distinguishable magnetic signal reporters with buoyancy-magnetism separation, was designed and constructed for simultaneous detection of carcinoembryonic (CEA) and α-fetoprotein (AFP) in intricate biological fluids. To construct such distinguishable magnetic signal reporters with signal transduction, amplification, and output, secondary antibodies of CEA and AFP were respectively functionalized on methylene blue (MB) and 6-(ferrocenyl)hexanethiol (FeC) modified Fe3O4@Au magnetic nanocomposites. Meanwhile, a multifunctional flotation probe with dual target recognition, capture, and isolation capability was prepared by conjugating primary antibodies (Ab1-CEA, Ab1-AFP) to hollow buoyant microspheres. The target antigens of CEA and AFP can trigger a flotation-mediated sandwich-type immunoreaction and capture a certain amount of the distinguishable magnetic signal reporter, which enables the conversion of the target CEA and AFP quantities to the signal of the potential-resolved MB and FeC. Thus, the MB and FeC currents of magnetically adsorbed distinguishable magnetic reporters can be used to determine the CEA and AFP targets simultaneously and precisely. Accordingly, the proposed strategy exhibited a delightful linear response for CEA and AFP in the range of 100 fg·mL-1-100 ng·mL-1 with detection limits of 33.34 and 17.02 fg·mL-1 (S/N = 3), respectively. Meanwhile, no significant nonspecific adsorption and cross-talk were observed. The biosensing platform has shown satisfactory performance in the determination of real clinical samples. More importantly, the proposed approach can be conveniently extended to universal detection just by simply substituting biorecognition events. Thus, this work opens up a new promising perspective for dual and even multiple targets and offers promising potential applications in clinical diagnosis.

Immobilization-free and label-free electrochemical DNA biosensing based on target-stimulated release of redox reporter and its catalytic redox recycling

Herein, we demonstrate a simple, homogenous and label-free electrochemical biosensing system for sensitive nucleic acid detection based on target-responsive porous materials and nuclease-triggered target recycling amplification. The Fe(CN)63− reporter was firstly sealed into the pores of Fe3O4 nanoparticles by probe DNA. Target DNA recognition triggered the controllable release of Fe(CN)63− for the redox reaction with the electron mediator of methylene blue enriched in the dodecanethiol assembled electrode and thereby generating electrochemical signal. The exonuclease III (Exo III)-assisted target recycling and the catalytic redox recycling between Fe(CN)63− and methylene blue contributed for the enhanced signal response toward target recognition. The low detection limit toward target was obtained as 478 fM and 1.6 pM, respectively, by square wave voltammetry and cyclic voltammetry methods. It also possessed a well-discrimination ability toward mismatched strands and high tolerance to complex sample matrix. The coupling of bio-gated porous nanoparticles, nuclease-assisted target amplification and catalytic redox recycling afforded the sensing system with well-controllable signal responses, sensitive and selective DNA detection, and good stability, reusability and reproducibility. It thus opens a new avenue toward the development of simple but sensitive electrochemical biosensing platform.

Low-cost inkjet-printed nanostructured biosensor based on CRISPR/Cas12a system for pathogen detection

The escalating global incidence of infectious diseases caused by pathogenic bacteria, especially in developing countries, emphasises the urgent need for rapid and portable pathogen detection devices. This study introduces a sensitive and specific electrochemical biosensing platform utilising cost-effective electrodes fabricated by inkjet-printing gold and silver nanoparticles on a plastic substrate. The biosensor exploits the CRISPR/Cas12a system for detecting a specific DNA sequence selected from the genome of the target pathogen. Upon detection, the trans-activity of Cas12a/gRNA is triggered, leading to the cleavage of rationally designed single-strand DNA reporters (linear and hairpin) labelled with methylene blue (ssDNA-MB) and bound to the electrode surface. In principle, this sensing mechanism can be adapted to any bacterium by choosing a proper guide RNA to target a specific sequence of its DNA. The biosensor's performance was assessed for two representative pathogens (a Gram-negative, Escherichia coli, and a Gram-positive, Staphylococcus aureus), and results obtained with inkjet-printed gold electrodes were compared with those obtained by commercial screen-printed gold electrodes. Our results show that the use of inkjet-printed nanostructured gold electrodes, which provide a large surface area, in combination with the use of hairpin reporters containing a poly-T loop can increase the sensitivity of the assay corresponding to a signal variation of 86%. DNA targets amplified from various clinically isolated bacteria, have been tested and demonstrate the potential of the proposed platform for point-of-need applications.

Electrochemical Impedimetric Platform Based on Con A@MIL-101 for Glycoprotein Detection.

An electrochemical impedimetric biosensing platform with lectin as a molecular recognition element has been established for the sensitive detection of glycoproteins, a class of important biomarkers in clinical diagnosis. One of the representative metal-organic framework materials, MIL-101(Cr)-NH2, was utilized as the supporting matrix, and its amino groups served as the anchors to immobilize the lectins of concanavalin A (Con A), constituting Con A@MIL-101(Cr)-NH2 for the determination of invertase (INV) as a model glycoprotein. The Con A concentration, immobilization time, and incubation time with INV were optimized. Under the optimal conditions, the degree of impedance increase was linearly proportional to the logarithm of INV concentration between 1.0 × 10-16 and 1.0 × 10-11 M, affording a limit of detection as low as 3.98 × 10-18 M. Good specificity, stability, reproducibility, and repeatability were demonstrated for the fabricated biosensing platform. Moreover, real mouse serum samples were spiked with different concentrations of INV. Excellent recoveries were obtained, which demonstrated the biosensing platform's capability of analyzing glycoproteins within a complex matrix.

Electrochemical microfluidic sensing platforms for biosecurity analysis.

Biosecurity encompasses the health and safety of humans, animals, plants, and the environment. In this article, "biosecurity" is defined as encompassing the comprehensive aspects of human, animal, plant, and environmental safety. Reliable biosecurity testing technology is the key point for effectively assessing biosecurity risks and ensuring biosecurity. Therefore, it is crucial to develop excellent detection technologies to detect risk factors that can affect biosecurity. An electrochemical microfluidic biosensing platform integrates fluid control, target recognition, signal transduction, and output and incorporates the advantages of electrochemical analysis technology and microfluidic technology. Thus, anelectrochemical microfluidic biosensing platform, characterized by exceptional analytical sensitivity, portability, rapid analysis speed, low reagent consumption, and low risk of contamination, shows considerable promise for biosecurity detection compared to traditional, more complex, and time-consuming detection technologies. This review provides a concise introduction to electrochemical microfluidic biosensors and biosecurity. It highlights recent research advances in utilizing electrochemical microfluidic biosensing platforms to assess biosecurity risk factors. It includes the use of electrochemical microfluidic biosensors for the detection of risk factors directly endangering biosecurity (direct application: namely, risk factors directly endangering the health of human, animals, and plants) and for the detection of risk factors indirectly endangering biosecurity (indirect application: namely, risk factors endangering the safety of food and the environment). Finally, we outline the current challenges and future perspectives of electrochemical microfluidic biosensing platforms.

Electrochemical biosensing platform based on AuNWs/rGO-CMC-PEDOT:PSS composite for the detection of superoxide anion released from living cells

Detection of superoxide anion (O2·-) levels holds significant importance for the diagnosis and even clinical treatments of oxidative stress-related diseases. Herein, we prepared a composite electrode material to encapsulate copper-zinc superoxide dismutase (SOD1) for biosensing of O2·-. The sensing material consists of gold nanowires (AuNWs), reduced graphene oxide (rGO), carboxymethyl cellulose (CMC) and PEDOT:PSS. CMC provides abundant -COOH to bind SOD1, with a high adsorption coverage of 1.499 × 10−9 mol cm−2 on the sensor surface. rGO and PEDOT endow the composite with significant conductivity, whereas PSS has antifouling capability. Moreover, AuNWs exhibit excellent electrical conductivity and a high aspect ratio, which promotes electron transfer, and ultimately enhances the catalytic performance of the enzyme. Meanwhile, SOD1(Cu2+) catalyzes the dismutation of O2·- to O2 and H2O2, and H2O2 is then electrochemically oxidized to generate amperometric signals for determination of O2·-. The sensor demonstrates outstanding detection performance for O2·- with a low detection limit of 2.52 nM, and two dynamic ranges (14.30 nM–1.34 μM and 1.34 μM–42.97 μM) with corresponding sensitivity of 0.479 and 0.052 μA μM−1cm−2, respectively. Additionally, the calculated apparent Michaelis constant (Kmapp) of 1.804 μM for SOD1 demonstrates the outstanding catalytic activity and the surface-immobilized enzyme's substrate affinity. Furthermore, the sensor shows the capability to dynamically detect the level of O2·- released from living HepG2 cells. This study provides an inovative design to obtain a biocompatible electrochemical sensing platform with plenty of immobilization sites for biomolecules, large surface area, high conductivity and flexibility.

Electrochemical biosensor for the evaluation of monoclonal antibodies targeting the N protein of SARS-CoV-2 virus

The emergence of COVID-19 caused by the coronavirus SARS-CoV-2 has prompted a global pandemic that requires continuous research and monitoring. This study presents a design of an electrochemical biosensing platform suitable for the evaluation of monoclonal antibodies targeting the SARS-CoV-2 nucleocapsid (N) protein. Screen-printed carbon electrodes (SPCE) modified with gold nanostructures (AuNS) were applied to design a versatile and sensitive sensing platform. Electrochemical techniques, including electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV), were used to investigate the interactions between immobilised recombinant N (rN) protein and several monoclonal antibodies (mAbs). The electrochemical characterisation of SPCE/AuNS/rN demonstrated a successful immobilisation of rN, enhancing the electron transfer kinetics. Affinity interactions between immobilised rN and four mAbs (mAb-4B3, mAb-4G6, mAb-12B2, and mAb-1G5) were explored. Although mAb-4B3 showed some non-linearity, the other monoclonal antibodies exhibited specific and well-defined interactions followed by the formation of an immune complex. The biosensing platform demonstrated high sensitivity in the linear range (LR) from 0.2 nM to 1 nM with limits of detection (LOD) ranging from 0.012 nM to 0.016 nM for mAb-4G6, mAb-12B2, and mAb-1G5 and limits of quantification (LOQ) values ranging from 0.035 nM to 0.139 nM, as determined by both EIS and SWV methods. These results highlight the system's potential for precise and selective detection of monoclonal antibodies specific to the rN. This electrochemical biosensing platform provides a promising route for the sensitive and accurate detection of monoclonal antibodies specific to the rN protein.

Two‐Dimensional Materials Integrated in Electrochemical Biosensors for Virus Detection: Property Engineering Strategies and Device Applications

AbstractElectrochemical biosensors have been widely used as advanced methods for virus detection. Ongoing efforts are being made to improve their performance by investigating novel materials as electrode modifiers. In this regard, two‐dimensional (2D) materials, such as graphene, transition metal dichalcogenides (TMDs), and transition metal carbides/nitrides (MXenes), have been extensively explored due to their exceptional structural and electrical properties for electrochemical biosensors. This review investigates and summarizes the recently developed 2D materials employed in virus detection. Various strategies to enhance the critical properties of 2D materials, including conductivity, surface area, active sites, selectivity, and wettability, on electrochemical biosensing platforms, which impact their performance, are discussed. Different types of 2D materials (pristine, derivatives, and composites) are described and subsequently evaluated regarding their applications in electrochemical biosensing. This review serves as a valuable guide for designing next‐generation, high‐performance electrochemical biosensors based on 2D materials.

Fabrication of cervical squamous cell carcinoma antigen immunosensor using graphene-polymer composites

An ultrasensitive electrochemical immunosensor was developed for detection of the cervical squamous cell carcinoma antigen (SCCA) biomarker using graphene-chitosan nanocomposites. Graphene oxide (GO) synthesized by a modified Hummer’s method was functionalized with chitosan biopolymer (CS) to produce CS-GO nanocomposites. Characterization by SEM, FTIR, Raman, XPS confirmed successful grafting of CS onto GO by electrostatic interactions. The CS-GO composite exhibited improved conductivity and biocompatibility. After optimizing the GO:CS ratio to 1:1, the nanocomposite was deposited on glassy carbon electrodes (GCE). Anti-SCCA antibodies were then immobilized covalently using pyrenebutyric acid crosslinker. The immunosensor fabrication was analyzed by EIS, CV, and DPV electrochemical techniques. The conditions including CS-GO ratio, antibody concentration, incubation time, pH, and voltage parameters were systematically optimized using orthogonal experimental design. Under optimal conditions, the immunosensor showed a linear detection range from 1 pg/mL to 100 ng/mL with a sensitivity of 196 μA/(ng/mL/cm2). The low limit of detection of 1 pg/mL was attributed to the high surface area and conductivity of the CS-GO transducer. Analysis of human serum samples spiked with SCCA demonstrated the reliability of the immunosensor for clinical applications. The graphene-nanocomposite electrochemical biosensing platform provides a rapid, low-cost, and ultrasensitive alternative to ELISA for SCCA detection in cervical cancer diagnostics.

Printing surface cuprous oxides featured liquid metal for non-enzymatic electrochemical glucose sensor

Electrochemical glucose sensors that rely on two-dimensional (2D) oxides have attracted significant attention owing to the strong sensing activity of 2D oxides, but their practical application is hindered by the complexity and high cost of fabrication of electrodes and integrated devices. Herein, a convenient and effective fabrication route that includes printing a Ga-based liquid metal (LM) as a current collection electrode, followed by growing electrochemically active 2D oxides directly on the surface of Ga-based LMs under mild conditions, is developed for non-enzyme-based electrochemical sensors. Specifically, 2D annealed Cu-Oxide (ACO) is successfully grown on a printed Ga electrode through a galvanic replacement reaction, resulting in the formation of a mechanically and electrically well-matched interface between the active sensing materials and the current collection substrate. Benefitting from the high quantity of 2D ACO and good charge transfer at the interface, the as-prepared ACO electrode exhibits attractive glucose sensing performance, with a wide linear range (1 μM-10 mM) of effective detection, low detection limit down to 1 μM, and high sensitivity of 0.87 μA·mM-1·cm-2. Our study highlights the potential of using LMs in bio-sensing applications and provides a non-enzyme-based electrochemical biosensor platform for effective glucose detection in diets and clinical diagnostic settings.

Carbon-stabilized porous silicon biosensor for the ultrasensitive label-free electrochemical detection of bacterial RNA gene fragments

Herein, we report a carbon-stabilized porous silicon (pSi)-based electrochemical biosensing platform for the label- and amplification-free detection of bacterial 16S rRNA gene fragments that facilitates pan-bacterial detection. The sensing approach combines thermally carbonized pSi (THCpSi) structures as novel porous electrochemical transducers, and a highly sensitive sensing mechanism based on partial blockage of the pores caused by hybridization of 16S rRNA gene fragment to the DNA capture probe immobilized within the pores. Pore blockage upon RNA hybridization was quantified via differential pulse voltammetry as a decrease in the oxidation current of the redox pair ([Fe(CN)6]3/4−) added to the measuring solution. The use of carbon-stabilized pSi to build the biosensor has additional benefits: it favors high density of the immobilized bioreceptors and a large electroactive surface area, both further enhancing the overall sensitivity of the biosensor. The easily adjustable pSi morphology is key to design diagnostic tools fit-for-purpose. By tailoring the pore diameter, pore blockage upon analyte hybridization can be maximized, thus enhancing sensitivity. By tailoring film thickness, the surface area can be adjusted to optimize the amount of immobilized bioreceptors and the electroactive surface area. An excellent sensing performance was achieved by building the biosensor on THCpSi structures featuring a 27 nm pore diameter and a 1.6 μm film thickness, whose external surface was coated with a thin layer of silicon nitride (Si3N4), the latter contributing to maximize the pore blockage. The biosensor achieved a limit of detection of 2.3 pM when tested in 5% fetal bovine serum.

Probing the influence of crosslinkers on the properties, response, and degradation of enzymatic hydrogels for electrochemical glucose biosensing through fluorescence analysis.

Drop-cast crosslinked hydrogels are a common platform for enzymatic electrochemical biosensors. Despite the widespread use of these complex systems, there are still several questions about how their physicochemical properties affect their performance, stability, and reproducibility. In this work, first-generation faradaic biosensors composed of glucose oxidase and branched polyethyleneimine (BPEI) are prepared using either glutaraldehyde (GA) or ethylene glycol diglycidyl ether (EGDGE) as crosslinkers. While EGDGE gels present an increasing electrochemical response with increasing crosslinker concentration, the current of GA gels decreases at high crosslinker concentration probably due to the hampered diffusion on tightly networked gels. We compared different strategies to use fluorescence microscopy to gain insight into the gel structure either by labeling the gel components with fluorophores or taking advantage of the intrinsic fluorescence of the imines formed upon crosslinking with GA. By monitoring the fluorescence of the crosslinking bonds and the electrochemical response, we demonstrate that hydrolysis, a common hydrogel degradation mechanism, is not responsible for the loss of electrical current over time in gels prepared with glutaraldehyde. Most hydrogel-based electrochemical biosensor studies do not perform specific experiments to determine the cause of the degradation and instead just infer it from the dependence of the current on the preparation conditions (most commonly concentrations). We show that, by taking advantage of several analytical techniques, it is possible to gain more knowledge about the degradation mechanisms and design better enzymatic biosensors.

Universal nanocomposite coating with antifouling and redox capabilities for electrochemical affinity biosensing in complex biological fluids.

Electrochemical affinity biosensors have the potential to facilitate the development of multiplexed point-of-care diagnostics in complex biological fluids. However, their commercial viability has been hindered by challenges such as electrode biofouling and the lack of inherent redox properties. To address this unmet need, we have developed a universal nanocomposite coating which is unique in its ability to not only allow oriented conjugation of the biorecognition element but also specific detection directly in complex biological fluids like serum and urine owing to its built-in antifouling and redox capabilities, thus improving suitability for point of care testing. This multifunctional coating comprises a 3D porous crosslinked bovine serum albumin matrix for oriented conjugation and antifouling properties with embedded graphene nanosheets modified with amino-ferrocene for enhanced conductivity and mediator-free biosensing. The coating showed minimal signal degradation despite prolonged exposure to 1% bovine serum albumin, artificial urine and untreated human serum for up to 30 days. To demonstrate its utility, we fabricated and tested proof-of-concept electrochemical immunosensors for bladder cancer protein biomarkers, specifically interleukin-8 (IL-8) and vascular endothelial growth factor (VEGF). The practical feasibility was highlighted by the excellent sensitivity and specificity observed for IL-8 and VEGF with a limit of detection of 41 pg mL-1 and 67 pg mL-1, respectively. Consequently, this universal nanocomposite-based electrochemical biosensing platform can be extended to the point of care testing of a broad spectrum of biomarkers present in complex biological fluids, thus enabling reliable and early diagnostics.

Nanomaterials in electrochemical nanobiosensors of miRNAs.

Nanomaterial-based biosensors have received significant attention owing to their unique properties, especially enhanced sensitivity. Recent advancements in biomedical diagnosis have highlighted the role of microRNAs (miRNAs) as sensitive prognostic and diagnostic biomarkers for various diseases. Current diagnostics methods, however, need further improvements with regards to their sensitivity, mainly due to the low concentration levels of miRNAs in the body. The low limit of detection of nanomaterial-based biosensors has turned them into powerful tools for detecting and quantifying these biomarkers. Herein, we assemble an overview of recent developments in the application of different nanomaterials and nanostructures as miRNA electrochemical biosensing platforms, along with their pros and cons. The techniques are categorized based on the nanomaterial used.

Catalytic MXCeO2 for enzyme based electrochemical biosensors: Fabrication, characterization and application towards a wearable sweat biosensor

Two-dimensional (2D) layered materials that integrate metallic conductivity, catalytic activity and the ability to stabilize biological receptors provide unique capabilities for designing electrochemical biosensors for large-scale detection and diagnostic applications. Herein, we report a multifunctional MXene-based 2D nanostructure decorated with enzyme mimetic cerium oxide nanoparticle (MXCeO2) as a novel platform and catalytic amplifier for electrochemical biosensors, specifically targeting the detection of oxidase enzyme substrates. We demonstrate enhanced catalytic efficiency of the MXCeO2 for the reduction of hydrogen peroxide (H2O2) and its ability to immobilize oxidase enzymes, such as glucose oxidase, lactate oxidase and xanthine oxidase. The designed biosensors exhibit high selectivity, stability, and sensitivity, achieving detection limits of 0.8 μM H2O2, 0.49 μM glucose, 3.6 μM lactate and 1.7 μM hypoxanthine, when the MXCeO2 and their respective enzymes were used. The MXCeO2 was successfully incorporated into a wearable fabric demonstrating high sensitivity for lactate measurements in sweat. The unique combination of MXenes with CeO2 offers excellent conductivity, catalytic efficiency and enhanced enzyme loading, demonstrating potential of the MXCeO2 as a catalytically active material to boost efficiency of oxidase enzyme reactions. This design can be used as a general platform for increasing the sensitivity of enzyme based biosensors and advance the development of electrochemical biosensors for a variety of applications.

Immunomultiple PCR-based electrochemical and lateral flow strategy for the simultaneous detection of liver cancer tumor markers.

Thecurrent use of the single serum biomarker α-fetoprotein (AFP) in clinical practice has limitations in terms of specificity and sensitivity. We propose a strategy that combines antigen capture polymerase chain reaction (AC-PCR), lateral flow assay (LFA), and electrochemical biosensors to detect both AFP and circulating tumor cells (CTCs) in liver cancer serum. First, we used the AC-PCR technique to achieve target separation, purification, signal conversion, and amplification, eliminating target heterogeneity. Then, we achieved rapid results through the LFA and electrochemical biosensor platforms. As a result, the proposed assay has limits of 5 cells/mL for CTCs and 5 µg/L for AFP. The proposed method was applied effectively tosimulated blood samples. This method has the potential to play a role in early liver cancer and provide a potential application for the diagnosis and precision treatment of liver cancer.

Mobile Point-of-Care Device Using Molecularly Imprinted Polymer-Based Chemosensors Targeting Interleukin-1β Biomarker.

Molecularly imprinted polymers (MIPs) have garnered significant attention as a promising material for engineering specific biological receptors with superior chemical complementarity to target molecules. In this study, we present an electrochemical biosensing platform incorporating MIP films for the selective detection of the interleukin-1β (IL-1β) biomarker, particularly suitable for mobile point-of-care testing (POCT) applications. The IL-1β-imprinted biosensors were composed of poly(eriochrome black T (EBT)), including an interlayer of poly(3,4-ethylene dioxythiophene) and a 4-aminothiophenol monolayer, which were electrochemically polymerized simultaneously with template proteins (i.e., IL-1β) on custom flexible screen-printed carbon electrodes (SPCEs). The architecture of the MIP films was designed to enhance the sensor sensitivity and signal stability. This approach involved a straightforward sequential-electropolymerization process and extraction for leaving behind cavities (i.e., rebinding sites), resulting in the efficient production of MIP-based biosensors capable of molecular recognition for selective IL-1β detection. The electrochemical behaviors were comprehensively investigated using cyclic voltammograms and electrochemical impedance spectroscopy responses to assess the imprinting effect on the MIP films formed on the SPCEs. In line with the current trend in in vitro diagnostic medical devices, our simple and effective MIP-based analytical system integrated with mobile POCT devices offers a promising route to the rapid detection of biomarkers, with particular potential for periodontitis screening.

Group selective aptamers: Broad-spectrum recognition of target groups in Cronobacter species and implementation of electrochemical biosensors as receptors

Aptamers are a versatile class of receptors with a high affinity and selectivity for specific targets. Although their ability to recognize individual targets has been extensively studied, some scenarios require the development of receptors capable of identifying all target groups. This study investigated the use of aptamers to achieve the broad-spectrum recognition of groups instead of individual targets. Aptamers were screened for selectively distinct groups of Cronobacter species associated with foodborne diseases. Seven Cronobacter spp. were divided into Group A (C. sakazakii, C. malonaticus, C. turicensis, and C. muytjensii) and Group B (C. dublinensis, C. condimenti, and C. universalis). Aptamers with exclusive selectivity for each group were identified, allowing binding to the species within their designated group while excluding those from the other group. The screened aptamers demonstrated reliable affinity and specificity with dissociation constants ranging from 1.3 to 399.7 nM for Group A and 4.0–24.5 nM for Group B. These aptamers have also been successfully employed as receptors in an electrochemical biosensor platform, enabling the selective detection of each group based on the corresponding aptamer (limit of detection was 7.8 and 3.2 CFU for Group A and Group B, respectively). The electrochemical sensor effectively detected the extent of infection in each group in powdered infant formula samples. This study highlights the successful screening and application of group-selective aptamers as sensing receptors, emphasizing their potential for diverse applications in different fields such as food safety, environmental monitoring, and clinical diagnostics, where the selective biosensing of target groups is crucial.