Search Results (748)

The rapid and sensitive quantification of antibiotic residues in aquatic animals is crucial for ensuring food safety and protecting public health. Electrochemical (bio)sensors show great potential in this field due to their quick response time, low cost, and ease of miniaturization. This paper presents a systematic review of advances in the electrochemical detection of eight classes of antibiotics: fluoroquinolones, sulfonamides, amphenicols, tetracyclines, nitrofurans, macrolides, aminoglycosides, and β-lactams in aquatic animal samples. It covers four types of sensors: direct electrochemical sensors, immunosensors, aptasensors, and molecularly imprinted sensors. The review emphasizes the electrochemical behavior of the targets, interface design, recognition elements, signal amplification strategies, and validation using real samples. It also summarizes the sample pretreatment methods for different classes of antibiotics. Finally, the paper analyzes key challenges related to adaptability to complex matrices, consistency in sample preparation, and validation with real-world samples. Additionally, it proposes future directions for development in this field. Full article

Food contamination by Aflatoxin M1 and Atrazine remains a critical food-safety concern, requiring sensitive detection methods that can operate reliably in complex matrices. Here, we report an AI-assisted antibody-functionalized electrochemical sensing platform for the detection and classification of Aflatoxin M1 and Atrazine across corn, corn flour, and protein matrices. The sensor used analyte-specific antibodies immobilized on an electrochemical electrode surface, where target binding produced measurable changes in the interfacial electrochemical response. Sensor performance was evaluated using cyclic voltammetry, coulometry, and electrochemical impedance spectroscopy (EIS), with EIS providing strong frequency-dependent signatures for concentration-dependent analysis. Spike-and-recovery studies further demonstrated the applicability of the platform in food-matrix conditions. To improve interpretation of complex electrochemical signals, full-spectrum EIS features were integrated with machine learning models for concentration-level classification into low, mid, and high groups. The AI workflow achieved an overall classification accuracy of 93.33%, with 96.67% specificity, 93.44% PPV, 96.66% NPV, and 0.982 AUC for Atrazine, and 96.70% specificity, 93.38% PPV, 96.67% NPV, and 0.987 AUC for Aflatoxin M1. In addition, analyte classification between Aflatoxin M1 and Atrazine reached 97.4% accuracy and 0.994 ROC-AUC. Overall, this work demonstrates a matrix-aware electrochemical immunosensing strategy enhanced by AI-based signal interpretation for food contaminant detection. Full article

A capacitive screen-printed electrode immunosensor operating in non-faradaic mode by dispensing redox probes was developed for the Coronavirus 2 Spike (S) protein. This new strategy enabled direct detection of the S protein by measuring changes in the electrochemical capacitance resulting from antigen–antibody interactions on the electrode surface, altering interfacial dielectric properties. To enhance analytical sensitivity and provide an electrode surface with attractive capacitive and conductive properties, an in-house graphite ink-based screen-printed electrode was developed and subsequently modified with a polypyrrole (PPy) layer in bulk-synthesized in the presence of Cetyltrimethylammonium bromide (CTAB). CTAB acted as a dispersing and structure-directing agent, promoting homogeneous distribution and guiding the PPy polymerization, resulting in a composite with improved charge density storage and high conductivity. Analytical signals of the S proteins in spiked serum were detected by measuring the Specific Capacitances taken from cyclic voltammograms. This capacitive immunosensor achieved a linear range from 1 to 100 µg/mL (R² = 0.989, p < 0.05), with a limit of detection of 0.45 µg/mL of S protein, which falls within the clinical range for COVID-19 diagnostics. Probe-free detection without ferri/ferrocyanide steps minimizes errors by probe adsorptions and is easy to use as a point-of-care, unlike conventional immunosensors. Full article

Acute respiratory diseases caused by viral pathogens such as Influenza A continue to represent a major global health challenge, emphasizing the need for rapid, sensitive, and accessible diagnostic tools. In this work, a carbon screen-printed electrode (SPCE)-based electrochemical immunosensor for the detection of an Influenza A (H1) antigen is reported, incorporating a comparative electrochemical evaluation of four electrode materials. Fe₃O₄ nanoparticles, Fe₃O₄@C nanoparticles, graphene quantum dots (GQDs), and gold nanoparticles (AuNPs) were systematically assessed by cyclic voltammetry to evaluate their electrocatalytic performance. The highest electrochemical response was selected for biosensor construction. The immunosensor was fabricated by immobilizing antibodies on a modified SPCE and characterized using differential pulse voltammetry (DPV). A concentration-dependent response was observed for H1 antigen concentrations ranging from 0 to 300 ng/mL, with a minimum detectable concentration (MDC) of 1 ng/mL and limit of detection (LOD) of 176 ng/mL and 45 ng/mL for serum and nasopharyngeal swabs, respectively. The biosensor performance was specifically evaluated in complex biological fluids, demonstrating reproducible performance and moderate selectivity against non-target influenza subtypes. Overall, this study highlights the critical role of electrode material selection in determining electrochemical immunosensor performance and supports the potential of SPCE-based platforms for the screening of an Influenza A (H1) antigen in point-of-care-oriented applications. Full article

Polyethylene (PE) microplastics are increasingly recognized as a critical environmental and food-safety concern; however, routine monitoring remains limited by conventional methods that are labor-intensive, time-consuming, and difficult to translate into rapid, on-site screening. Here, we report a machine learning-guided electrochemical fingerprinting platform for rapid PE microplastic detection using a chitosan–PE interfacial film coupled with electrochemical impedance spectroscopy (EIS) and coulometry. The platform generated concentration-dependent electrical fingerprints in artificial ocean water, captured through Bode, Nyquist, and charge–time responses. Quantification was achieved across 1–256 ng/mL with strong linearity (R² = 0.976) and an ultralow LoD of 0.1 ng/mL, demonstrating high analytical sensitivity. Practical applicability was validated through spike–recovery in ocean water (R² = 0.967) and shrimp-derived matrices with matrix-matched normalization, yielding recoveries of 90–105% across low, mid, and high spike levels. Under the tested particle set, PE produced stronger responses than non-target polypropylene (PP) and polystyrene (PS), supporting empirical polymer discrimination. Machine learning classification using impedance-derived features achieved an AUC = 0.98, with 100% correct identification of Low and 95.24% correct identification of High samples. Overall, this electrochemical–ML framework enables rapid, sensitive, and matrix-tolerant PE microplastic screening in environmental water and seafood-related matrices, offering a promising pathway toward portable microplastic monitoring. Full article

C-reactive protein (CRP) is one of the most essential biomarkers for the early detection of inflammation and infection. In this study, we developed a sensitive and selective electrochemical immunosensor for CRP detection, leveraging the unique properties of gold nanoparticles (AuNPs). A nanostructured layer of AuNPs was deposited onto a screen-printed carbon electrode (SPCE), followed by the formation of a self-assembled monolayer (SAM) of L-cysteine and EDC/sulfo-NHS chemistry. The antibody was covalently immobilized onto the modified electrode through optimized dual-crosslinking chemistry. Detection conditions were systematically optimized, with pH 8.0 in Tris buffer providing the best electrochemical response. Electrochemical characterization was performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) in a 5 mM K₃[Fe(CN)₆]/K₄[Fe(CN)₆] redox probe solution containing 0.1 M KCl. CRP detection was achieved by monitoring the increase in charge transfer resistance (Rct) upon specific binding of the target CRP antigen to the immobilized antibody. Spiked recovery experiments showed spiked recovery rates ranging from 98.01% to 107.14%, with a standard deviation below 4%. Regeneration studies demonstrated high efficiency, confirming the suitability of the sensor interface for repeated and reliable measurements. Under optimized conditions, the immunosensor exhibited excellent analytical performance, including a low limit of detection (LOD) of 0.16 µg/mL, a wide linear detection range of 5–100 µg/mL, high selectivity against 13 potential interferents (including inflammatory cytokines), and good reproducibility with a relative standard deviation (RSD) of 3.69%. The sensor also showed strong stability, retaining more than 95% of its signal after 15 days, and high regeneration efficiency of 97% over seven cycles. These results highlight the strong potential of the proposed immunosensor for point-of-care (POC) applications due to its simple fabrication, cost-effectiveness, user accessibility, and robust analytical performance. Full article

Alpha-fetoprotein (AFP) is widely utilized for auxiliary diagnosis of primary hepatocellular carcinoma. Therefore, the development of a facile immunosensor is essential for clinical applications. This study aims to develop a simple immunoassay for AFP detection. By incorporating silicon quantum dots (SiQDs) into etching hollow gold nanoshells (EHGNs) via precise nanomanipulation, we designed molecular probes based on SiQDs@EHGNs complex immobilized capture antibodies, which can convert the antigen/antibody binding process into fluorescent divergence signals for AFP measurement. This strategy enabled one-step fluorescence sensing for AFP detection with a linear range of 3.125–200.0 ng/mL and LOD of 0.234 ng/mL. The detection results of 15 clinical serum real samples demonstrated a 93.7% correlation with the market-accepted ECLIA method. The proposed method take advantages of simplicity and rapid response, offering a novel approach for tumor marker analysis with significant potential. Full article

Neurofilament light chain (NfL) is a promising biomarker of axonal injury across acute and chronic neurodegeneration, which can improve drug discovery and disease monitoring models. Traditional in vivo animal models cannot fully mimic human pathophysiology of neurodegenerative diseases (NDDs), but in vitro models based on human cells solve this problem, reducing the time and cost of drug testing. We developed an electrochemical immunosensor for NfL detection in cell culture media to monitor acute neuronal injury in in vitro models. The biosensor was designed in two configurations: the label-free system, which directly detects NfL in the sample via the antibody–antigen interaction, and the sandwich configuration, which incorporates two additional antibodies. Detection was examined using electrochemical techniques, including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA). The sensor demonstrated a detection limit of 3–9 pg mL⁻¹, and a dynamic working range spanning from 10 up to 10⁷ pg mL⁻¹. Importantly, NfL was successfully detected in physiological media collected from cultured neurons that were differentiated from the long-term human neuroepithelial-like stem cells. This discovery highlights the platform’s applicability for in vitro neurodegenerative models. The immunosensor offers a sensitive, scalable, and cost-effective alternative for neurodegeneration detection in drug testing applications. Full article

The development of reliable electrochemical interfaces for biosensor applications requires materials that combine high conductivity, large effective surface area, and suitable platforms for biomolecule immobilization. In this work, a hybrid electrochemical platform based on screen-printed carbon electrodes (SPCEs) modified with electropolymerized polypyrrole (PPy) and electrodeposited silver particles (AgPs) is presented for the subsequent immobilization of Ki-67 antibodies. PPy films were synthesized under optimized electrochemical conditions, producing homogeneous, porous, and electrochemically stable coatings that significantly enhanced the doping/undoping processes from 0.3280 C/0.3284 C to 0.3281 C/0.3284 C for SPCE and SPCE-PPy, respectively. Subsequently, silver particles were deposited onto the PPy matrix, resulting in a well-dispersed and uniform distribution of AgPs, promoted by the interaction between Ag⁰ and the nitrogen groups in the polymer backbone. The synergistic combination of PPy and AgPs resulted in improved charge-transfer properties and enhanced electrochemical reversibility, thereby decreasing the peak-to-peak separation of the ferricyanide/ferrocyanide redox couple used as a probe by 40%. Immobilization of Ki-67 antibodies was achieved via direct interaction with AgPs, resulting in a marked passivation effect, as evidenced by the suppression of redox probe signals, confirming successful biofunctionalization. The proposed SPCE-PPy-AgP architecture provides a robust, reproducible, and versatile platform for antibody immobilization, as demonstrated by oxidation and reduction peaks with relative standard deviations (RSDs) of 3.18% and 4.43%, respectively, highlighting its potential for developing label-free electrochemical immunosensors for clinically relevant proliferation biomarkers. Full article

Brucellosis is a globally prevalent zoonosis that causes abortion and infertility in livestock, leading to substantial economic losses. Sensitive and reliable quantification of Brucella antibodies, particularly at trace levels, is critical for early diagnosis. In this work, an electrochemical immunosensor was developed by integrating electric field-assisted antigen immobilization with an electrode platform. The electrode was first electrochemically pretreated to improve interfacial reproducibility, and then sequentially modified with L-cysteine and glutaraldehyde to construct an antigen-coupling layer. During antigen immobilization, a custom-built electric field device was applied to regulate the interfacial arrangement of Brucella antigens. The fabrication process was characterized by scanning electron microscopy and cyclic voltammetry, and the analytical performance was evaluated by electrochemical impedance spectroscopy and voltammetric measurements. Under the optimized conditions, the proposed immunosensor exhibited a linear response to Brucella antibodies over the range of 1 × 10⁻⁶–10 IU/mL, with a correlation coefficient of 0.99 and a detection limit of 2.04 × 10⁻⁷ IU/mL. The sensor also showed acceptable specificity, repeatability, and short-term storage stability, with recoveries of 93.15–99.14% in spiked milk samples. These results indicate that electric field-assisted immobilization can serve as a useful interfacial regulation strategy for Brucella immunosensing and support the analytical feasibility of the proposed platform under controlled experimental conditions. Further validation in more complex biological matrices is still required. Full article

Disruption of the intestinal barrier is a hallmark of inflammatory bowel disease (IBD) and drives both epithelial injury and neutrophil-mediated inflammation, yet rapid, multiplexed assessment of these processes remains an unmet clinical need. Intestinal fatty acid binding protein (iFABP) and fecal calprotectin (FC) provide complementary insights into barrier integrity and mucosal inflammation, but conventional ELISA-based assays are time-consuming, low-throughput, and require large sample volumes. Here, we introduce a dual electrochemical sandwich immunosensor enabling simultaneous quantification of iFABP and FC on screen-printed dual carbon electrodes (SPdCEs). Capture antibodies were immobilized via electrografting of p-aminobenzoic acid diazonium salt, while a V₂O₅/MWCNTs-HRP–streptavidin nanocomposite amplified the electrocatalytic reduction in hydrogen peroxide, enhancing sensitivity. The platform achieved detection limits of 0.01 pg mL⁻¹ (iFABP) and 1 pg mL⁻¹ (FC) with a total assay time of 1 h 20 min and sample volume of just 5 μL, outperforming conventional ELISA in speed and efficiency. High repeatability, reproducibility, and accurate recovery in enriched fecal samples confirmed analytical robustness. By integrating multiplexed detection, nanostructured signal amplification, and robust electrode engineering, this immunosensor provides a rapid, sensitive, and low-volume platform for point-of-care and decentralized monitoring of IBD, enabling timely clinical decision-making and longitudinal patient management. Full article

The detection of biological markers is critical not only for the early diagnosis of cancer but also for adjustments in antitumor therapy. Rapid, sensitive, and selective detection and monitoring of the content of specific biomarkers in real time are key to point-of-care testing diagnostics. We report the detection of heat shock proteins by fluorescence immunoassay with the appropriate phage antibodies, with a minimum detection limit of 1 ng/mL. The fluorescence immunoassay data were confirmed by dot immunoassay and by circular dichroism studies. The results of the study may help in the adaptation of the fluorescence immunoassay to cancer diagnostics. Full article

Early intervention is pivotal for mitigating the progression of Alzheimer’s disease (AD). This study presents an electrochemical immunosensor targeting synaptic vesicle glycoprotein 2A (SV2A) to facilitate early AD diagnosis. A sensing interface was engineered using a nanocomposite of graphene oxide (GO) and 3-carboxyl polypyrrole (3-COOH-PPy). Leveraging the synergistic effects between the large specific surface area of GO and the superior conductivity of 3-COOH-PPy, the composite established an efficient electron transport network. This architecture provided abundant active sites for capture antibody immobilization while significantly enhancing interfacial electron transfer kinetics. Coupling this interface with an enzyme-mediated signal amplification strategy based on the horseradish peroxidase (HRP)-catalyzed TMB/H₂O₂ system, the immunosensor achieved high sensitivity. It exhibited a wide linear range of 2 ng/mL to 16 μg/mL with a low limit of detection (LOD) of 0.15 ng/mL. Furthermore, successful detection in C57 mouse serum samples validated the method’s reliability and potential for clinical application. In conclusion, this immunosensor offers a sensitive and robust platform for the early diagnosis of AD. Full article

Background/Objectives: In the area of pharmacology and clinical research, it is necessary to use versatile technologies able to quantify last-line antibiotic molecules with high specificity and sensitivity. This article describes the development of two types of immunosensors based on amperometric and surface plasmon resonance (SPR) measurements and their applicability in the measurement/assessment of therapeutic drug monitoring (TDM) of four last-line antibiotics such as vancomycin, colistin, daptomycin and meropenem in human plasma. In this study, ligand immobilization by preconcentration assays, sensor surface regeneration, determination of sensitivity and correlation of plasma sample quantification results by HPLC were considered. Results: In the case of the electrochemical biosensor the IC50 values obtained were 3.49 μg/L for vancomycin (VAN), 5.44 μg/L for colistin (COL), 0.82 μg/L for meropenem (MER) and 5.10 μg/L for daptomycin (DAP). For the SPRi biosensor the LODs achieved were 19 ng/mL for VAN, 9 μg/L for COL, 12 μg/L for MER and 12.3 μg/L for DAP. Finally, both electrochemical biosensor and the SPRi optical biosensor showed that for the four antibiotics the standard deviations were less than 10% with respect to the HPLC results, with ranges for VAN between ~5–6 µg/mL, for COL ~0.2–0.7 µg/mL, for MER ~4.5–5.5 µg/mL and for DAP ~0.09–0.65 µg/mL. Conclusions: These kinds of biosensors provide a precise and sensitive strategy, together with real-time determination, to quantify last-line antibiotics, with working ranges like those shown by robust techniques such as HPLC and great potential for the clinic. Full article

Crop fungal and viral diseases cause annual economic losses exceeding USD 150 billion globally, demanding rapid, sensitive, and field-deployable diagnostic technologies. This review critically evaluates recent advances in electrochemical biosensing platforms for early crop pathogen detection, focusing on immunosensors, genosensors, aptasensors, and VOC-based systems. Reported analytical performances demonstrate ultralow detection capabilities, including 0.3 fg mL⁻¹ for viral coat proteins, 15 DNA copies for bacterial pathogens, 0.5 fg µL⁻¹ RNA detection for viroids, and nanomolar-level VOC sensing (35–62 nM), with response times ranging from 2 to 60 min. Comparative analysis reveals that genosensors and aptasensors generally achieve the lowest LODs due to nucleic acid amplification or high-affinity recognition, while immunosensors provide robust protein-level specificity validated against ELISA. Volatile organic compound (VOC) sensors enable non-invasive, pre-symptomatic monitoring but face specificity challenges. Despite strong laboratory performance, practical adoption is limited by matrix-derived electrochemical interference, environmental instability of biorecognition elements, workflow complexity, and insufficient standardization across studies. Emerging innovations, including magnetic bead enrichment, nanoporous and graphene-based electrodes, microfluidic integration, AI-assisted impedance interpretation, and biodegradable substrates, are progressively addressing these bottlenecks. This review emphasizes that successful field translation requires holistic workflow engineering, matrix-matched validation, and harmonized performance metrics rather than incremental sensitivity improvements alone. By integrating analytical chemistry, nanomaterials engineering, and agricultural decision-support frameworks, electrochemical biosensing platforms hold significant potential to enable decentralized, rapid, and sustainable crop disease management. Full article