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Tricyclazole is commonly used to prevent rice blast to meet the carbohydrate intake needs of half of the global population, and a large number of toxicological reports indicate that monitoring of tricyclazole is necessary. Here, we analyzed the structure of tricyclazole and designed different hapten derivatization strategies to prepare a high-performance monoclonal antibody (half inhibition concentration of 1.61 ng/mL), and then a lateral flow immunochromatographic sensor based on gold nanoparticles for the detection of tricyclazole in rice, with a limit of detection of 6.74 μg/kg and 13.58 μg/kg in polished and brown rice, respectively. The recoveries in rice were in the range of 84.6-107.4%, no complex pretreatment was required for comparison with LC-MS/MS, and the comparative analysis demonstrated that our method had good accuracy and precision. Therefore, the developed lateral flow immunochromatographic analysis was a reliable and rapid means for the on-site analysis of tricyclazole in rice., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Developing the portable CRP detection technologies that are suitable for point-of-care (POC) and primary care management is of utmost importance, and advancing the electrochemical immunosensors hold promise for POC implementation. Nevertheless, non-specific adsorption of numerous interfering proteins in complex biological media contaminates immunosensors, thereby restricting the reliability in detection efficacy. In this study, a three-dimensional flower-leaf shape amyloid bovine serum albumin/gold nanoparticles/polyaniline (AL-BSA/AuNPs/PANI) coating on the surface of the electrode was developed, which demonstrated strong anti-adsorption properties against bovine serum albumin, plasma, and cells. The immunosensor exhibited a good linear relationship to CRP response, featuring a detection limit of 0.09 μg/mL, consistent with clinical reference range. In addition, the CRP immunosensor demonstrated excellent specificity in other inflammation-related proteins and commendable anti-interference performance for CRP detection in plasma and whole blood tests. Importantly, by combining the development of a USB flash disk-type portable electrochemical workstation with a reagent-free mode, the developed CRP electrochemical immunosensor delivered ideal results in clinical samples. The anti-fouling performance, sensitivity and specificity of the immunosensor, as well as its flexible test modes in clinical samples, provide important scientific basis for developing POC detection technologies of vital biomarkers in complex biological media., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Sensitive and accurate detection of thiamethoxam in tea is significant to ensuring consumer health. In this study, surface-enhanced Raman scattering (SERS) tags were prepared by using a polyphenol-mediated coating engineering strategy. This approach involved the self-assembly of tannic acid (TA) and self-polymerization of benzene-1,4-dithiol (BDT) on the surface of gold nanoparticles, resulting in the formation of Au@pBDT-TA. The SERS tags possess high Raman signals and antibody adsorption properties, avoiding the complex decoration or label steps of SERS reporters. We discovered that Au@pBDT-TA, composed of gold nanoparticles at 40 nm and a pBDT-TA thickness of 10 nm, was optimal for the development of the SERS lateral flow immunoassay (LFIA). In comparison to the gold nanoparticle-based LFIA, the SERS-LFIA demonstrated 4-fold and 720-fold enhancements in visual and quantitative limits of detection in buffer solution. The SERS-LFIA demonstrated quantitative limits of detection of 0.06 and 0.1 ng/g for black and green tea, respectively, with a broader linear range spanning over 2 orders of magnitude and a short detection time of 20 min. The proposed SERS-LFIA not only offers a sensitive and reliable method for monitoring thiamethoxam in tea but also possesses a versatile potential that can be easily adapted for the trace detection of various other targets.

Introduction: Due to most likely use of Bacillus anthracis in biological terrorism agents, the rapid and sensitive detection of its spores is crucial in both taking prophylactic measures and proper treatment. This study aimed to develop an amperometric electrochemical immunosensor for the detection of B. anthracis spores., Methods: A new amperometric biosensor was designed using a combination of magnetic beads and multiplex screen-printed electrodes. This method measures changes in current intensity resulting from oxidation and reduction in the working electrode directly to spore concentrations., Results: A standard curve was formed to test the number of live spores between 2 × 102-2 × 104 spores/ml concentrations. LOD and LOQ values were found to be 92 and 272 spores/ml, respectively. No cross-reactions were seen for Bacillus subtilis, Bacillus cereus and Bacillus thuringiencis spores., Conclusions: It is shown that the designed Anthrax immunosensor has high sensitivity and selectivity with rapid detection results., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Diseases mediated by cytokine storms are often characterized by an overexuberant pace of pathogenesis accompanied by significant morbidity and mortality. Thus, near real-time (NRT) detections via a site-of-inflammation (SOI) sampling of proinflammatory cytokines are essential to ensure a timely and effective treatment of acute inflammations, which up to now, has not been fully possible. In this work, we proposed a novel NRT and SOI immunosensor using ZIF-8 signal amplification together with an off-on strategy. To achieve NRT detections via a SOI sampling, the body fluid of choice is the dermal interstitial fluid (ISF). The significant merits of ISF over blood are the quality, quantity and diversity of ISF-based biomarkers; the fluid is non-coagulating, making it feasible to perform multiple or continuous samplings and the sampling is minimally invasive. Our immunosensor requires only 5 μL of ISF to achieve a simultaneous detection of five highly potent proinflammatory cytokines: IL-6, IFN-γ, IL-1β, TNF-α, IP-10. We employed a microneedle array patch (MAP) together with a trifurcated nozzle pump to extract a mean volume of between 30 and 60 μL of ISF in 20 min. Under optimal conditions, the biosensor is capable of high-quality performance that exhibits a lower limit of detection (LOD) of 5.761 pg/mL over a wide linear range of 5.761 -3 ‒ 20.00 ng/mL. We believe our immunosensor for NRT detections via a SOI sampling of ISF-biomarkers offers new theranostic opportunities that may not be possible with blood-based biomarkers., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Diabetes is a chronic disease with significant complications, necessitating regular treatment and checkups, which can be costly and time-consuming for patients. To address this, we developed the Sliding Microneedle (MN)-Lateral flow immunoassay strip (LFIAs) device that combines the advantages of MNs and LFIAs to detect IL-6, an independent biomarker for diabetes complications. This device offers rapid and highly sensitive detection of IL-6 by extracting interstitial fluid (ISF) through MNs and transferring it to LFIAs. The stainless MN, embedded in the 3D-printed Sliding MN-LFIAs device, was inserted into the skin at a 20° angle, minimizing blood contamination risk. With a filter paper attached to the MN surface, the device collected 4.65 ± 0.05 μL of ISF containing IL-6 within 90 s. The ISF was then transferred to the LFIAs using a running buffer. After a 15-min reaction, silver enhancement (SE) treatment was applied, allowing for the highly sensitive and specific detection of IL-6 at 10 2  pg/mL concentrations. The Sliding MN-LFIAs device successfully distinguished between normal and diabetic rat models, demonstrating its potential as an effective tool for detecting diabetes complications quickly and affordably., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Developing non-passivating and fully integrated electrode arrays for point-of-care testing of carcinoembryonic antigen (CEA) is crucial, as the serum level of CEA is closely associated with colorectal cancer. Herein, we propose a simple, low-cost, and eco-friendly template-assisted filtration method for the scalable preparation of carbon nanotube-bridged Ti 3 C 2 T x MXene (MX@CNT) electrode arrays with a conductive network. Furthermore, we fabricate a homogeneous electrochemical (HEC) sensor for CEA detection by integrating a magnetic-bead-based alkaline phosphatase-linked immunoassay (MB-aElisa), which enables the in-situ generation of the electroactive substance 1-naphthol (1-NP). Benefiting from the unique electrochemical characteristics of a MX@CNT electrode array, such as ultra-low background signal and superior electrocatalytic activity towards the hydrolyzed 1-NP, the MB-aElisa-based HEC sensor specifically measures CEA within a detection range spanning from 0.005 to 1.0 ng mL -1 , achieving a detection limit of 1.6 pg mL -1 . Subsequently, this biosensing prototype is successfully utilized for the detection of CEA in serum specimens obtained from colorectal cancer patients. More importantly, the integration of MB-aElisa with a MX@CNT electrode array not only marks a significant advancement but also enables the creation of a one-step homogeneous electrochemical immunosensing platform, serving as a paradigm for the highly sensitive and selective measurement of trace tumor markers in complex biological samples., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Home testing technology strategy is critical for early screening of disease. However, current home testing technologies often require complex processes, which limits their application. In this study, a time-resolved cascade logic gate microfluidic chip (TCLMC) was revealed to enable capillary force-based one-step operation without manual intervention or professional equipment. By analogy with logic gates in the circuit, TCLMC could automatically control the fluid flow and regulate the incubation time to optimize the immunoassay. The limit of detection of TCLMC for SARS-CoV-2 and influenza B virus (Flu B) was 134.94 and 79.17 pg mL -1 within 10 min. Additionally, this study tested saliva samples from 12 Flu B patients and 24 healthy controls to verify its clinical application. The results showed that TCLMC had high sensitivity (100%), specificity (100%), and accuracy (100%). This study provides a new one-step strategy for home testing and demonstrates its great potential in the diagnosis field., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

The current work shows the advancement of an additive manufactured multiplex immunosensor for the detection of dengue serotypes 1&2 in dengue patients on a single device with the LOD of 12.5 ng/ml. In this work, we created a QR-Code enabled additive manufactured case comprised of a paper-based electrode coated with ZnO NPs, which helps to enhance the detection signal and make it more selective, both serotype antibodies (DENV1-Ab & DENV2-Ab) were employed against DENV serotypes (DENV1-Ag & DENV2-Ag. QR-code technology was also integrated with the established platform to deliver sensor supporting information so that anybody may quickly obtain supporting sensing result details by scanning with a smartphone. The proposed highly advanced platform successfully detected DENV serotypes in dengue patients and showing a wide range of detection from 12.5 to 200 ng/ml with a LOD of 12.5 ng/ml.The results were also validated with conventional testing, i.e., Indirect Fluorescence Antibody Test (IFAT), so the developed multiplex-sensor became more applicable for the detection of DENV serotypes on a single tool having high sensitivity and selectivity, with a potential of commercialization., Competing Interests: Declaration of competing interest There is no conflicts of interest amongst any authors., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The broad availability of smartphones has provided new opportunities to develop less expensive, portable, and integrated point-of-care (POC) platforms. Here, a platform that consists of three main components is introduced: a portable housing, a centrifugal microfluidic disc, and a mobile phone. The mobile phone supplies the electrical power and serves as an analysing system. The low-cost housing made from cardboard serves as a platform to conduct tests. The electrical energy stored in mobile phones was demonstrated to be adequate for spinning a centrifugal disc up to 3000 revolutions per minute (RPM), a rotation speed suitable for majority of centrifugal microfluidics-based assays. For controlling the rotational speed, a combination of magnetic and acoustic tachometry using embedded sensors of the mobile phone was used. Experimentally, the smartphone-based tachometry was proven to be comparable with a standard laser-based tachometer. As a proof of concept, two applications were demonstrated using the portable platform: a colorimetric sandwich immunoassay to detect interleukin-2 (IL-2) having a limit of detection (LOD) of 65.17 ng/mL and a fully automated measurement of hematocrit level integrating blood-plasma separation, imaging, and image analysis that takes less than 5 mins to complete. The low-cost platform weighing less than 150 g and operated by a mobile phone has the potential to meet the REASSURED criteria for advanced diagnostics in resource limited settings., (© 2024. The Author(s).)

In this study, a sensitive dual-signal electrochemiluminescence (ECL) immunosensor was developed for okadaic acid (OA) detection utilizing copper nanoclusters (CuNCs) and Ru(bpy) 3 2+ -doped silica nanoparticles (RuSiNPs). Interestingly, the CuNCs could simultaneously enhance both cathodic (-0.95 V) and anodic (+1.15 V) ECL signals of RuSiNPs, forming a dual-signal ECL sensing platform. Further, RuSiNPs@CuNCs were used as immunomarkers by covalently conjugating them with an anti-OA monoclonal antibody (mAb) to form probes. Finally, dual ECL signals of the immunosensor were fabricated and showed good linear relationships with OA concentrations in the range of 0.05-70 ng mL -1 , having a median inhibitory concentration (IC 50 ) of 1.972 ng mL -1 and a limit of detection of 0.039 ng mL -1 . Moreover, the constant ratio of the cathodic and anodic ECL peaks achieved self-calibration of the detection signal and improved the reliability of the results. Finally, we successfully applied the ECL sensor to detect OA in spiked oyster samples., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Early and rapid diagnostic of acute myocardial infarction (AMI) during its developing stage is crucial due to its high fatality rate. Heart-type fatty acid binding protein (h-FABP) is an ideal biomarker for the quantitative diagnosis of AMI, surpassing traditional markers such as myoglobin, creatine phosphokinase-MB, and troponin in terms of sensitivity, specificity, and prognostic value. To obtain diagnostic and prognostic information, a precise and fully quantitative measurement of h-FABP is essential, typically achieved through an immunosorbent assay like the enzyme-linked immunosorbent assay. Nevertheless, this method has several limitations, including extended detection time, complex assay procedures, the necessity for skilled technicians, and challenges in implementing automated detection. This research introduces a novel biosensor, utilizing aggregation-induced emission nanoparticles (AIENPs) and integrated with a digital microfluidic (DMF) workstation, designed for the sensitive, rapid, and automated detection of h-FABP in low-volume serum samples. AIENPs and magnetic beads in nanoscale were served as the capture particles and the fluorescent probe, which were linked covalently to anti-h-FABP antibodies respectively. The approach was based on a sandwich immunoassay and performed on a fully automated DMF workstation with assay time by 15 min. We demonstrated the determination of h-FABP in serum samples with detection limit of 0.14 ng/mL using this biosensor under optimal condition. Furthermore, excellent correlations (R 2  = 0.9536, n = 50) were obtained between utilizing this biosensor and commercialized ELISA kits in clinical serum detecting. These results demonstrate that our flexible and reliable biosensor is suitable for direct integration into clinical diagnostics, and it is expected to be promising diagnostic tool for early detection and screening tests as well as prognosis evaluation for AMI patients., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The multiple-readout capability of multimodal detection enhances the flexibility, reliability, and accuracy of lateral flow immunoassay (LFIA). The conjugation of two different metal-organic frameworks (MOFs) as a new-generation composite material offers extraordinary opportunities for developing multimodal LFIA. It is anticipated to compensate limitations of traditional single colorimetric signal LFIA and improve the analysis performance. Herein, an ultra-bright fluorescent AIE-MOF was proposed and coupled with an in-situ growth of Prussian blue (PB) nanoparticles strategy to obtain a novel multimodal signal tracer (AIE-MOF@PB). Thereafter, it was successfully applied to develop the multimodal LFIA platform for the detection of nitrofurazone metabolites. The synergy of AIE-MOF and PB endows AIE-MOF@PB with superb water dispersibility, robust fluorescence emission, brilliant colorimetric signal, marvelous photothermal conversion, and enhanced antibody coupling efficiency, all of which facilitate a highly sensitive triple-readout LFIA platform. The detection sensitivity improved by at least 5-fold compared with the colloidal gold-based LFIA. This work not only inspires the rational design of aggregation-induced emission luminogens (AIEgen)-based complex materials but also highlights the promising potential in flexible point-of-care applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

5-formylcytosine (5 fC) and 5-carboxylcytosine (5caC) serve as key intermediates in DNA demethylation process with significant implications for gene regulation and disease progression. In this study, we introduce a novel electrochemical sensing platform specifically designed for the sensitive and selective detection of 5 fC and 5caC in DNA. Protein A-modified magnetic beads (ProtA-MBs) coupled with specific antibodies facilitate the immunorecognition and enrichment of these modified bases. Signal amplification is achieved through several chemical reactions involving the interaction between N 3 -kethonaxl and guanine, copper-free click chemistry for the attachment of dibenzocyclooctyne (DBCO)-Biotin, and the subsequent recognition by streptavidin-conjugated horseradish peroxidase (SA-HRP). The assay's readout is performed on a disposable laser-induced graphene (LIG) electrode, modified with the bead-antibody-DNA complex in a magnetic field, and analyzed using differential pulse voltammetry in a system employing hydroquinone (HQ) as the redox mediator and H 2 O 2 as the substrate. This immunosensor displayed excellent sensitivity, with detection limits of 14.8 fM for 5 fC across a 0.1-1000 pM linear range and 87.4 fM for 5caC across a 0.5-5000 pM linear range, and maintained high selectivity even in the presence of interferences from other DNA modifications. Successful application in quantifying 5 fC and 5caC in genomic DNA from cell extracts, with recovery rates between 97.7% to 102.9%, underscores its potential for clinical diagnostics. N 3 -kethoxal was used for the first time in an electrochemical sensor. This work not only broadens the toolkit for detecting DNA modifications but also provides a fresh impetus for the development of point-of-care testing (POCT) technologies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled., (Copyright © 2024 Elsevier B.V. All rights reserved.)

A spatial-resolved and self-calibrated photoelectrochemical (PEC) biosensor has been fabricated by a multifunctional CeO 2 /CdS heterostructure, achieving portable and sensitive detection of carcinoembryonic antigen (CEA) using a homemade 3D printing device. The CeO 2 /CdS heterostructure with matched band structure is prepared to construct the dual-photoelectrodes to improve the PEC response of CeO 2 . In particular, as the photoactive nanomaterial, the CeO 2 also plays the role of peroxidase mimetic nanozymes. Therefore, the catalytic performance of CeO 2 with different morphologies (e.g., nano-cubes, nano-rods and nano-octahedra) have been studied, and CeO 2 nano-cubes (c-CeO 2 ) achieve the optimal catalytic activity. Upon introducing CEA, the sandwich-type immunocomplex is formed in the microplate using GOx-AuNPs-labeled second antibody as detection antibody. As a result, H 2 O 2 can be produced from the catalytic oxidization of glucose substrate by GOx, which is further catalyzed by CeO 2 to form •OH, thus in situ etching CdS and decreasing the photocurrents. The self-calibration is achieved by the dual-channel photoelectrodes on the homemade 3D printing device to obtain the photocurrents ratio, thus effectively normalizing the fluctuations of external factors to enhance the accuracy. This integrated biosensor with a detection limit as low as 0.057 ng mL -1 provides a promising way for ultrasensitive immunoassay in clinic application in complex environments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

In recent years, an increase in the number of chronic kidney disease (CKD) cases has led to a global health burden majorly affecting underdeveloped and developing nations. A key biomarker for assessing the kidneys' normal functioning is creatinine, which is filtered out from the blood by the kidney. Thus, timely and specific detection of creatinine becomes necessary for diagnosis and subsequent treatment of CKD. Hence, in this study, we have tried to develop a field-deployable, software-integrated immunosensor for the detection of creatinine in a serum sample. The immunosensor was developed by incorporating gold nanoparticles, boron doped MXene, polyaniline, and anticreatinine antibody using an appropriate bioconjugation reaction. The developed sensor was able to detect creatinine in a linear dynamic range of 10 nM to 0.1 M with a limit of detection of 1.72 (±0.07) nM. The sensor was integrated with an indigenously developed software named "CretCheck" which simplifies the process of data analysis. The software integrated personalized biosensing device was used to find the creatinine concentrations directly from the obtained analytical signals. The developed immunosensor with the integrated software can also be implemented directly in primary health care facilities for creatinine detection in the future.

Lateral Flow Immunoassay (LFI) is a disposable tool designed to detect target substances using minimal resources. For qualitative analysis, LFI does not require a device (i.e., reader) to interpret test results. However, various studies have been conducted to implement quantitative analysis using LFI systems, incorporating LFI along with electrical/electronic readers, to overcome the limitations associated with qualitative LFI analysis. The reader used for the quantitative analysis of LFI should ensure mobility for easy on-site diagnostics and inspections, be user-friendly in operation, and have a fast processing speed until the results are obtained. Due to these requirements, smartphones are increasingly utilized as readers in quantitative analysis of LFI. Among the various components constituting a smartphone, high-performance cameras can serve as sensors converting visual signals into electrical signals. With powerful processing units, large storage capacity, and network capabilities for transmitting analysis results, smartphones are also utilized as interfaces for quantitative analysis. Absolutely, the widespread global use of smartphones is a key advantage, leading to their utilization as diagnostic devices for acquiring, analyzing, storing, and transmitting assay test results. This paper summarizes research cases where smartphones are utilized as readers for quantitative LFI systems used in confirming contamination in food or the environment, detecting drugs, and diagnosing diseases in humans or animals. The systems are classified based on the types of label particles used in the assay, and efforts to improve the quantitative analysis performance for each are examined. Cases where smartphones were used as LFI readers for the diagnosis of the 2019 Coronavirus Disease (COVID-19), which has recently caused significant global damage, have also been investigated., Competing Interests: Declaration of competing interest The author declares no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Despite high sensitivity of nanoparticle-on-mirror cavities, a crucial branch of plasmonic nanomaterials, complex preparation and readout processes limit their extensive application in biosensing. Alternatively, liquid metals (LMs) combining fluidity and excellent plasmonic characteristics have become potential candidates for constructing plasmonic nanostructures. Herein, we propose a microfluidic-integration strategy to construct LM-based immunoassay platform, enabling LM-based nanoplasmonic sensors to be used for point-of-care (POC) clinical biomarker detection. Flowable LM is introduced onto protein-coated Au nanoparticle monolayer to form a "mirror-on-nanoparticle" nanostructure, simplifying the fabrication process in the conventional nanoparticle-on-mirror cavities. When antibodies were captured by antigens coated on the Au nanoparticle monolayer, devices respond both thickness and refractive index change of biomolecular layers, outputting naked-eye readable signals with high sensitivity (limit of detection: ∼ 604 fM) and a broad dynamic range (6 orders). This new assay, which generates quantitative results in 30 min, allows for high-throughput, smartphone-based detection of SARS-CoV-2 antibodies against multiple variants in clinical serum or blood samples. These results establish an advanced avenue for POC testing with LM materials, and demonstrate its potential to facilitate diagnostics, surveillance and prevalence studies for various infectious diseases., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

For every epidemic outbreak, the prevention and treatments in resource-limited areas are always out of reach. Critical to this is that high accuracy, stability, and more comprehensive analytical techniques always rely on expensive and bulky instruments and large laboratories. Here, a fully integrated and high-throughput microfluidic system is proposed for ultra-multiple point-of-care immunoassay, termed Dac system. Specifically, the Dac system only requires a handheld portable device to automatically recycle repetitive multi-step reactions including on-demand liquid releasing, dispensing, metering, collecting, oscillatory mixing, and discharging. The Dac system performs high-precision enzyme-linked immunosorbent assays for up to 17 samples or targets simultaneously on a single chip. Furthermore, reagent consumption is only 2% compared to conventional ELISA, and microbubble-accelerated reactions shorten the assay time by more than half. As a proof of concept, the multiplexed detections are achieved by detecting at least four infection targets for two samples simultaneously on a singular chip. Furthermore, the barcode-based multi-target results can rapidly distinguish between five similar cases, allowing for accurate therapeutic interventions. Compared to bulky clinical instruments, the accuracy of clinical inflammation classification is 92.38% (n = 105), with a quantitative correlation coefficient of R 2 = 0.9838, while the clinical specificity is 100% and the sensitivity is 98.93%., (© 2024 Wiley‐VCH GmbH.)

A mid-infrared label-free immunoassay-based biosensor is an effective device to help identify and quantify biomolecules. This biosensor employs a surface-enhanced infrared absorption spectroscopy, which is a highly potent sensing technique for detecting minute quantities of analytes. In this study, a biosensor was constructed using a metamaterial absorber, which facilitated strong coupling effects. For maximum coupling effect, it is necessary to enhance the near-field intensity and the spatial and spectral overlap between the optical cavity resonance and the vibrational mode of the analyte. Due to significant peak splitting, conventional baseline correction methods fail to adequately analyze such a coupling system. Therefore, we employed a coupled harmonic oscillation model to analyze the spectral distortion resulting from the peak splitting induced by the strong coupling effect. The proposed biosensor with a thrombin-binding aptamer-based immunoassay could achieve a limit of detection of 267.4 pM, paving the way for more efficient protein detection in clinical practice., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Jongwon Lee reports financial support was provided by National Research Foundation of Korea. Joo-Yun Jung reports financial support was provided by Korea Ministry of Trade Industry and Energy. Joo-Yun Jung reports financial support was provided by National Research Council of Science and Technology. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Coronavirus disease 2019 (COVID-19) is a highly contagious illness caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), resulting in a global health crisis. The primary diagnostic method for COVID-19 is quantitative reverse transcription PCR, which is time-consuming and requires expensive instrumentation. Here, we developed an electrochemical biosensor for detecting SARS-CoV-2 biomarkers using a 3D porous polyacrylamide/polyaniline hydrogel (PPG) electrode prepared by UV photopolymerization and in situ polymerization. The electrochemical immunosensor for detecting SARS-CoV-2 N protein via the immune sandwich principle demonstrated a lower detection limit of 42 pg/mL and comparable specificity to a commercial enzyme-linked immunosorbent assay, which was additionally validated in pseudoviruses. The electrochemical sensor for hydrogen peroxide showed a low detection limit of 0.5 μM and excellent selectivity, which was further confirmed in cancer cells under oxidative stress. The biomarkers of SARS-CoV-2 were successfully detected due to the signal amplification capability provided by 3D porous electrodes and the high sensitivity of the antigen-antibody specific binding. This study introduces a novel three-dimensional electrode with great potential for the early detection of SARS-CoV-2., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Heterologous strategy has promising applications in improving the sensitivity of competitive immunoassay. In this study, the potential heterologous coating antigens (HEA) were screened from eight imidacloprid (IMI) structural analogs based on the cross-reactivity (CR) of a prepared antibody. Computer-aided molecular modeling was used to predict the optimal HEA. Compared with the homologous coating antigen (HOA), the predicted HEA prepared from acetamiprid (CR = 0.23 %) increased the detection sensitivity of the enzyme-linked immunoassay and colloidal gold nanoparticle-based lateral flow immunoassay (HOA-Au-LFIA) by 5.6 and 4.1 times, respectively. Subsequently, the HEA and aggregation-induced emission fluorescent labels were integrated into a lateral flow immunoassay platform (HEA-AIE-LFIA). The limit of detection was 0.12 ng mL -1 for HEA-AIE-LFIA, which was 7.7-fold lower than that of HOA-Au-LFIA. Furthermore, HEA-AIE-LFIA was applied to detect IMI in food samples with excellent recoveries (86.41 %-111.25 %). Overall, this strategy of screening for superior HEA has great potential for improving LFIA sensitivity., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Here, a photoelectrochemical (PEC) immunosensor based on the FJU-200@CdSe heterostructure was developed for epidermal growth factor receptor (EGFR) detection. This is the first application of FJU-200 in PEC. After modification using CdSe quantum dots (QDs), FJU-200 and CdSe QDs formed an S-scheme heterostructure due to the interleaved energy band structure and the difference in Fermi energy (Ef) levels, which generated an efficient and stable PEC signal. When EGFR bound specifically to the antibody, a large spatial site resistance was generated, which hindered the electron transfer at the interface and the PEC signal was quenched. The proposed PEC sensing platform exhibited excellent detection performance for EGFR, with a good linear relationship with the photocurrent change value (ΔI) in the detection range of 10 fg/mL-100 ng/mL, and the detection limit was as low as 1.08 fg/mL. This work illustrates the potential electron transfer pathway between FJU-200 and CdSe QDs and creatively applies to the construction of PEC immunosensors, providing a new option for the detection of EGFR as well as other substances to be tested., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The lateral flow immunoassay (LFIA) is predominant in rapid diagnostic tests owing to its cost-effectiveness and operational simplicity. However, the conventional LFIA exhibits limited sensitivity and is susceptible to human variance for the result readout, impacting result interpretation. In this study, we introduced a novel one-step copper deposition-induced signal amplification lateral flow immunoassay (osa-LFIA) that markedly enhances the detection sensitivity for Staphylococcus aureus (protein A) and Pseudomonas aeruginosa (exotoxin A). Utilizing gold nanoparticles (AuNPs) as a catalyst, this approach employs ascorbic acid to reduce Cu 2+ to Cu 0 , depositing on AuNPs at the test line and amplifying the signal. A user-friendly design features a three-dimensional paper structure incorporating pre-dried reagents, enabling a streamlined, efficient testing process. The osa-LFIA significantly lowers detection limits to 3 ng mL -1 for protein A and 10 ng mL -1 for exotoxin A, offering a tenfold improvement over conventional LFIA. Additionally, we developed a portable grayscale detection device, achieving less than 10% error in quantitative analysis compared to the data acquired and analyzed in the lab. This entire process, from detection to signal amplification, is completed in just 20 min. For the clinical trial, we utilized the osa-LFIA to test synovial fluid samples infected with Staphylococcus aureus. We also successfully detected different concentrations of the exotoxin A in parallel, with a recovery value of 96%-110%. Our findings demonstrate the osa-LFIA's potential as a rapid, highly sensitive, and simple-to-use diagnostic tool for detecting various pathogens, significantly advancing the field of rapid diagnostic testing., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Reluctant reproducibility and accuracy make electrochemical immunosensors suffering from high possibility of false negative/positive results, and it is the main obstacle that hinders them into an eligible alternative technology to the gold-standard method. It has been demonstrated sporadically previously that ratiometry helps deal with this issue but to what extent this could be beneficial and why it could fulfill is yet to be explored. In this study, to the best of our knowledge, for the first time, we have attempted to answer these questions through comprehensive experiments. For this purpose, labeled and label-free electrochemical immunosensors for SARS-CoV-2 pseudovirus quantification are constructed as a model electrochemical immunosensor. Conventional and ratiometric immunosensors are prepared by using electrochemically synthesized graphene modified electrodes coupled with various electrochemical probe pairs. It was found that the electrocatalyst modification at the electrode interface makes the predominant contribution to immunosensor sensitivity, while appropriate ratiometry provided electrochemical immunosensors with significantly enhanced reproducibility, accuracy, as well as sensing stability. Further, the experiments confirmed that the improvement in sensor performance achieved by ratiometry is primarily through overcoming the inherent errors and dynamic variations of the base electrode. It is also demonstrated electrochemical immunosensors made thereof could easily rival the performances of the gold-standard PCR method, in the view of immunoassay diagnosis. Therefore, it is of great promise to evolve electrochemical immunosensors into an eligible substitute technique towards the prevalent nucleic acid detection method in point-of-care testing (POCT), with the aid of electrochemical ratiometry., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Drop-casted polypyrrole (PPY) nanomaterial-based point-of-care Traumatic Brain Injury (TBI) immunosensing platforms reported previously demand trained manpower at field-test, due to poor adhesion between nanomaterial and electrode surface, limiting the point-of-care purpose. The usage of conventional clean-room-based physical and chemical vapor deposition techniques in creating strong adhesion is limited on account of cost and process complexity. Addressing this technical gap, we report a novel low-cost clean-room-free technique that can effectively electrodeposit the PPY simultaneously onto the working areas of array of Interdigitated microelectrodes (IDμEs) from the precursor solution. Through optimization of deposition cycles and molar concentration ratio of monomer and oxidizing agents, a high-quality nanomaterial was electrodeposited on IDμEs' surface. Further, by using the electrodeposited PPY as a bioelectrical transducer, the TBI-specific UCHL1 and GFAP target analytes were simultaneously detected in terms of variation of DC-Resistance and AC-Capacitance parameters, recorded through chemiresistive I-V and chemicapacitive C-F responses of bioelectrodes, respectively. Such simultaneous multianalyte-detection in terms of multiple parameters increases the diversity of decision-making parameters by several folds, inherently aids in enhancing the diagnostic accuracy of TBI test kit. Here, the efficiency of the electrodeposited PPY-based chemiresistive and chemicapacitive immunosensing platforms in detecting TBI-specific target analytes simultaneously in real-time human-plasma samples was analyzed in terms of sensitivity, resolution, LoD, RoD, long-term stability (30 weeks), and the same is compared with drop-cast PPY-based immunosensing platform. Notably, the electrodeposited PPY sensing platforms showed superior performance in terms of sensitivity, LoD, device variability and long-term stability without demanding any trained manpower in the field., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Accurately differentiating respiratory diseases caused by viruses is challenging because of the similarity in their early or clinical symptoms. Moreover, different infection sources require different treatments. However, the current diagnostic methods have limited differentiating efficiency and sensitivity. We developed a dual-system immunosensor with a bilayer fluorescent label as a signal amplifier for the on-site, sensitive, and accurate identification of multiple respiratory viruses (RVs). The nanomaterial, comprising a polystyrene (PS) nanosphere core encapsulated by two layers of CdSe@ZnS-COOH quantum dots (QDs), outperforms the conventional color and fluorescent labels in RV detection. The dual-system detection platform, comprising a PS@DQD-based lateral flow immunoassay (LFIA) and a PS@DQD-based homogeneous sensor, enables qualitative and quantitative screening of multiple respiratory viruses within 10 and 30 min, respectively, depending on the specific detection requirements for different application scenarios. This remarkable method provides 51.2 to 1000 times sensitivity improvement over commercial antigen detection kits and greater than 12.5 to 100 times improvement over QD-based immunosensors. Furthermore, we comprehensively evaluated the specificity, reproducibility, and stability of the integrated dual-system detection platform, demonstrating its reliability. Remarkably, the respiratory viral testing was validated using biological samples, thus illustrating its promise and convenience in the detection of respiratory viruses., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Vitamin B12 is an essential micronutrient required for the proper functioning of the human body. Vitamin B12 deficiency is primarily causative of various neurolological disorders alongwith recurrence of oral ulcers and burning sensations which are early signs of condition such as pernicious anemia. Other complications associated with Vitamin B12 deficiency include risk of heart failure due to anemia, risk of developing autoimmune disorders and gastric cancer. Therefore, to obstruct these communal health issues, early detection of Vit B12 is highly needed. However, screening of vitamin B12 insufficiency is hindered by the low sensitivity of the conventional vitamin B12 test. Holotranscobalamin (holoTC) is an early indicator of the negative vitamin B12 balance as it is the first protein to decline in the serum. We report a novel impedimetric immunosensor based on flower-like poly (3,4-ethylenedioxythiophene) (PEDOT) nanostructural film impregnated with silver molybdate nanoparticles (Ag 2 MoO₄ NPs) deposited on fluorine-doped tin oxide electrode. The prepared electrodes were characterized by Field emission scanning electron microscopy (FE-SEM) with energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and electrochemical studies. The activated anti-holoTC antibody was immobilized and optimized to capture the target in a response time of 15 min. The electrochemical performance of the sensor was carried out by using the electrochemical impedance spectroscopy technique (EIS) and a good linear relationship between ΔR ct and holoTC was obtained in the range from 0.1 pg mL -1 to 100 ng mL -1 with a detection limit of 0.093 pg mL -1 . The proposed sensor was successfully applied in human serum samples for holoTC detection. The experimental results showed that the immunosensor is highly selective towards holoTC and presented an acceptable stability of 20 days with reproducibility RSD ≤4%. To the best of our knowledge, this is the first developed electrochemical immunosensor for holoTC detection., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Some biomarkers of acute aortic dissection (AAD) can be used for the potential supplementary diagnosis of AAD, such as C-reactive protein (CRP), smooth muscle myosin heavy chain (SmMHC), and D-dimer (D-D). However, the current measurement methods for common markers primarily rely on sophisticated instruments. The operation process is complicated, and the reagents used are expensive. To provide chronic disease monitoring and home self-examination services for potential AAD patients in real time, we developed a smartphone-based multichannel magnetoelastic (ME) immunosensing device to detect protein levels. Our immunosensor reduced the aforementioned restrictions and demonstrated excellent performance for the supplementary diagnosis of AAD. In this paper, we successfully combined the intelligent terminal with the hardware system to sample the resonance frequency shift (RFS) on the multichannel ME immunosensor. According to the target detection objects with their respective antibodies in the immune binding response, multiple experiments were conducted to detect multiple groups of samples, and we found that a CRP concentration, a SmMHC concentration, and a D-D concentration in the range of 0.1-100μg/mL, 1-4ng/mL, and 0.25-5μg/mL were linearly proportional to the RFS of the ME immunosensor, respectively. For CRP, SmMHC, and D-D, the sensitivities were 13.37Hz/μg∙mL -1 , 155.19Hz/ng∙mL -1 , and 332.72Hz/μg∙mL -1 , respectively, and the detection limits were 2.634×10 -3 μg/mL, 1.155×10 -2 ng/mL, and 3.687×10 -3 μg/mL, respectively. The experiments demonstrated that the accuracy and stability of our device were comparable to those of the vector network analyzer (VNA, Calibration instrument)., Competing Interests: Declaration of competing interest There are no conflicts to declare., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this study, we incorporated nanometal surface energy transfer (NSET) in lateral flow immunoassay (LFIA) and explored the relationship between fluorescence quenching efficiency and detection sensitivity to improve sensitivity of NSET-LFIA system. We developed nine gold nanoparticles (GNPs) with absorption spectrum in the range of 520-605 nm as acceptors and quantum dot microspheres (QDMs) with emission spectrum of 530, 570, and 610 nm as donors. By analyzing the overlap integral area, fluorescence quenching efficiency, and detection sensitivity of 27 donor-acceptor pairs, we observed that the larger overlap integral area led to higher fluorescence quenching efficiency and detection sensitivity. A maximum fluorescence quenching efficiency of 91.0% was obtained from the combination of GNPs at 605 nm and QDMs at 610 nm, achieving the highest detection sensitivity. We developed NSET-LFIA for the detection of T2 toxin with a limit of detection of 0.04 ng/mL, which was 10-times higher than that obtained via conventional GNP-LFIA. NSET-LFIA represents a versatile, ultrasensitive and valuable screening tool for small molecules in real samples., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2024. Published by Elsevier B.V.)

Antibody-enzyme complexes (AECs) are ideal for immunosensing. Although AECs using antibody fragments can be produced by bacterial hosts, their low affinity limits their sensing applications. We have improved the affinity of AECs by combining two antibodies using Catcher/Tag systems; however, it requires multiple antibodies and an enzyme production process. In this study, to realize the production of AECs harboring multiple antibody fragments in a single production process, we report a versatile development method of unique AECs based on a multimeric enzyme structure. Using the homotetrameric enzyme, lactate oxidase (LOx), as a labeling enzyme, tetravalent AECs were developed as an electrochemical immunosensor. Homogeneous tetravalent AECs were successfully fabricated by fusing the anti-epidermal growth factor receptor (EGFR) variable domain of a heavy chain of heavy chain antibody to the N-terminus of LOx. The prepared AECs bound to EGFR, maintain their enzyme activity, and worked well as sensing elements in electrochemical sandwich enzyme-linked immunosorbent assay. Moreover, tetravalent AECs exhibited higher sensitivity than monovalent AECs because of their avidity. The fabricated AECs were successfully used in a wash-free homogeneous electrochemical detection system combined with magnetic separation. Our findings offer new insights into the applications of the LOx tetrameric enzyme for the fabrication of AECs with tetravalent antibodies, which may serve as scaffolds for immunosensors., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Photocurrent-polarity conversion strategies are typically realized by constructing complex photovoltaic electrodes or changing the relevant conditions, but most involve poor photogenerated carrier transfer efficiency and cumbersome experimental steps. To this end, a photoelectrochemical (PEC) biosensor by utilizing ascorbic acid (AA)-induced photocurrent-polarity-switching was proposed for the detection of carcinoembryonic antigen (CEA). Under light excitation, the electron donor AA was oxidized by the photogenerated holes of photoactive material Co-NC/CdS, resulting in the conversion of cathodic photocurrent to the anodic direction. In the presence of the target CEA, alkaline phosphatase (ALP) was introduced into the microplates by the sandwiched immunoreaction, which then catalyzed the production of AA from ascorbic acid-2-phosphate (AAP). Finally, the catalytic product AA was transferred onto Co-NC/CdS-modified screen-printed carbon electrode, thus activating photocurrent-polarity-switching platform. The anodic photocurrent values gradually increased with increasing CEA concentration in the range of 0.02-80 ng mL -1 and reached a limit of detection (LOD) of 8.47 pg mL -1 (S/N = 3). In addition, the results of actual sample detection prove the reliability of the constructed PEC biosensor. Importantly, this work relies on a mobile smartphone wireless Bluetooth device coupled with the PEC biosensor for immediate detection, providing another idea for detecting CEA in clinical diagnosis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Herein, we have manufactured a newly designed bifunctional impedimetric and amperometric immunosensor for rapidly detecting erythromycin (ERY) in complicated environments and food stuffs. For this, bimetallic cobalt/cerium-layered double hydroxide nanosheets (CoCe-LDH NSs), which was derived from Co-based zeolite imidazole framework via the structure conversion, was simultaneously utilized as the bioplatform for anchoring the ERY-targeted antibody and for modifying the gold and screen printed electrode. Basic characterizations revealed that CoCe-LDH NSs was composed of mixed metal valences, enrich redox, and abundant oxygen vacancies, facilitating the adhesion on the electrode, the antibody adsorption, and the electron transfers. The manufactured impedimetric and amperometric immunosensor based on CoCe-LDH has showed the comparable sensing performance, having a wide linear detection range from 1.0 fg mL -1 to 1.0 ng mL -1 with the ultralow detection limit toward ERY. Also, the portable, visualized, and efficient analysis of ERY was then attained at the smartphone-assisted CoCe-LDH-based SPE., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

A label-free electrochemical immunosensor was developed to rapidly detect tilmicosin (TMC) residues in pork and milk. The immunosensor was constructed by immobilizing a high-affinity monoclonal antibody against TMC on an rGO-PEI-Ag nanocomposite-modified electrode. The rGO-PEI-Ag nanocomposites were prepared by mixing polyethyleneimine (PEI) modified reduced graphene oxide (rGO) with AgNO 3 solution. The prepared rGO-PEI-Ag nanocomposites showed good redox activity and conductivity, as characterized by ultraviolet-visible spectroscopy (UV-Vis), transmission electron microscopy (TEM), and X-ray diffraction (XRD). During the preparation process, staphylococcal protein A (SPA) was added to targetedly bind the Fc segment of the monoclonal antibody. The immunosensor showed a low detection limit (LOD) of 0.0013 ng/mL, a linear range of 0.01-100 ng/mL, and recoveries ranging from 92.77 to 100.02% in pork and 92.26-101.23% in milk. Furthermore, the immunosensor exhibited good stability, reproducibility, and specificity in detecting TMC in pork and milk real samples., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Aflatoxin B 1 is highly mutagenic in humans, and long-term exposure can impair immunity and increase the risk of cancer. It is imperative to develop immunoassays with convenient operation and high sensitivity to detect aflatoxin B 1 . This study presents a polystyrene microcolumn-mediated magnetic relaxation switching immunosensor based on a tyramine signal amplification strategy for detecting aflatoxin B 1 . An environmentally friendly hand-held polystyrene microcolumn was designed as an effective immunoreaction carrier, remaining 91% efficiency after 12 repeated uses. And the microcolumn provides a user-friendly procedure for rapid separation and reagent switching within 3 s by simple stirring in solution. The combination of a strong anti-interference magnetic relaxation switching biosensing and an efficient tyramine signal amplification enables the quantitative detection of aflatoxin B 1 in the range of 0.01-10 ng/mL, with a limit of detection of 0.006 ng/mL. This method has potential application in the rapid detection of trace food contaminants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Nowadays, notable progress has been achieved in detecting foodborne toxins by employing nanoenzyme-based lateral flow immunoassay (NLFIA) sensors in point-of-care testing (POCT). It continues to be a major challenge to maximize the enzyme-like performance of nanozymes for educe any potential uncertainties in catalytic process. In this study, we employed a facile and efficient self-assembly approach to fabricate nucleoid-shell structured biomimetic nanospheres CuS@Au-Pt (CAP), which demonstrates enhanced brightness of the colorimetric signal, excellent affinity, and excellent peroxidase activity. The integration of CAP with a competitive-assay NLFIA platform enabled sensitive immunochromatographic detection of bongkrekic acid (BA), with LOD as low as 0.66 ng/mL. After signal amplification through enzyme-like reaction, the detection range was extended around 1-fold. Additionally, CAP-NLFIA effectively detected BA with a recovery rate of 80.96-119.36% for real samples. The study proposes using CAP as a signal reporter in a dual-readout LFIA, which can establish a high throughput sensitive detection platform., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Celery is a food allergen that must be included in the ingredient list of commercial food products in the European Union. This is a challenge for the food industry because of potential cross-contamination and undeclared ingredients because of their low concentrations. So, the food industry requires expedited high-performance analytical methods. The development, validation and application of a magnetic nanomaterial-based voltammetric immunosensor is reported to quantify a major celery allergen (Api g 1), achieving a low limit of detection (32 pg·mL -1 , in a 40-μL sample). The applicability of the biosensor was evaluated by analysing twenty food products and the lowest Api g 1 content (1.1 ± 0.9 mg·kg -1 ) was quantified in a cooked sample. The selectivity of the method and the interference of similar fresh products (e.g., parsley, basil) were evaluated. This portable and easy-to-use biosensor can be a fit-for-purpose solution to tackle a major problem for the food industry., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Pyrimethanil (PYR) is a fungicide that is harmful to consumers when present in foods at concentrations greater than maximum permitted residue levels. High-performance immunoprobes and dual-readout strategy may be useful for constructing sensitive lateral flow immunoassay (LFIA). Herein, the prepared litchi-like Au-Ag bimetallic nanospheres (LBNPs) exhibited high mass extinction coefficients and fluorescence quenching constants. Benefiting from LBNPs and dual-readout mode, the limits of detection of LBNPs-CM-LFIA and LBNPs-FQ-LFIA for PYR were 0.957 and 0.713 ng mL -1 , which were 2.54- and 3.41-fold lower than that of gold nanoparticles-based LFIA, respectively. The limits of quantitation of LBNPs-CM-LFIA and LBNPs-FQ-LFIA were 3.740 and 1.672 ng mL -1 , respectively. LBNPs-LFIA was applied to detect PYR in cucumber and grape samples with satisfactory recovery (90%-111%). LBNPs-LFIA showed good agreement with LC-MS/MS for the detection of PYR in the samples. Accordingly, this sensitive and accurate dual-readout LFIA based on LBNPs can be effectively applied for food safety., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

High fluorescence intensity microspheres such as aggregation-induced emission fluorescence microspheres (AIEFM) have improved the sensitivity of lateral flow immunoassay (LFIA). The preparation of immune probes in LFIA usually adopts the chemical coupling strategy with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide for antibody coupling, which has the problems of low coupling efficiency, tedious coupling process, and poor repeatability. A biocompatible metal-phenolic network (MPN), which contains large amounts of phenols and galloyl groups, could easily, quickly, and stably couple with antibodies. Herein, we proposed a strategy based on MPN modification on ultrabright AIEFM surface as a novel label for the rapid detection of carbendazim. The limit of detection of AIEFM@MPN-LFIA was 0.019 ng/mL, which was 4.9 times lower than that of AIEFM-LFIA. In spiked samples, the average recoveries of AIEFM@MPN-LFIA ranged from 80% to 118% (coefficient of variation <13.45%). Therefore, AIEFM@MPN was a promising signal label that could improve the detection performance of LFIA., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

This work proposed a simple and ultrasensitive nanozyme-based immunoassay on a filtration device for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid protein (NP). Gold core porous platinum shell nanoparticles (Au@Pt NPs) were synthesized with high catalytic activity to oxidize 3,3',5,5'-tetramethylbenzidine, leading to an oblivious color change. The filtration device was designed based on the size difference of magnetic beads, filter membrane pore, and Au@Pt NPs. A simple, rapid, and consistent washing procedure can be performed with the help of a plastic syringe. This detection method could realize the quantitative detection of SARS-CoV-2 NP within 80 min for point-of-care needs. The limit of detection for the SARS-CoV-2 antigen was 0.01 ng/mL in buffer. The coefficients of variation of the assay were 1.78% for 10 ng/mL SARS-CoV-2 antigen, 2.03% for 1 ng/mL SARS-CoV-2 antigen, and 2.34% for the negative sample, respectively. The specificity of the detection platform was verified by the detection of various respiratory viruses. This simple and effective detection system was expected to promote substantial progress in the development and application of virus immunodetection technology.

Exhaled breath electrochemical sensing is a promising biomedical technology owing to its portability, painlessness, cost-effectiveness, and user-friendliness. Here, we present a novel approach for target analysis in exhaled breath by integrating a comfortable paper-based collector into an N95 face mask, providing a universal solution for analyzing several biomarkers. As a model analyte, we detected SARS-CoV-2 spike protein from the exhaled breath by sampling the target analyte into the collector, followed by its detection out of the N95 face mask using a magnetic bead-based electrochemical immunosensor. This approach was designed to avoid any contact between humans and the chemicals. To simulate human exhaled breath, untreated saliva samples were nebulized on the paper collector, revealing a detection limit of 1 ng/mL and a wide linear range of 3.7-10,000 ng/mL. Additionally, the developed immunosensor exhibited high selectivity toward the SARS-CoV-2 spike protein, compared to other airborne microorganisms, and the SARS-CoV-2 nucleocapsid protein. Accuracy assessments were conducted by analyzing the simulated breath samples spiked with varying concentrations of SARS-CoV-2 spike protein, resulting in satisfactory recovery values (ranging from 97 ± 4 to 118 ± 1%). Finally, the paper-based hybrid immunosensor was successfully applied for the detection of SARS-CoV-2 in real human exhaled breath samples. The position of the collector in the N95 mask was evaluated as well as the ability of this paper-based analytical tool to identify the positive patient.

Dye-encoded bead-based assays are widely used for diagnostics. Multiple bead populations are required for multiplexing and can be produced using different dye colors, labeling levels, or combinations of dye ratios. Ready-to-use multiplex bead populations restrict users to specific targets, are costly, or require specialized instrumentation. In-house methods produce few bead plexes or require many fine-tuning steps. To expand bead encoding strategies, we present a simple, safe, and cost-effective bench-top system for generating bead populations using photobleaching. By photobleaching commercially available dye-encoded magnetic beads for different durations, we produce three times as many differentiable bead populations on flow cytometry from a single dye color. Our photobleaching system uses a high-power LED module connected to a light concentrator and a heat sink. The beads are photobleached in solution homogeneously by constant mixing. We demonstrate this photobleaching method can be utilized for cross-testing antibodies, which is the first step in developing immunoassays. The assay uses multiple photobleached encoded beads conjugated with capture antibodies to test many binding pairs simultaneously. To further expand the number of antibodies that can be tested at once, several antibodies were conjugated to the same bead, forming a pooled assay. Our assay predicts the performance of antibody pairs used in ultrasensitive Simoa assays, narrowing the number of cross-tested pairs that need to be tested by at least two-thirds and, therefore, providing a rapid alternative for an initial antibody pair screening. The photobleaching system can be utilized for other applications, such as multiplexing, and for photobleaching other particles in solution.

Detecting progesterone (P4) concentration in cow serum is essential for monitoring the pregnancy progress after fertilization and is significant for the dairy farming industry and veterinary medicine. This study reports enzyme-free immunomagnetic beads (IMBs)-based competitive immunoassay for detecting P4 by P4-bovine serum albumin (BSA)-modified biosensors. The anti-P4 antibody-conjugated IMBs serve as collectors to capture P4 in undiluted serum samples to prevent the biosensor surface from biosample contamination and as insulated labels to report the electron-transfer resistance signal of electrochemical impedance spectroscopy (EIS) measurement. The IMBs and P4-containing samples were mixed for 15-30 min, capable of obtaining stable P4@IMB complexes. The 0.2-kGauss pulsed magnetic field (PMF) of the 20-s pulse width and 20-s relaxation time applied for 5 min can shorten the immunoreaction time between the P4@IMBs and the P4-BSA-modified biosensor and reduce the IMB's nonspecific adsorption on the biosensor surface. This competitive immunoassay's cut-off value and detection limit were 7.71 ng/mL and 7.33 ng/mL, respectively, which is lower than the serum's P4 plateau concentration (over 8 ng/mL) of dairy cows on days 6-16 of estrus cycles and that in pregnancy. The IMB-based immunoassay combining the PMF attraction and the label-free EIS measurement exhibits promising potential for rapidly detecting P4 in undiluted serum., Competing Interests: Declaration of competing interest All authors declare no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The capacitive immunosensor, known for its label-free simplicity, has great potential for point-of-care diagnostics. However, the interaction between insulation and recognition layers on the sensing electrode greatly affects its performance. This study introduces a pioneering dual-layer strategy, implementing a novel combination of acrylic resin (AR) and nitrocellulose (NC) coatings on screen-printed carbon electrodes (SPCEs). This innovative approach not only enhances the dielectric properties of the capacitive sensor but also streamlines the immobilization of recognizing elements. Particularly noteworthy is the superior reliability and insulation offered by the AR coating, surpassing the limitations of traditional self-assembled monolayer (SAM) modifications. This dual-layer methodology establishes a robust foundation for constructing capacitive sensors optimized specifically for liquid medium-based biosensing applications. The NC coating in this study represents a breakthrough in effectively immobilizing BSA, unraveling the capacitive response intricately linked to the quantity of adsorbed recognizing elements. The results underscore the prowess of the proposed immunosensor, showcasing a meticulously defined linear calibration curve for anti-BSA (ranging from 0 to 25 μg/ml). Additionally, specific interactions with anti-HAS and anti-TNF-α further validate the versatility and efficacy of the developed immunosensor. This work presents a streamlined and highly efficient protocol for developing label-free immunosensors for antibody determination and introduces a paradigm shift by utilizing readily available electrodes and sensing systems. The findings are poised to catalyze a significant acceleration in the advancement of biosensor technology, opening new avenues for innovative applications in point-of-care diagnostics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The label probe plays a crucial role in enhancing the sensitivity of lateral flow immunoassays. However, conventional fluorescent microspheres (FMs) have limitations due to their short fluorescence lifetime, susceptibility to background fluorescence interference, and inability to facilitate multi-component detection. In this study, carboxylate-modified Eu(III)-chelate-doped polystyrene nanobeads were employed as label probes to construct a multiple time-resolved fluorescent microsphere-based immunochromatographic test strip (TRFM-ICTS). This novel TRFM-ICTS facilitated rapid on-site quantitative detection of three mycotoxins in grains: Aflatoxin B1 (AFB1), Zearalenone (ZEN), and Deoxynivalenol (DON). The limit of detection (LOD) for AFB1, ZEN, and DON were found to be 0.03 ng/g, 0.11 ng/g, and 0.81 ng/g, respectively. Furthermore, the TRFM-ICTS demonstrated a wide detection range for AFB1 (0.05-8.1 ng/g), ZEN (0.125-25 ng/g), and DON (1.0-234 ng/g), while maintaining excellent selectivity. Notably, the test strip exhibited remarkable stability, retaining its detection capability even after storage at 4 °C for over one year. Importantly, the detection of these mycotoxins relied solely on simple manual operations, and with a portable reader, on-site detection could be accomplished within 20 min. This TRFM-ICTS presents a promising solution for sensitive on-site mycotoxin detection, suitable for practical application in various settings due to its sensitivity, accuracy, simplicity, and portability., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Ensuring the safety of animal-derived foods requires the reliable and swift identification of enrofloxacin residues to monitor the presence of antibiotics. In this regard, we synthesized, tuned, and investigated the optical properties of a bimetallic metal-organic framework (Ce/Zr-UiO 66). The investigation was facilitated by employing a polydopamine-coated pipette tip with high adsorption efficiency, serving as an immunoreactive carrier. Subsequently, an immunofunctionalized variant of Ce/Zr-UiO 66, referred to as Ce/Zr-UiO 66@ Bovine serum albumin-enrofloxacin, was developed as an optical probe for the rapid and sensitive identification of enrofloxacin across a variety of samples. The method can accurately detect enrofloxacin at concentrations as low as 0.12 ng/mL, with a determination time of under 15 min; furthermore, it demonstrates exceptional efficacy when applied to food, environmental, and clinical samples. The implementation of this methodology offers a valuable means for cost-effective, rapid, and on-site enrofloxacin determination., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Conventional lateral flow immunoassay (LFIA) usually suffers from poor antimatrix interference, unsatisfactory sensitivity, and lack of quantitative ability for target analyte detection in food matrices. In response to these limits, here, multifunctional nanomaterial ZnFe 2 O 4 nanoparticles (ZFOs) were developed and integrated into LFIA for powerful magnetic separation/enrichment and colorimetric/photothermal target sensing. Under optimum conditions, the detection for clenbuterol (CL) with magnetic enrichment achieves 9-fold higher sensitivity compared to that without enrichment and 162-fold higher sensitivity compared to that based on traditional colloidal golds. Attributing the improved performances of ZFOs, CL can be detected at ultralow levels in pork and milk with 10 min of immunoreaction time. The vLODs were 0.01 μg kg -1 for two modes, and the cutoff values of CL were about 5 and 3 μg kg -1 , respectively. More importantly, the enrichment ZFO-mediated LFIA (ZE-LFIA) exhibits a similar limit of detection (LOD) in both buffer solution and food matrix, demonstrating a universal resistance to the food matrix. The multitudinous performance merits of this ZE-LFIA with high sensitivity, matrix tolerance, accuracy, and specificity have ensured a broad application potential for target detection of clenbuterol and can serve as an experience for other veterinary drug residues' detection.

Abscisic acid (ABA) plays an important regulatory role in plants. It is very critical to obtain the dynamic changes of ABA in situ for botanical research. Herein, coupled with paper-based analysis devices, electrochemical immunoelectrodes based on disposable stainless steels sheet were developed for ABA detection in plants in situ. The stainless steel sheets were modified with carbon cement, ferrocene-graphene oxide-multi walled carbon nanotubes nanocomposites, and ABA antibodies. The system can detect the ABA in the range of 1 nM to 100 μM, with a limit of detection of 100 pM. The ABA content in tomato leaves under high salinity was detected in situ. The trend of ABA changes was similar to the expression of SlNCED1 and SlNCED2 . Overall, this study offers an approach for in situ detection of ABA in plants, which will help to study the regulation mechanism of ABA in plants and to promote the development of precision agriculture.

Current diagnostic tests for high sensitivity detection of protein biomarkers involve long incubation times or require bulky/expensive instrumentation, hindering their use for point-of-care testing. Here, we report a microfluidic electrochemical immunosensor that employs a unique finger-actuated mixer for rapid, ultrasensitive measurements of protein biomarkers. Mixing was implemented during the incubation steps, which accelerated biomolecular transport and promoted immunocomplex formation, leading to enhanced analytical sensitivity and a shortened detection time. Electrochemical measurements were performed using a handheld diagnostic device consisting of a smartphone and miniature potentiostat. Proof of principle was demonstrated by using this platform for quantitative measurements of C-X-C motif chemokine ligand 9 (CXCL9), a serological biomarker for autoimmune and inflammatory diseases, which could be detected in human plasma at concentrations as low as 4.7 pg mL -1 in <25 min. The ability to rapidly detect protein biomarkers with high sensitivity in a point-of-care format makes this device a promising tool for diagnostic testing, particularly in resource-limited settings.

Considering that cancer has become the second leading cause of death in humans, it is essential to develop an analytical approach that can sensitively detect tumor markers for early detection. We report an attenuated photoelectrochemical (PEC) immunoassay based on the organic-inorganic heterojunction 10MIL-88B(FeV)/ZnIn 2 S 4 (10M88B(FeV)/ZIS) as a photoactive material for monitoring carcinoembryonic antigen (CEA). The 10M88B(FeV)/ZIS heterojunctions have excellent light-harvesting properties and high electrical conductivity, which are attributed to the advantages of both organic and inorganic semiconductors, namely, remarkable photogenerated carrier separation efficiency and long photogenerated carrier lifetime. Horseradish peroxidase (HRP) in the presence of H 2 O 2 can catalyze 3,3'-diaminofenamide (DAB) producing brown precipitates (oxDAB), which is then loaded onto the 10M88B(FeV)/ZIS heterojunction to reduce the photocurrent and enable the quantitative detection of CEA. Under optimal conditions, the photocurrent values of the PEC biosensor are linearly related to the logarithm of the CEA concentrations, ranging from 0.01 ng mL -1 to 100 ng mL -1 with a detection limit (LOD) of 4.0 pg mL -1 . Notably, the accuracy of the PEC biosensor is in agreement with that of the human CEA enzyme-linked immunosorbent assay (ELISA) kit., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)