Search Results (167)

The fabrication of SERS nanotags with efficient antibody loading and high signal enhancement remains a challenging task for combining surface-enhanced Raman spectroscopy (SERS) and lateral flow immunoassay (LFIA). In this study, bimetallic Au^DTNB@PDA^DTNB@Ag nanoparticles with a polydopamine (PDA)-based internal nanogap were synthesized and functionalized with anti-prolactin monoclonal antibodies to produce SERS nanotags. Here, polydopamine serves both as a spacer providing a nanogap between the core and the shell, and as a reaction layer to capture Raman reporter 5,5′-dithiobis(2-nitrobenzoic acid) (DTNB) within the nanogap. Regimes (conditions, protocols) for conjugating antibodies to Au^DTNB@PDA^DTNB@Ag were selected to preserve both the binding affinity for the target analyte and the Raman activity of the SERS nanotag. The SERS nanotag provides plasmonic absorption for visible colorimetric readout, as well as strong SERS signals for highly sensitive quantitative immunoassay. Measuring the Raman intensities of DTNB in the test zone after performing LFIA made it possible to determine prolactin with a detection limit of 0.2 ng/mL in the working range from 1 to 10 ng/mL. The achieved limit of detection was 10-fold lower than the LFIA coupled with colorimetric readout (4.7 ng/mL). The recoveries of prolactin from spiked serum samples were in the range of 70.2–82.6% with relative standard deviations of 2.3–6.8%. Overall, the Au^DTNB@PDA^DTNB@Ag nanotag demonstrated high stability, Raman activity, and specificity, indicating that the SERS nanotag with PDA-assisted internal nanogap is promising for use in SERS immunoassay of other target analytes. Full article

Decentralized diagnostics is undergoing a transformative shift from qualitative screening to high-precision quantification, driven by the clinical demand for rapid, point-of-care (POC) syndromic triage. Multiplexed lateral flow immunoassays (mLFIAs) serve as the foundational platform for this transition. However, their performance is limited by systemic factors such as fluidic lag, conjugate depletion, and spectral crosstalk. This review evaluates recent advances in engineered nanomaterials and artificial intelligence (AI)-driven detection as the dual pillars of next-generation multiplexing. The review covers different types of nanomaterial reporters—such as multicolor quantum dots, surface-enhanced Raman scattering nanotags, upconversion nanoparticles, surface-modified magnetic nanoparticles, and fluorescent nanodiamonds—that help address analytical challenges in lateral flow assays. We then discuss AI and machine learning methods, including convolutional neural networks, support vector machines, random forests, and transfer learning, that convert raw multi-channel signals into useful clinical data. Finally, we highlight the main challenges that still need to be addressed before these platforms can become WHO-ASSURED-compliant POC devices. The combination of engineered nanomaterial reporters and computational intelligence is transforming lateral flow assays into quantitative tools that can provide lab-quality clinical information at the POC. Full article

Chloramphenicol is a broad-spectrum antimicrobial agent whose use in food-producing animals is prohibited in many countries due to its association with severe adverse effects, including idiosyncratic aplastic anemia and genotoxicity. Despite these restrictions, chloramphenicol residues continue to be detected in food products, environmental compartments, and biological matrices, highlighting the need for reliable and sensitive analytical monitoring. This review provides a comprehensive overview of current analytical strategies for the detection of drugs in food and environmental samples, covering screening and confirmatory techniques, sample preparation approaches, and regulatory aspects. Rapid screening methods, such as enzyme-linked immunosorbent assays (ELISAs), lateral flow immunoassays (LFIAs), and biosensors based on antibodies, aptamers, and molecularly imprinted polymers, enable fast and cost-effective preliminary detection. Recent advances in nanomaterials and signal amplification strategies, including fluorescent reporters and surface-enhanced Raman scattering (SERS), have significantly improved sensitivity and assay performance. However, confirmatory methods based on liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) remain the reference standard due to their superior selectivity, sensitivity, and quantitative reliability. Attention is given to sample preparation workflows, including QuEChERS-based protocols and microextraction techniques, which enable efficient analysis of complex matrices. Finally, current regulatory frameworks and analytical challenges related to zero-tolerance policies are discussed, emphasizing the importance of robust and validated analytical methods for effective monitoring and food safety assurance. Full article

Antibiotic residues in aquatic products pose a serious food safety concern, whereas conventional laboratory methods often fail to meet the demand for on-site rapid screening. This study systematically reviews the research progress from 2021 to 2025 on both the risks of antibiotic residues in aquatic products and the development of rapid on-site detection technologies. First, based on a literature survey covering major aquatic products (e.g., fish, shrimp, and shellfish), the widespread occurrence of multiple antibiotics at high concentrations was documented, with quinolones and sulfonamides identified as the most frequently detected classes. To address the need for on-site testing, this review focuses on six rapid detection techniques: fluorescent sensor (FRS), lateral flow immunoassay (LFIA), surface-enhanced Raman scattering (SERS), enzyme-linked immunosorbent assay (ELISA), electrochemical sensor (ECRS), and colorimetric sensor (CRS). The core principles, technical advantages, recent application cases (e.g., integration with smartphones and novel nanomaterials), and development trends for each method are analyzed. Finally, it discusses the current challenges faced by existing on-site detection approaches and their potential solutions. Technology selection strategies tailored to different application scenarios (e.g., aquaculture farms, distribution channels, and consumer-level use) are also proposed. Full article

Escherichia coli O157:H7 (E. coli O157:H7) is a highly virulent foodborne pathogen with an extremely low infectious dose, making its rapid and accurate detection in food and environmental samples critically important. In recent years, significant progress has been made in immunological techniques for the rapid identification of E. coli O157:H7. This review systematically summarizes advances in immunological methods for the detection of E. coli O157:H7 over the past decade, focusing on lateral flow immunoassays (LFIA), enzyme-linked immunosorbent assays (ELISA), immunosensors (optical and electrochemical), and nanobody-based technologies. Key aspects such as detection principles, specificity, antibody types (monoclonal, polyclonal, nanobodies), signal readout mechanisms, and applicability to different sample matrices are compared. Performance parameters, including limit of detection (LOD), specificity, detection time, and matrix compatibility, are summarized to evaluate the advantages and limitations of each method. Furthermore, international food safety standards and regulations (ISO 16654, FDA BAM, USDA) are reviewed to highlight the practical and regulatory requirements of these techniques. On this basis, the role of immunological detection technologies in on-site rapid testing is discussed, with a focus on improvements in sensitivity, specificity, and practicality. Finally, future directions are outlined, including multiplexed assays, integration with molecular biology techniques, and engineering applications of nanobody and recombinant technology. Full article

Conventional colorimetric lateral flow immunoassays (LFIAs) often suffer from insufficient sensitivity for detecting trace low-molecular-weight contaminants like mycotoxins. The development of colorimetric probes with a high molar extinction coefficient is therefore critical for enhancing detection performance. Although silver nanoparticles (AgNPs) exhibit an extremely high molar extinction coefficient, their practical application in LFIA is hindered by inherent chemical instability and suboptimal visual contrast. To address these limitations, we have engineered robust and high-performance polydopamine-functionalized AgNPs (Ag@PDA NPs) as advanced LFIA signal probes, which were successfully used for detecting aflatoxin B₁ (AFB₁) in maize. The multifunctional PDA nanoshell effectively shields the Ag core from oxidation and other destabilizing factors, ensuring superior long-term stability and significantly enhancing colorimetric contrast. Moreover, it improves the colloidal hydrophilicity, enabling faster and more uniform migration kinetics along the test strip. Leveraging these engineered properties, the developed assay achieved a limit of detection (LOD) of 0.23 ng mL⁻¹ for AFB₁ in buffer, representing a remarkable 2.17-fold sensitivity enhancement over conventional colloidal gold-based LFIAs. Validation in spiked maize samples confirmed high reliability, with recoveries ranging from 95.70% to 119.28% and precision (inter-/intra-assay CVs) below 13.03%. Full article

Background/Objectives: Human pythiosis, caused by Pythium insidiosum, is associated with severe morbidity and high mortality when diagnosis is delayed. Culture-based diagnosis is time-consuming and may be insensitive in clinical specimens, highlighting the need for rapid point-of-care serodiagnostic tools. Here, we developed and clinically evaluated the Anti-Pin Antibody Test Strip, a whole-blood-compatible lateral flow immunoassay (LFIA) for detecting anti-P. insidiosum antibodies. Methods: Secretory protein antigens of P. insidiosum were prepared and conjugated to gold nanoparticles for LFIA development. Analytical performance was assessed by determining the limit of detection (LOD) using serial dilutions of pythiosis serum and by evaluating cross-reactivity with sera from patients with other infections. Interference testing examined common anticoagulants and adverse sample conditions (hemolysis, lipidemia, and icterus). Clinical performance was evaluated using 258 serum samples, comprising 48 pythiosis-positive and 210 pythiosis-negative specimens confirmed by immunoblotting and/or culture. Test results were read at 5 min. Results: The assay LOD was a serum titer of 1:1000. No cross-reactivity was observed across the tested infectious and immunologic panels, and no interference was detected from anticoagulants or adverse sample conditions. Whole-blood testing showed no red blood cell interference. In clinical evaluation, sensitivity was 100.00% (48/48), specificity was 95.24% (200/210), and accuracy was 96.12%, with a PPV of 82.76% and an NPV of 100.00%. Conclusions: The Anti-Pin Antibody Test Strip provides rapid (5 min), operationally simple serodiagnosis and may support screening/triage of suspected pythiosis, particularly where laboratory methods are limited. Full article

Early detection of cancer biomarkers in blood is critical for improving patient outcomes; however, conventional immunoassays often rely on complex instrumentation and are not well suited for point-of-care testing or multiplexed analysis. Herein, we present a dual-mode colorimetric–surface-enhanced Raman scattering (SERS) lateral flow immunoassay (LFIA) platform for multiplexed detection of cancer biomarkers, employing elongated rod-shaped silver nanoshells (ERNSs) as SERS nanotags. The ERNS features a rough Ag shell with internally incorporated Raman labeling compounds (RLCs), enabling plasmonic extinction for visual readout and strong SERS signals for quantitative analysis while preserving the external metal surfaces for efficient antibody conjugation. Leveraging these advantages, a multiplex LFIA capable of simultaneously detecting prostate-specific antigen (PSA) and carbohydrate antigen 19-9 (CA19-9) on a single strip was successfully demonstrated. Visual inspection enabled rapid discrimination of samples at or near clinically relevant cut-off levels, while Raman analysis achieved limits of detection of 8.0 × 10⁻³ ng/mL for PSA and 5.4 × 10⁻² U/mL for CA19-9, corresponding to approximately 500-fold and 685-fold lower concentrations than their respective clinical thresholds. This ERNS-based colorimetric–SERS LFIA integrates rapid screening and highly sensitive quantification within a single platform and offers a versatile nanoprobe design strategy for multiplex biomarker detection and liquid biopsy-based diagnostic applications, with potential relevance to point-of-care settings. Full article

Cerium oxide (CeO₂) nanozymes, also known as nanoceria have emerged as a versatile class of catalytic nanomaterials capable of mimicking key redox enzymes, including oxidases and peroxidases. Their tunable Ce³⁺/Ce⁴⁺ redox cycling, high density of oxygen vacancies, and exceptional resistance to thermal, pH, and storage stress distinguish CeO₂ from conventional enzyme labels, such as horseradish peroxidase (HRP). In immunoassays, CeO₂ enables H₂O₂-free TMB (3,3′,5,5′-tetramethylbenzidine) oxidation, generating strong chromogenic signals with minimal background. Although CeO₂ nanozymes have been explored in colorimetric, chemiluminescent, and photoactive immunoassays, their integration into lateral flow immunoassays (LFIAs) remains limited, with only a few hybrid CeO₂-containing systems reported to date. This mini-review highlights the limitations of conventional peroxidase-based formats and explains how CeO₂’s redox cycling (Ce³⁺/Ce⁴⁺) and oxygen-vacancy-driven catalysis deliver stable, reagent-free signal amplification. Emphasis is placed on the synthetic control of CeO₂, conjugation chemistry with antibodies, and integration into LFIA architectures. CeO₂ enables hydrogen-peroxide-free colorimetric detection with improved robustness and sensitivity, positioning it as a promising catalytic label for point-of-care testing. However, it may aggregate in high-ionic-strength buffers, and its synthesis cost increases for highly uniform, vacancy-engineered materials. Surface functionalization with polymers or dopants and optimized dispersion strategies can mitigate these issues, guiding future practical implementations. Full article

Background: In Bangladesh, a number of sex workers are involved in commercial sex work in different brothels in both legal and illegal settlements due to reasons such as lack of social support, depression, forced sex, abuse, violence, polyamory, being kidnapped, and unemployment. In this study, we tried to evaluate the demographic characteristics and prevalence of viral and sexually transmitted diseases (STDs) among the study population. Methods: A total of 250 female sex workers were interviewed and tested from the Daulatdia brothel of Rajbari district, Bangladesh, who had been working there for at least 1 month. Through questionnaires, demographic data were collected. Primarily, lateral flow immunoassay (LFIA) tests were used to investigate HCV (Hepatitis C Virus), HBV (Hepatitis B Virus), and Syphilis, which were reconfirmed using enzyme-linked immunosorbent assay (ELISA) in cases of positive results. Results: The mean age was 27.51 ± 6.69 years with a range of 18–50 years. Most of them (n = 243, 97.98%) had elementary knowledge of STDs. We determined that overall, 96 (38.40%) were positive for either of these diseases. Individually, 10 (4.00%), 18 (7.20%), and 68 (27.20%) were positive for HCV, HBV, and syphilis, respectively. Conclusions: Our observation indicates that females of all ages should be strictly protected from forced sex work. Current sex workers should be educated regarding the dangers and protective mechanisms of STDs. In addition, as a public health concern, regular clinical check-ups and STD associated diagnoses are necessary to ensure the safety of FSW from these highly infectious and concerning diseases. Due to their socio-economic condition, proper treatment and rehabilitation are highly recommended. Full article

It is crucial to identify Enterobacterales that produce carbapenemase to treat and manage hospital infections. The suggested techniques for their identification need a lengthy wait, technical knowledge, and training. Lateral flow immunoassays (LFIAs) provide a solution to these requirements. Thus, this study compared LFIA with phenotypic and genotypic tests for carbapenemase-producing bacteria. Fifty clinical isolates of carbapenem-resistant superbugs were examined. KPC, VIM, NDM, IMP, and OXA-48-like enzymes were evaluated and compared with phenotypic tests and LFIA. Regarding the phenotypic characteristics, the mCIM was positive in 37/50 (74%), and the eCIM was positive in 21/50 (42%). Regarding using LFIA, 41 out of the total isolates (82%) gave a positive red line with one or more of the tested genes. The most frequently detected gene was bla_NDM (27/50 (54%)), and the least detected one was bla_IMP (14/50 (28%)), which was in accordance with the PCR results. While investigating the accuracy of LFIA vs. PCR, it was found that LFIA had 100% sensitivity in the detection of the bla_NDM and bla_OXA genes, with 85.2% and 91.4% specificity, respectively, while for the bla_IMP, bla_KPC, and bla_VIM genes, the values were 91.7% and 92.1%, 94.1% and 90.9%, and 95.5% and 89.3%, respectively. The overall accuracy of LFIA ranged from 92 to 94%. Our comparison with molecular assays revealed remarkable agreement, so we propose that this test might be utilized as a supplementary tool. Full article

A lateral flow immunoassay (LFIA) utilizing two types of marker conjugates—magnetite nanoparticles (MNPs) with specific antibodies and gold nanoparticles (GNPs) with anti-species antibodies—was proposed and realized for the detection of the pesticide paraquat. In this assay, the MP conjugate is used to concentrate the target analyte from the tested sample and then to form labeled immune complexes at the test strip, while the GNP conjugate is then applied for the integration into the formed complexes in the binding zone. The magnetic preconcentration allows for working with large volumes of samples, and the following treatment by the GNP conjugate enhances the coloration by five times for reliable analyte revelation in lower concentrations. In the course of the assay implementation, its conditions have been optimized, and the efficiency of the paraquat determination in orange samples was confirmed. The achieved detection limits were 1.2–3.7 ng/mL for visual assessment and 0.12–0.48 ng/mL for the instrumental one, with paraquat detection rates ranging from 96% to 120%. The implementation of the assay in combination with the stage of magnetic concentration allows for the collection of paraquat from large volumes of samples and detects it in this way in concentrations up to two orders of magnitude smaller. Full article

Mimotope-based immunoassays offer an eco-friendly alternative to chemically synthesized antigens for the quantitative analysis of small molecules, but their use for practical on-site and high-throughput residue monitoring remains limited. Herein, we report the selection, production, and application of a phage display–derived mimotope targeting an anti-uniconazole monoclonal antibody (UCZ-mAb), with the aim of developing two complementary immunoassays that enable sensitive, eco-friendly detection of UCZ residues in agricultural samples. A 12-mer phage-displayed peptide library was screened to identify UCZ-specific mimotopes, and a selected sequence was genetically fused to SpyTag and expressed in Escherichia coli to generate a SpyTagged mimotope. Leveraging the SpyCatcher/SpyTag self-assembly system, the SpyTagged mimotope was directionally conjugated onto SpyCatcher-functionalized time-resolved fluorescence beads (TRFBs) and subsequently used as a signal-labeled competitive antigen in a lateral flow immunoassay (LFIA) designed for rapid on-site screening. In parallel, a wash-free magnetic separation immunoassay (MSIA) suitable for green, high-throughput screening in routine laboratories was established using self-assembled mimotope-TRFB probes. The LFIA and MSIA exhibited half-maximal inhibitory concentrations (IC₅₀) of 3.70–6.72 μg/kg and 16.4–18.3 μg/kg, respectively, in real samples. Spiked-sample recoveries ranged from 91.1 to 107.8% for LFIA and 92.6–115.7% for MSIA, demonstrating acceptable accuracy and precision. These results indicate that the SpyTagged mimotope–based LFIA and MSIA provide complementary, reliable, and sensitive platforms for on-site screening and high-throughput monitoring of UCZ residues in agricultural samples, while avoiding the drawbacks associated with traditional chemical antigen synthesis. Full article

Aflatoxin B₁ (AFB₁), a highly toxic and carcinogenic mycotoxin, poses significant public health risks due to its widespread contamination of staple food crops such as peanuts and maize. Although conventional lateral flow immunoassays (LFIAs) are widely employed for rapid on-site screening, their limited sensitivity frequently compromises accurate quantification at trace levels. To improve the analytical performance of LFIAs, we developed a novel time-resolved fluorescence-based lateral flow immunoassay (TRFN-LFIA) by integrating reverse artificial antigen labeling with time-resolved fluorescence signal amplification. This method enhances detection sensitivity and enables rapid, ultra-sensitive, visible, and quantitative determination of AFB₁ in peanut and maize samples. Under optimized conditions, the TRFN-LFIA achieved a visible limit of detection (vLOD) of 0.30 ng/mL (2.22 µg/kg), a quantitative limit of detection (qLOD) of 0.04 ng/mL (0.30 μg/kg), and a half-maximal inhibitory concentration (IC₅₀) of 0.09 ng/mL. Recoveries from spiked peanut and maize samples ranged from 81.33% to 117.86%, with coefficients of variation (CVs) below 13.04%. Analysis of 21 real samples (13 maize and 8 peanut samples) yielded results highly consistent with those obtained by liquid chromatography–tandem mass spectrometry (LC-MS/MS). Moreover, the method demonstrates significant advantages in terms of detection speed, cost-effectiveness, and operational convenience. Therefore, the results established the TRFN-LFIA method as a reliable and practical tool for on-site rapid detection of AFB₁ in contaminated food matrices, providing both a rapid and accurate approach for trace-level quantification and a novel strategy for enhancing the sensitivity of lateral flow immunoassays. Full article

Background: Rapid and high-throughput diagnostic methods are essential for controlling the spread of infectious diseases, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Lateral flow immunoassay (LFIA) strips provide a cost-effective and user-friendly platform for point-of-care testing. However, the sensitivity of conventional LFIA kits is often limited by the performance of their detection probes. This study reports a highly sensitive LFIA strip for detecting the SARS-CoV-2 nucleocapsid (NP) protein using platinum-decorated poly(2-vinylpyridine) nanoparticles (Pt-P2VPs) as probes. Methods: Monoclonal antibodies against SARS-CoV-2 NP were conjugated with Pt-P2VPs and incorporated into LFIA strips. The test line was coated with anti–SARS-CoV-2 NP monoclonal antibody, and the control line with goat anti-mouse IgG. Recombinant proteins, viral strains, and nasopharyngeal swab specimens from patients were used to evaluate assay performance, with reverse transcription polymerase chain reaction (RT-PCR) as the reference standard. Diagnostic accuracy was assessed using nonparametric statistical tests. Results: Pt-P2VP-based LFIA strips enabled sensitive detection of recombinant NP and inactivated SARS-CoV-2, with minimal cross-reactivity. In 200 clinical specimens (100 PCR-negative and 100 PCR-positive), the assay achieved 74% sensitivity and 100% specificity, with strong correlation to viral RNA load. Compared with conventional LFIA kits, Pt-P2VP strips demonstrated superior sensitivity at lower viral loads. Conclusions: Pt-P2VPs represent a promising probe material for enhancing LFIA performance and may facilitate the development of rapid, sensitive, and scalable immunoassays for infectious disease diagnostics in biomedical applications. Full article