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This study evaluated the application of carboxylated multi-walled carbon nanotubes (MWCNTs) as a label in immunochromatographic assay for morphine detection. MWCNTs were carboxylated using nitric acid and characterized by Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, field emission scanning microscopy (FESEM), and dynamic light scattering (DLS). The optimum concentration of polyvinyl pyrrolidone (PVP) as a surfactant for homogenous dispersion of MWCNTs was determined by ultraviolet-visible spectroscopy to be 0.5 mg/mL. The zeta potential of MWCNTs before adding PVP was −41.9 ± 1.02 mV, and after adding PVP, −54.1 ± 0.25 mV. On the surface of MWCNTs, the anti-morphine antibody (AM antibody) had a binding effectiveness ranging from 91.1% to 95.5%. The AM antibody-MWCNTs were conjugated to create immunochromatographic test strips. The visual limit of detection (vLOD) was 1.0 ng/mL and the cutoff concentration (COC) was 10.0 ng/mL. Compared to previous study, carboxylated-MWCNTs as a one-dimensional nanomaterial improved the sensitivity of immunochromatographic assay strips and may be utilized to develop the sensitive immunochromatographic assays. [ABSTRACT FROM AUTHOR]

Herbicide residues in agricultural products can have adverse effects on the environment and human health, therefore, there is an urgent need to establish a sensitive, rapid, and wide-ranging detection method. In this study, haptens of phenylurea herbicides (PUs) and sulfonylurea herbicides (SUs) were analyzed and designed based on computational simulation techniques, and two high-performance broad-spectrum monoclonal antibodies against PUs and SUs were prepared. On this basis, a multi-colloidal gold immunochromatography assay (multi-CGIA) was developed to simultaneously detect 13 herbicides in wheat. The visual limit of detection (vLOD) for PUs including diuron, chlortoluron, neburon, chlorbromuron, and linuron was 1–2 µg/kg. The vLOD for SUs including metsulfuron methyl, ethametsulfuron-methyl, sulfometuron-methyl, tribenuron methyl, cinosulfuron, triasulfuron, chlorimuron-ethyl, and chlorsulfuron was 2–10 µg/kg. The results of real sample determination indicated that the multi-CGIA is accurate, stable, and reliable, and adaptable to on-site preliminary screening of actual samples. [ABSTRACT FROM AUTHOR]

Background and Aim: In animal husbandry, antibiotics are frequently used as growth promoters, as well as for illness prevention and treatment. They are considered important toxic and allergenic contaminants of food and a serious risk factor for the spread of antibiotic resistance. National and international regulatory authorities have established limits on the permissible residue of antibiotics in food. Immunochromatographic test strips are the most efficient tools for the simple and rapid control of antibiotics for food safety. In these tests, each antibody specific to a particular antibiotic is labeled with a marker, which complicates the manufacturing technology and increases the cost of the test. This study aimed to develop a multiplex immunochromatographic assay (ICA) to determine streptomycin (STR), tetracycline (TC), and chloramphenicol (CAP) residues in milk by indirect labeling of antibiotic-specific antibodies. Materials and Methods: Test strips were composed using 15 μm pore size CNPC nitrocellulose membranes, GFB-R4 separation, and AP045 adsorption pads. The applied reactants include TC and STR conjugates with bovine serum albumin, and CAP-soybean trypsin inhibitor conjugate; anti-TC, anti-STR, and anti-CAP mouse monoclonal antibodies; goat anti-mouse immunoglobulin G (GAMI) conjugated with gold nanoparticles (GNPs) and staphylococcal protein A. Milk samples were collected from cows and goats that had not been injected with any antibiotics. STR and TC/CAP at concentrations of 0.27–600 ng/mL and 0.04–30 ng/mL were added to skim milk, respectively. Milk samples were tested by ICA and calibration curves were constructed to determine the sensitivity of the assay for each antibiotic used. Results: A multiplex ICA of three antibiotic residues in milk was achieved through labeling of immune complexes using a single reagent, GNPs-GAMI. The visual limits of detection (LOD) were 600 ng/mL, 10 ng/mL, and 30 ng/mL for STR, TC, and CAP in cow and goat milk, respectively. Instrumental LODs gave higher sensitivity when analyzed goat milk to STR, TC, and CAP (1.2, 0.05, and 1.3 ng/mL) than cows’ milk (7.27, 0.96, and 2.07 ng/mL, respectively). Conclusion: The developed approach for manufacturing multiplex ICA tests for the detection of antibiotic residues in milk does not involve labeling specific antibodies and is implemented using only GNP conjugates with anti-species antibodies.

INTRODUCTION. The quality evaluation of live anthrax vaccines will benefit from the implementation of alternative testing methods that are capable of specific identification of the Bacillus anthracis spore antigen using the appropriate diagnostic products that are authorised in the Russian Federation for the detection of B. anthracis spores.AIM. This study aimed to investigate the applicability of immunofluorescence analysis to the identification of live anthrax vaccines and compare this method with immunochromatography.MATERIALS AND METHODS. The study used commercial batches of a live anthrax vaccine and Russian diagnostic products, including diagnostic dry adsorbed fluorescent anti-anthrax spore immunoglobulins and an immunochromatographic assay (ICA) reagent kit for rapid detection and identification of B. anthracis spores (ICA system for B. anthracis). For smears and ICA system reactions, the authors prepared working solutions of bacterial suspensions at spore concentrations typical of the B. anthracis STI-1 vaccine strain. The spore concentrations were achieved using the pharmacopoeial reference standard (RS) for the opacity of bacterial suspensions of 10 international units (IU). Identification reactions involved the registration of immune complex formation.RESULTS. Immunofluorescence tests of the live anthrax vaccine demonstrated bright greenish-yellow envelope fluorescence with an intensity score of 3+ to 4+ for smears stained with diagnostic immunoglobulins at 1:32 and 1:64 dilutions. Immunochromatographic tests of the live anthrax vaccine detected the spore antigen at vaccine concentrations of 109 and 108 spores/mL, with the test strips showing two distinct dark-pink lines indicative of immunoprecipitation. According to the results obtained using the selected methods, the tested microbial culture was confirmed as B. anthracis.CONCLUSIONS. Immunochromatography and immunofluorescence tests with appropriate diagnostic preparations are convenient and reliable tools for the species-specific detection of B. anthracis STI-1 spores in the live anthrax vaccine. The results obtained in the anthrax vaccine identification tests provide a basis for recommending the above methods as supplementary alternatives to Ziehl–Neelsen bacteriological staining, which is currently prescribed by the State Pharmacopoeia of the Russian Federation.

A heavy-chain antibody (VHH) library against procymidone (PRM) was constructed via immunizing Bactrian camels. Through careful biopanning, seven nanobodies (Nbs) with different sequences were obtained. The variability in their performance was primarily attributed to the amino acid differences in complementarity-determining region 3 (CDR3), as analyzed by molecular docking. The Nb exhibiting the highest sensitivity, named NbFM5, was biotinylated and conjugated to streptavidin-labeled gold nanoparticles to preserve the epitope's activity and prevent a decrease in sensitivity due to traditional random electrostatic adsorption. Subsequently, a simple and sensitive immunochromatographic assay (ICA) was developed for rapid detection of PRM based on biotinylated Nb (btNb). The developed btNb-ICA showed a cut-off value of 200 ng/mL for visual judgment and a half-inhibitory concentration (IC50) of 6.04 ng/mL for quantitative detection. The limit of detection (LOD) was as low as 0.88 ng/mL. The recoveries in actual samples of crops ranged from 82.2 to 117.3%, aligning well with the results obtained from GC-MS/MS (R2 = 0.995). In summary, the developed btNb-ICA demonstrated high specificity and good accuracy for the rapid detection of PRM residues in vegetables. The total analysis time from preparing the sample to obtaining the result was less than 25 min.

Aflatoxin B1 (AFB1), a widespread contaminant in food and feeds, poses a threat to the health of animals and humans. Consequently, it is significant to develop a rapid, precise and highly sensitive analytical method for the detection of AFB1. Herein, we developed an immunochromatographic strip (ICS) based on a tetrahedral DNA (TDN) immunoprobe for AFB1 determination in rice bran oil. Three sizes of TDN immunoprobes (AuNP-TDN13bp-mAb, AuNP-TDN17bp-mAb, AuNP-TDN26bp-mAb) were constructed, and the performance of these three immunoprobes, including the effective antibody labeling density and immunoaffinity, was measured and compared with that of the immunoprobe (AuNP-mAb) developed using the physical adsorption method. Subsequently, the optimal TDN immunoprobe, namely AuNP-TDN13bp-mAb, was selected to prepare the immunochromatographic strip (ICS) for the qualitative and quantitative detection of AFB1 in rice bran oil. The visual limits of detection (vLODs) of the ICS based on AuNP-TDN13bp-mAb and AuNP-mAb were 0.2 ng/mL and 2 ng/mL, with scanning quantitative limits (sLOQs) of 0.13 ng/mL and 1.4 ng/mL, respectively. The ICS demonstrated a wide linear range from 0.02 ng/mL to 0.5 ng/mL, with good specificity, accuracy, precision, repeatability, and stability. Moreover, a high consistency was observed between the constructed ICS and ultra-high-performance liquid chromatography (UPLC) in the quantification of AFB1. The results indicated that the introduction of TDN was beneficial for promoting efficient antibody labeling, protecting the bioactivity of immunoprobes, and increasing the sensitivity of detection, which would provide new perspectives for the achievement of the highly sensitive detection of mycotoxins. [ABSTRACT FROM AUTHOR]

Paclitaxel (PTX), methotrexate (MTX), and 5-fluorouracil (5-FU) are commonly-used small molecule anti-tumor drugs for breast cancer. Unfortunately, drug resistance occurs with long-term treatment or excessive use, and the high concentrations of PTX, MTX, and 5-FU in patients may lead to side effects with dose-limiting toxicities, such as myelosuppression, hepatotoxicity, and peripheral neuropathy. Therefore, concentration monitoring of PTX, MTX, and 5-FU in clinical treatment is very important. We prepared highly sensitive and specific monoclonal antibodies using several haptens, and established a multiple paper-based sensor utilizing optical signals of gold nanoparticles, which simultaneously detected PTX, MTX, and 5-FU in human plasma or urine with 10 min. A portable scanner for quantitative detection in plasma and urine samples was used, and the calculated limit of detection (cLOD) values were 0.002 and 0.142 µg/mL for PTX, 0.187 and 0.976 ng/mL for MTX, and 0.057 and 0.128 µg/mL for 5-FU, respectively. In the recovery test, the recovery rates and the coefficient of variation were 85.84%–108.81% and 1.23%–8.80%, respectively, indicating the reliability and accuracy of the multiple gold immunochromatographic strip (GIS). In addition, for the determination of collected clinical plasma samples, the correlation between the test data of the multiple GIS and liquid chromatography–tandem mass spectrometry (LC–MS/MS) was good. Therefore, the developed multiple GIS could be applied to the rapid detection of PTX, MTX, and 5-FU in different clinical samples. [ABSTRACT FROM AUTHOR]

Background: Cannabis is among the earliest mind-altering drugs known to man and has been around for at least 4000 years. Today it is world's most commonly used illicit drug, with more than 300 million regular users. The aim of the study is detection of tetrahydrocannabinol (THC) in urine using immunochromatographic assay-a qualitative method. Materials and method: Retrospective study was done based on the report of urine tests conducted in the Dept. of Forensic Medicine in one year from July 2022 to June 2023. Consent from the individual brought for examination by the police. Results and Conclusion: Total 118 cases were studied; all were males among which 93were positive and 25negative. It is a preliminary screening test for cannabis substance abuse which will help the Police for further investigation. [ABSTRACT FROM AUTHOR]

Bisphenol A has been reported to be a ubiquitous contaminant, and exposure to this compound can lead to adverse effects in human health. In the study, monoclonal antibody against BPA (anti-BPA mAb) with high affinity (3.74 × 109 L/mol) secreted by cell line 2E3 was successfully screened. Inspired by the signal amplification of nanoparticles, anti-BPA mAbs were labeled with nano-materials including colloidal gold (AuNP) and gold nanoflowers (AuNF) for preparation of immunoprobes and AuNP-/AuNF-based test strips. The developed AuNP- and AuNF-based test strips achieved the rapid and sensitive detection of BPA within 10 min, with the limit of detection (LOD) of 25 μg/mL and 3.125 μg/mL, respectively. The detection result in BPA spiked samples measured by the proposed methods was consistent with that detected by LC-MS method. The preparation process of as-prepared test strip is time-saving and considered as ideal candidates method for rapid screening BPA in real samples.

ABSTRACTWith the large number of atypical cases in the mpox outbreak, which was classified as a global health emergency by the World Health Organization (WHO) on 23 July 2022, rapid diagnosis of mpox and diseases with similar symptoms to mpox such as chickenpox and respiratory infectious diseases in the early stages of viral infection is key to controlling the spread of the outbreak. In this study, antibodies against the monkeypox virus A29L protein were efficiently and rapidly identified by combining rapid mRNA immunization with high-throughput sequencing of individual B cells. We obtained eight antibodies with a high affinity for A29L validated by ELISA, which were was used as the basis for developing an ultrasensitive fluorescent immunochromatographic assay based on multilayer quantum dot nanobeads (SiTQD-ICA). The SiTQD-ICA biosensor utilizing M53 and M78 antibodies showed high sensitivity and stability of detection: A29L was detected within 20 min, with a minimum detection limit of 5 pg/mL. A specificity test showed that the method was non-cross-reactive with chickenpox or common respiratory pathogens and can be used for early and rapid diagnosis of monkeypox virus infection by antigen detection. This antibody identification method can also be used for rapid acquisition of monoclonal antibodies in early outbreaks of other infectious diseases for various studies.

Herein, a catalytic amplification enhanced dual-signal immunochromatographic assay (ICA) based on Pt nanoparticles (Pt NPs) modified with Ti3C2Tx MXene (Ti3C2Tx@Pt) was first developed for chloramphenicol (CAP) in animal-derived foods. Due to the large specific surface area and abundant active sites of Ti3C2Tx@Pt, they can be loaded with hundreds of Pt NPs to enhance their catalytic activity, resulting in a significant increase in the detection sensitivity; the sensitivity was up to 50-fold more sensitive than the reported ICA for CAP. The LODs of the developed method for milk/chicken/fish were 0.01 μg/kg, the LOQs were 0.03 μg/kg and the recovery rates were 80.5–117.0%, 87.2–118.1% and 92.7–117.9%, with corresponding variations ranging from 3.1 to 9.6%, 6.0 to 12.7% and 6.0 to 13.6%, respectively. The linear range was 0.0125–1.0 μg/kg. The results of the LC-MS/MS confirmation test on 30 real samples had a good correlation with that of our established method (R2 > 0.98), indicating the practical reliability of the established method. The above results indicated that an ICA based on the Ti3C2Tx@Pt nanozyme has excellent potential as a food safety detection tool. [ABSTRACT FROM AUTHOR]

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Toxoplasma gondii (T. gondii) is a parasitic zoonosis that causes abortion or congenital diseases. The purpose of this study is to establish a immunochromatographic assay (ICA) method using time-resolved fluorescence microspheres (TRFM) for T. gondii quantitative detection in serum. Firstly, we activated the TRFM and then coupled with anti-T. gondii antibodies (mAb1) and anti-BSA-DNP antibodies to prepare the TRFM-mAb1 probes and TRFM-BSA-DNP probes. Then, we optimized the coupling pH, T line antibody concentration, probes usage and detection time. Finally, we established the T. gondii-TRFMICA method and assemble the T. gondii-TRFMICA kit, the standard curve, sensitivity, precision, specificity, clinical sensitivity and specificity were evaluated. Under the optimized conditions, the T. gondii-TRFMICA test was achieved within 20 min with the sensitivity 0.1 ng/mL. The recoveries were ranging from 100–110% with the intra-assay and inter-assay CV lower than 10%. The kits have detection specificity for positive serum of several common infectious diseases and some common serum components, and have high detection sensitivity and specificity in human and cat clinical samples. A TRFMICA kit for T. gondii quantitative detection was successfully prepared with high sensitivity, specificity, precision and clinical sensitivity and specificity. We recommend TRFMICA as a promising technique in the clinical diagnosis and monitoring of toxoplasmosis in human and animals.

In this study, a highly sensitive monoclonal antibody (mAb) was developed for the detection of aflatoxin B1 (AFB1) in maize and feed. Additionally, indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and time-resolved fluorescence immunoassay assay (TRFICA) were established. Firstly, the hapten AFB1-CMO was synthesized and conjugated with carrier proteins to prepare the immunogen for mouse immunization. Subsequently, mAb was generated using the classical hybridoma technique. The lowest half-maximal inhibitory concentration (IC50) of ic-ELISA was 38.6 ng/kg with a linear range of 6.25–100 ng/kg. The limits of detections (LODs) were 6.58 ng/kg and 5.54 ng/kg in maize and feed, respectively, with the recoveries ranging from 72% to 94%. The TRFICA was developed with a significantly reduced detection time of only 21 min, from sample processing to reading. Additionally, the limits of detection (LODs) for maize and feed were determined to be 62.7 ng/kg and 121 ng/kg, respectively. The linear ranges were 100–4000 ng/kg, with the recoveries ranging from 90% to 98%. In conclusion, the development of AFB1 mAb and the establishment of ic-ELISA for high-throughput sample detection, as well as TRFICA for rapid detection presented robust tools for versatile AFB1 detection in different scenarios. [ABSTRACT FROM AUTHOR]

A sensitive immunochromatographic assay (ICA) using time-resolved fluorescence microspheres (TRFMs) coupled with an indirect-labeling mode was developed for simultaneously determining 22 kinds of β-lactams in milk samples. The TRFMs labeled anti-receptor monoclonal antibodies (mAbs) conjugated to penicillin-binding proteins (PBPs) as ternary TRFMs-mAb-PBPs (TMP) nanoscaffolds provide excellent solubility, brightness, and stability. Thanks to the fact that they not only fully expose the binding sites of PBPs, thereby enhancing the biological affinity of PBPs towards the target, but also generated superb fluorescence signals, the versatile TMP manifested unique possibilities as efficient probes for ICA with remarkable enhancement in sensitivity in β-lactams screening. The results showed that the standard curves of the 22 varying β-lactams displayed linearity in their respective concentration ranges (R2 > 0.98), with the cutoff values of 1–100 ng/mL. The constructed TMP-ICA was successfully applied to the analysis of real milk, with consistent results compared with liquid chromatography-tandem mass spectrometry (LC-MS), providing an effective method for sensing β-lactams in food matrices. [ABSTRACT FROM AUTHOR]

A rapid, reliable, sensitive, and multiplex colloidal gold immunochromatographic assay (CGIA) was developed for the simultaneous detection of three polyether ionophore antibiotics (PEs) in chicken muscle. The IC50 values of the optimized CGIA were 1.63, 1.94, and 1.18 ng/mL with a linear range of 0.87-3.04 ng/mL, 0.85-4.41 ng/mL, and 0.57-2.44 ng/mL for maduramicin (MAD), monensin (MON), and salinomycin (SAL), respectively. The cut-off values were 10, 5, and 5 ng/mL, respectively. The whole testing process was completed within 15 min. A parallel analysis in blind chicken muscle samples was conducted by liquid chromatography-tandem mass spectrometry (LC-MS/MS), the developed CGIA did not appear false-positive and false-negative. The results show that the established method could provide a rapid and effective approach for on-site screening and determination of PEs residues in chicken muscle samples. [ABSTRACT FROM AUTHOR]

Lead ions are a toxic metal that can enter the human body through the diet and negatively impact human health. A wide variety of foods, such as vegetables, meat, aquatic product, and drinking water, can be contaminated with lead ions. In this study, a highly sensitive immunochromatographic assay (ICA) based on antibody-oriented probe and silver enhancement was established for the qualitative and quantitative determination of lead ions in drinking water. The recombinant protein A (PrA) was used in probe preparation to improve antibody bioactivity while silver enhancement method was applied to enhance the signal reporter of ICA. It was determined that the visual limit of detection and the scanning limit of quantification of the ICA based on antibody-oriented probe and silver enhancement for lead ions in drinking water were 0.2 ng/mL and 0.08 ng/mL, respectively. The results obtained from developed ICA strip and ICP-MS had no obvious difference using statistical analysis of t test. Compared to previously reported ICA methods for lead ions, the developed ICA method enabled analyzing lead ions in drinking water with a superior sensitivity and detection range. [ABSTRACT FROM AUTHOR]

Aflatoxin B1 (AFB1), a widespread contaminant in food and feeds, poses a threat to the health of animals and humans. Consequently, it is significant to develop a rapid, precise and highly sensitive analytical method for the detection of AFB1. Herein, we developed an immunochromatographic strip (ICS) based on a tetrahedral DNA (TDN) immunoprobe for AFB1 determination in rice bran oil. Three sizes of TDN immunoprobes (AuNP-TDN13bp-mAb, AuNP-TDN17bp-mAb, AuNP-TDN26bp-mAb) were constructed, and the performance of these three immunoprobes, including the effective antibody labeling density and immunoaffinity, was measured and compared with that of the immunoprobe (AuNP-mAb) developed using the physical adsorption method. Subsequently, the optimal TDN immunoprobe, namely AuNP-TDN13bp-mAb, was selected to prepare the immunochromatographic strip (ICS) for the qualitative and quantitative detection of AFB1 in rice bran oil. The visual limits of detection (vLODs) of the ICS based on AuNP-TDN13bp-mAb and AuNP-mAb were 0.2 ng/mL and 2 ng/mL, with scanning quantitative limits (sLOQs) of 0.13 ng/mL and 1.4 ng/mL, respectively. The ICS demonstrated a wide linear range from 0.02 ng/mL to 0.5 ng/mL, with good specificity, accuracy, precision, repeatability, and stability. Moreover, a high consistency was observed between the constructed ICS and ultra-high-performance liquid chromatography (UPLC) in the quantification of AFB1. The results indicated that the introduction of TDN was beneficial for promoting efficient antibody labeling, protecting the bioactivity of immunoprobes, and increasing the sensitivity of detection, which would provide new perspectives for the achievement of the highly sensitive detection of mycotoxins.

Abstract Background Rapid and accurate identification of carbapenemase-producing organism (CPO) intestinal carriers is essential for infection prevention and control. Molecular diagnostic methods can produce results in as little as 1 h, but require special instrumentation and are expensive. Therefore, it is urgent to find an alternative method. The broth enrichment-multiplex lateral flow immunochromatographic assay was recently reported, but using it to directly detect CPO intestinal carriers in rectal swabs still requires the evaluation of many samples. The aim of this study was to compare the performance of these two methods, and to explore the control measures of CPO infection. Methods Through CPO selective culture, PCR and DNA sequencing, 100 rectal swabs confirmed to be CPO-positive and 100 rectal swabs with negative results were collected continuously. After eluting the rectal swabs with saline, three aliquots were used: one for counting, one for detection by Xpert Carba-R, and one for culture in broth for 0 h, 1 h, 2 h, 3 h and 4 h, followed by NG-Test CARBA 5 assessment. The sensitivity and specificity of the NG-Test CARBA 5 method after different incubation times were calculated. The limit of detection (LoD) of this assay after 4 h broth incubation was estimated by examining the bacterial suspensions and simulated faecal suspensions prepared with CPOs producing different types of carbapenemases. Results Xpert Carba-R demonstrated a combined sensitivity of 99.0% and specificity of 98.0%. The sensitivity and specificity were higher than 90.0% for the different enzyme types. The specificities of five common carbapenemases detected by the broth enrichment NG-Test CARBA 5 combined method after different incubation times were 100%. The sensitivities increased with increasing incubation time. At 4 h, the Klebsiella pneumoniae carbapenemase (KPC), New Delhi metallo-beta-lactamase (NDM), imipenemase (IMP), Verona integron-encoded metallo-beta-lactamase (VIM), and oxacillinase (OXA) -48 detection sensitivities were 93.0%, 96.3%, 100%, 100% and 85.7%, respectively. The LoDs were between 102 and 104 CFU/mL for all five enzymes after 4 h of incubation. Conclusions This investigation highlighted that the broth enrichment-multiplex lateral flow immunochromatographic assay can be used as a new method for screening CPOs in rectal swabs.

Infections caused by extended-spectrum β-lactamase-producing Enterobacterales have increased rapidly and are mainly attributed to the production of CTX-M enzymes. This study evaluated the NG-Test® CTX-M MULTI lateral flow assay (CTX-M LFA) and the Rapid ESBL NP® test (ESBL NP test) for rapid detection of CTX-M-producing Enterobacterales directly in midstream urine (MSU) samples. Testing was performed on 277 clinical MSU samples in a hospital microbiology laboratory from November 2022 to January 2023; 60 of these samples (30 positive for ESBL producers and 30 positive for non-ESBL producers) were tested retrospectively after the identification and susceptibility results were obtained, and 217 samples were tested prospectively immediately after a Gram stain showing the presence of Gram-negative bacilli. The results were compared against phenotypic detection of ESBL and molecular testing as the reference methods. Overall, 67 of the 277 samples were culture-positive for ESBL-producing Enterobacterales. PCR for the blaCTX-M gene was positive for all ESBL-producing Enterobacterales isolates. All CTX-M LFA results were interpretable, while three of the ESBL NP test results were noninterpretable. The sensitivity of the CTX-M LFA (100%, 95% CI 94.6–100%) was higher than that of the ESBL NP test (86.6%, 95% CI 76.0–93.7%). Both tests had high specificities (CTX-M LFA, 99.1%, 95% CI 96.6–99.9% and ESBL NP test, 100%, 95% CI 98.2–100%). In conclusion, both the CTX-M LFA and the ESBL NP test can deliver rapid results that could improve antimicrobial stewardship for urinary tract infections. [ABSTRACT FROM AUTHOR]

Herein, a catalytic amplification enhanced dual-signal immunochromatographic assay (ICA) based on Pt nanoparticles (Pt NPs) modified with Ti3C2Tx MXene (Ti3C2Tx@Pt) was first developed for chloramphenicol (CAP) in animal-derived foods. Due to the large specific surface area and abundant active sites of Ti3C2Tx@Pt, they can be loaded with hundreds of Pt NPs to enhance their catalytic activity, resulting in a significant increase in the detection sensitivity; the sensitivity was up to 50-fold more sensitive than the reported ICA for CAP. The LODs of the developed method for milk/chicken/fish were 0.01 μg/kg, the LOQs were 0.03 μg/kg and the recovery rates were 80.5–117.0%, 87.2–118.1% and 92.7–117.9%, with corresponding variations ranging from 3.1 to 9.6%, 6.0 to 12.7% and 6.0 to 13.6%, respectively. The linear range was 0.0125–1.0 μg/kg. The results of the LC-MS/MS confirmation test on 30 real samples had a good correlation with that of our established method (R2 > 0.98), indicating the practical reliability of the established method. The above results indicated that an ICA based on the Ti3C2Tx@Pt nanozyme has excellent potential as a food safety detection tool.

Due to universal contamination and synergistic toxicity of multiple mycotoxins in foodstuff, reliable and high-throughput detection methods for multiple mycotoxins are urgently needed in corn products. In this study, a novel dual-channel immunochromatographic assay (ICA) based on improved up-conversion nanoparticles (IUCNPs) was developed for rapidly detecting aflatoxin B1 (AFB1) and zearalenone (ZEN). The synthesized IUCNPs doped by 30% Lu3+ showed a larger size, more regular structure, and brighter fluorescence intensity than conventional UCNPs. The limits of detection (LODs) of single-channel ICA test strips for AFB1 and ZEN detection were 0.01 and 0.1 ng/mL, respectively. After the optimization, the dual-channel ICA of AFB1 and ZEN in 10 min was conducted, resulting in low detection limits of 0.025 and 0.1 ng/mL, respectively. Moreover, the built assay was revealed to be highly specific for six other food-contaminated mycotoxins, and exhibited excellent accuracy, with corresponding R2 of 0.9931 and 0.9982 in calibration curves, respectively. Long-term storage experiments indicated that the dual-channel test strips had superior stability and precision. The LODs of AFB1 and ZEN in spiked maize were 0.025 and 0.25 μg/kg, demonstrating great sensitivity and matrix tolerance. Furthermore, the IUNCP-ICA was validated by high-performance liquid chromatography (HPLC) analyses, and a satisfactory consistency was obtained in 15 natural maize samples. Thus, the IUCNPs-ICA proposed in this work realized rapid and sensitive detection of AFB1 and ZEN, providing broad application potential in on-site screening for multiple mycotoxins in agricultural products. [ABSTRACT FROM AUTHOR]

Vancomycin (VAN) has a narrow therapeutic window and variable pharmacokinetic properties, which require timely monitoring of plasma concentration to adjust the dosage for better effectiveness. A sensitive and quantitative immunochromatographic method was developed to detect VAN in plasma. The linear response range of the method to detect plasma VAN was 1.25–50 μg/mL. The intra‐ and inter‐assay coefficients were 4.68% and 8.81%, respectively, while the recovery was 89.10%–98.32%. The clinical comparative experiment results demonstrated a good correlation (r > 0.90) between the fluorescent immunochromatographic strip test and the mass spectrum. In this study, a simple, rapid, and high‐sensitivity immunochromatographic method was established for detecting VAN, which helped establish the basis for further application of monitoring plasma concentration. [ABSTRACT FROM AUTHOR]

Recently increasing concerns from the scientists and public have been paid for seawater pollution due to tetracycline (TC) overuse in maricultural area. However, there are few methods or instruments that can be used for specific and rapid detection of this antibiotic in seawater. In this study, the colloidal gold immunochromatographic assay (CG-ICA) was used to achieve this goal. A commercialized monoclonal antibody against TC (anti-TC mAb) was selected because of its higher sensitivity (half-maximal inhibitory concentration of 2.38 µg L−1). The prepared CG particles (average diameter of 20 nm) were used to label anti-TC mAb at pH 8.0. The conjugate pad was formed by spraying the CG-labeled anti-TC mAb on a glass fibre membrane followed by proper dryness. The test pad was made by immobilizing artificial antigen and anti-mouse mAb in the test line and the control line, respectively, in a nitrocellulose membrane. The test strip, assembled with sample pad, conjugate pad, test pad and absorbent pad, could be used to detect TC during seawater sample flowing through these components in turn. The results could be observed by the naked eye in 10 min. The visible limit of detection (vLOD) was 20 µg L−1 for TC in seawater. The CG-ICA test results were in good agreement with those of liquid chromatography-tandem mass spectrometry (LC-MS/MS). The assay also showed that, oxytetracycline (OTC) and chlortetracycline (CTC), as the structural analogues of TC, did not interfere with TC determination. Furthermore, the TC concentration given by test strip could not be affected by the fluctuation of temperature (10°C–30°C), pH (7–9) and salinity (0–40) of seawater. Therefore, CG-ICA is a suitable tool for rapid, on-site, and semi-quantitative detection of TC in seawater. [ABSTRACT FROM AUTHOR]

Background: Rapid and accurate identification of carbapenemase-producing organism (CPO) intestinal carriers is essential for infection prevention and control. Molecular diagnostic methods can produce results in as little as 1 h, but require special instrumentation and are expensive. Therefore, it is urgent to find an alternative method. The broth enrichment-multiplex lateral flow immunochromatographic assay was recently reported, but using it to directly detect CPO intestinal carriers in rectal swabs still requires the evaluation of many samples. The aim of this study was to compare the performance of these two methods, and to explore the control measures of CPO infection. Methods: Through CPO selective culture, PCR and DNA sequencing, 100 rectal swabs confirmed to be CPO-positive and 100 rectal swabs with negative results were collected continuously. After eluting the rectal swabs with saline, three aliquots were used: one for counting, one for detection by Xpert Carba-R, and one for culture in broth for 0 h, 1 h, 2 h, 3 h and 4 h, followed by NG-Test CARBA 5 assessment. The sensitivity and specificity of the NG-Test CARBA 5 method after different incubation times were calculated. The limit of detection (LoD) of this assay after 4 h broth incubation was estimated by examining the bacterial suspensions and simulated faecal suspensions prepared with CPOs producing different types of carbapenemases. Results: Xpert Carba-R demonstrated a combined sensitivity of 99.0% and specificity of 98.0%. The sensitivity and specificity were higher than 90.0% for the different enzyme types. The specificities of five common carbapenemases detected by the broth enrichment NG-Test CARBA 5 combined method after different incubation times were 100%. The sensitivities increased with increasing incubation time. At 4 h, the Klebsiella pneumoniae carbapenemase (KPC), New Delhi metallo-beta-lactamase (NDM), imipenemase (IMP), Verona integron-encoded metallo-beta-lactamase (VIM), and oxacillinase (OXA) -48 detection sensitivities were 93.0%, 96.3%, 100%, 100% and 85.7%, respectively. The LoDs were between 102 and 104 CFU/mL for all five enzymes after 4 h of incubation. Conclusions: This investigation highlighted that the broth enrichment-multiplex lateral flow immunochromatographic assay can be used as a new method for screening CPOs in rectal swabs. [ABSTRACT FROM AUTHOR]

Background: Mycotoxins are secondary metabolites produced by fungi, which have serious effects on humans and animals. In this study, we selected the monodispersed polystyrene fluorescent microspheres with good luminescence performance and strong stability as markers to conjugate with four mycotoxins antibodies for preparing fluorescent probes. We have developed a fluorescent microsphere based immunochromatographic assay (FMICA) to detect sensitively and quickly zearalenone (ZEN), aflatoxin B1 (AFB1), fumonisin B1 (FB1), and ochratoxin A (OTA) in cereal. Results: Under optimal experimental conditions, the procedure of this method can be completed within 10 min. The limit of detection (LOD) of FMICA for ZEN, AFB1, FB1, and OTA is 0.072, 0.093, 0.32, and 0.19 μg L−1, respectively. And FMICA has good specificity and no cross‐reactivity with other mycotoxins. Four mycotoxins in naturally contaminated cereal samples (corn, rice, and oat) are detected by this method, and the results are highly consistent with that of ultra‐performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS). Conclusion: The developed FMICA has good accuracy, high sensitivity, simplicity, convenience, rapidity, and low cost, and it could be employed for sensitive and quantitative detecting of mycotoxins in cereal on‐site. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Introduction: Miroestrol (Mi) and deoxymiroestrol (Dmi) are trace, yet potent, phytooestrogens found in white Kwao Krua [Pueraria candollei var. mirifica (Airy Shaw & Suvat.) Niyomdham, PM]. However, the analysis of these substances is difficult because of complex matrix effects and their various analogues. In addition, alteration in the cross‐reactivity of a gold nanoparticle (AuNP)‐based immunochromatographic assay (ICA) resulting from the electrostatic adsorption between antibodies and AuNPs has not yet been evaluated. Objectives: This study aims to develop, characterise, and validate ICA with a monoclonal antibody exhibiting similar reactivity against Mi and Dmi (MD‐mAb). Materials and Methods: The ICA performance was validated for cross‐reactivity and performance in comparison with those of indirect competitive enzyme‐linked immunosorbent assays (icELISAs) with MD‐mAb and mAb exhibiting specificity against Mi (Mi‐mAb). Results: The ICA showed a limit of detection (LOD) at 1 and 16 μg/mL for Mi and Dmi, respectively. The cross‐reactivity of the ICA with Dmi was lower (6.25%) than that observed with the icELISA (120%). Cross‐reactivity of ICA against other compounds of the PM was also correlated with those of icELISA; no false‐positive/negative results were observed. The repeatability and reproducibility of the ICA were confirmed. The results obtained using ICA in samples of PM are correlated with the concentrations determined through icELISAs. Conclusion: An ICA with MD‐mAb was constructed and validated. However, direct conjugation via the electrostatic adsorption of mAb‐AuNPs was expected to alter the cross‐reactivity of ICA, especially that of the analyte analogue Dmi. Immunochromatographic assay (ICA) was validated for cross‐reactivity and its performance and compared with those of indirect competitive enzyme‐linked immunosorbent assays (icELISAs). The ICA showed a limit of detection (LOD) of 1 μg/mL for miroestrol. The cross‐reactivity of ICA towards deoxymiroestrol was different from that of icELISA with the same mAb. The cross‐reactivity of the ICA against other compounds of Pueraria candollei var. mirifica (Airy Shaw & Suvat.) Niyomdham (PM) was correlated with those of icELISAs. The electrostatic conjugation of monoclonal antibody and gold nanoparticle (mAb‐AuNP) was expected to alter the ICA cross‐reactivity of the analogue. [ABSTRACT FROM AUTHOR]

Cyproheptadine hydrochloride (CYP), used as human and veterinary drug, has been used illegally as feed additive for food-producing animals, which could remain in food and jeopardize human health. There is a need for on-site detection of CYP residue in animal-derived food. In this study, a hapten was designed, and a specific monoclonal antibody (mAb) was developed to detect CYP with an IC50 of 1.38 ng/mL and negligible cross-reactivity (CR) for other analogs. Forthermore, a high sensitive immunochromatographic assay (QBs-ICA) was developed using quantum dot nanobeads as reporters. The assay showed the linear detection range (IC20-IC80) of 0.03-0.52 ng/mL, the limit of detection (LOD) and visual detection limit (VDL) reached to 0.01 and 0.625 ng/mL, respectively. Spiked recovery study in pig urine and pork confirmed that the QBs-ICA was applicable for on-site testing. This assay showed better sensitivity and speedy than the reported instrumental analysis and immunoassays.

A bispecific monoclonal antibody (BsMAb) that can simultaneously recognize aflatoxin B1 (AFB1) and amantadine (AMD) was prepared. Quantum dot nanobead immunochromatographic assay (QB-ICA) based on the BsMAb was developed for the simultaneous detection of AFB1 and AMD in four feed samples (suckling pig feed, piglet feed, sow feed, and compound feed for laying ducks). Under optimal experimental conditions, the LOD values of QB-ICA for AFB1 in four feed samples were 0.188, 0.221, 0.233, and 0.306 μg/kg, respectively. The LOD values of QB-ICA for AMD in the same feed samples were 0.125, 0.187, 0.076, and 0.191 μg/kg, respectively. The recovery rates of QB-ICA for AFB1 and AMD ranged from 91.55% to 150.87% and from 91.62% to 138.42%, respectively. The variation coefficients were all less than 15%. The proposed QB-ICA had high reliability and specificity for the simultaneous detection of AFB1 and AMD, providing a platform for simultaneous detection of hazardous substances.

Rapid detection of extended-spectrum-β-lactamase (ESBL) is of paramount importance to accelerate clinical decision-making, optimize antibiotic treatment, and implement adequate infection control measures. This study was aimed at assessing the impact of direct detection of CTX-M ESBL-producers on antimicrobial management of Escherichia coli bloodstream infections over a 2-year period. This study included all E. coli bloodstream infection (BSI) events that were serially processed through a rapid workflow with communication to the clinicians of direct detection of CTX-M ESBL-producers and conventional culture-based workflow. Antimicrobial management was retrospectively analyzed to assess the contribution of the rapid test result. A total of 199 E. coli BSI events with a report of direct detection of CTX-M ESBL production results were included. Of these, 33.7% (n = 67) and 66.3% (n = 132) were reported as positive and negative CTX-M producers, respectively. Detection of CTX-M positive results induced more antibiotic therapy modifications (mainly towards carbapenem-containing regimens, p < 0.01), and antimicrobial susceptibility testing results of CTX-M ESBL-producing E. coli isolates induced more antibiotic escalations towards carbapenem-containing regimens (p < 0.01). Direct detection of CTX-M ESBL-producing E. coli resulted in a remarkable rate of antibiotic optimizations on the same day of blood culture processing. Observing antibiotic management following the availability of antimicrobial susceptibility testing results, additional early optimizations in escalation could probably have been made if the rapid test data had been used. Detection of CTX-M negative results resulted in few therapeutic changes, which could have probably been higher, integrating epidemiological and clinical data. [ABSTRACT FROM AUTHOR]

In this study, a highly sensitive monoclonal antibody (mAb) was developed for the detection of aflatoxin B1 (AFB1) in maize and feed. Additionally, indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and time-resolved fluorescence immunoassay assay (TRFICA) were established. Firstly, the hapten AFB1-CMO was synthesized and conjugated with carrier proteins to prepare the immunogen for mouse immunization. Subsequently, mAb was generated using the classical hybridoma technique. The lowest half-maximal inhibitory concentration (IC50) of ic-ELISA was 38.6 ng/kg with a linear range of 6.25–100 ng/kg. The limits of detections (LODs) were 6.58 ng/kg and 5.54 ng/kg in maize and feed, respectively, with the recoveries ranging from 72% to 94%. The TRFICA was developed with a significantly reduced detection time of only 21 min, from sample processing to reading. Additionally, the limits of detection (LODs) for maize and feed were determined to be 62.7 ng/kg and 121 ng/kg, respectively. The linear ranges were 100–4000 ng/kg, with the recoveries ranging from 90% to 98%. In conclusion, the development of AFB1 mAb and the establishment of ic-ELISA for high-throughput sample detection, as well as TRFICA for rapid detection presented robust tools for versatile AFB1 detection in different scenarios.

ABSTRACT: Staphylococcal enterotoxin A (SEA) is an important biotoxin, produced by Staphylococcus aureus under appropriate conditions, and often contaminates milk and dairy products. Herein, an anti-SEA monoclonal antibody (anti-SEA mAb) was prepared by injecting the SEA protein in BALB/c mice, and a novel immunochromatographic assay (ICA) was developed for the rapid and sensitive determination of SEA in pasteurized milk by using highly luminescent quantum dot beads (QB) as signal amplification probe. Given the 1020-fold enhancement in the photoluminescence intensity of QB to the original quantum dot, the proposed QB-ICA exhibits high sensitivity for SEA determination in real milk samples with a limit of detection of 1.89 ng/mL, and shows good dynamic linearity for SEA quantitative detection from 2 to 150 ng/mL within 15 min of test time. The proposed QB-ICA also shows good selectivity to SEA detection with a negligible cross-reaction to common analogs, including staphylococcal enterotoxins B, C, D, and E. In addition, the accuracy and precision of QB-ICA were assessed by analyzing SEA-fortified milk samples. The average recoveries of intra- and interassays range from 85.5 to 128.1%, and the coefficients of variation range from 4.6 to 14.2%, indicating an acceptable accuracy for the quantitative detection of SEA in real milk samples. In summary, this work provides a powerful and rapid analysis tool for the sensitive monitoring of SEA contamination in pasteurized milk samples.

Streptococcus pneumoniae (S. pneumoniae) is a prominent pathogen of bacterial pneumonia and its rapid and sensitive detection in complex biological samples remains a challenge. Here, we developed a simple but effective immunochromatographic assay (ICA) based on silica-Au core-satellite (SiO2@20Au) SERS tags to sensitively and quantitatively detect S. pneumoniae. The high-performance SiO2@20Au tags with superior stability and SERS activity were prepared by one-step electrostatic adsorption of dense 20 nm AuNPs onto 180 nm SiO2 core and introduced into the ICA method to ensure the high sensitivity and accuracy of the assay. The detection limit of the proposed SERS-ICA reached 46 cells/mL for S. pneumoniae and was 100-fold more sensitive than the traditional AuNPs-based colorimetric ICA method. Further, considering its good stability, specificity, reproducibility, and easy operation, the SiO2@20Au-SERS-ICA developed here has great potential to meet the demands of on-site and accurate detection of respiratory pathogens. [ABSTRACT FROM AUTHOR]

Objectives Based on the information from the random inspection of foods by the China Food and Drug Administration in 2022, the contamination levels of lead ions are high in many edible products. Traditional methods of detecting lead ions cannot meet the requirements of on-site analysis of food due to the need for large equipment. The immunochromatographic assay (ICA) is an effective, rapid, on-site analytical technique for determining lead ions in foods. However, the performance of ICA based on the traditional probe (AuNP-mAb) is limited by ignoring the influence of the antibody orientation. Materials and Methods In this study, we developed an efficient technology for constructing a universal probe (AuNP-PrA-mAb) based on the oriented immobilization of antibody. The performance of ICA was largely improved due to specific binding of the Fc region of the antibody with recombinant protein A (PrA) on the surface of a gold nanoparticle (AuNP). The ICA based on a universal probe was applied for the qualitative and quantitative detection of lead ions in Procambarus clarkii within 30 min. Meanwhile, a simple and fast pretreatment method based on dilute acid extraction was developed for pretreating the P. clarkii containing lead ions. Results The visual limit of detection and the scanning limit of quantization of the developed ICA strip for lead ions were 0.5 ng/mL and 0.28 ng/mL, respectively. The sensitivity of ICA based on universal probe was 10-fold higher than that of the ICA using traditional probe. Furthermore, the detection results had no obvious difference between the ICA and ICP-MS with t -test statistical method. Conclusions The developed ICA based on a universal probe presented broad application prospects in detecting contaminants in foods. [ABSTRACT FROM AUTHOR]

Bacteremia caused by extended-spectrum β-lactamases-producing Enterobacterales has increased rapidly and is mainly attributed to CTX-M enzymes. This study aimed to evaluate the NG-Test® CTX-M MULTI lateral flow assay (CTX-M LFA) for rapid detection of CTX-M producers in blood cultures (BCs) positive for Gram-negative bacilli in spiked and clinical BCs. Retrospective testing was performed on BC bottles spiked with a collection of well-characterized Enterobacterales isolates producing CTX-M (n = 15) and CTX-M-like (n = 27) β-lactamases. Prospective testing of clinical, non-duplicate BCs (n = 350) was performed in two hospital microbiology laboratories from April 2021 to March 2022 following detection of Gram-negative bacilli by microscopic examination. Results were compared against molecular testing as the reference. In the spiked BCs, the CTX-M LFA correctly detected all CTX-M producers including 5 isolates with hybrid CTX-M variants. However, false-positive results were observed for several CTX-M-like β-lactamases, including OXY-1-3, OXY-2-8, OXY-5-3, FONA-8, -9, -10, 11, 13 and SFO-1. In clinical BCs, the CTX-M LFA showed 100% (95% CI, 96.0–100%) sensitivity and 99.6% (97.9–100%) specificity. In conclusion, this study showed that rapid detection of CTX-M producers in BC broths can be reliably achieved using the CTX-M LFA, thus providing an opportunity for early optimization of antibiotics. [ABSTRACT FROM AUTHOR]

A bispecific monoclonal antibody (BsMAb) that can simultaneously recognize aflatoxin B1 (AFB1) and amantadine (AMD) was prepared. Quantum dot nanobead immunochromatographic assay (QB-ICA) based on the BsMAb was developed for the simultaneous detection of AFB1 and AMD in four feed samples (suckling pig feed, piglet feed, sow feed, and compound feed for laying ducks). Under optimal experimental conditions, the LOD values of QB-ICA for AFB1 in four feed samples were 0.188, 0.221, 0.233, and 0.306 μg/kg, respectively. The LOD values of QB-ICA for AMD in the same feed samples were 0.125, 0.187, 0.076, and 0.191 μg/kg, respectively. The recovery rates of QB-ICA for AFB1 and AMD ranged from 91.55% to 150.87% and from 91.62% to 138.42%, respectively. The variation coefficients were all less than 15%. The proposed QB-ICA had high reliability and specificity for the simultaneous detection of AFB1 and AMD, providing a platform for simultaneous detection of hazardous substances. [ABSTRACT FROM AUTHOR]

The identification of the origin of biological stains at the crime scene is one of the important components of forensic science. In this study, it was aimed to evaluate the specificity performance of Seratec-PMB Test, which is used to differentiate menstrual blood from peripheral blood, on blood samples collected from dead bodies. Moreover, our purpose is to investigate the relationship between D-dimer accumulation in postmortem blood and other factors using this method. In this study, Seratec-PMB test is applied to peripheral blood samples of 200 dead bodies and the test results were compared in terms of parameters including age, gender, time between being found dead and sample collection, the cause of death. In Seratec-PMB Test, 71% of postmortem blood samples were positive and 29% were negative for D-dimer presence. A significant relationship was reported in the distribution of test results by age. SERATEC®-PMB test afforded a high rate of positive results in postmortem peripheral blood. It should be remembered that the test may give false positive results for postmortem peripheral blood. Since the test is a semi-quantitative test, it was understood that it would not allow any interpretation about the cause of death. [Med-Science 2022; 11(1.000): 159-65]

• Ti 3 C 2 Tx@CdTe was prepared via PEI mediation with strong environmental resistance. • Ti 3 C 2 Tx@CdTe was equipped with both colorimetric and fluorescent outputs. • The sensitivity was up to 100-fold more sensitive than the reported ICA for CAP. In this study, Ti 3 C 2 Tx was coupled with CdTe quantum dots via plyethylenimine (PEI) mediation to form composite nanomaterials with dual colorimetric and fluorescent properties, which had strong pH, high ion strength, and organic solvent resistance. Then, this novel Ti 3 C 2 Tx@CdTe was firstly applied to develop a dual-mode immunochromatographic assay (ICA) for chloramphenicol (CAP) detection in animal-derived foods. The limits of detection of the colorimetric and fluorescent modes for CAP in milk/chicken/fish were 0.01 and 0.005 μg/kg, the limits of quantification were 0.025 and 0.016 μg/kg, the recovery rates were between 85.7% and 129.0% and 84.0%-119.2%, with the corresponding variations ranged from 6.5% to 14.8% and 6.4%-14.9%, respectively. The sensitivity of fluorescence mode was up to 100-fold higher than that of the reported ICA for CAP detection. The results of the confirmatory experiment on 30 samples showed good consistency with that of our established method (R2>0.93). The above results indicated that Ti 3 C 2 Tx@CdTe had superior detection performance and can provide a dual-mode signal calibration, high stability and sensitivity selection for immunoassay detection platforms. [ABSTRACT FROM AUTHOR]

This paper introduces a strategy for synthesizing haptens by introducing a quaternary ammonium cationic spacer arm into the imidazole ring, resulting in the preparation of a novel monoclonal antibody with high sensitivity and specificity against imazalil. Based on this, GICA has been developed for the highly sensitive detection of imazalil residues in citrus, banana, and apple samples. [Display omitted] • A novel monoclonal antibody with high sensitivity and specificity against imazalil was produced. • A novel cationic hapten strategy, supported by theoretical chemistry techniques, enhances the immune response. • Imazalil residues could be effectively monitored using the immunoassay method developed. Imazalil is an imidazole fungicide that controls fruit diseases by inhibiting ergosterol synthesis but has resulted in residues in food. There is a need to develop rapid immunoassays suitable for on-site food safety monitoring and primary screening of large samples. The development of high-performance antibodies represents a pivotal front-end process in the establishment of immuno-rapid assays for harmful small molecules. This study innovatively adopted a hapten preparation strategy by introducing a quaternary ammonium cationic arm to enhance specific immune responses without exposing the common fragment imidazole ring. Theoretical chemistry techniques, including electrostatic potential, lipophilic potential, molecular structure superposition, and frontier molecular orbital energy gap-based molecular softness, were used to analyze the structural features of the quaternary ammonium cationic hapten IMZ-A. The results showed that IMZ-A retained imazalil's microelectronic and macroscopic three-dimensional spatial superposition structures and showed increased softness for higher bioreactivity. The obtained imazalil monoclonal antibody demonstrates high specificity and sensitivity, with an IC 50 of 1.96 ng mL−1. A colloidal gold immunochromatographic assay was developed, detecting imazalil residues in fruit samples within 7 min, with a qLOD of 0.57–2.05 ng mL−1 and an IC 50 of 3.67–12.41 ng mL−1 in citrus, apple, and banana samples. This work offers a convenient and highly sensitive immunoassay for large-scale on-site detection of trace imazalil residues. More significantly, it provides a novel and general design idea for hapten, namely, introducing cations into hapten molecules to improve their specific immune potential. [ABSTRACT FROM AUTHOR]

[Display omitted] • A natural insect-derived nanoparticle was proposed as a signal tag in ICA. • CANPs have ultra-bright red color and instantaneous labeling capability. • The antibodies labeling process is less than 1 min. • A CANPs-ICA was developed for detection of chloramphenicol in natural water. With the increasing international attention to environmental protection, higher requirements are put forward for green detection technology with simple preparation, sustainable material application, and efficient result output. Herein, we firstly proposed the natural insect-derived nanoparticle with ultra-bright and instantaneous labeling capability as a signal tag for stable and efficient immunochromatographic assay (ICA) to meet above challenges. The FDA-approved insect-extracted carmine (E120) nanoparticles (CANPs) were specifically regulated by pH changes to enhance dispersity and produce an ultra-bright color as signal tags. Notably, owing to the rich functional groups in CANPs, the CANPs-probe formed rapidly and efficiently (less than 1 min) to improve the reproducibility and precision, getting rid of the high cost and resources (9-fold reduction of mAbs). As proof of concept, the CANPs-based ICA strategy realized ultra-bright red bands on the test trip, without background within 15 min for chloramphenicol (CAP) detection, attained more than 457-fold improvements in LOD over classic AuNP-ICA and a 5-fold reduction in cost in each detection. Its excellent application potential has been verified in different natural waters with recoveries ranging from 91.93-126.45 %. This study reveals a promising strategy for green detection technology for antibiotics in natural water. [ABSTRACT FROM AUTHOR]

α-Lactalbumin (α-La) is a common allergenic protein in dairy products, posing a potential hazard to human health. Therefore, there is an urgent need to develop an efficient and sensitive analytical method to assess the α-La content in food. After screening by cell fusion assay, we obtained a pair of monoclonal antibodies (mAbs) (mAb 1 and 9). The calculated limit of detection of the sandwich enzyme-linked immunosorbent assay (ELISA) was 3.99 ng/mL. By labeling mAbs with colloidal gold, we developed a sensitive and rapid immunochromatographic assay (ICA) strip method for the detection of α-La in dairy products. The established ICA strips showed high sensitivity and specificity for the detection of α-La, with a calculated limit of detection and a visual limit of detection of 10.33 and 50 ng/mL, respectively. The average recoveries for the determination of raw cow's milk and recombined milk using ICA strips ranged from 97.60% to 102.96%. The ICA strips showed good correlation with the high-performance liquid chromatography (HPLC) method when analyzing actual samples. The above results indicated that both methods can be used for the determination of α-La in dairy products. [ABSTRACT FROM AUTHOR]

Infections caused by extended-spectrum β-lactamase-producing Enterobacterales have increased rapidly and are mainly attributed to the production of CTX-M enzymes. This study evaluated the NG-Test® CTX-M MULTI lateral flow assay (CTX-M LFA) and the Rapid ESBL NP® test (ESBL NP test) for rapid detection of CTX-M-producing Enterobacterales directly in midstream urine (MSU) samples. Testing was performed on 277 clinical MSU samples in a hospital microbiology laboratory from November 2022 to January 2023; 60 of these samples (30 positive for ESBL producers and 30 positive for non-ESBL producers) were tested retrospectively after the identification and susceptibility results were obtained, and 217 samples were tested prospectively immediately after a Gram stain showing the presence of Gram-negative bacilli. The results were compared against phenotypic detection of ESBL and molecular testing as the reference methods. Overall, 67 of the 277 samples were culture-positive for ESBL-producing Enterobacterales. PCR for the blaCTX-M gene was positive for all ESBL-producing Enterobacterales isolates. All CTX-M LFA results were interpretable, while three of the ESBL NP test results were noninterpretable. The sensitivity of the CTX-M LFA (100%, 95% CI 94.6–100%) was higher than that of the ESBL NP test (86.6%, 95% CI 76.0–93.7%). Both tests had high specificities (CTX-M LFA, 99.1%, 95% CI 96.6–99.9% and ESBL NP test, 100%, 95% CI 98.2–100%). In conclusion, both the CTX-M LFA and the ESBL NP test can deliver rapid results that could improve antimicrobial stewardship for urinary tract infections.

Immunochromatographic tests are of particular interest as tools for monitoring toxic environmental pollutants. In this regard, the aim of this study was to develop an immunochromatographic test system for the detection of surfactant nonylphenol in water. Two schemes of the assay were compared; they are characterized by detection limits of 1.1 and 0.4 μg/mL and recoveries of nonylphenol from spring water in the range of 78–113.7%.

This study established a portable and ultrasensitive detection method based on recombinase polymerase amplification (RPA) combined with high-sensitivity multilayer quantum dot (MQD)-based immunochromatographic assay (ICA) to detect the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The RPA-MQD-based ICA method is reported for the first time and has the following advantages: (i) RPA is free from the constraints of instruments and can be promoted in point-of-care testing (POCT) scenarios, (ii) fluorescence ICA enhances the portability of detection operation so that the entire operation time is controlled within 1 h, and (iii) compared with common colorimetric-based RPA-ICA, the proposed assay used MQD to provide strong and quantifiable fluorescence signal, thus enhancing the detection sensitivity. With this strategy, the proposed RPA-MQD-based ICA can amplify and detect the SARS-CoV-2 nucleic acid on-site with a sensitivity of 2 copies/reaction, which is comparable to the sensitivity of commercial reverse transcription quantitative polymerase chain reaction (RT-qPCR) kits. Moreover, the designed primers did not cross-react with other common respiratory viruses, including adenovirus, influenza virus A, and influenza virus B, suggesting high specificity. Thus, the established portable method can sensitively detect SARS-CoV-2 nucleic acid without relying on equipment, having good application prospects in SARS-CoV-2 detection scenarios under non-lab conditions. [ABSTRACT FROM AUTHOR]

This study evaluated the performances of immunoassays (LFIA and ELISA) designed for SARS-CoV-2 Antigen (Ag)-detection in nasopharyngeal (NP) and serum samples in comparison to RT-PCR. NP samples from patients with respiratory symptoms (183 RT-PCR-positive and 74 RT-PCR-negative samples) were collected from March to April and November to December 2020. Seroconversion and antigen dynamics were assessed by symptom onset and day of RT-PCR diagnosis. Serum samples from 87 COVID-19 patients were used to investigate the added value of Ag quantification, at diagnosis and during follow-up. The sensitivity of COVID-VIRO-LFIA on samples with Ct ≤ 33, considered as the contagious threshold, was 86% on NPs (CI 95%: 79–90.5) and 76% on serum samples (CI 95%: 59.4–88), with a specificity of 100%. Serum N-Ag was detected during active infection as early as day two from symptom onset, with a diagnostic sensitivity of 81.5%. Within one week of symptom onset, diagnostic sensitivity and specificity reached 90.9% (95% CI, 85.1%–94.6%) and 98.3% (95% CI, 91.1%–99.9%), respectively. Serum N-Ag concentration closely correlated with disease severity. Longitudinal analysis revealed the simultaneous increase of antibodies and decrease of N-Ag. Sensitivities of COVID-VIRO-LFIA and COV-QUANTO-ELISA tests on NP and serum samples were close to 80%. They are suitable COVID-19-laboratory diagnostic tests, particularly when blood samples are available, thus reducing the requirement for NP sampling, and subsequent PCR analysis. ELISA titers may help to identify patients at risk of poor outcomes. [ABSTRACT FROM AUTHOR]

Direct and sensitive detection of multiple illegal additives in complex food samples is still a challenge in on-site detection. In this study, an ultrasensitive immunochromatographic assay (ICA) using magnetic Fe3O4@Au nanotags as a capture/detection difunctional tool was developed for the direct detection of β2-adrenoceptor agonists in real samples. The Fe3O4@Au tag is composed of a large magnetic core (~160 nm), a rough Au nanoshell, dense surface-modified Raman molecules, and antibodies, which cannot only effectively enrich targets from complex solutions to reduce the matrix effects of food samples and improve detection sensitivity, but also provide strong colorimetric/surface-enhanced Raman scattering (SERS) dual signals for ICA testing. The dual readout signals of the proposed ICA can meet the detection requirements in different environments. Specifically, the colorimetric signal allows for rapid visual detection of the analyte, and the SERS signal is used for the sensitive and quantitative detection modes. The proposed dual-signal ICA can achieve the simultaneous determination of two illegal additives, namely, clenbuterol hydrochloride and ractopamine. The detection limits for the two targets via colorimetric and SERS signals were down to ng mL−1 and pg mL−1 levels, respectively. Moreover, the proposed assay has demonstrated high accuracy and stability in real food samples. [ABSTRACT FROM AUTHOR]

Mercury is a major pollutant in food crops. In this study, we synthesized an anti-mercury monoclonal antibody (mAb; IC50 was 0.606 ng mL−1) with high sensitivity and specificity and different immunogens and coating antigens and developed an immuno-chromatographic assay (ICA) for the detection of mercury in rice. The ICA strip had a visible detection limit of 20 ng g−1 and a cut-off value of 500 ng g−1 in rice. The performance of the ICA strip was consistent with that of ICP-MS and ic-ELISA. The recoveries of mercury in rice ranged from 94.5% to 113.7% with ic-ELISA and from 93.6% to 116.45% with ICP-MS. Qualitative analysis by ICA can be obtained with the naked eye. The ICA strip is an effective and practical method for the rapid and high-throughput determination of mercury in rice. [ABSTRACT FROM AUTHOR]

The unique fluorescence properties of aggregation-induced emission (AIE) fluorescent microspheres (FMs) make them ideal signal markers. Traditional synthesis methods are complex, labor-intensive, and hazardous, leading to AIEFMs that lack biocompatibility and require further modification for immunoprobe preparation. This study introduces a novel hydrophobic force-driven method for rapid synthesis of highly biocompatible FMs (H-FMs), demonstrating their benefits in immunochromatographic assay (ICA) applications. The metal-polyphenol network (MPN) shell around the AIEgen core structure of H-FMs is quickly and safely formed by depositing MPN onto AIEgen nano-aggregates, achieving high dye utilization, affordability, and design flexibility, while producing H-FMs with fluorescence across 300-800 nm. The excellent biocompatibility of H-FMs eliminates the need for additional modifications, allowing antibodies to be coupled swiftly (within 10 min) with a high coupling efficiency of 93.4 %. The resulting immunoprobes exhibit strong target recognition and 90.6 % fluorescence retention over 30 days. These features support their application in double antibody sandwich and competitive ICA formats, with detection limits of 9.62 × 10² CFU/mL for E. coli O157:H7 and 0.0081 ng/mL for AFM1. This study provides new insights into designing fluorescent probes for safety monitoring of hazardous materials in the environment., 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.)