Development of a quantum dots based immunochromatographic strip for rapid and on-site detection of African swine fever virus.

African swine fever (ASF) is a lethal disease caused by ASF virus (ASFV), severely impacting the global swine industry. Though nuclear acid-based detection methods are reliable, they are laboratory-dependent. In this study, we developed a device-independent, user friendly and cost-effective quantum dots based immunochromatographic strip (QDs-ICS) with high specificity and sensitivity for the rapid and on-site detection of ASFV antigen. For the preparation of the QDs-ICS, we generated a monoclonal antibody (mAb) mAb-8G8 and polyclonal antibody (pAb) against ASFV-p72 protein. The pAb was labelled with QDs to be used as the detection probe and the mAb-8G8 was coated on the nitrocellulose membrane as the test line. Our results proved that the strip displayed no cross-reactivity with other swine viruses and detection limit of the QDs-ICS was down to 1 ng/mL for the ASFV-p72 protein with great reproducibility. The strip also exhibited high stability with a storage period up to 12 months under room temperature. Twenty blind samples and one hundred clinical samples were examined by the QDs-ICS, conventional PCR and real-time PCR method, respectively. Results showed that the agreement rate between the QDs-ICS and PCR method was 100%, and the agreement rate between the strip and real-time PCR was 94%. The novel QDs-ICS developed here would be an effective tool for on-site detection of ASFV.

Touchpad-based immunochromatographic strip for detecting the skin surface proteins.

This study demonstrates, for the first time, the proof-of-concept of a novel immunosensor, a touchpad-based immunochromatographic strip, that non-invasively extracts and detects skin surface proteins. The strip was composed of a nitrocellulose membrane at the center, where a spot of anti-human IgG capture antibody was physically adsorbed. The capture antibody spot was covered with a glass fiber membrane impregnated with phosphate-buffered saline (PBS) to extract skin surface proteins, avoiding direct contact of the human skin with the capture antibodies. Skin surface IgG was detected in two steps: (1) touching the capture antibody via a glass fiber membrane containing PBS, and (2) dipping the strip into the Au-nanoparticle-labeled secondary antibody to visualize the existence of the captured skin surface IgG on the strip. We qualitatively demonstrated that using a very small amount of PBS while maintaining contact with the skin, skin surface proteins can be concentrated and detected, even with a relatively low-sensitivity immunochromatographic chip. This sensor is expected to be a potential biosensor for the non-invasive diagnosis of the integrity of human skin.

Rapid lateral flow test for Mycobacterium tuberculosis complex and non-tuberculous mycobacteria differentiation.

The diagnosis of mycobacterial infections, including both the Mycobacterium tuberculosis complex (MTBC) and non-tuberculous mycobacteria (NTM), poses a significant global medical challenge. This study proposes a novel approach using immunochromatographic (IC) strip tests for the simultaneous detection of MTBC and NTM. Traditional methods for identifying mycobacteria, such as culture techniques, are hindered by delays in distinguishing between MTBC and NTM, which can affect patient care and disease control. Molecular methods, while sensitive, are resource-intensive and unable to differentiate between live and dead bacteria. In this research, we developed unique monoclonal antibodies (mAbs) against Ag85B, a mycobacterial secretory protein, and successfully implemented IC strip tests named 8B and 9B. These strips demonstrated high concordance rates with conventional methods for detecting MTBC, with positivity rates of 93.9% and 85.9%, respectively. For NTM detection, the IC strip tests achieved a 63.2% detection rate compared to culture methods, considering variations in growth rates among different NTM species. Furthermore, this study highlights a significant finding regarding the potential of MPT64 and Ag85B proteins as markers for MTBC detection. In conclusion, our breakthrough method enables rapid and accurate detection of both MTBC and NTM bacteria within the BACTEC MGIT system. This approach represents a valuable tool in clinical settings for distinguishing between MTBC and NTM infections, thereby enhancing the management and control of mycobacterial diseases. KEY POINTS: • Panel of mAbs for differentiating MTB versus NTM • IC strips for diagnosing MTBC and NTM after the BACTEC MGIT • Combined detection of MTP64 and Ag85B enhances diagnostic accuracy.

Development and evaluation of time-resolved rapid immunofluorescence test for detection of TSOL18 specific antibody in porcine cysticercosis infections.

BACKGROUND: Porcine cysticercosis, a serious zoonotic parasitic disease, is caused by the larvae of Taenia solium and has been acknowledged by the World Organization for Animal Health. The current detection methods of Cysticercus cellulosae cannot meet the needs of large-scale and rapid detection in the field. We hypothesized that the immunofluorescence chromatography test strip (ICS) for detecting Cysticercus cellulosae, according to optimization of a series of reaction systems was conducted, and sensitivity, specificity, and stability testing, and was finally compared with ELISA. This method utilizes Eu3+-labeled time-resolved fluorescent microspheres (TRFM) coupled with TSOL18 antigen to detect TSOL18 antibodies in infected pig sera. RESULTS: ICS and autopsy have highly consistent diagnostic results (n = 133), as determined by Cohen's κ analysis (κ = 0.925). And the results showed that the proposed ICS are high sensitivity (0.9459) with specificity (0.9792). The ICS was unable to detect positive samples of other parasites. It can be stored for at least six months at 4℃. CONCLUSIONS: In summary, we established a TRFM-ICS method with higher sensitivity and specificity than indirect ELISA. Results obtained from serum samples can be read within 10 min, indicating a rapid, user-friendly test suitable for large-scale field detection.

Rapid and simultaneous detection of five mycotoxins and their analogs with a gold nanoparticle-based multiplex immuno-strip sensor.

Mycotoxins, as secondary metabolites produced by fungi, have been the focus of researchers in various countries and are considered to be one of the major risk factors in agricultural products. There is an urgent need for a rapid, simple and high-performance method to detect residues of harmful mycotoxins in agricultural foods. We have developed a gold nanoparticle-based multiplexed immunochromatographic strip biosensor that can simultaneously detect fifteen mycotoxins in cereal samples. With this optimized procedure, five representative mycotoxins, deoxynivalenol (DON), zearalenone (ZEN), T-2 toxin (T-2), tenuazonic acid (TEA) and alternariol (AOH) were detected in the range of 0.91-4.77, 0.04-0.56, 0.11-0.68, 0.12-1.02 and 0.09-0.75 ng/mL, respectively. The accuracy and stability of these measurements were demonstrated by analysis of spiked samples with recoveries of 91.8%-115.3% and coefficients of variation <8.7%. In addition, commercially available samples of real cereals were tested using the strips and showed good agreement with the results verified by LC-MS/MS. Therefore, Our assembled ICA strips can be used for the simultaneous detection of 5 mycotoxins and their analogs (15 mycotoxins in total) in grain samples, and the results were consistent between different types of cereal foods, this multiplexed immunochromatographic strip biosensor can be used as an effective tool for the primary screening of mycotoxin residues in agricultural products.

Broad-Spectrum Antibody-Based Immunochromatographic Strip Assay for Rapid Screening of Bisphenol A Diglycidyl Ether and Its Derivatives in Canned Foods.

Bisphenol A diglycidyl ether (BADGE) is widely present in the inner coating of metal food cans, from which it can migrate into food and generate harmful derivatives during storage, such as bisphenol A (2,3-dihydroxypropyl) glycidyl ether, bisphenol A (3-chloro-2-hydroxypropyl) glycidyl ether, and bisphenol A (3-chloro-2-hydroxypropyl) (2,3-dihydroxypropyl) glycidyl ether. Here, a gold-nanoparticle-based immunochromatographic strip assay based on a broad-spectrum polyclonal antibody was developed for the simultaneous detection of BADGE and its derivatives, which could be accomplished within 15 min. The quantitative analysis of the visualization results was performed using Adobe Photoshop CC 2021, and the detection limit, defined as the concentration causing 15% inhibition, was 0.97 ng/mL. The recoveries of BADGE and its derivatives at various spiking levels in canned food samples ranged from 79.86% to 93.81%. The detection results of the proposed immunochromatographic strip assay were validated via high-performance liquid chromatography, showing a good correlation coefficient (R2 = 0.9580).

Overview-gold nanoparticles-based sensitive nanosensors in mycotoxins detection.

Food-borne mycotoxins is one of the food safety concerns in the world. At present, nanosensors are widely used in the detection and analysis of mycotoxins due to their high specificity and sensitivity. In nanosensor-based mycotoxindetections, the sensitivity is mainly improved from two aspects. On the one hand, based on the principle of immune response, antigens and antibodies can be modified and developed. Such as single-domain heavy chain antibodies, aptamers, peptides, and antigen mimotopes. On the other hand, improvements and innovations have been made on signal amplification materials, including gold nanoparticles (AuNPs), quantum dots, and graphene, etc. Among them, gold nanoparticles can not only be used as a signal amplification material, but also can be used as carriers for identification elements, which can be used for signal amplification in detection. In this article, we systematically summarized the emerging strategies for enhancing the detection sensitivity of traditional gold nanoparticles-based nanosensors, in terms of recognition elements and signal amplification. Representative examples were selected to illustrate the potential mechanism of each strategy in enhancing the colorimetric signal intensity of AuNP and its potential application in biosensing. Finally, our review suggested the challenges and future prospects of gold particles in detection of mycotoxins.

Rapid detection of porcine circovirus type 2 by a red latex microsphere immunochromatographic strip.

To establish a rapid and specific antigen detection method for porcine circovirus type 2 (PCV2), monoclonal antibodies (mAbs) were produced against the PCV2 epidemic strains and a red latex microsphere immunochromatographic strip was established. A total of eight anti-PCV2b and four anti-PCV2d mAbs were produced, and seven mAbs were confirmed to react with PCV2a, PCV2b, and PCV2d strains using an immunoperoxidase monolayer assay. The results of micro-neutralization tests showed that the mAbs 2C8, 9H4, 10G7, 7B9, and 7C7 had good neutralizing activity, whereas the neutralizing activity of the mAbs 4B3, 4C9, 6H9, and 7E2 was lower than 50%. Three mAbs, 4B3, 7C7, and 9H4, and PCV2 pAb were selected for the establishment of a red latex microsphere immunochromatographic strip, and the combination of mAb 7C7 labeled with red latex microspheres and mAb 9H4 exhibited the greatest detection ability. The immunochromatographic strip had minimum detection limits of 102.5 TCID50/0.1 ml, 100.7 TCID50/0.1 ml, and 101.5 TCID50/0.1 ml for PCV2a/CL, PCV2b/MDJ, and PCV2d/LNHC, respectively. Furthermore, no cross-reactivity was found for African swine fever virus, classical swine fever virus, porcine respiratory and reproductive syndrome virus, porcine parvovirus, porcine pseudorabies virus, porcine circovirus type 1, transmissible gastroenteritis virus, porcine epidemic diarrhea virus, porcine rotavirus, or porcine deltacoronavirus using the immunochromatographic strip. Using PCR as a reference standard, the detection sensitivity, specificity, and overall coincidence rate of the immunochromatographic strip were 81.13%, 100%, and 90.00%. Additionally, the detection ability of the immunochromatographic strip was correlated with that of virus titration. The immunochromatographic strip was used to detect 183 clinical disease samples, and the average positive detection rate was 22.95%. In summary, this method has good sensitivity and specificity and is simple, convenient, and quick to operate. It has high application value for on-site diagnosis of PCV2 and virus quantification. KEY POINTS: • A red latex microsphere immunochromatographic strip for PCV2 detection was developed. • The method was not only simple to operate, but also takes less time. • The method had good sensitivity and specificity.

Development of a p72 trimer-based colloidal gold strip for detection of antibodies against African swine fever virus.

African swine fever virus (ASFV) causes a highly contagious and often lethal swine viral disease, and leads to tremendous economic losses to the swine industry. Unfortunately, there are no vaccines and effective antiviral agents available to prevent and control ASFV outbreaks. Therefore, it is necessary to develop simple and rapid strategies to monitor ASFV-infected pigs to restrain its spread. In the current study, ASFV capsid protein p72 was expressed along with its chaperone pB602L to form trimers in human embryonic kidney 293 (HEK293) cells. The p72 trimers were subsequently labeled with colloidal gold to develop a immunochromatographic strip. The strip showed high specificity to ASFV-positive serum and no cross-reactivity to other swine virus positive sera. Importantly, the strip showed a higher sensitivity of detecting ASFV antibodies in both positive standard serum and clinical serum samples than a commercial enzyme-linked immunosorbent assay (ELISA) kit. Taken together, these results demonstrate the strip as a reliable diagnostic tool against ASFV infection, which will be appropriate for application in prevention and control of ASFV. KEY POINTS : • ASFV p72 trimers were successfully generated. • A colloidal gold strip was developed based on ASFV p72 trimers. • The strip is appropriate for detecting ASFV antibodies in the field.

Development of a Rapid Fluorescent Diagnostic System for Early Detection of the Highly Pathogenic Avian Influenza H5 Clade 2.3.4.4 Viruses in Chicken Stool.

Rapid diagnosis is essential for the control and prevention of H5 highly pathogenic avian influenza viruses (HPAIVs). However, highly sensitive and rapid diagnostic systems have shown limited performance due to specific antibody scarcity. In this study, two novel specific monoclonal antibodies (mAbs) for clade 2.3.4.4 H5Nx viruses were developed by using an immunogen from a reversed genetic influenza virus (RGV). These mAbs were combined with fluorescence europium nanoparticles and an optimized lysis buffer, which were further used for developing a fluorescent immunochromatographic rapid strip test (FICT) for early detection of H5Nx influenza viruses on chicken stool samples. The result indicates that the limit of detection (LoD) of the developed FICT was 40 HAU/mL for detection of HPAIV H5 clade 2.3.4.4b in spiked chicken stool samples, which corresponded to 4.78 × 104 RNA copies as obtained from real-time polymerase chain reaction (RT-PCR). An experimental challenge of chicken with H5N6 HPAIV is lethal for chicken three days post-infection (DPI). Interestingly, our FICT could detect H5N6 in stool samples at 2 DPI earlier, with 100% relative sensitivity in comparison with RT-PCR, and it showed 50% higher sensitivity than the traditional colloidal gold-based rapid diagnostic test using the same mAbs pair. In conclusion, our rapid diagnostic method can be utilized for the early detection of H5Nx 2.3.4.4 HPAIVs in avian fecal samples from poultry farms or for influenza surveillance in wild migratory birds.

Development of an immunochromatographic strip for rapid detection of H7 subtype avian influenza viruses.

BACKGROUND: H7N9 avian influenza virus (AIV) including highly and low pathogenic viruses have been detected in China since 2013. H7N9 AIV has a high mortality rate after infection in humans, and most human cases have close contacted with poultry in the live poultry market. Therefore, it is necessary to develop a rapid point-of-care testing (POCT) technique for H7N9 AIV detection. METHODS: The H7N9 AIV was inactivated and purified, and was used as the antigen to immunize BALB/c. Twelve H7-HA specific monoclonal antibodies (McAbs) were produced through the hybridoma technique. The McAb 10A8 was conjugated with colloid gold as detecting antibody; McAb 9B6 was dispensed on the nitrocellulose membran as the capture test line and the Goat-anti mouse IgG antibody was dispensed as control line respectively. The immunochromatographic strip was prepared. RESULTS: The analysis of ELISA and virus neutralization test showed that the obtained McAbs specifically recognized H7 HA. Based on the prepared strip, the detection of H7 AIV was achieved within 10 min. No cross-reaction occurred between H7 AIVs and other tested viruses. The detection limit of the strip for H7 was 2.4 log10EID50/0.1 mL for chicken swab samples. CONCLUSION: The McAbs were specific for H7 and the immunochromatographic strip developed in this study was convenient, rapid and reliable for the detection of H7 AIV. The strip could provide an effective method for the rapid and early detection of H7 AIV.

Development of a rapid and sensitive immunochromatographic strip based on EuNPs-ES fluorescent probe for the detection of early Trichinella spiralis-specific IgG antibody in pigs.

Trichinellosis, which is caused by nematodes of the genus Trichinella, is one of the most important zoonotic parasite diseases in the world. A rapid and sensitive immunochromatographic strip (ICS) based on Eu (III) nanoparticles (EuNPs) was developed for the detection of Trichinella spiralis (T. spiralis) infection in pigs. T. spiralis muscle larvae excretory secretory or preadult worm excretory secretory (ML-ES or PAW-ES) antigens were conjugated with EuNPs probes to capture T. spiralis-specific antibodies in pig sera, after which the complex bound to mouse anti-pig IgG deposited on the test line (T-line), producing a fluorescent signal. In the pigs infected with 100, 1000 and 10 000 ML, seroconversion was first detectable for the EuNPs-ML-ES ICS at 30, 25 and 21 days post-infection (dpi) and for the EuNPs-PAW-ES ICS at 25, 21 and 17 dpi. These results show that EuNPs-PAW-ES ICS detects anti-Trichinella IgG in pigs 4-5 days earlier that test using ML-ES antigens. Our ICS have no cross reaction with other parasite infection sera. Furthermore, the detection process could be completed in 10 min. This study indicated that our ICS can be used for the detection of the circulating antibodies in early T. spiralis infection and provide a novel method for on-site detection of T. spiralis infection in pigs.

A quantum dot fluorescent microsphere based immunochromatographic strip for detection of brucellosis.

BACKGROUND: Brucellosis is a serious zoonosis disease that frequently causes significant economic loss in animal husbandry and threatens human health. Therefore, we established a rapid, accurate, simple and sensitive fluorescent immunochromatographic strip test (ICST) based on quantum dots (QDs) for detection the antibodies of Brucella infection animals serum. RESULTS: The test strips were successfully prepared by quantum dot fluorescent microspheres (QDFM) as tracers, which were covalently coupled to an outer membrane protein of Brucella OMP22. The outer membrane protein OMP28 and monoclonal antibodies of OMP22 were separately dispensed onto a nitrocellulose membrane as test and quality control lines, respectively. The critical threshold for determining negative or positive through the ratio of the fluorescent signal of the test line and the control line (HT / HC) is 0.0492. The repeatability was excellent with an overall average CV of 8.78%. Under optimum conditions, the limit of detection was 1.05 ng/mL (1:512 dilution). With regard to the detection of brucellosis in 150 clinical samples, the total coincidence rate of ICST and Rose Bengal plate test (RBPT) was 97.3%, the coincidence rate of positive samples was 98.8%, the coincidence rate of negative samples was 95.3%, the sensitivity of RBPT is 1:32, and no cross reaction with the sera of other related diseases was observed. CONCLUSION: In our present study, the QDFM has promising application for on-site screening of brucellosis owing to its high detection speed, high sensitivity, high specificity and low cost.

Development and evaluation of a convenient immunochromatographic strip test for rapid detection of cyprinid herpesvirus 2 (CyHV-2).

Cyprinid herpesvirus 2 (CyHV-2) has become a serious threat to the gibel carp Carassius auratus gibelio industry and has led to enormous losses worldwide. We have therefore developed an immunochromatographic strip (ICS) to enable rapid on-site detection of CyHV-2 by aquaculture facility staff. The ICS employs 2 monoclonal antibodies (MAbs 2C3-1E6 and 3H2-1G5) against the ORF25 protein, a CyHV-2 membrane protein, as the capture and detection antibodies, respectively. Indirect immunofluorescence assay (IIFA) and Western blotting of CyHV-2-infected fathead minnow cells indicated that the 2 MAbs could specifically bind CyHV-2 by recognizing ORF25 antigen. Sandwich ELISA showed that the detection limit of ORF25 protein halved when MAb 2C3-1E6 served as the capture antibody compared to MAb 3H2-1G5. The test for detecting purified CyHV-2 using the ICS could be completed in 10 min and the sensitivity was 1 µg ml-1. Sensitivity of the ICS remained stable following storage at 4, 25 and 37°C for 6 mo. Tissue homogenate from gibel carp with and without obvious gill hemorrhages was subjected to CyHV-2 detection using the ICS: the results were in good accordance with conventional PCR. Our ICS does not require highly trained technicians or specialized equipment, making it suitable for rapid diagnosis of CyHV-2 infection both in the laboratory and in the field.

Ultrasensitive and simultaneous detection of 6 nonsteroidal anti-inflammatory drugs by colloidal gold strip sensor.

In this work, an oxicam group-selective monoclonal antibody against 6 nonsteroidal anti-inflammatory drugs (NSAID; meloxicam, lornoxicam, piroxicam, sudoxicam, droxicam, and tenoxicam) was prepared. Also, a spacer arm with carboxyl group was derived at the hydroxyl of meloxicam to generate the meloxicam hapten. The half-maximal inhibitory concentrations (IC50) were, respectively, 0.31 ng/mL for meloxicam, 0.49 ng/mL for lornoxicam, 2.90 ng/mL for piroxicam, 1.95 ng/mL for sudoxicam, 3.08 ng/mL for droxicam, and 5.36 ng/mL for tenoxicam. A colloidal gold immunochromatographic strip based on the monoclonal antibody was developed for the detection of these 6 NSAID in milk. The results could be obtained by the naked eye in 10 min, and the cut-off values and the visual limits of detection in real samples were 5, 5, 10, 10, 25, and 25 ng/mL, and 0.25, 1, 0.5, 0.5, 1, and 1 ng/mL, respectively. This immunochromatopgraphic strip is a suitable tool for on-site detection and screening of oxicam NSAID in milk samples.

Lateral flow immunogold assay as a rapid detection tool for screening of congenital hypothyroidism.

Congenital hypothyroidism (CH) is one of the most common preventable causes of mental retardation. The majority of infants are diagnosed after detection through newborn screening programs using thyroid-stimulating hormone (TSH) test. A rapid immunochromatographic lateral flow assay based on monoclonal antibodies (MAbs) colloidal gold nanoparticles was developed in a sandwich format for the detection of TSH. Two MAbs binding distinct TSH epitopes are used; one is conjugated to the detection reagent while the other is immobilized at the test line on the membrane. The colloidal gold was prepared by the reduction of gold salt coupled with MAbs and this optimal concentration was determined by spectrophotometry method. The sensitivity of our developed lateral flow immunoassay was determined using 5, 10, 15, 25 and 50 µUI/mL of TSH. The color intensity of the test line was directly proportional to the TSH concentration and the visual limit of detection was 10 µUI/mL. Twenty samples of umbilical cord serum were analyzed by the developed strips and the intensity of the signal was in agreement with the results obtained by the conventional radioimmunoassay method. The results suggest that this rapid test can be used in initial screening for congenital hypothyroidism especially in rural areas.

Occurrence, Distribution, and Genomic Characteristics of Plum Pox Virus Isolates from Common Apricot (Prunus armeniaca) and Japanese Apricot (Prunus mume) in China.

Plum pox, or Sharka disease, caused by infection with plum pox virus (PPV), results in enormous economic losses to the stone fruit industry. However, the frequency and distribution of PPV remain unclear in China, the world's largest stone fruit producer. Systemic visual surveys were performed on stone fruit trees in China from 2008 to 2018, and the results suggest that plum pox disease is widely distributed on common apricots (Prunus armeniaca) and Japanese apricots (Prunus mume), with an average symptoms incidence rate >30% in the latter. In samples collected from Beijing, Nanjing, Shanghai, Wuhan, Wuxi, and Yuncheng, PPV was detected in 77% (85 of 110) of collected samples by immunochromatographic (IC) strip tests and reverse transcription PCR, and 96% (67 of 70) of samples showing Sharka symptoms were PPV positive. Transmission electron microscopy revealed filamentous particles of ∼640 × 12.5 nm (n = 19) in size and pinwheel inclusions in symptomatic plants but not in the asymptomatic and PPV-negative plants. Full-length genomes were determined for four isolates (three from Japanese apricot and one from common apricot), and phylogenetic analyses indicated that all four isolates belong to a clade PPV-D, despite slight differences in genome size. These findings not only highlight the widespread occurrence and distribution of PPV in China but also provide detailed information about the genomic characteristics and evolutionary position of PPV isolates in China.

Ten Years of Lateral Flow Immunoassay Technique Applications: Trends, Challenges and Future Perspectives.

The Lateral Flow Immunoassay (LFIA) is by far one of the most successful analytical platforms to perform the on-site detection of target substances. LFIA can be considered as a sort of lab-in-a-hand and, together with other point-of-need tests, has represented a paradigm shift from sample-to-lab to lab-to-sample aiming to improve decision making and turnaround time. The features of LFIAs made them a very attractive tool in clinical diagnostic where they can improve patient care by enabling more prompt diagnosis and treatment decisions. The rapidity, simplicity, relative cost-effectiveness, and the possibility to be used by nonskilled personnel contributed to the wide acceptance of LFIAs. As a consequence, from the detection of molecules, organisms, and (bio)markers for clinical purposes, the LFIA application has been rapidly extended to other fields, including food and feed safety, veterinary medicine, environmental control, and many others. This review aims to provide readers with a 10-years overview of applications, outlining the trends for the main application fields and the relative compounded annual growth rates. Moreover, future perspectives and challenges are discussed.

Semi-quantitative and quantitative detection of ochratoxin A in agricultural by-products using a self-assembling immunochromatographic strip.

BACKGROUND: The toxicity and health risks of mycotoxins have encouraged increased awareness and strict monitoring of these contaminants in agricultural by-products. In this paper, we developed and tested a sensitive, selective, and self-assembling immunochromatographic (IC) strip for on-site detection of ochratoxin A (OTA). We were able to demonstrate semi-quantitative and quantitative detection of OTA in agricultural by-product samples. RESULTS: The optimized IC strip had a limit of detection (LOD) of 0.5 ng mL-1 OTA using the naked eye for semi-quantitative detection. When a digitized strip reader was used to achieve quantitative results, the LOD for OTA was reduced to 0.1 ng mL-1 with a linear detection range of 0.1-10 ng mL-1 . We also evaluated the specificity, stability, accuracy, and precision of the IC strip and demonstrated high performance in all of these areas. We then confirmed the ability of the IC strip to visually detect OTA contamination in authentic agricultural by-product samples from the markets in China. Furthermore, quantitative detection of OTA using the IC strip showed that the concentration of OTA ranged from 1.7 to 101.3 ng g-1 in the positive agricultural by-product samples, correlating well with the measurements obtained via liquid chromatography with tandem mass spectrometry. CONCLUSION: The results indicated that this proposed IC strip was capable of sensitive, semi-quantitative, quantitative, and on-site detection of OTA contamination in agricultural by-product samples. © 2020 Society of Chemical Industry.

Evaluation of three immunochromatographic tests for rapid detection of antibodies against SARS-CoV-2.

Lateral flow immunoassays (LFIA) for rapid detection of specific antibodies (IgM and IgG) against SARS-CoV-2 in different human specimens have been developed in response to the pandemic. The aim of this study is to evaluate three immunocromathographic assays (Sienna®, Wondfo® and Prometheus®) for detection of antibodies against SARS-CoV-2 in serum samples, considering RT-qPCR as a reference. A total of 145 serum samples from 145 patients with clinical suspicion of COVID-19 were collected: all of the samples were tested with Sienna®, 117 with Wondfo® and 89 with Prometheus®. The overall results of sensitivity, specificity, positive predictive value and negative predictive value obtained were as follows: 64.4%, 75%, 85.5% and 47.8% with Sienna®; 45.2%, 81.8%, 80.5% and 47.4% with Wondfo® and 75.5%, 12.5%, 51.4% and 29.4% with Prometheus®. The accuracy of the test for Sienna®, Wondfo® and Prometheus® was 67.6%, 59% and 47.2%, with a prevalence of COVID-19 of 69.7%, 62.4% and 55.1% respectively. Sensitivity of the three tests (Sienna®, Wondfo® and Prometheus® respectively) along the three different stages was 36.6%, 18.8% and 68.6% in the early stage (first week); 81.3%, 74.1% and 90.9% in the intermediate stage (second week) and 100%, 83.3% and 100% in the late stage (third week). The results demonstrate that even though Prometheus® presented a high sensitivity, the specificity was notably lower than the other two tests. Sienna® showed the greatest contrast between sensitivity and specificity, achieving the best accuracy, followed by Wondfo®. The sensitivity of the three ICT assays was higher in late stages of the disease.