Yanni Chen

Gold immunochromatographic sensor for the rapid detection of twenty-six sulfonamides in foods

A gold immunochromatographic sensor (GICS) was developed for the rapid detection of 26 sulfonamides in honey samples. The sensor was based on a group-specific monoclonal antibody (mAb) that can recognize all 26 sulfonamides. Three haptens (hapten 1 with a thiazole ring, hapten 2 with a benzene ring, and hapten 3 with a straight carbon chain) were used for antigen preparation. With hybridoma technology, a group-specific mAb was screened with a 50% maximal inhibitory concentration (IC50) against sulfathizole (STZ) and the other 25 analogues ranging from 0.08 to 90.18 ng/mL. Mono-dispersed gold nanoparticles were conjugated with the mAb to develop the lateral immunochromatographic strip. A labeled antibody concentration of 0.1 μg/mL and a coating antigen concentration of 0.2 μg/mL in the test line were chosen for strip preparation. Under optimized conditions, the visual limits of detection (vLOD) for the concentrations of STZ, sulfamethoxazole, sulfamethizole, sulfadiazine, sulfamerazine, sulfadimethoxine, sulfamonomethoxine, sulfameter, sulfamethoxypyridazine, and sulfachloropyridazine were 5, 0.25, 0.25, 10, 5, 10, 25, 2.5, 5, 0.25, and 10 μg/kg, respectively. Scanner analysis in honey samples revealed good performance for detection of the 26 sulfonamides. Commercial honey samples were tested with the sensor and positive results were confirmed with high-performance liquid chromatography. The proposed strip sensor provides a convenient method for the rapid and reliable determination of sulfonamides pollutants in honey samples.

Development of a monoclonal antibody assay and a lateral flow strip test for the detection of paromomycin residues in food matrices

ABSTRACT A monoclonal antibody (MAb) was produced against paromomycin and used in the development of an immunoassay and a lateral flow strip test for the detection of paromomycin residues in food matrices. The MAb had 25.1% cross-reactivity with neomycin, but was insensitive to other aminoglycosides. Tested under optimized conditions in 0.01 M phosphate-buffered saline, the half maximum inhibitory concentration (IC50) of the MAb was 0.61 ng/ml for paromomycin and 2.43 ng/ml for neomycin, with results obtained within 90 min. The mean recoveries from spiked food matrices were within the range of 64.56–105.85% for paromomycin and 54.08–100.55% for neomycin. The strip test results for different food matrices were obtained within 5 min and showed visual detection limits of 2.5–20 ng/ml (µg/kg) for paromomycin and 10–30 ng/ml for neomycin. Therefore, the developed immunoassay and strip test can be used in food analysis for routinely monitoring not only paromomycin but also neomycin residues.

Development of an enzyme-linked immunosorbent assay (ELISA) for natamycin residues in foods based on a specific monoclonal antibody

An indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was developed based on a sensitive and specific monoclonal antibody (mAb) against natamycin (Nata) for Nata detection in milk, juice, yoghurt, and cheese samples. The working range of ic-ELISA was 0.64–4.46 μg L−1 with an IC50 value of 1.69 μg L−1. The average recoveries of milk, juice, yoghurt, and cheese samples spiked with Nata were 103–121%, 103–121%, 84–114%, and 89–108%, respectively. The results indicated that ic-ELISA can be effectively applied for Nata analysis in these food products.

Ultrasensitive Immunochromatographic Strip for Fast Screening of 27 Sulfonamides in Honey and Pork Liver Samples Based on a Monoclonal Antibody

Group-specific monoclonal antibodies (Mabs) with selectivity for 27 sulfonamides were developed based on new combinations of immunogen and coating antigen. The Mab was able to recognize 27 sulfonamides with 50% inhibition concentration (IC50) values ranging from 0.15 to 15.38 μg/L. In particular, the IC50 values for five sulfonamides (sulfamethazine, sulfaquinoxaline, sulfamonomethoxine, sulfadimethoxine, and sulfamethoxazole) were 0.51, 0.15, 0.56, 0.54, and 2.14 μg/L, respectively. On the basis of the Mab, an immunochromatographic lateral flow strip test was established for rapid screening of sulfonamides in honey samples. The visual limit of detection of the strip test for most sulfonamides in spiked honey samples was below 10 μg/kg, satisfying the requirements of authorities. Positive honey and pork liver samples, which had been confirmed by high-performance liquid chromatography/mass spectrometry, were used to validate the reliability of the proposed strip test. The immunochromatographic lateral flow strip test provides a rapid and convenient method for fast screening of sulfonamides in honey samples.

Development of a specific monoclonal antibody assay and a rapid testing strip for the detection of apramycin residues in food samples

ABSTRACT A specific monoclonal antibody (MAb) against apramycin (AP) was produced and used to develop an indirect competitive enzyme-linked immunosorbent assay (idcELISA) and a rapid testing strip for the detection of AP residues in foods. MAb exhibited negligible cross-reactivity with other aminoglycosides. Under optimized conditions in 0.01 M PBS, the half maximum inhibitory concentration (IC50) of MAb was 0.41 ng/ml with a limit of detection (LOD) of 0.15 ng/ml. The ELISA results were obtained within 90 min. The mean recoveries from all the spiked food samples were within the range of 79.02–105.49%, with coefficients of variation in the range of 2.21–11.4%. The strip test results obtained within 5 min had visual LODs in the range 2.5–5 µg/kg (ng/ml) for all food samples tested. Therefore, the developed strip test represents a fast and convenient detection method of AP residues in foods.

Establishment of a monoclonal antibody-based indirect enzyme-linked immunosorbent assay for the detection of trimethoprim residues in milk, honey, and fish samples

ABSTRACT A specific monoclonal antibody (mAb) against trimethoprim (TMP) was produced and a mAb-based indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was established to detect TMP residues in milk, honey, and fish samples. The working range of ic-ELISA and IC50 was 1.83–9.36 and 4.14 µg L−1. The average recoveries of TMP from TMP-spiked milk, honey, and fish sample were 103.5–118.0%, 100.3–107.1%, and 91.5–108.1%, respectively. The results revealed that our developed mAb-based ic-ELISA can be effectively applied to detect TMP residues in these food products.

Development of a monoclonal antibody assay and immunochromatographic test strip for the detection of amikacin residues in milk and eggs

ABSTRACT An amikacin-sensitive monoclonal antibody (MAb) assay and immunochromatographic test strip were developed and applied for the detection of amikacin residues in bovine milk and chicken eggs. The immunoassay was specific to amikacin and showed no cross-reactivity with other aminoglycosides. The half maximum inhibitory concentration (IC50) of the assay was 0.65 ng/mL and the results were obtained within 90 min. Recoveries from spiked food matrices were within the range of 73.55–84.61% for bovine milk and 73.70–105.75% for whole egg. The strip test results were obtained within 10 min and showed a visual detection limit of 5.0 ng/mL for both food matrices. These results show that the MAb immunoassay and strip test developed in this study are very specific to amikacin and sufficiently sensitive for detection and routine monitoring of amikacin residues in food.

Development of an antibody-based colloidal gold immunochromatographic lateral flow strip test for natamycin in milk and yoghurt samples

ABSTRACT An immunochromatographic lateral flow strip test was developed for the detection of natamycin (Nata) residues in milk and cheese samples. Monoclonal antibody (mAb) against Nata was produced with a half maximal inhibitory concentration of 1.85 μg L−1. MAb conjugated with gold nanoparticles was the detection reagent. Nata conjugated with ovalbumin via the 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide method immobilized on a nitrocellulose membrane was the capture reagent. This semi-quantitative method required only 15 min to complete. The optimum concentrations of coating antigen and mAb were 0.15 µg mL−1 and 0.2 µg mL−1, respectively. Based on an optical density scanner, the visual limit of detection of Nata was 5 μg L−1 and 10 μg kg−1 in milk and yoghurt samples, respectively.

Gold immunochromatographic assay for trimethoprim in milk and honey samples based on a heterogenous monoclonal antibody

ABSTRACT Three heterogenous haptens (3,4,5-Trimethoxybenzoic acid [H1], 3,4,5-Trimethoxyphenylacetic acid [H2], 3-(3,4,5-Trimethoxyphenyl) propanoic acid [H3]) were used to synthesize immunogens, with the aim of screening a more sensitive monoclonal antibody (mAb) for trimethoprim (TMP). H2 proved to be the best heterogenous hapten. The mAb was specific with no cross-reactivity with other structurally related chemicals. The 50% maximal inhibitory concentration of the mAb against TMP was 1.98 µg L−1, which is more sensitive compared with the mAb reported in our previous work. A mAb-based gold immunochromatographic assay (GICA) was established to analyze TMP residues in milk and honey samples. The concentration of coating antigen in test line and concentration of mAb conjugated with gold nanoparticles was 0.3 µg mL−1 and 0.25 µg mL−1, respectively. Under optimized conditions, the visual limit of detection concentration of TMP spiked in milk and honey samples was 10 µg L−1 and 15 µg kg−1, respectively. The proposed GICA provides rapid and simple determination of TMP residues in milk and honey samples.