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Ochratoxin A (OTA) in samples was captured and concentrated by immunoaffinity chromatography (IAC) and detected by enzyme-linked immunosorbent assay (ELISA). The anti-OTA monoclonal antibodies used in IAC and ELISA came from different clone strains, belonging to different idiotypes, and there were differences between their selectivity for binding to OTA targets. The combined use of IAC and ELISA could effectively filter out the interference from OTA analogues, thus improving the specificity and sensitivity of immunological analysis. The limit of detection (LOD) for OTA in spiked samples was 0.2 ng/g, the quantification limit was 0.4 ng/g, and the average recovery was 75.9%. Although the recovery of the IAC-ELISA method was slightly lower than that of ELISA, the sensitivity was increased by 60 times. For 49 real samples, the proportion of samples that tested positive by this combined method was 100% consistent with the result of the national standard method, with a missed detection rate of 0%. Therefore, the developed method exhibited significant advantages in accuracy. As a comprehensive immunoassay, this method does not require any large-scale instruments or equipment, and has no strict requirement on the operating environment, thereby making it easy for grassroot laboratories to analyze OTA in samples.

Salmonella is the main cause of human diarrhea worldwide, which seriously endangers human and animal health. Traditional detection methods are time -consuming and cumbersome, so it is of great significance to carry out rapid, simple and sensitive visual detection methods. In this paper, a probe that can bind to the target sequence was designed and combined with gold nanoparticles (AuNPs). The target sequence was amplified by saltatory rolling circle amplification (SRCA). After denaturation at high temperature, it became a single chain. After binding with the probe on gold nanoparticles, gold nanoparticles were released. Under the action of MgS04, the aggregation showed blue visible to the naked eye, which was judged to be positive and negative to be purple. Therefore, a simple, fast and sensitive visual detection method was established. The results showed that the method had good specificity and could distinguish 8 Salmonella positive and 8 non -Salmonella negative. The sensitivity of visual detection was 5.5 x100 CFU/mL. The milk samples were artificially contaminated with Salmonella, and the detection limit was 3.7x100 CFU/mL. Comparison with GB 4789.4-2016 method for detection of 50 actual samples, the sensitivity of this method was 100.00%, the specificity was 97.87%, and the coincidence rate was 98.00%. The SRCA-AuNPs visual detection method established in this paper has high application value, and the results are visible visually, which is suitable for on-site visual detection and grassroots units. [ABSTRACT FROM AUTHOR]

Objective: A loop-mediated isothermal amplification (LAMP) technology with two loop primers was developed for rapidly detecting Enterobacter sakazakii in powdered infant formula., Methods: Sequences of 16S-23S rRNA of Enterobacter sakazakii (ATCC29544) were used as target sequences, to design outer primers, inner primers and loop primers. We judged the results of detection, through visible to the naked eye of the white precipitate., Results: The sensitivity of the LAMP assay was 0.101 CFU/mL; the detection limit of artificial contamination was 1.1 CFU/g. The detection could be finished about an hour from dealing with the sample to report the results with DNA kit. Compared with LAMP, the sensitivity of the PCR assay was 101 CFU/mL and the detection limit of artificial contamination was 1100 CFU/g in three hours. To apply the same method of extracting DNA, from dealing with the sample to report the results, it took about three hours., Conclusion: Therefore, this LAMP-based assay is sensitive and fast. These results indicate that LAMP can provide a rapid yet simple test for the detection of Enterobacter sakazakii in powdered infant formula.