It is imperative to develop practicable pathogenic bacteria detection methods. We devised a biosensor for the ultrasensitive detection of Salmonella typhimurium (S. typhi), termed as SCOUT‐dCas9 (ultrasensitive, cross‐validating, on‐site, and dUal‐mode test using CRISPR/dCas9). Simply, the species‐specific invA gene of S. typhi was amplified using loop‐mediated isothermal amplification with a biotinylated primer, which can be specifically “pulled down” by “antibody‐like” dCas9‐single guide RNA to form a ternary complex. SYBR Green I and streptavidin‐modified alkaline phosphatase were used to functionalize them to generate fluorescent and colorimetric signals, respectively. With this strategy, the target could be dexterously converted into bimodal signals that were cross‐validated to afford more reliable results. For both modes, SCOUT‐dCas9 was able to detect as low as 1 CFU/mL with a dynamic range from 1 to 109 CFU/mL. Lastly, SCOUT‐dCas9 had satisfactory selectivity and was capable of detecting S. typhi‐contaminated real food samples. SCOUT‐dCas9 provides a robust platform for bacterial detection.
The pandemic caused by SARS-CoV-2 has a huge impact on the global economy. SARS-CoV-2 could possibly and potentially be transmitted to humans through cold-chain foods and packaging (namely good-to-human), although it mainly depends on a human-to-human route. It is imperative to develop countermeasures to cope with the spread of viruses and fulfil effective surveillance of cold-chain foods and packaging. This review outlined SARS-CoV-2-related cold-chain food incidents and current methods for detecting SARS-CoV-2. Then the needs, challenges and practicable countermeasures for SARS-CoV-2 detection, specifically for cold-chain foods and packaging, were underlined. In fact, currently established detection methods for SARS-CoV-2 are mostly used for humans; thus, these may not be ideally applied to cold-chain foods directly. Therefore, it creates a need to develop novel methods and low-cost, automatic, mini-sized devices specifically for cold-chain foods and packaging. The review intended to draw people’s attention to the possible spread of SARS-CoV-2 with cold-chain foods and proposed perspectives for futuristic cold-chain foods monitoring during the pandemic.
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