A rapid nucleic acid detection platform based on phosphorothioate-DNA and sulfur binding domain.

Nucleic acid detection plays a key role in diverse diagnosis and disease control. Currently available nucleic acid detection techniques are challenged by trade-offs among speed, simplicity, precision and cost. Here, we described a novel method, designated SENSOR (Sulfur DNA mediated nucleic acid sensing platform), for rapid nucleic acid detection. SENSOR was developed from phosphorothioate (PT)-DNA and sulfur binding domain (SBD) which specifically binds double-stranded PT-modified DNA. SENSOR utilizes PT-DNA oligo and SBD as targeting module, which is linked with split luciferase reporter to generate luminescence signal within 10 min. We tested detection on synthesized nucleic acid and COVID-19 pseudovirus, achieving attomolar sensitivity combined with an amplification procedure. Single nucleotide polymorphisms (SNP) could also be discriminated. Indicating SENSOR a new promising nucleic acid detection technique.

Fast visual monitoring of the freshness of beef using a smart fluorescent sensor.

Spoiled meat contains many pathogenic bacteria; hence, the intake of spoiled food can lead to various illnesses. To screen the freshness of food, in this study, we devised a ratiometric fluorescence sensor dicyanovinyl coumarin (CMDC) for the determination of cadaverine, an important biomarker for the spoilage of meat. CMDC underwent aza-Michael addition with cadaverine, exhibiting high sensitivity, fast response (50 s), and distinct fluorescence color transition. Test strips fabricated using CMDC showed a noticeable color change from red to green when exposed to cadaverine vapor. The test strips were successfully used to visually monitor the spoilage of beef based on the fluorescence color change. Furthermore, the as-developed test strip coupled with a smartphone provides a simple tool for consumers and suppliers to obtain information about meat quality.

A smartphone-adaptable fluorescent sensing tag for non-contact and visual monitoring of the freshness of fish.

Fish-based food products play important roles in our daily diet. The related food safety is vitally essential for human health, thus it is very necessary to screen the freshness of fish-based foods. In this work, we presented a ratiometric fluorescent probe PTCN for the determination of cadaverine, a metabolic biomarker of the spoilage of fish. PTCN displayed a ratiometric fluorescence response towards cadaverine with good specificity, high sensitivity (LOD = 46 nM) and ultra-fast response (<15 s), and thus has been successfully utilized to determine cadaverine from the spoilage of fish. PTCN was fabricated into cheap and portable sensing tags, which can visually detect gaseous cadaverine with obvious fluorescence color transformation from red to green and a low detection limit (8.65 ppm). Moreover, the PTCN tags were used as smart fluorescent tags for non-contact and visual monitoring of cadaverine in fish. Furthermore, the ratiometric fluorescence signals were utilized to create a smartphone-adaptable digital sensing profile for indicating cadaverine in fish products.