Citrate analysis using capillary electrophoresis and complexation with Eu3+-tetracycline

A competitive aptamer binding-based CRISPR-cas biosensor for sensitive detection of tetracycline residues in biological samples

Tetracycline (TC) is widely used in veterinary medicine and animal feed; however, TC residues in food pose a risk to human health. Thus, the sensitive and selective detection of TC is needed to ensure food safety. Herein, we developed a CRISPR-Cas12a biosensor with competitive aptamer binding to detect TC residues. The aptasensor, formed by hybridizing activator DNA with TC-specific aptamers on streptavidin-modified magnetic beads, releases activator DNA in a TC concentration-dependent manner. This activated the Cas12a-crRNA complex, which cleaved single-strand DNA reporters to generate a detectable fluorescence signal. The TC signal was amplified through a two-step incubation reaction, with a detection limit as low as 9.45 × 10-5 μg L-1. The assay showed high selectivity and good recovery rates in various biological samples (e.g., honey, milk, fish), demonstrating the applicability of the biosensors in pollutant detection.

Synthesis of N-doped and P-doped silicon quantum dots and their applications for tetracycline detection in the honey samples and antibacterial properties

The abuse of tetracycline can lead to its residue in animal derived foods, posing many potential hazards to human health. Therefore, rapid and accurate detection of tetracycline is an important means to ensure food safety. Nitrogen doped and phosphorus doped silicon quantum dots (N-SiQDs, P-SiQDs) with remarkable optical stability were fabricated via a one-pot hydrothermal procedure in this study. Upon the excitation at 346 nm, N-SiQDs and P-SiQDs emitted fluorescence at 431 nm and 505 nm, respectively. Two SiQDs had the potential to serve as a probe for detecting low concentrations of tetracycline (TC), employing a mechanism of the static quenching effect. The calibration curves of N-SiQDs and P-SiQDs were linear within the range of 0-0.8 μM and 0-0.4 μM, the limits of detection were low as 5.35 × 10-4 μmol/L and 6.90 × 10-3 μmol/L, respectively. This method could be used successfully to detect TC in honey samples. Moreover, the remarkable antibacterial efficacy of two SiQDs could be attributed to the generation of a large number of intracellular reactive oxygen species. The SEM images showed that the structure of bacterial cell was disrupted and the surface became irregular when treated with both SiQDs. These properties enabled potential usage of SiQDs as excellent antibacterial material for different biomedical applications.