Magnetic Relaxation Switching Immunosensors via a Click Chemistry-Mediated Controllable Aggregation Strategy for Direct Detection of Chlorpyrifos.

Chlorpyrifos (CPF) is the most frequently found organophosphate pesticide residue in solid food samples and can cause increasing public concerns about potential risks to human health. Traditional detection signals of such small molecules are mostly generated by target-mediated indirect conversion, which tends to be detrimental to sensitivity and accuracy. Herein, a novel magnetic relaxation switching detection platform was developed for target-mediated direct and sensitive detection of CPF with a controllable aggregation strategy based on a bioorthogonal ligation reaction between tetrazine (Tz) and trans-cyclooctene (TCO) ligands.

Contamination-free V-shaped ultrafast reaction cascade transferase signal amplification driven CRISPR/Cas12a magnetic relaxation switching biosensor for bacteria detection.

Foodborne pathogenic bacteria seriously endanger human health and must be rapidly identified for control. Magnetic relaxation switching biosensors (MRS) are ideal for rapid bacteria detection due to their high signal-to-noise ratio and immunity to sample matrix signal interference. However, conventional MRS still has some challenges in terms of sensitivity, specificity, and stability due to insufficient cross-linking or non-specific binding of magnetic nanoparticles (MNPs) to the target.