Magnetic mesoporous silica nanocarriers integrated aptamer-based colorimetric biosensor enables sensitive detection of P. aeruginosa

P. aeruginosa , a highly adaptable and drug-resistant Gram-negative bacterium, poses a serious threat to public healthcare. We developed a magnetic mesoporous silica nanocarriers integrated aptamer-based colorimetric biosensor (MMNCS) for P. aeruginosa rapid and sensitive detection. In the biosensor, magnetic mesoporous silica nanoparticles served as carriers for the horseradish peroxidase (HRP), with aptamers acting as specific capture probes to target bacteria. In the presence of P. aeruginosa , the biosensor anchored onto the bacterial surface, leading to pore closure and suppression of TMB oxidation by HRP. The established colorimetric biosensor achieved remarkable performance in a broad range (10 to 10 5  CFU/mL), high sensitivity (limit of detection, 0.8 CFU/mL) and rapid assay time (15 min). Furthermore, the MMNCS platform was evaluated in tap water, artificial urine, artificial saliva and human serum samples, exhibiting good recoveries of 95.47% to 105.65% and a relative standard deviation between 0.93% and 4.17%. The approach provides a low-cost, sensitive and rapid platform for early screening detection of pathogenic bacteria.