A rapid, sensitive, and straightforward bacterial capture tool -boronic acid-functionalized Fe3O4 nanoparticle- for antimicrobial susceptibility testing.

Pathogenic multi-resistant bacterial infections represent a significant and persistent threat to public health. The development of a rapid, accurate, and convenient method for antimicrobial susceptibility testing (AST) is crucial for the timely diagnosis of pathogenic bacteria in clinical settings and is essential for the rational use of antibiotics. However, the low abundance of pathogenic multi-resistant bacteria in patient samples typically necessitates a waiting period of 24 h to 3 days to obtain positive samples for AST. To address this challenge, a novel, rapid, and straightforward bacterial capture tool- phenylboronic acid-functionalized Fe3O4 nanoparticles (B-Fe3O4NPs)-has been developed to enrich pathogenic bacteria without compromising their viability. Relying on the selective binding affinity to cis-diol groups on bacterial surfaces in alkaline aqueous solutions, B-Fe3O4NPs can effectively capture low concentrations of pathogenic bacteria from urine within 30 min, without affecting their activity. The magnetic properties of B-Fe3O4NPs facilitate the enrichment of captured bacteria into a small volume solution, thereby providing high-concentration positive samples for subsequent analysis. The enriched complex "bacteria-B-Fe3O4" effectively facilitated the performance of AST, with results obtained within 12 h- an interval generally deemed adequate for providing clinicians with guidance on medication. In comparison to the conventional clinical AST method, the B-Fe3O4NPs demonstrated a 93.75% accuracy and 74.23% reduction in processing time, indicating their potential for rapid and effective bacterial enrichment and seamless integration into an automated AST instrument. These findings support that B-Fe3O4NPs possess significant potential as a powerful tool for the early diagnosis of pathogenic multi-resistant bacteria in clinical settings.