Fe2+/Fe3+ Conversation-Mediated Magnetic Relaxation Switching for Detecting Staphylococcus Aureus in Blood and Abscess via Liposome Assisted Amplification

Rapid and accurate detection of pathogenic bacteria of Staphylococcus aureus ( S. aureus ) is of importance in the field of clinical research and practical application. Herein, we report a magnetic relaxation switching (MRS)-based strategy for detecting S. aureus in complex samples via the assistance of signal amplification system of liposome. In this design, vancomycin (Van) modified 200 nm magnetic beads (MB 200 -Van) and biotinylated immunoglobulin (Biotin-IgG) were employed as capture probes for S. aureus which following labelled by biotinylated liposomes loading with glucose molecule (Biotin-liposome@Glu, BLGs) based on the affinity of biotin with streptavidin. The released glucose molecules combining with glucose oxidase generated Fe 3+ , causing transverse relaxation time ( T 2 ) signal change. The combination of dual recognition of S. aureus , liposome assisted signal amplification, and the MRS-based assay achieved direct and specific detection of S. aureus in blood and abscess samples. The as-proposed method for S. aureus assay in this study shows potential application for infectious diagnosis in clinical.