Fig. 9. (A) Antibacterial ability of AMP modified Fe₃O₄NPs in solid medium (left): the blank is E. coli treated with pure Fe₃O₄NPs; antibacterial ability of AMP modified Fe₃O₄NPs in whole blood (right), in which the whole blood treated with AMP modified Fe₃O₄NPs or pure Fe₃O₄NPs was cultivated with bacteria first, and then whole blood was spiked in LB medium for further cultivation; the blank is whole blood treated with pure Fe₃O₄NPs and cultivated with bacteria; (B) illustration of AMP modified Fe₃O₄NPs as an antimicrobial agent for the inactivation of bacteria in the storage of blood, and its capture of bacteria for the SERS detection of bacteria before the use of blood; (C) cytotoxicity of AMP modified Fe₃O₄NPs on cells; doxorubicin (DOX) is the positive control group; experiments were performed in triplicate; values represent the relative viability compared to untreated cells as means ± SEM of one representative experiment (n = 3); the error bar represents the standard error of the mean (SEM); (D) SERS spectra of whole blood from patients infected with P. aeruginosa, S. aureus or E. coli. Blood without any bacteria is used as the control (E) pairwise Mahalanobis distances of E. coli, S. aureus and P. aeruginosa. The arrow means that only one patient infected with E. coli was misclassified.