Vancomycin-Modified Mesoporous Silica Nanoparticles for Selective Recognition and Killing of Pathogenic Gram-Positive Bacteria Over Macrophage-Like Cells

Rapid, reliable recognition and detection of bacteria from an authentic specimen have been gained increasing interests in the past decades. Various materials have been designed and prepared for implementation of bacterial recognition and treatment in the artificial systems. However, in the complicated physiological condition, the macrophages always compromise the outcomes of bacterial detection and/or treatment. In this work, we demonstrated the vancomycin-modified mesoporous silica nanoparticles (MSNs⊂Van) for efficiently targeting and killing gram-positive bacteria over macrophage-like cells. Owing to the specific hydrogen bonding interactions of vancomycin toward the terminal d-alanyl-d-alanine moieties of gram-positive bacteria, the MSNs⊂Van exhibited enhanced recognition for gram-positive bacteria due to the multivalent hydrogen binding effect. Furthermore, the fluorescent molecules (FITC) were covalently decorated inside of mesopores of MSNs for tracking and visualizing the MSNs⊂Van during the detection/treatment processes. Upon incubation of FITC decorated MSNs with bacteria (i.e., S. aureus and E. coli as gram-positive and gram-negative bacteria, respectively) or macrophage-like cells (Raw 264.7), the fluorescence signals in S. aureus were 2–4 times higher than that in E. coli and no detectable fluorescence signals were observed in Raw 264.7 cells under the same condition. Finally, the MSNs⊂Van showed unambiguous antibacterial efficacy without decrease in cell viability of macrophage-like cells. This new strategy opens a new door for specific detection and treatment of pathogenic bacteria with minimized side effects.