Binding of PNPs to platelet-adhering pathogens for antibiotic delivery. (A) SEM images of MRSA252 bacteria after incubation with PBS (top left), bare NPs (top right), RBCNPs (bottom left), and PNPs (bottom right). Scale bar, 1 mm. (B) Normalized fluorescence intensity of dye-loaded nanoformulations retained on MRSA252 based on flow cytometric analysis. Bars represent means ± s.d. (n = 3). (C) In vitro antimicrobial efficacy of free vancomycin, vancomycin-loaded RBCNPs (RBCNP-Vanc), and vancomycin-loaded PNPs (PNP-Vanc). Bars represent means ± s.d. (n = 3). (D-I) In vivo antimicrobial efficacy of free vancomycin at 10 mg kg-1 (Vanc-10), RBCNP-Vanc-10, PNP-Vanc-10, and free vancomycin at 6 times the dosing (Vanc-60, 60 mg kg-1) was examined in a mouse model of systemic infection with MRSA252. After 3 days of treatments, bacterial loads in different organs including blood (D), heart (E), lung (F), liver (G), spleen (H) and kidney (I) were quantified. Bars represent means ± s.e.m. (n=14). *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001, ****p ≤ 0.0001. Reproduced with permission.[33] Copyright 2015, Springer Nature.