Encapsulation of Photothermal Nanoparticles in Stealth and pH-Responsive Micelles for Eradication of Infectious Biofilms In Vitro and In Vivo

Abstract

Photothermal nanoparticles can be used for non-antibiotic-based eradication of infectious biofilms, but this may cause collateral damage to tissue surrounding an infection site. In order to prevent collateral tissue damage, we encapsulated photothermal polydopamine-nanoparticles (PDA-NPs) in mixed shell polymeric micelles, composed of stealth polyethylene glycol (PEG) and pH-sensitive poly(β-amino ester) (PAE). To achieve encapsulation, PDA-NPs were made hydrophobic by electrostatic binding of indocyanine green (ICG). Coupling of ICG enhanced the photothermal conversion efficacy of PDA-NPs from 33% to 47%. Photothermal conversion was not affected by micellar encapsulation. No cytotoxicity or hemolytic effects of PEG-PAE encapsulated PDA-ICG-NPs were observed. PEG-PAE encapsulated PDA-ICG-NPs showed good penetration and accumulation in a Staphylococcus aureus biofilm. Penetration and accumulation were absent when nanoparticles were encapsulated in PEG-micelles without a pH-responsive moiety. PDA-ICG-NPs encapsulated in PEG-PAE-micelles found their way through the blood circulation to a sub-cutaneous infection site after tail-vein injection in mice, yielding faster eradication of infections upon near-infrared (NIR) irradiation than could be achieved after encapsulation in PEG-micelles. Moreover, staphylococcal counts in surrounding tissue were reduced facilitating faster wound healing. Thus, the combined effect of targeting and localized NIR irradiation prevented collateral tissue damage while eradicating an infectious biofilm.

Polydopamine-functionalized selenium nanoparticles as an efficient photoresponsive antibacterial platform

“…More importantly, Se@PDA-ICG showed better in vitro antibacterial effects than similar types of nanomaterial, such as PDA-ICG-NPs encapsulated in mixed-shell polymeric micelles. 19 The bacterial survival rate of S. aureus was approximately 40% after treatment with PDA-ICG-NPs under the laser for 10 min (808 nm 1.3 W cm −2 ). The antimicrobial porous collagen scaffolds containing chitosan and Se NPs were only effective in inhibiting S. aureus but not E. coli at all.…”

Polydopamine-functionalized Selenium Nanoparticles as a Photoresponsive Synergistic Antibacterial Platform

“…The antibacterial rate of the Se@PDA-ICG group was 52.7%, and that of Se@PDA-ICG + NIR was 100%, indicating an excellent sterilization effect on S. aureus of Se@PDA-ICG. More importantly, Se@PDA-ICG showed better in vitro antibacterial effects compared to similar type of nanomaterials, such as PDA-ICG-NPs encapsulated in mixed shell polymeric micelles [31]. The bacterial survival rate of S. aureus was approximately 40% after dealing with the PDA-ICG-NPs under the laser for 10 min (808 nm 1.3 W/cm 2 ).…”

Strategies and materials for the prevention and treatment of biofilms

“…The PDA-ICG-NPs were prepared by Gao et al using polyethylene glycol (PEG) and poly(beta-amino ester) (PAE), a pH-responsive mixed shell polymer, to encapsulate ICG-coated PDA. The presence of electrostatic interaction enables the transportation of PDA-ICG-NPs in the bloodstream, facilitating their targeted delivery, penetration, and accumulation on biofilms [ 94 ].…”