Recyclable magnetite-silver heterodimer nanocomposites with durable antibacterial performance.

Yong, Chunyan; Chen, Xiaoqin; Xiang, Qian; Li, Qiang; Xing, Xiaodong · Bioact Mater · 2018

basic_science · Level V

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Abstract

There is a significant need for magnetite-silver nanocomposites that exhibit durable and recyclable antimicrobial activity. In this study, magnetic iron oxide nanoparticles (Fe<sub>3</sub>O<sub>4</sub> NPs) coated with ethylenediamine-modified chitosan/polyacrylic acid copolymeric layer (Fe<sub>3</sub>O<sub>4</sub>@ECS/PAA) were fabricated. Subsequently, directly deposited silver (Ag) NPs procedure was carried out to form the antibacterial heterodimers of Fe<sub>3</sub>O<sub>4</sub>@ECS/PAA-Ag NPs. The composition and morphology of the resultant nanostructures were confirmed by FT-IR, XRD, TEM and TGA. The overall length of the heterodimers was approximately 45 nm, in which the mean diameter of Fe<sub>3</sub>O<sub>4</sub>@ECS/PAA NPs reached up to 35 nm, and that of Ag NPs was around 15 nm. The mass fraction of silver NPs in the nanocomposites was about 63.1%. The obtained Fe<sub>3</sub>O<sub>4</sub>@ECS/PAA NPs exhibited good colloidal stability, and excellent response to additional magnetic field, making the NPs easy to recover after antibacterial tests. In particular, the Fe<sub>3</sub>O<sub>4</sub>@ECS/PAA-Ag NPs retained nearly 100% biocidal efficiency (10<sup>6</sup>-10<sup>7</sup> CFU/mg nanoparticles) for both Gram-negative bacteria <i>E. coli</i> and Gram-positive bacteria <i>S. aureus</i> throughout ten cycles without washing with any solvents or water, exhibiting potent and durable antibacterial activity.