Size-Dependent Antibacterial Activity of Silver Nanoparticle-Loaded Graphene Oxide Nanosheets.

Thi Truong,Dave Chen,Yu-Kuo Liu,Shingjiang Lue,Yu-Tzu Huang,Selvaraj Kumar

doi:10.3390/nano10061207

Abstract

A series of graphene oxide (GO) suspensions with different particle sizes (<100 nm, ~100 nm, ~1 µm and >1 µm) were successfully fabricated after 0, 30, 60 and 120 min of sonication, respectively. The antibacterial properties of GO suspensions showed that >1 µm GO size resulted in a loss of nearly 50% of bacterial viability, which was higher than treatment by ~100 nm GO size (25%) towards Escherichia coli (E. coli). Complete entrapment of bacteria by the larger GO was observed in transmission electron microscopy (TEM). Silver nanoparticles (Ag NPs) were doped onto GO samples with different lateral sizes to form GO–Ag NP composites. Resulting larger GO–Ag NPs showed higher antibacterial activity than smaller GO–Ag NPs. As observed by Fourier transform infrared spectroscopy (FTIR), the interaction between E. coli and GO occurred mainly at the outer membrane, where membrane amino acids interact with hydroxyl and epoxy groups. The reactive oxygen species (ROS) and the considerable penetration of released Ag+ into the inner bacterial cell membrane result in loss of membrane integrity and damaged morphology. The present work improves the combined action of GO size effect with constant Ag loadings for potential antibacterial activity.

Highlights

To date, the rapid development of bacterial infections has threatened health and life
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Summary

Introduction

The rapid development of bacterial infections has threatened health and life. Antibiotic resistance is making some infections extremely difficult to treat [1]. This issue has resulted in an urgent demand for advanced nanomaterials [2,3]. Graphene oxide (GO) is composed of single-atom-thick sheets of sp2-bonded carbon with oxygen-containing functional groups. It is a typical two-dimensional material made of carbon atoms in a honeycomb crystal lattice [6] and can be modified into various derivatives and composites [7]. Thereby, the functional groups of GO, including carboxyl groups (–COOH), epoxy groups (–C–O–C) which possibly bonded to, and consumed, bacteria [13]

Methods

Results

Conclusion