Fabrication of Antibacterial Graphene Oxide/Copper Nanocomposites

Summary

Herein, we introduce graphene oxide/copper (GO/Cu) nanocomposites as an antibacterial nanomaterial. The antibacterial effectiveness of the GO/Cu nanocomposites was evaluated against both antibiotic-resistant gram-positive and gram-negative bacteria.

Abstract

Antibiotics are currently the most used antibacterial treatment for killing bacteria. However, bacteria develop resistance when continually overexposed to antibiotics. Developing antimicrobial agents that can replace existing antibiotics is essential because antibiotic-resistant bacteria have resistance mechanisms for all current antibiotics and can promote nosocomial infections. To address this challenge, in this study, we propose graphene oxide/copper (GO/Cu) nanocomposites as antibacterial materials that can replace the existing antibiotics. GO/Cu nanocomposites are characterized by transmission electron microscopy and scanning electron microscopy. They show that copper (Cu) nanoparticles are well-grown on the graphene oxide sheets. Additionally, a microdilution broth method is used to confirm the efficacy of the antimicrobial substance against methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (P. aeruginosa), which are frequently implicated in nosocomial infections. Specifically, 99.8% of MRSA and 84.7% of P. aeruginosa are eliminated by 500 µg/mL of GO/Cu nanocomposites. Metal nanocomposites can eradicate antibiotic-resistant bacteria by releasing ions, forming reactive oxygen species, and physically damaging the bacteria. This study demonstrates the potential of antibacterial GO/Cu nanocomposites in eradicating antibiotic-resistant bacteria.

Introduction

Bacterial infections have a significant impact on public health. Pathogenic bacteria, in particular, can evade the body's protective mechanisms and cause diseases¹. Antibiotics are widely used to treat bacterial infections. However, the inappropriate use of antibiotics has precipitated the emergence of antibiotic-resistant bacteria. Currently, nosocomial infections attributable to antibiotic-resistant bacteria have caused notable complications in healthcare facilities². Unfortunately, bacteria have resistance mechanisms for all current antibiotics³. Therefore, developing ....

Protocol

1. Preparation of the GO/Cu nanocomposites

NOTE: The size and morphology of Cu nanoparticles that grow on the GO nanosheets are determined by the degree of GO oxidation, the concentration of the Cu precursor, and the concentration of the reducing agent²⁶.

1. Prepare 10 mL of 1 mg/mL GO suspension in a glass bottle. Sonicate the GO suspension for 1 h until GO is well dispersed in distilled (DI) water.
2. Prepare a 20 mM CuCl₂ s.......

Discussion

Herein, we report a low-cost and simple method for preparing GO nanosheets deposited with Cu nanoparticles, which would be a potentially efficient method for eradicating antibiotic-resistant bacteria. The critical step in synthesizing GO/Cu nanocomposites is thoroughly dispersing GO and CuCl₂ in the solution and maintaining an elevated temperature while mixing them. Further, the redox step must be conducted quickly because the reducing agent causes a reduction reaction as soon as it comes in contact with water.......

Materials

Name	Company	Catalog Number	Comments
Antibiotic-Antimycotic	Gibco	15240062
Clinical MDR bacterial strains	Chung-Ang University Hospital (Seoul, South Korea)
Copper(II) chloride dihydrate	Duksan	10125-13-0
Field Emission Scanning Electron Microscope (FE-SEM)	Carl Zeiss	SIGMA
Graphene oxide	Sigma	796034
Sodium Borohydride	Sigma	71320
Transmission Electron Microscopy (TEM)	JEOL	JEM-2100
Tryptic Soy Agar	BD difco	236950
Tryptic Soy Broth	BD difco	211825