Health and environmental impacts of graphene-based materials need to be thoroughly evaluated before their potential applications. Graphene has strong cytotoxicity toward bacteria. To better understand its antimicrobial mechanism, we compared the antibacterial activity of four types of graphene-based materials (graphite (Gt), graphite oxide (GtO), graphene oxide (GO), and reduced graphene oxide (rGO)) toward a bacterial model—Escherichia coli. Under similar concentration and incubation conditions, GO dispersion shows the highest antibacterial activity, sequentially followed by rGO, Gt, and GtO. Scanning electron microscope (SEM) and dynamic light scattering analyses show that GO aggregates have the smallest average size among the four types of materials. SEM images display that the direct contacts with graphene nanosheets disrupt cell membrane. No superoxide anion (O2•–) induced reactive oxygen species (ROS) production is detected. However, the four types of materials can oxidize glutathione, which serves ...

Antibacterial Activity of Graphite, Graphite Oxide, Graphene Oxide, and Reduced Graphene Oxide: Membrane and Oxidative Stress

Two-dimensional carbon-based nanomaterials, including graphene oxide and graphene, are potential candidates for biomedical applications such as sensors, cell labeling, bacterial inhibition, and drug delivery. Herein, we explore the biocompatibility of graphene-related materials with controlled physical and chemical properties. The size and extent of exfoliation of graphene oxide sheets was varied by sonication intensity and time. Graphene sheets were obtained from graphene oxide by a simple (hydrazine-free) hydrothermal route. The particle size, morphology, exfoliation extent, oxygen content, and surface charge of graphene oxide and graphene were characterized by wide-angle powder X-ray diffraction, atomic force microscopy, X-ray photoelectron spectroscopy, dynamic light scattering, and zeta-potential. One method of toxicity assessment was based on measurement of the efflux of hemoglobin from suspended red blood cells. At the smallest size, graphene oxide showed the greatest hemolytic activity, whereas ag...

Cytotoxicity of graphene oxide and graphene in human erythrocytes and skin fibroblasts.

The need for novel antibiotics comes from the relatively high incidence of bacterial infection and the growing resistance of bacteria to conventional antibiotics. Consequently, new methods for reducing bacteria activity (and associated infections) are badly needed. Nanotechnology, the use of materials with dimensions on the atomic or molecular scale, has become increasingly utilized for medical applications and is of great interest as an approach to killing or reducing the activity of numerous microorganisms. While some natural antibacterial materials, such as zinc and silver, possess greater antibacterial properties as particle size is reduced into the nanometer regime (due to the increased surface to volume ratio of a given mass of particles), the physical structure of a nanoparticle itself and the way in which it interacts with and penetrates into bacteria appears to also provide unique bactericidal mechanisms. A variety of techniques to evaluate bacteria viability, each with unique advantages and disadvantages, has been established and must be understood in order to determine the effectiveness of nanoparticles (diameter ≤ 100 nm) as antimicrobial agents. In addition to addressing those techniques, a review of select literature and a summary of bacteriostatic and bactericidal mechanisms are covered in this manuscript.

/pdf/antimicrobial-applications-of-nanotechnology-methods-and-3wk73xhftt.pdf

Antimicrobial applications of nanotechnology: methods and literature

We have developed a biocompatible antibacterial system based on polyethylene glycol functionalized molybdenum disulfide nanoflowers (PEG-MoS2 NFs). The PEG-MoS2 NFs have high near-infrared (NIR) absorption and peroxidase-like activity, which can efficiently catalyze decomposition of low concentration of H2O2 to generate hydroxyl radicals (·OH). The conversion of H2O2 into ·OH can avoid the toxicity of high concentration of H2O2 and the ·OH has higher antibacterial activity, making resistant bacteria more vulnerable and wounds more easily cured. The PEG-MoS2 NFs combine the catalysis with NIR photothermal effect, providing a rapid and effective killing outcome in vitro for Gram-negative ampicillin resistant Escherichia coli (Ampr E. coli) and Gram-positive endospore-forming Bacillus subtilis (B. subtilis) as compared to catalytic treatment or photothermal therapy (PTT) alone. Wound healing results indicate that the synergy antibacterial system could be conveniently used for wound disinfection in vivo. Inte...

Functionalized Nano-MoS2 with Peroxidase Catalytic and Near-Infrared Photothermal Activities for Safe and Synergetic Wound Antibacterial Applications

Related Systems: New Insights into Biosensing, Bioimaging, Genomics, Diagnostics, and Therapy Jun Yao,† Mei Yang,† and Yixiang Duan*,†,‡ †Research Center of Analytical Instrumentation, Analytical and Testing Center, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China ‡Research Center of Analytical Instrumentation, College of Life Sciences, Sichuan University, Chengdu, Sichuan 610064, China

Chemistry, Biology, and Medicine of Fluorescent Nanomaterials and Related Systems: New Insights into Biosensing, Bioimaging, Genomics, Diagnostics, and Therapy

To further our understanding on the antibacterial activity of single-walled carbon nanotubes (SWCNTs), high purity SWCNTs with average diameter of 0.83 nm and (7,5) chirality as dominate (n,m) structure were dispersed in a biocompatible surfactant solution. Ultraviolet-visible-near-infrared radiation absorption spectroscopy was employed to monitor the aggregation of SWCNTs. The results demonstrated that individually dispersed SWCNTs were more toxic than SWCNT aggregates toward bacteria (gram-negative Escherichia coli, Pseudomonas aeruginosa, and gram-positive Staphylococcus aureus, Bacillus subtilis). Individually dispersed SWCNTs can be visualized as numerous moving "nano darts" in the solution, constantly attacking the bacteria; thereby, degrading the bacterial cell integrity and causing the cell death. Controlled experimental results suggested that inhibiting cell growth and oxidative stress were not the major causes responsible for the death of cells. Furthermore, the detrimental effects of Co metal residues (up to 1 mug/mL) on SWCNT samples can be ruled out. Atomic force microscope study conducted in suspension proved that the death rates of bacteria were strongly correlated with their mechanical properties; soft cells were more vulnerable to SWCNT piercing. The antibacterial activity of SWCNTs can be remarkably improved by enhancing the SWCNT physical puncture on bacteria in the following ways: (1) dispersing SWCNTs individually to sharpen the nano darts; (2) increasing SWCNT concentration to raise the population density of nano darts; and (3) elevating the shaking speed of incubation to speed up the nano darts. This study elucidated several factors controlling the antibacterial activity of pristine SWCNTs and it provided an insight in developing strategies that can maximize the SWCNT application potentials while minimizing the health and environment risks.

Sharper and faster "nano darts" kill more bacteria: a study of antibacterial activity of individually dispersed pristine single-walled carbon nanotube.

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Sharper and faster "nano darts" kill more bacteria: a study of antibacterial activity of individually dispersed pristine single-walled carbon nanotube.