Gold nanoparticles assisted early antibacterial activity of ZnO nanorods on Ti substrate in the dark : enhanced extracellular electron transfer from bacteria to the materials

Research output: Conference Papers (RGC: 31A, 31B, 32, 33)32_Refereed conference paper (no ISBN/ISSN)peer-review

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Detail(s)

Original languageEnglish
Publication statusPublished - Dec 2019

Conference

Title15th International Conference on Plasma Based Ion Implantation & Deposition (PBII&D 2019)
LocationSheraton Shenzhen Nanshan
PlaceChina
CityShenzhen
Period19 - 22 December 2019

Abstract

Introduction: Nano ZnO is an appealing candidate in antibacterial applications. [1] However, among these studies, bactericidal mechanisms were concluded based on the experimental results after the long duration of materials-bacteria interactions (more than 6 hours, usually 12h or 24h). The detailed interactions in early contact are still unknown, which needs to be illustrated. Titanium and its alloys are promising options for bear-loading implants due to their appropriate mechanical properties along with outstanding biocompatibility. However, their poor activity against bacterial colonization gets in the way of biomedical applications. [2] Noble metal nanoparticles (e.g. gold nanoparticles) have been found to be promising in enhancing the performances of ZnO nanomaterials, especially in absorption of the light and acceptance of electrons. [3] Accordingly, Au assisted enhanced antibacterial behavior of ZnO nanorods might be foreseeable. 
Materials and Methods: Aligned ZnO nanorods are synthesized on the Ti substrate by the silane coupling agent-assisted seed layer formation and hydrothermal process. Subsequently, Au@ZnO composites are prepared through the magnetron sputtering of gold nanoparticles. The morphology and structure of the samples were observed by scanning electron microscopy (SEM). The compositions and chemical state of the sample surface were obtained by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Ion releasing was characterized through inductively coupled plasma mass spectroscopy (ICP-MS). The antibacterial properties of the samples were characterized by using SEM, colony counting, and live-dead staining. 
Results and Discussion: The results demonstrated that Gold nanoparticles modified ZnO nanorods inhibited more than 80% E. coli in a short time (1h). The antibacterial process takes place in the absence of the light, and no ROS are produced by the materials at the early stage. Meanwhile, the zinc ions released from the materials are still not enough to inhibit bacterial growth. Extracellular electron transport accounts for is observed from the bacteria to the materials’ surface leading to the final bacteria death. The electron of the respiratory chains on the E. coli membrane can be transported to the ZnO nanorods when the bacteria are in close contact with the surface of the materials. The modification of the Au nanoparticles can form metal-semiconductor contact, not only providing more capturers of electrons, but also enhance the transport of the electrons, which speeds up the death of the bacteria (Figure 1). 
Conclusions: Gold nanoparticles modified ZnO nanorods are prepared on the metallic Ti surface through hydrothermal synthesis and magnetron sputtering. The early antibacterial mechanisms of Au-loaded ZnO nanorods in the dark are investigated. Extracellular electron transport from the bacteria to the materials’ surface leads to the final bacteria death in the early stage.

Research Area(s)

  • Zinc oxide nanorods, Au nanoparticles, antibacterial activity, early-stage, extracellular electron transfer

Citation Format(s)

Gold nanoparticles assisted early antibacterial activity of ZnO nanorods on Ti substrate in the dark : enhanced extracellular electron transfer from bacteria to the materials. / Tang, Kaiwei; Wang, Guomin; Chu, Paul K. .

2019. Paper presented at 15th International Conference on Plasma Based Ion Implantation & Deposition (PBII&D 2019), Shenzhen, China.

Research output: Conference Papers (RGC: 31A, 31B, 32, 33)32_Refereed conference paper (no ISBN/ISSN)peer-review