Hierarchical Ag Nanostructures Fabricated from Silver Coordination Polymers for Antibacterial Surface.

Jin-Song Jung,Su-Bin Lee,Su-Joung Ko,Hong-Beom Lee,Jae-Min Oh,Hyoung-Jun Kim

doi:10.3390/polym11010155

Abstract

A hierarchical silver nanostructure with improved antibacterial property was fabricated utilizing silver coordination polymer. Octadecanethiolate–silver polymer was synthesized to have a layered structure and was coated on silicon wafer by drop-casting method utilizing hydrophobic–hydrophobic interaction. Thus, the silver coordination polymer was calcined under reductive condition to produce zero-valent silver with a hierarchical nanostructure. X-ray diffraction patterns revealed that layered silver coordination polymer successfully transformed to hexagonal silver upon calcination. According to scanning electron and atomic force microscopy, silver coordination polymer with ~145.5 nm size was homogeneously coated on the surface before calcination, and it evolved micrometer-sized lumps and grooves which were composed of ~58.8 nm sized Ag nanoparticles. The hierarchical structure—micrometer lump/groove consisting of Ag nanoparticles—would be advantageous to kill bacteria; micrometer-grooves provide physical condition (pocket for bacteria capture) and the Ag nanoparticles from the neighboring lump endow chemical condition (antibacterial property of released Ag+). The antibacterial activity test on Escherichia coli via colony forming inhibitory assay indeed exhibited an improved antibacterial activity of hierarchical Ag nanostructure compared with the surface simply coated with Ag nanoparticles. From the line profile of atomic force microscopy, the bacterium trapped in the hierarchical Ag nanostructure was shown to interact intimately with Ag surface.

Highlights

Silver nanoparticle (AgNP) is one of the widely utilized nanomaterials having antibacterial, catalytic, optical properties, and so on [1,2,3]
It was clearly shown that the surface morphology of Ag-hc@silicon wafer (Si) and AgNP@Si were different from each other as shown in Figure 4, we further examined surface topology with atomic force microscopy (AFM) in three-dimensional image mode
As a matter the silver nanoparticle with hierarchical structure (Ag-hc@Si) showed much improved antibacterial activity of 99.9% than the surface coated with equivalent amount of silver (AgNP@Si) having antibacterial activity ~37.5%

Summary

Introduction

Silver nanoparticle (AgNP) is one of the widely utilized nanomaterials having antibacterial, catalytic, optical properties, and so on [1,2,3]. Antibacterial property of AgNPs has long been applied to commercial products such as fabrics, cosmetic materials, toothpastes, filters, kitchen utensils, shampoos, and humidifiers [4,5,6,7]. Antibacterial mechanism of AgNPs is known to derive from dissolved silver ion; monovalent silver ion is dissolved from the surface of AgNPs having large specific surface area, and the ion can kill microbes in various ways. Some researchers support the idea that the released silver cations interact with the thiol groups in bacteria proteins, affecting the replication of DNA [8]. AgNPs surely contain antibacterial property in the material point of view

Methods

Results

Conclusion