ABSTRACT
A sago starch biopolymer with embedded silver nanoparticles has been studied as a material for the prevention of microbial growth. Approximately 8 nm in size, silver nanoparticles have been synthesized by reduction of the silver salt in aqueous solution in the presence of sago starch using sodium borohydride as a reducing agent. The obtained solutions were cast on glass plates to obtain thin supported silver-starch nanocomposite films. The morphology of the nanocomposites was investigated by scanning and transmission electron microscopy. UV-Vis absorption spectroscopy showed that during the film formation a part of the silver nanoparticles has been trapped in the water present in the sample, which enabled their partial oxidation into active Ag(+) species. The oxidation of the silver nanoparticles was confirmed by X-ray photoelectron spectroscopy. The antimicrobial activity tests have shown that the nanocomposite material can be successfully employed to prevent the viability and growth of the common pathogens Staphylococcus aureus, Escherichia coli and Candida albicans.
Subject(s)
Anti-Bacterial Agents/pharmacology , Escherichia coli/drug effects , Nanocomposites , Silver/pharmacology , Staphylococcus aureus/drug effects , Starch/pharmacology , Anti-Bacterial Agents/chemistry , Borohydrides/chemistry , Candida albicans/drug effects , Candida albicans/physiology , Escherichia coli/physiology , Metal Nanoparticles/chemistry , Microscopy, Electron, Scanning , Microscopy, Electron, Transmission , Nanocomposites/chemistry , Photoelectron Spectroscopy , Silver/chemistry , Spectrum Analysis , Staphylococcus aureus/physiology , Starch/chemistry , Temperature , Water/chemistryABSTRACT
Adsorption of sulfide ions onto a surface of starch capped silver nanoparticles upon addition of thioacetamide was investigated. UV-vis absorption spectroscopy revealed that the adsorption of the sulfide ion on the surface of the silver nanoparticles induced damping as well as blue shift of the silver surface plasmon resonance band. Further increase in thioacetamide concentration led to shift of the resonance band toward higher wavelengths indicating the formation of the continuous Ag2S layer on the silver surface. Thus fabricated nanoparticles were investigated using electron microscopy techniques (TEM, HRTEM, and HAADF-STEM) and X-ray photoelectron spectroscopy (XPS), which confirmed their core-shell structure.
Subject(s)
Biopolymers/chemistry , Nanoparticles/chemistry , Silver/chemistry , Starch/chemistry , Sulfur/chemistry , Adsorption , Microscopy, Electron, Transmission , Nanoparticles/ultrastructure , Spectrophotometry , Sulfides/chemistry , Surface Plasmon Resonance , Surface Properties , Thioacetamide/chemistry , X-Ray DiffractionABSTRACT
We report the preparation of CdS nanorods using a thiosemicarbazide complex of cadmium [Cd(NH2CSNHNH2)2Cl2]. The precursor was decomposed in tri-n-octylphosphine oxide (TOPO) at 280 degrees C to give TOPO capped CdS nanoparticles; nano-dimensional rods of the material are clearly visible in transmission electron microscopy (TEM); the particles have been further characterised by X-ray diffraction (XRD) and selected area electron diffraction (SAED) and optical measurements.
