title: Green synthesis and stabilization of gold nanoparticles in chemically modified chitosan matrices.
abstract: Chitosan-N-2-methylhydroxypyridine-6-methylcorboxylate (Ch-PDC) and chitosan-N-2-methylhydroxypyridine-6-methylhydroxy thiocarbohydrazide (Ch-PDC-Th) were synthesized for the first time using chitosan as precursor. Chitosan, Ch-PDC, Ch-PDC-Th were used in the synthesis of gold nanoparticles (AuNP) in aqueous medium. Chitosan and Ch-PDC-Th possess reducing properties which enabled the 'green' synthesis of AuNPs. The stabilization of the AuNPs was as a result of the thiocarbide (SC) and amine (NH(2)) groups in the chitosan matrix. The modified chitosan, its derivatives and the resulting AuNPs were characterized by Fourier transform infrared (FTIR) spectroscopy, Ultraviolet-visible (UV-vis) spectroscopy, Raman scattering measurements, powder X-ray diffraction (PXRD) and thermo gravimetric analysis (TGA). Particle size, morphology, segregation and individuality of the AuNPs were examined by transmission electron microscope (TEM) and energy dispersion spectroscopy (EDS). An average AuNPs size of 20 nm was observed for chitosan and Ch-PDC-Th while Ch-PDC was 50 nm. In comparison, AuNPs resulting from Ch-PDC-Th precursor has the most enhanced Raman and fluorescent intensities and was stable for over 2 months.
authors.affiliation: Department of Chemical Technology, University of Johannesburg, PO Box 17011, Doornfontein 2028, South Africa.
authors.forename: Anand D
authors.initials: AD
authors.lastname: Tiwari
authors.forename: Ajay K
authors.initials: AK
authors.lastname: Mishra
authors.forename: Shivani B
authors.initials: SB
authors.lastname: Mishra
authors.forename: Omotayo A
authors.initials: OA
authors.lastname: Arotiba
authors.forename: Bhekie B
authors.initials: BB
authors.lastname: Mamba
mesh_terms: D048271:Chitosan / Q000138:chemical synthesis* / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D006834:Hydrazines / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D013052:Spectrometry, X-Ray Emission; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D013818:Thermogravimetry; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D006834:Hydrazines; D014867:Water; C011368:thiocarbohydrazide; D006046:Gold; D048271:Chitosan