Commercial flakes of graphite were prepared into functionalized graphene oxide (GO) by chemical treatment. After the exfoliation and intercalation of graphene into functionalized graphene oxide that formed stable colloidal dispersion in polar aprotic solvent, the reduction process was undertaken by continuous stirring with hydrazine hydrate. The reduced material was characterized by X-ray diffraction (XRD), attenuated total reflectance (ATR) FT-IR, ultraviolet visible (UV-vis), atomic force microscopy (AFM) and Raman spectroscopy which confirm the oxidation of graphite and reduction of graphene oxide into graphene sheet.

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HDA-capped ZnO nanoparticles were prepared by solvothermal method using solvents of different polarities. A number of parameters were kept constant such as temperature, pressure, time, and pH while solvents were varied, that is, water, ethanol, and acetone. The TEM was used for the structural properties and morphologies such as spheres, mixture of rods, and spheres and stars were obtained in ethanol, acetone, and water, respectively, in a given reaction time of 15 minutes. Both ethanol and acetone gave rods with high aspect ratio primarily because of the lengths of the rods. Water and ethanol have the hydroxyl groups which interact with nanoparticles from nucleation, growth, and termination giving rise to nonspherical shapes. The hydroxyl group promotes growth in a nonuniform way resulting in stars and rods. The optical features were typical of ZnO nanoparticles with excitonic peaks in the range 368 to 374 nm from their absorption spectra. The XRD patterns of the particles gave the most stable form of ZnO which is the hexagonal phase, with high degree of crystallinity and with the 101 plane predominant in all solvents.

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Chitosan is a polymeric compound with functional groups which enable surface binding to nanoparticles and antibacterial activity. The antimicrobial activity was studied using silver nanoparticles with varied concentrations of chitosan. The nanoparticles were synthesized through a simple and environmentally friendly method at room temperature. Spherical particles with average sizes between 2 and 6 nm were obtained and their crystallinity showed a face-centered cubic phase. The evidence of chitosan presence on the nanoparticle surface was confirmed by the characteristic diffraction peak of chitosan and by FTIR spectra where the bonding of amine group could be depicted. The chitosan-capped silver nanoparticles showed good antibacterial and antifungal activities with MIC values between 0.20 and 1.5 mg.mL-1 compared to those obtained from most of references (up to 6.25 mg.mL-1) on the selected gram-positive (Staphylococcus aureus, Enterococcus faecalis), gram-negative (Klebsiella pneumoniae, Pseudomonas aeruginosa ) bacteria and fungi (Candida albicans, Cryptococcus neoformans).