Multifunctional oil-produced reduced graphene oxide - Silver oxide composites with photocatalytic, antioxidant, and antibacterial activities.

Graphene-based nanomaterials that combine significant photocatalytic, antioxidant and antibacterial activity are very attractive candidates for biomedical and environmental applications. Conventional chemical synthesis routes may contaminate the resultant materials with toxic molecules, compromising their properties and limiting their use in biomedical applications. Ideally, to avoid any contamination, the nanomaterials should be synthesized from non-toxic precursors and reagents, e.g. foodstuff via a simple technology that does not rely on the use of hazardous chemicals yet produces materials of high quality. Here, we report an environmentally friendly, low cost reduced graphene oxide-silver-silver oxide nanocomposite with strong photocatalytic, antioxidant and antibacterial activity for environmental remediation. The reduced graphene oxide (FRGO) is synthesized from edible sunflower oil via a simple flame synthesis method. Next, silver nanoparticles (Ag/AgO/Ag2O) are produced by phytochemical reduction of AgNO3 using a reducing agent based on flavonoids from Coleus aromaticus (Mexican mint), also used in food industry. Thus-obtained FRGO-Ag/AgO/Ag2O composite is characterized using X-ray diffraction spectroscopy, scanning electron microscopy, fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The degradation of anionic textile dye Methylene blue (MB) is used as a measure of photocatalytic activity of FRGO and FRGO/Ag/AgO/Ag2O, with solution pH, initial dye concentration, and quantity of the catalyst considered as influencing factors. FRGO-Ag/AgO/Ag2O composites show strong antioxidant activity, with improved radical inhibition as well as dye degradation properties when compared to pristine FRGO.

Evaluation of antioxidant and wound healing potentials of Sphaeranthus amaranthoides Burm.f.

BACKGROUND: Sphaeranthus amaranthoides commonly known as sivakaranthai is used in folklore medicine for the treatment of skin diseases. METHODS: The antioxidant activity of the extract and its fraction was evaluated by using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity, total antioxidant capacity, and total phenolic content. The tested plant extracts showed variable degrees of antioxidant activity. In the present study, methanolic extract of the whole plant of S. amaranthoides and a flavonoid fraction obtained from column chromatography were studied for wound healing activity by incorporating the sample in simple ointment base. Wound healing activity was studied in excision wound model in rats, following which, wound contraction, period of epithelization, hydroxyproline content, and collagen levels in the scab were studied. RESULTS: Methanolic extract showed the highest antioxidant effect (72.05%) and diethyl ether extract has the least (29.34%) compared to the standard (74.53%). Treatment of wound with ointment containing 5% (w/w) methanolic extract and 5% (w/w) flavonoid fraction exhibited better wound healing activity than positive control (silver sulfadiazine). Finally, histopathology studies conformed wound healing activity in Sphaeranthus amaranthoides. The methanolic extract and flavonoid fraction exhibited good wound healing activity probably due to the presence of phenolic and flavonoid constituents. The methanolic extract and flavonoid fraction significantly enhanced the rate of wound contraction and the period of epithelialization comparable to silver sulfadiazine.

Gold and silver nanoparticles from Trianthema decandra: synthesis, characterization, and antimicrobial properties.

BACKGROUND: There is an increasing commercial demand for nanoparticles due to their wide applicability in various markets, including medicine, catalysis, electronics, chemistry, and energy. In this report, a simple and ecofriendly chemical reaction for the synthesis of gold and silver nanoparticles from Trianthema decandra (Aizoaceae) has been developed. METHODS AND RESULTS: On treatment of aqueous solutions containing chloroauric acid or silver nitrate with root extract of T. decandra, stable gold or silver nanoparticles were rapidly formed. The kinetics of reduction of gold and silver ions during the reaction was analyzed by ultraviolet-visible spectroscopy. Field emission-scanning electron microscopy showed formation of gold nanoparticles in various shapes, including spherical, cubical, triangular, and hexagonal, while silver nanoparticles were spherical. The size of the gold nanoparticles was 33-65 nm and that of the silver nanoparticles was 36-74 nm. Energy dispersive x-ray and Fourier transform infrared spectroscopy confirmed the presence of metallic gold and metallic silver in the respective nanoparticles. The antimicrobial properties of the synthesized nanoparticles were analyzed using the Kirby-Bauer method. The results show varied susceptibility of microorganisms to the gold and silver nanoparticles. CONCLUSION: It is believed that phytochemicals present in T. decandra extract reduce the silver and gold ions into metallic nanoparticles. This strategy reduces the cost of production and the environmental impact. The silver and gold nanoparticles formed showed strong activity against all microorganisms tested.