Synthesis of new zinc oxide and gold nanoparticles conjugated to curcumin for environmental and biomedical applications -

Abstract

Curcumin-conjugated ZnO nanostructures (Zn(cur)O) were synthesized through a simple precipitation method where the curcumin employed during the synthesis process got conjugated to ZnO through strong interactions. The compound was characterized with SEM, FTIR, XRD, ZP, UV–Vis absorption spectroscopy, and photoluminescence spectroscopy. The absorption spectra confirmed sensitization of ZnO to the visible light. Photoluminescence properties of Zn(cur)O and ZnO were compared and found that exciton emission was enhanced in Zn(cur)O and the visible emission suppressed. The environmental potential application of the compound was explored by removing toxic pollutants as arsenic and three PAHs from water samples. High concentrations of perylene, fluoranthene, and chrysene were removed faster using the modified ZnO than bare ZnO depending on the extent of curcumin incorporated during synthesis. The degradation was found to be faster for PAHs having less number of aromatic rings; with 167 mg-L Zn(cur)O loading, 93percent removal of 11.4 μg-L fluoranthene after 25 minutes was achieved, 88percent for 12.6 μg-L perylene after 3.4h, and 93percent for 11.1 μg-L chrysene after 2.2h . Adsorption and fluorescence sensing potential was also tested on arsenite. With relatively low material loading (43 ppb), the Zn(cur)O nanostructures removed As(III) below the minimum contamination level (MCL) from 100 ppb samples within 30 minutes. The compound reached up to 75percent removal-adsorption capacity with 903 ppb concentrations after 3 hours with the same loading. Bare ZnO didn’t bring down the arsenic contamination below its MCL even after 3 hours. Kinetics of adsorption fitted very well to pseudo second order model with exceptional adsorption rates that reflected the high affinity of the compound to As(III). These results presented the compound as an attractive alternative for a simple single-step treatment option to treat arsenic-contaminated natural water with high adsorption rates without the pre-treatment requirement for cu