Non-Destructive Harvesting of Biogenic Gold Nanoparticles from Jatropha curcas Seed Meal and Shell Extracts and their Application as Bio-Diagnostic Photothermal Ablaters-Lending Shine to the Biodiesel Byproducts
A potential non-destructive harvesting of gold nanoparticles (Au NPs) employing the seed shell and detoxified-defatted seed meal aqueous extracts of Jatropha curcas is reported. The reduction potential of the shell and meal extracts were tested at varied ratios with chloroauric acid under physical parameters of increasing pressure and temperature. The optimal ratio of chloroauric acid to seed meal/shell extracts was determined to be 1:1 under constant shaking in water bath at 60ºC yielding nearly isotropic nanoparticles, which was confirmed by UV-Vis spectroscopy, HRTEM and AFM analysis. With increasing concentrations (1:2, 1:3, 1:4) of reducing agents, temperature (121ºC) and pressure (12 lbs), anisotropy with respect to particle shape and size increased in order. FT-IR, TGA and HRTEM provided evidence of bio-capping of the nanoparticles with biomolecules present in the parent reducing sources. The biocompatibility of these nanoparticles was tested on neuronal HCN-1A and brain cancer glioma Gl-1 cell lines, which revealed their superior cyto-amiability when compared with conventionally synthesized Au NPs. The biodiagnostic and photothermal ablation potential of the Au NPs were also tested and affirmed with the luminescent signals recorded from the cellular cytoplasm indicating the efficient internalization of these nanoparticles as well as the apoptotic events encountered upon irradiating the cells with laser. Nearly 100% of the cells underwent sudden apoptosis within 1 min of laser treatment, providing enough evidence for the thermal ablation potential of the Au NPs. To support the claim of non-destructive harvesting of nanoparticles, the protein and ash content of the seed meal and seed shell, respectively, were analyzed before and after the aqueous extraction. Minimal loss in these inherent characteristic potentials of the seed meal and shell emphasizes the sustainable utilization of bio-resources achieved in this report.
Financed by the National Centre for Research and Development under grant No. SP/I/1/77065/10 by the strategic scientific research and experimental development program:
SYNAT - “Interdisciplinary System for Interactive Scientific and Scientific-Technical Information”.