In the present report, three different shapes of chitosan-capped gold nanoparticles (nanospheres, nanostars, and nanorods) were synthesized to investigate the effects of shape on cytotoxicity and cellular uptake in cancer cells. Green tea extract was utilized as a reducing agent to reduce gold salts to gold nanospheres. Gold nanostars were prepared using an as-prepared nanosphere solution as a seed solution. Gold nanorods were synthesized using a conventional method. All three types of gold nanoparticles showed their characteristic surface plasmon resonance bands upon UV-visible spectrophotometry. In high-resolution transmission electron microscopy images, lattice structures were clearly observed in all three shapes, confirming the crystalline nature of the nanoparticles. All three colloidal solutions of gold nanoparticles retained colloidal stability in various solutions. To assess cytotoxicity, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed on four cancer cell lines. The cytotoxicity was the highest in nanorods, followed by nanostars and finally nanospheres. The cellular uptake of gold nanoparticles in human hepatocyte carcinoma cells (HepG2) was measured, and the results followed the order nanospheres > nanorods > nanostars. The outcomes of the current study may assist in the shape design of gold nanoparticles for therapeutic applications as drug delivery vehicles in the field of nanomedicine.

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In the present report, green synthesis of titanium dioxide nanoparticles (TiO2 NPs) was performed by upcycling mangosteen (Garcinia mangostana) pericarp extract (methanol and ethyl acetate extracts). Field emission scanning electron microscopy images revealed an aggregated structure with a highly porous network of TiO2 NPs. TiO2 NPs synthesized with ethyl acetate extract (EtOAc-TiO2 NPs) exhibited more monodispersity and possessed smoother surfaces than the control TiO2 NPs (Con-TiO2 NPs) and TiO2 NPs synthesized with methanol extract (MeOH-TiO2 NPs). High-resolution X-ray diffraction patterns clearly confirmed that TiO2 NPs had a crystalline nature. A mixture of anatase and rutile was observed in Con-TiO2 NPs and MeOH-TiO2 NPs, while EtOAc-TiO2 NPs had only anatase with the smallest size (12.50 ± 1.81 nm). Ethyl acetate extract contained the highest amount of α-mangostin; thus, the surface of TiO2 NPs was functionalized with ethyl acetate extract. The functionalized TiO2 NPs synthesized with ethyl acetate extract (EtOAc-TiO2-αm) showed the highest 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl (DPPH) radical scavenging activity. In vitro cell viability on mouse fibroblast cells (NIH3T3) indicated that the newly synthesized TiO2 NPs did not show any significant cytotoxicity. Therefore, the TiO2 NPs in the present report have the potential to be used in cosmetic applications such as sunscreens.

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