Shape-dependent cytotoxicity and cellular uptake of gold nanoparticles synthesized using green tea extract

Abstract

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.

Phytosynthesized Metallic Nanoparticles—between Nanomedicine and Toxicology. A Brief Review of 2019′s Findings

“…Thus, a comparison of phytosynthesized Au NPs spheres (8.7 nm) and stars (99 nm) with chemically obtained nanorods (length/width = 60.4/16.4 nm) revealed a superior effect of nanostars (IC 50 = 81.8 µM, compared with the nanospheres-IC 50 = 127.1 µM), although both were inferior to the nanorods (IC 50 = 22.7 µM) against human hepatocyte carcinoma cells (HepG2). As corroborated with their findings regarding the cellular uptake of the NPs (best for nanospheres-58%-followed by nanorods and nanostars), the results support the conclusion that the final cytotoxic potential of the NPs represents the results of synergic influence of multiple factors [96].…”

“…As proven by their results, the size had little impact on the cytotoxicity properties compared with the morphology. Thus, the best results were obtained for the rod-shaped NPs (not presented in Table 3, EC 50 (half maximal effective concentration) = 22.7 µM), followed by the star-shaped and spherical NPs, although their dimensions increased in the order of sphere to rods to stars [96].…”

“…Vinay et al [92] used both cell lines and the Allium cepa assay for the evaluation of the cytotoxicity of phytosynthesized NPs, identifying antimitotic activity and chromosomal aberrations (chromosome-breaks, chromosome-stickiness, laggard chromosomes, and clumped chromosomes) that represented very good indicators of the genotoxic potential, thus making them a viable alternative for replacing cell lines in antitumoral studies [93]. Gold nanoparticles that were obtained by using green tea extract were also proved to possess antitumoral effects on different cell lines (human gastric adenocarcinoma, epithelial cervix adenocarcinoma, hepatocyte carcinoma and colorectal adenocarcinoma cells) [96]. More importantly, the authors compared the effect of phytosynthesized Au NPs with different sizes and shapes (spheres and stars), with the rod-shaped being obtained via chemical synthesis.…”

“…El-Hawary et al [84] studied the potential of Ag NPs that were obtained by using two cultivars (with similar compositions) of Jasminum sambac L. The nanoparticles with smaller dimensions (8.83 nm) exhibited a higher cytotoxic potential against MCF-7 cells and human bladder carcinoma cells (5637) ( Table 3) and lower toxicity towards immortal keratinocyte cells (HaCaT) ( Table 4), as compared with the higher dimension NPs. When evaluating the overall influence of the morphology of the NPs, literature data suggest that the shape represents a more important factor than the size [96]. Thus, a comparison of phytosynthesized Au NPs spheres (8.7 nm) and stars (99 nm) with chemically obtained nanorods (length/width = 60.4/16.4 nm) revealed a superior effect of nanostars (IC 50 = 81.8 µM, compared with the nanospheres-IC 50 = 127.1 µM), although both were inferior to the nanorods (IC 50 = 22.7 µM) against human hepatocyte carcinoma cells (HepG2).…”

Interactions of Nanoparticles and Biosystems: Microenvironment of Nanoparticles and Biomolecules in Nanomedicine

“…Shape is a physicochemical property that influences the toxicity of materials [58]. Nanoparticles have different shapes and structures such has tubes, fibers, spheres, planes, etc.…”