## 3 Results
### Discussion  
The different-sized nanoparticles GNPs-1, GNPs-2, and GNPs-3 were synthesized via the colloidal solution process, as described in the Materials and Methods section. Their special size facilitates application for various biological and biomedical purposes, such as drug delivery, DNA damage, cancer, and cytotoxicity, due to their enhanced surfaces and catalytic properties [7]. The processed GNPs-1, GNPs-2, and GNPs-3 were characterized with various instruments such as TEM and HR-TEM, which disclosed their particle size and crystalline properties. The morphology of processed structures were confirmed through TEM, which illustrated that the nanostructures possessed three different-sized NPs, spherical in shape, with nearly smooth surfaces and crystalline in nature. The average diameters of the GNPs were, respectively, 10-15 nm for GNPs-1, 20-30 nm for GNPs-2, and 45 nm for GNPs-3. HR-TEM of the prepared nanostructures showed lattice spacing of 0.235 nm, 0.234 nm, and 0.236 nm, respectively, between the two fringes, equal to the findings of previously published literature and confirming that the materials are highly crystalline in nature [65]. The hydrodynamic size and zeta potential results are in agreement with other data and consistent with TEM and HR-TEM. Very small and different-sized NPs have the ability to change their physiological and physicochemical character in optoelectronic applications, such as LEDs and solar cells.  
A number of applications in optoelectronics are well established, but limited work is available in relation to anticancer applications with nanostructures, in terms of their diverse sizes and varied concentrations. The colloidal solution provides worthy results, which are very significant with respect to cancer cells that have underlying assumptions and restrictions. The diverse-sized nanoparticles GNPs-1, GNPs-2, and GNPs-3 have the ability to inhibit cancer cell growth [66]. It is hypothesized that the different sizes and shapes of NPs can possibly produce ROS generation in cell suspension, which is an important factor responsible for forming free radicals (FRs), which may be able to penetrate the outer walls of cells and enter into the inner walls of cell membranes. FRs also exhibit the possibility of reacting with internal organelles, creating an enzymatic change and resulting in disorganization of cells and cells contents.  
ROS plays a significant role in cytotoxicity with NPs, suggesting that extreme generation reduces cellular antioxidant capacity [67]. Gold nanoparticles have the potential to regulate the growth/death of cell organelles, as well as biochemical and enzymatic changes of cancer cells [67]. This result shows that GNPs-1, GNPs-2, and GNPs-3 are potent  
Figure 8: Quantification of mRNA fold change and apoptotic genes (p53, Bax, and casp3) were evaluated. HepG2 cells were treated with 25 \(\mathrm{\SIUnitSymbolMicro}\)/mL of GNPs-1, GNPs-2, and GNPs-3 for 24 h. For internal control, glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was used. The values are mean \(\pm\) SE of three independent experiments.  
materials for use in growth inhibition of cancer cells. These results indicate that varied concentrations and different sizes of nanostructures are able to easily enter into and react with cells, as is evident from the MTT, NRU, and ROS studies.  
In most of the previous works, researchers have employed either a high concentration of nanostructures or complex materials for toxicity studies, which may be harmful for human exposure [68,69]. From the entirety of relevant experiments, it appears that low-concentration and small-size NPs (10 nm) would be increasingly helpful in controlling the growth of cancer cells without any adverse effects on the human body [68,69].