The results indicate that both bio- and chem-AuNPs are largely ineffective at inducing ROS generation in MDA-MB-231 cells, whereas H2O2- and AgNP-treated groups showed remarkable increase in ROS generation (Figure  9).

Figure 9 The effect of AuNPs in ROS generation. Relative fluorescence of DCF was measured using a spectrofluorometer with excitation at 485 nm and emission at 530 nm. The results are expressed as the mean ± SD of three separate experiments, each of which contained three replicates. Treated groups with bio- and chem-AuNPs were not find more statistically different from the control group based on the Student’s t test. (p > 0.05). H2O2- and AgNP-treated groups were statistically buy CB-839 different from the control group based on the Student’s t test (*p < 0.05). Chuang et al. [71] extensively GDC-0973 in vitro studied the exposure of three different-sized AuNPs in human gastric carcinoma (AGS) and human lung adenocarcinoma epithelial (A549) cells. Their results suggest that significant

increases of ROS generation occur with certain concentrations of AuNPs in AGS cells. Conversely, no obvious increases were observed for A549 cells in any of the three sizes of AuNPs. The authors eventually concluded that ROS signaling may play a role in AuNP-induced apoptotic cell death in AGS cells. Furthermore, western blot analyses revealed that the expression of proteins involved in the anti-oxidative defense system was not significantly modulated any of the three sizes of AuNPs in both lines, except for a modest increase in TrxR-1 and SOD-1 in AGS cells [71]. Altogether, our results

suggest that biologically synthesized very AuNPs have significant biocompatibility and could possibly be used for ultrasensitive detection, gene transfer, biomolecular imaging, drug delivery, and cancer therapy. Conclusion Synthesis of nanoparticles using biological systems is an important area of nanobiotechnology. Here we show a simple, rapid, clean, efficient, cost-effective, and green method for the synthesis of biocompatible AuNPs using Ganoderma spp. extract as a reducing and stabilizing agent. The as-prepared AuNPs were characterized via UV-vis, XRD, FTIR, EDX, DLS, and TEM. The biologically derived AuNPs were spherical, discrete, and the average size was 20 nm. The biocompatibility effect of AuNPs was investigated using cell viability, LDH, and ROS assays. The results indicate that biologically derived AuNPs are biocompatible. Finally, this eco-friendly method provides an alternative route for large-scale production of biocompatible AuNPs that can be used in catalysis, sensors, electronics, and biomedical applications, especially for cancer therapy. Acknowledgements This work was supported by the KU-Research Professor Program of Konkuk University. Dr Sangiliyandi Gurunathan was supported by a Konkuk University KU-Full-time Professorship.