Increasing apoptosis induction and minimizing side effects of biosynthesized silver nanoparticles by utilizing halloysite nanotubes containing folic acid

Since silver nanoparticles (Ag NPs) may not perform well due to low solubility and passive entry, two types of drug delivery systems based on halloysite nanotubes (HNTs) were synthesized. These systems aim to increase the performance and solubility of Ag NPs, as well as enhance their delivery to HCT116 colon cancer cells using folic acid (FA). Ag NPs were successfully anchored onto the surface of HNTs using Acacia luciana flower extract, marking a novel approach that led to the synthesis of HNTs-Ag NPs and HNTs-FA-Ag NPs. The cytotoxicity assay showed that even at the lowest concentration, HNTs-FA-Ag NPs can reduce cell viability to below 30% after 48 and 72 h of treatment. They are even more effective than cisplatin. The effectiveness of the synthesized HNTs in inhibiting the growth of cancer cells was further confirmed by staining the protein content of the cells with sulforhodamine B. Real-time PCR results indicated that the presence of FA in the structure of HNTs-FA-Ag NPs activates the mitochondrial intrinsic pathway in HCT116 cells, leading to a 4.71-fold increase in the expression ratio of Bak1/Bclx compared to the control. Furthermore, the reduction in the expression of AKT1, a protein responsible for cell survival and treatment resistance, by HNTs-FA-Ag NPs can be attributed to the presence of FA. This enhances the ability of Ag NPs to inhibit metastases of HCT116 cells. Finally, both modified HNTs demonstrated a protective impact on erythrocytes and reduced oxidative stress. Specifically, HNTs-FA-Ag NPs did not induce any inflammatory response in erythrocytes and did not increase TLR6 gene expression. Therefore, it is expected that HNTs-FA-Ag NPs possess therapeutic capabilities with fewer side effects.