Chitosan-Coated Gold Nanoparticles' Folic Acid Conjugates for Targeted Delivery of Papain Enzyme: An Extended Nanoplatform Approach for Cancer Therapy

Abstract

Cancer is a significant global public health concern, being the second leading cause of mortality, accounting for one in six cases worldwide. Researchers have employed various approaches in cancer treatment, with nanobiotechnology emerging as a standout technique for developing anticancer agents. This study assessed the anticancer activity of chitosan (CS)-coated gold nanoparticles (AuNPs) and a combination of AuNPs–papain (Pap)–folic acid (FA) nanomaterial platforms against Michigan Cancer Foundation-7 (MCF-7) cancer cell lines. A range of methods, including ultraviolet–visible (UV–Vis), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and zeta potential, were used to characterize the prepared nanomaterials. AuNPs and AuNPs–Pap–FA exhibited UV–Vis absorption at 525 and 558 nm, respectively. In the XRD test, the AuNPs peaks were found at 32°, 39°, 45°, 65°, and 78.5°, and the AuNPs–CS–Pap–FA peaks were identified at 29, 37°, 45°, 65°, and 78.5°. SEM revealed irregularly dispensed oval shapes of AuNPs. TEM images confirmed the shape of the AuNPs before and after the coating with Pap and FA. The mean diameter of the AuNPs was 15 nm, and for the AuNPs–CS–Pap–FA, it was 22.5 nm. Acridine orange–ethidium bromide (AO/EB) staining, flow cytometry assay, 2,2-diphenyl-1-picrylhydrazyl (DPPH), and in vitro hemolysis assays were conducted. The maximum scavenging activity was observed with AuNPs–CS–Pap–FA, reaching up to 90%. In the in vitro hemolytic rate test, AuNPs–Pap–FA at low concentrations (3.12, 6.25, and 12.5 μg mL⁻¹) was within the permissible levels. The AuNPs–CS–Pap–FA at a concentration of 100 μg mL⁻¹ reduced the viability of MCF-7 cells to 10% when compared to nontreated cells. The highest expression of caspase-8 was achieved after treating the cell line with AuNPs–CS–Pap–FA. The AuNPs–CS–Pap–FA nanopreparation exhibited remarkable in vitro activity and holds promise as a potential candidate for further development towards clinical applications as an anticancer agent.