ZIF-8/polydopamine nanocomposite functionalized with hyaluronic acid and folic acid for pH-responsive resveratrol delivery and apoptosis induction in colorectal cancer

In this study, a multifunctional nanocomposite based on zeolitic imidazolate framework-8 was engineered for the enhanced delivery of resveratrol to colorectal carcinoma cells. The system comprised resveratrol-encapsulated ZIF-8 nanoparticles sequentially modified with polydopamine, hyaluronic acid, and folic acid (ZIF-8-Res-PDA-HA-FA). Physicochemical characterization revealed a Z-average hydrodynamic diameter of 194 nm, a polydispersity index of 0.197, and a zeta potential of - 40.55 mV, indicative of a narrow size distribution and robust colloidal stability. Drug encapsulation efficiency achieved 81.9%, with in vitro release kinetics demonstrating pH-responsive behavior characterized by 58.7% cumulative release reached 59.9% at pH 5.5 and 33.2% at pH 7.4 after 72 h, and further increased to 81.4% at pH 5.5 by 120 h, confirming acid-triggered drug liberation. Molecular docking simulations of resveratrol against the Bcl-2 BH3 groove yielded a modest binding affinity (S-score = - 6.23 kcal/mol) with a single validated hydrogen bond to Ala4 (2.83 Å); however, this computational prediction does not constitute evidence of cellular target engagement, and functional assays were not performed. In HCT116 cells, the nanocomposite exhibited concentration-dependent cytotoxicity with a calculated IC₅₀ of 54.4 µg/mL following 24-h exposure, while human dermal fibroblasts retained > 70% viability at concentrations up to 500 µg/mL, suggesting preferential antiproliferative activity against malignant cells. Flow cytometric analysis confirmed apoptotic induction, with treatment reducing cellular viability from 97.4% to 58.7% and increasing late-stage apoptosis to 28.4% at 74 µg/mL. Quantitative PCR demonstrated transcriptional upregulation of p53 (9.96-fold) and p21 (2.3-fold) at 48 h, whereas caspase-8 expression remained at baseline levels, implicating the intrinsic apoptotic pathway as the predominant mechanism. Wound-healing assays at sub-cytotoxic concentrations revealed significant inhibition of cellular motility (25-30% closure versus 85-90% in controls; p < 0.001). Receptor-mediated cellular uptake was not experimentally verified in this study; therefore, the observed cellular effects cannot be attributed to active targeting. While these findings demonstrate in vitro therapeutic potential, several critical limitations must be addressed: receptor-mediated cellular recognition was not experimentally verified, protein-level confirmation of gene expression changes is absent, and in vivo pharmacokinetics remain to be established.