Rationally engineered PEGylated l-citrulline functionalized baicalein encapsulated HSA nanopolymer guided by molecular docking for tumor microenvironment responsive and redox modulated colon cancer therapy.

Colon cancer remains a major global health burden characterized by uncontrolled proliferation, oxidative stress, and poor responsiveness to conventional therapies, underscoring the need for biocompatible and targeted nanotherapeutic interventions. In this study, a novel pH-responsive human serum albumin-based nanocarrier, HSA-BA@PEG-LC NPs, was designed for the efficient and selective delivery of baicalein (BA) to colon cancer cells. Molecular docking analysis demonstrated strong binding affinities of BA with Hsp90 inhibitors and with human serum albumin (HSA), as well as a notable interaction between l-citrulline (LC) and the cationic amino acid transporter 1 (CAT-1), highlighting their potential roles in anticancer modulation. The engineered nanoparticles exhibited a uniform spherical morphology (232 nm), low polydispersity index (PDI < 0.3), and high colloidal stability (-27.21 mV). Spectroscopic analyses (FTIR and 1H NMR) confirmed successful encapsulation of BA and PEG-LC surface conjugation, with an encapsulation efficiency of 86.62% and pH-dependent sustained release favoring acidic tumor conditions. In HCT-116 cells, HSA-BA@PEG-LC NPs demonstrated enhanced internalization, strong cytoplasmic accumulation, and pronounced cytotoxicity (IC50 = 5.42 µg mL-1), while maintaining safety toward normal lymphocytes. Mechanistically, treatment induced elevated ROS levels, GSH depletion, mitochondrial depolarization, nuclear condensation, cytoskeletal collapse, and G0/G1 cell-cycle arrest. Furthermore, the formulation displayed potent antioxidant activity across DPPH, NO, SOD, and lipid peroxidation assays, with IC50 values approaching ascorbic acid, validating synergistic PEG-LC functionalization and HSA-mediated stabilization as a promising redox-driven nanoplatform for targeted colon cancer therapy.