Protoporphyrin-grafted halloysite nanotubes for boosted photodynamic activity in chitosan nanocomposite films

Chitosan-based materials are widely explored for biomedical applications due to their biocompatibility, biodegradability, and excellent film-forming ability. In this work, we report the development of hybrid chitosan films reinforced with halloysite nanotubes (Hal) covalently functionalized with protoporphyrin IX (PPIX), aiming to enhance their photodynamic properties. Photodynamic therapy (PDT) has emerged as a promising and minimally invasive technique for cancer treatment due to its selectivity and low toxicity. However, the clinical use of many photosensitizers, such as PPIX, is limited by their poor solubility in water. The covalent anchoring of PPIX onto the external surface of Hal significantly improved its availability in water, which was further enhanced upon coordination with Zn2+ ions. The resulting Hal-PPIX nanomaterials were characterized by spectroscopic and microscopic techniques and evaluated, both chemically and biologically, for their ability to generate reactive oxygen species (ROS) under visible light irradiation. As proof of concept, the nanomaterials were incorporated into chitosan films and studied for their mechanical properties and AFM was employed to investigate the surface morphology of them. The results demonstrate the potential of these bio-based nanocomposites as promising candidates for topical photodynamic therapy, particularly in skin cancer treatment.