Influence of Cellulose Morphology on the Biological Performance of Cellulose–BODIPY Hybrid Materials

Cellulose-based materials have gained increasing interest as promising platforms for the development of photoactive systems owing to their biocompatibility, high surface area, and tunable morphology. An allyl-functionalised boron dipyrromethene (BODIPY) derivative was incorporated into cellulose nanocrystals (CNC), cellulose nanofibers (CNF), and cellulose foam through covalent and non-covalent approaches. The effect of cellulose morphology on the biological performance of the resulting hybrid materials was investigated. Covalent incorporation was achieved by thiol–ene coupling with thioglycolic acid-functionalised CNC (CNC–SH), whereas physical adsorption was employed for CNF and cellulose foam. Scanning electron microscopy revealed distinct cellulose architectures, ranging from dense CNC aggregates and fibrillar CNF networks to highly porous cellulose foam, which affected the distribution and accessibility of the photosensitizer within the different matrices. Biological evaluation demonstrated lower cytotoxicity under dark conditions than under irradiation, together with pronounced light-induced cytotoxicity for the physically incorporated materials in human breast cancer cell lines (MCF-7 and HCC-1806), while non-malignant Vero cells maintained high viability under the same conditions. These findings suggest that cellulose morphology, together with photosensitizer accessibility and material dispersibility, contributes to the biological performance of cellulose–BODIPY hybrid materials and provides a basis for the rational design of photoactive polysaccharide-based platforms.