Characterization and pH-Responsive Drug Release Kinetics of Nanobiocomposite using Carbon Nanotubes for Colon Cancer Stem Cells by Photodynamic Therapy

Photodynamic Therapy (PDT) is a minimally invasive approach that leverages light, a photosensitizer, and oxygen to generate reactive oxygen species (ROS) for selective cancer cell destruction. In this study, a novel nanobiocomposite was developed by conjugating single-walled carbon nanotubes (SWCNTs) with hyaluronic acid (HA) and loading them with the photosensitizer chlorin e6 (Ce6), forming SWCNTs-HA-Ce6. This multifunctional platform harnesses the targeting ability of HA, the phototherapeutic efficiency of Ce6, and the high surface area and stability of SWCNTs. High-resolution transmission electron microscopy (HR-TEM) confirmed the nanostructured morphology of the composite. Stability assessments revealed robust performance under both physiological (pH 7.4) and intracellular (pH 5.5) conditions. In vitro drug release studies demonstrated a pH-responsive, sustained release of Ce6, with release kinetics best fitting zero-order, Higuchi, and Korsmeyer-Peppas models, indicating a controlled and diffusion-based mechanism. Cytotoxicity assays against colon cancer stem cells showed a significant photodynamic effect, confirming the potential of SWCNTs-HA-Ce6 as an effective therapeutic platform for targeted PDT in colon cancer. This study underscores the promise of engineered Nanobiocomposites in enhancing selectivity, stability, and therapeutic efficacy in photodynamic cancer therapy.