Sustained release of epigallocatechin gallate from calcium carbonate nanoparticles: promising therapy for colorectal cancer

Nanotechnology has provided an enabling platform for innovations in site-specific cancer therapy and personalized oncomedicine. One of the most important advances in this area is the creation of nanomedicines that target cancer cells, which facilitates the progress of precise therapeutic interventions. Efficient drug delivery into tumor cells remains one of the critical challenges in cancer therapy. However, cancer-cell-targeted nanomedicines that function within the intricate milieu of the tumor microenvironment have shown potential to improve therapeutic efficiency. Epigallocatechin gallate (EGCG), the major phytochemical in Phyllanthus emblica (amla), is known for its anticancer and anti-inflammatory properties. In this study, we developed pH-responsive calcium carbonate nanoparticles (CCNPs) as a nanocarrier for EGCG to enhance its intracellular delivery and therapeutic efficacy. EGCG was physically adsorbed onto the surface of CCNPs. The synthesized nanoparticles were characterized using UV–visible spectroscopy, scanning electron microscopy (SEM), dynamic light scattering (DLS), zeta potential analysis, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). In-vitro drug release studies demonstrated a sustained and more prominent release of EGCG at the acidic pH (4.8) typical of the tumor microenvironment. The biological activity of EGCG-loaded CCNPs was evaluated using the MTT assay and apoptosis analysis. The results showed significant cytotoxicity against colorectal cancer cells (COLO-320 DM), while blank CCNPs exhibited low toxicity and high biocompatibility. Intracellular uptake studies further confirmed the preferential accumulation of nanoparticles within colorectal cancer cells. Flow cytometry-based apoptosis assays revealed that EGCG-conjugated CCNPs induced considerable cancer cell death. These findings suggest that EGCG-loaded calcium carbonate nanoparticles may serve as an effective and biocompatible drug delivery platform for targeted colorectal cancer therapy.