Internalizable insulin-BSA-chlorin E6 conjugate is a more effective photosensitizer than chlorin E6 alone

Experiments with human hepatoma PLC/PRF/5 cells involving the use of two different tests (colony formation and Trypan blue exclusion) have demonstrated a significantly higher photosensitizing activity of chlorin e6 conjugates with bovine serum albumin (BSA) and internalizable ligand insulin as compared to that of chlorin e6 itself. Receptor-mediated internalization of insulin-BSA-chlorin e6 conjugates ensures greater photosensitization of cells than the binding of those conjugates to cell surface receptors. The suitability of such conjugates permitting the delivery of a photosensitizer to most sensitive cell structures is discussed.