Magnetic Targeting to Cancer Cells using mTHPC-Maghemite Nano Particles to Improve Photodynamic Therapy

Photodynamic Therapy (PDT) is a promising therapeutic modality for cancer. However, current protocols using bare drugs have several limitations, impeding their beneficial clinical effects. Here, we introduce a new approach for an efficient PDT treatment, based on magnetic manipulations. It involves a PDT drug, meso-tetrahydroxy-phenylchlorin (mTHPC) photosensitizer, coordinatively attached to cerium-doped maghemite nanoparticles (MNPs) that serve as carriers for the drug. These MNPs are small (~ 6 nm diameter), enabling successful coordinative attachment of any Lewis base of N/S/O type as a ligand to the Ce^3/4+ cations. These MNPs are superparamagnetic, biocompatible, and therefore suitable to function as drug carriers. The resulting mTHPC-MNPs are stable in aqueous suspensions, designed to be an efficient drug delivery system for PDT, and enabling magnetic targeting to cancer cells. MDA-MB231 (human breast cancer) cells were incubated with mTHPC-MNPs. The nanocomposite showed a high internalization into the cells. Then the cells were irradiated with a 650 nm laser beam to mimic the PDT procedure. Our study shows higher rates of cell death in cells incubated with the mTHPC-MNPs compared to the control cells. In addition, we demonstrate that a gradient of magnetic field attracts the particles, thus allowing the drug to be selectively exposed to specific areas. This leads to a more localized and effective PDT treatment compared to the free mTHPC drug. Currently, this system is investigated in in vivo models. Using these new mTHPC-MNPs may form the basis for a better-localized PDT strategy for a wide range of cancers.