Porous CaCO 3 carriers loaded with scintillation nanoparticles and photosensitizer molecules for photodynamic activation

We report the creation of a novel composition on the base of porous CaCO3 microspheres loaded with both scintillating gadolinium orthovanadate nanoparticles doped with europium ions GdVO4:Eu3+ (VNPs) and Methylene Blue (MB) photosensitizer molecules. It has been shown that upon both UV- and X-ray excitations of VNPs, an excitation energy transfer from VNPs to MB dye molecules takes place that is revealed in the donor VNPs luminescence intensity and lifetime decrease, as well as MB FRET-induced luminescence appearance. The rise time of the acceptor MB luminescence, which follows the donor decay time has been observed that allows distinguishing of nanosecond acceptor emission due to direct acceptor excitation from the much longer-lived sub-millisecond FRET-induced acceptor one. Using the rise time of acceptor luminescence, FRET efficiency (E = 59%) rate constant (kt=2.28·103s−1) and physical separation of the donor to acceptor within CaCO3 microparticles (rda=2.45nm) at the optimal acceptor concentration have been calculated. The efficiency of created CaCO3@VNPs@MB composition in free radical generation has been analyzed.