Calcite Single Crystals as Hosts for Atomic-Scale Entrapment and Slow Release of Drugs

Doxorubicin (DOX)/CaCO₃ single crystals act as pH responsive drug carrier. A biomimetic approach demonstrates that calcite single crystals are able, during their growth in the presence of doxorubicin, to entrap drug molecules inside their lattice along specific crystallographic directions. Alterations in lattice dimensions and microstructural parameters are determined by means of high-resolution synchrotron powder diffraction measurements. Confocal microscopy confirms that doxorubicin is uniformly embedded in the crystal and is not simply adsorbed on the crystal surface. A slow release of DOX was obtained preferentially in the proximity of the crystals, targeting cancer cells. The anticancer drug doxorubicin is entrapped inside the lattice of calcite single crystals. High-resolution synchrotron powder diffraction and confocal fluorescence microscopy allow to exactly localize doxorubicin molecules in the calcite crystal. The pH sensitive CaCO₃ solubility releases slowly the entrapped molecules in proximity of the crystals, only when the dissolution occurs, targeting cancer cells that uptake the released drug.