Tailored intracellular delivery via a crystal phase transition in 400 nm vaterite particles

Porous vaterite containers of 400 nm size are studied with respect to intracellular drug delivery appli- cations. A generic crystal phase transition from vaterite to calcite serves as a novel payload release mecha- nism, which reveals a delayed burst-release. This will permit control of the pharmacokinetics allowing for applications like preventive drug administration or scheduled application of pharmaceuticals during long term therapy. Experiments with two types of payloads, providing di ff erent molecular weights and zeta- potentials, demonstrate a fl exible way of tailoring the payload delivery time via the molecular properties of the cargo. A dual in vitro cellular uptake experiment with human ovarian carcinoma cells ES2 and human fi broblasts MRC5 shows no cytotoxicity, no in fl uence on cell viability, and fast penetration of substance-loaded containers into cells. Flow cytometry analysis proves high uptake rates and 3D micro- scopy analysis reveals the intracellular distribution