Design and testing of paramagnetic liposome-based CEST agents for MRI visualization of payload release on pH-induced and ultrasound stimulation.

The development of nanomedicines in cancer therapy is constantly growing because of the advantages associated with the use of nanosized drug delivery systems. Among them, the possibility of accurate spatiotemporal control of the release of the chemotherapeutic from the carrier is one of the most interesting and clinically relevant. To further improve the therapy outcome, the clinical translation of imaging protocols for the in vivo visualization of the release step is of paramount importance. In this work, the combination of the great chemical versatility of liposomes and the outstanding potential of MRI chemical exchange saturation transfer agents has been successfully harnessed to image the selective release of the liposomal content stimulated by endogenous (variation of pH) and externally applied (nonfocused ultrasound) stimuli. The use of clinically safe components (both liposomes and MRI agents) and the good results obtained in vitro hold promise for a successful future in vivo translation.