Theranostic Nanoprobe Mediated Simultaneous Monitoring and Inhibition of P-Glycoprotein Potentiating Multidrug-Resistant Cancer Therapy.

Multidrug resistance is a major cause of failure in the clinical cancer therapy, in which the overexpression of P-glycoprotein (P-gp) plays a crucial role. Herein, we fabricate a theranostic nanoprobe with the function of simultaneous detection and inhibition of P-gp to diagnose and combat multidrug-resistant cancer in vitro and in vivo. For constructing the nanoprobe, elacridar modified quantum dots (QDs-Ela), acting as a gatekeeper, are grafted onto the doxorubicin (DOX) loaded, folic acid (FA) decorated mesoporous silica nanoparticles (MSNs). Upon targeted uptake by multidrug-resistant cancer cells, Bel-7402/ADR are used as a model, the acidic environment results in QDs-Ela removal from the nanoprobe, and subsequent DOX release. The removed QDs-Ela could specifically combine with P-gp in the cancer cell membrane and inhibit their active sites, which prevents the efflux of intracellular DOX and increases the retention of DOX. Another way, the fluorescence intensity of the binding QDs-Ela quantifies the P-gp expression level. Subsequently, in vitro and in vivo experiments both demonstrate the enhanced multidrug-resistant cancer therapy efficacy, i.e., nanoprobe has 10 times better curative effect than free DOX. In addition, due to the conjugation of FA, the nanoprobe exhibits a selective cell targeting ability to Bel-7402/ADR cells. This nanoplatform paves a new avenue for the accurate treatment of multidrug-resistant cancers.