Background: Platinum (II) (Pt(II))-based anticancer drugs dominate the chemotherapy field of ovarian cancer. However, the patient's quality of life has severely limited owing to dose-limiting toxicities and the advanced disease at the time of diagnosis. Multifunctional tumor-targeted nanosized ultrasound contrast agents (glutathione (GSH)-sensitive platinum (IV) (Pt(IV)) prodrug-loaded phase-transitional nanoparticles, Pt(IV) NP-cRGD) were developed for precise theranostics against ovarian cancer. Methods: Pt(IV) NP-cRGD were composed of a perfluorohexane (PFH) liquid core, a hybrid lipid-polymer shell with PLGA12k-PEG2k and DSPE-PEG1k-Pt(IV), and an active targeting ligand, the cRGD peptide (PLGA: poly(lactic-co-glycolic acid), PEG: polyethylene glycol, DSPE: 1,2-distearoyl-sn-glycero-3-phosphoethanolamine, cRGD: cyclic Arg-Gly-Asp). Pt(IV), a popular alternative to Pt(II), was covalently attached to DSPE-PEG1k to form the prodrug, which fine-tuned lipophilicity and improved cellular uptake. The potential of Pt(IV) NP-cRGD as contrast agents for ultrasound (US) imaging was assessed in vitro and in vivo. Moreover, studies on the antitumor efficiency and antitumor mechanism of Pt(IV) NP-cRGD assisted by US were carried out. Results: Pt(IV) NP-cRGD exhibited strong echogenic signals and excellent echo persistence under an US field. In addition, the GSH-sensitive and US-triggered drug delivery system maximized the therapeutic effect while reducing the toxicity of chemotherapy. The mechanistic studies confirmed that Pt(IV) NP-cRGD with US consumed GSH and enhanced reactive oxy gen species (ROS) levels, which further causes mitochondria-mediated apoptosis. Conclusion: A multifunctional nanoplatform based on phase-transitional Pt(IV) NP-cRGD with US exhibited excellent echogenic signals, brilliant therapeutic efficacy and limited side effect, suggesting precise theranostics against ovarian cancer.
Keywords: mitochondrial apoptosis; ovarian cancer.; phase transition; platinum (IV); ultrasound contrast agents.