pH-responsive and targeted delivery of curcumin via phenylboronic acid-functionalized ZnO nanoparticles for breast cancer therapy.

Nanoparticle-mediated targeted delivery of bioactive natural compounds has recently been gaining much interest for breast cancer therapy. Herein, phenyl boronic acid (PBA)-conjugated and pH-responsive ZnO nanoparticles (diameter ∼40 nm) were synthesized for the tumor tissue-specific delivery of curcumin. PBA conjugation facilitates the targeted delivery of curcumin to the sialic acid overexpressed in breast cancer cell membranes. Curcumin-loaded ZnO nanoparticles (ZnO-PBA-Curcumin) caused apoptotic cell death in MCF-7 human breast cancer cells by inducing oxidative stress and mitochondrial damage. Further, in vivo intravenous (i.v.) administration of ZnO-PBA-Curcumin was found to effectively decrease tumor growth in Ehrlich ascites carcinoma (EAC) tumor-bearing mice via the enhanced accumulation of curcumin. Interestingly, ZnO-PBA-Curcumin did not show any signs of systemic toxicity. The cytotoxic potential of the nanohybrid ZnO-PBA-Curcumin is attributed to the combinatorial cytotoxic effects of curcumin and ZnO in cancer cells. Collectively, ZnO-PBA-Curcumin may represent a potential treatment modality for breast cancer therapy. This study provides insight into the tumor cell targeting mechanism using PBA functionalization, and the anticancer efficacy of curcumin-loaded pH-sensitive nanohybrids can be attributed to the differential oxidative stress-inducing properties of curcumin and Zn+2 ions.