iRGD mediated pH-responsive mesoporous silica enhances drug accumulation in tumors

The limited penetration of nanocarriers into tumors and the slow release of drugs from these carriers to tumor cells are significant challenges in cancer therapy. In this study, we developed a novel drug delivery carrier derived from mesoporous silica, dually modified with the tumor-homing cyclic peptide iRGD (CRGDKGPDC) and the pH-responsive polymer poly(2-ethyl-2-oxazoline) (PEOz) for treating triple-negative breast cancer. The carrier selectively bound to the αvβ3 integrin receptor, which is specifically expressed in MDA-MB-231 breast cancer cells and vessels. Subsequently, it penetrated deep into the tumor parenchyma through NRP-1 receptor-dependent internalization, with the drug-loaded particles releasing drugs rapidly in the acidic cytoplasmic environment. Results indicated that the drug release rate of PEOz-modified formulations was pH-dependent. Lysosomal escape experiments demonstrated that PEOz-modified particles efficiently escaped lysosomes to release drugs. In vitro cytotoxicity assays revealed that iRGD-functionalized particles were more cytotoxic to NRP-1-positive MDA-MB-231 cells compared to NRP-1-negative MCF-7 cells. Cellular uptake studies demonstrated that iRGD mediated enhanced endocytosis of nanoparticles into MDA-MB-231 cells. In vitro tumor cell spheroid penetration assays confirmed that the PEOz and iRGD dual-modified carrier facilitated deeper distribution of DOX in multicellular spheroids compared to free DOX. Moreover, in a nude mouse model of triple-negative breast cancer, the dual-modified drug-loaded carrier significantly inhibited tumor growth without inducing weight loss or liver and kidney damage. This dual-modified mesoporous silica presents a novel and promising delivery carrier for enhancing cancer treatment.