The Pennsylvania State University Schreyer Honors College Department of Biomedical Engineering the Effects of Bioconjugation of Calcium Phosphosilicate Nanoparticles on the Delivery to Breast Cancer Cells

Conventional chemotherapeutic treatments for breast cancer produce high systemic concentrations while local concentrations in the diseased tissue are relatively low. In contrast, targeted therapeutics provide the promise of low systemic dosage, and therefore, modest or no side effects, while producing high local concentrations at the tumor. Fluorescent, 20nm diameter, calcium phosphosilicate nanoparticles (CPSNPs) synthesized in our laboratory were used as in vitro model particulate systems to evaluate targeted uptake in human breast cancer. The uptake of the CPSNPs in MDA-MB-231 breast cancer cells was analyzed to demonstrate the efficacy of the target approach using anti-CD71 as a target for the triple negative MDA-MB-231. To simulate the circulating conditions of human blood in vitro, the breast cancer cells were exposed to the CPSNPs for 30, 60, or 120 minutes under shear provided by a cone-plate viscometer placed in an incubator maintained at 37°C and 5% CO2 to mimic the conditions of blood circulation. Flow cytometry was used to quantify the uptake of the CPSNPs, doped with RhodamineWT, by the cells. In addition, commercial, fluorescent, 1 micron diameter polymeric spheres were used as a control to demonstrate the efficacy of the target approach using anti-CD71 as a target for the triple negative MDA-MB-231. The results support the in vitro anti-CD71 targeted uptake of both the CPSNPs and the microspheres by the MDA-MB-231 cells. The uptake of the anti-CD71 functionalized particles was significantly higher under both ii high and low shear conditions than either the methoxy-PEG or citrate functionalized particles. Furthermore, preliminary steps were taken to test the efficacy of docetaxelencapsulating CPSNPs in mitigating tumor cell extravasation during metastasis. Free docetaxel concentrations as low as 1x10 -5 M and 1x10 -6 M were found to significantly reduce breast cancer cell extravasation across an endothelial cell monolayer, thereby demonstrating the promise of docetaxel-CPSNPs in hindering tumor cell metastasis.