Synthesis and In Vitro Analysis of Dual‐Functionalized Mesoporous Silica Nanoparticles for Targeted Theranosis of ER(+) Breast Cancer

Mesoporous silica nanoparticles have been extensively utilized for targeted drug delivery; the drugs are encapsulated in the pores, while the surface can be modified to make the nanoparticles target-specific. The work presented here focuses on the development of multifunctional theranostic mesoporous silica nanoparticles with estrogen receptor-positive [ER(+)] breast cancer as the target. The surface of the nanoparticles was dually functionalized to make the nanoparticles target-specific using an estradiol derivative via a facile click reaction and to attach a ^99mTc complexing agent (DTPA) for SPECT imaging. The size of the spherical nanoparticles was 80-110 nm, and the nanosystem was subjected to various physicochemical analysis techniques. Mesoporous nanoparticles were loaded with tamoxifen, an FDA-approved ER antagonist. Drug release at pH 5.8 was much more rapid than at physiological pH 7.4, a beneficial characteristic for controlled drug delivery at the tumor site. Cellular internalization and competitive binding studies indicated estradiol-mediated preferential uptake by MCF-7 cells. The nanocarrier exhibited good antiproliferative activity towards the ER(+) MCF 7 cells with a 92% decline in cellular viability in 48 h, whereas the cellular viability of the estrogen receptor-negative [ER(-)] MDA-MB-231 cells remained > 60%. Thus, our results suggest a high theranostic potential of MSN-Est for breast cancer management.