Facile Incorporation of “Aggregation-Induced Emission”-Active Conjugated Polymer into Mesoporous Silica Hollow Nanospheres: Synthesis, Characterization, Photophysical Studies, and Application in Bioimaging

Typical aggregation-induced emission (AIE) luminogens tetraphenylethylene (TPE) and triphenylamine have been used to construct an AIE-active conjugated polymer, namely, poly(N,N-diphenyl-4-(4-(1,2,2-triphenylvinyl)styryl)aniline) (PTPA), which consist of D-π-A architecture by Wittig polymerization. We fabricated mesoporous silica hollow nanospheres (MSHNs) which were encapsulated with the AIE-active polymer for applications in cellular imaging. It exhibits a positive solvatochromism effect by increasing solvent polarity, supported by theoretical calculation using density functional theory. The structure of the monomers and polymer was confirmed by Fourier transform infrared, nuclear magnetic resonance, and high-resolution mass spectrometry techniques. Considering the advantage of high brightness in the fluorescence of PTPA, it was encapsulated into MSHNs by a noncovalent approach, and the surface was functionalized with an anti-EpCAM (antiepithelial cell adhesion molecule) aptamer through conjugation with γ-glycidoxypropyltrimethoxysilane for targeting cancer cells specifically. The aptamer-functionalized Apt-MSHNs exhibited excellent biocompatibility with the liver cancer-Huh-7 cells used for this study and was efficiently internalized by these cells. Because EpCAM are overexpressed in multiple carcinomas, including liver cancer, these aptamer-conjugated AIE MSHNs are therefore good candidates for targeted cellular imaging applications.