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

Abstract

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.

Mesoporous Silica Nanoparticles in Bioimaging

“…These features mean HMSNs represent ideal candidates for both the loading and delivery of chemical agents (e.g., carbon dots, organic dyes, fluorine compounds, etc.) [ 41 , 42 , 43 ]. HMSNs can be produced by several different methods—“soft-templating”, “hard-templating” and “self-templating” [ 44 , 45 ]—as illustrated by Figure 2 .…”

An Olefin Copolymer with Aggregation‐Induced Emission Characteristics Synthesized by Using Metallocene Catalyst

“…Using metallocene catalyst system, ethylene copolymer containing AIEgen monomer (VTBE) was obtained for the first time by olefin coordination polymerization. 13 C-NMR confirmed that the obtained polymer was a "real copolymer," not a mixture of ethylene homopolymer and VTBE. The molecular weight of the copolymer decreases with the increase of VTBE incorporation, and the molecular weight distribution accords with the characteristics of the polymer obtained by a typical single site catalyst.…”

“…Polymer Characterization: Solution 13 C NMR experiments were performed on a Bruker AVANCEIII-400 MHz spectrometer with a 10 mm PASEX 13 C-1 H/D Z-GRD probe. All sample solutions were prepared with 200 mg of the polymer material dissolved in 2.5 mL of 1,1,2,2-tetrachloro-1,2-dideuterioethane (C 2 Cl 4 D 2 ) in a 10 mm tube at 130-140°C.…”

“…Occasional stirring was necessary to achieve a homogeneous solution. All 13 C NMR experiments were performed at 125°C and 10 s relaxation delay.…”

“…Figure2shows the13 C-NMR spectra of runs 4 (poly(E-co-VTBE)) and 5 (poly(E-co-St)). The nomenclature of carbon atoms in ethylene copolymer with VTBE or styrene is illustrated in Figure3.…”