Polymerizable AEE-active Dye with Optical Activity for Fluorescent Nanoparticles Based on Phenothiazine: Synthesis, Self-assembly and Biological Imaging

Abstract

In consideration of various advantages such as less harmful, higher sensitivity, and deeper imaging depth, etc, AIE materials with long-wave emission are attracting extensive attention in many fields of vascular visualization, organelle imaging, cells tracker, forensic detection, bioprobe and chemosensor, etc. In this paper, a novel fluorescent (R)-PVHMA monomer with chirality and aggregation-induced emission enhancement (AEE) characteristics was acquired through enzymatic transesterification reaction basing on phenothiazine, and its〖 [α]〗_D^(25 ℃) value was about -6.39° with 3.08eV energy level of HOMO and LUMO situations by the quantum calculations. Afterwards, a series of PEG-PVH1 and PEG-PVH2 copolymers with chirality feature were achieved through RAFT polymerization of the obtained (R)-PVHMA and PEGMA with various feed ratios. When the feed molar ratio of (R)-PVHMA increased to 29.6% from 21.5%, its actual molar fractions in the PEG-PVH1 and PEG-PVH2 copolymers accordingly increased to 25.7% from 18.1%. The molecular weight of PEG-PVH1 was about 2.2×104 with narrow PDI, and their kinetics estimation showed a first-order quasilinear procedure. In aqueous solution, the amphiphilic copolymers PEG-PVH could self-assembles into about 100 nm nano-particles. In a 90% water solution of H2O and THF mixture, the fluorescence intensity had the maximum value, and the emission wavelength presented at 580 and 630 nm. The investigation of cytotoxicity and cells uptake showed that PEG-PVH FONs had outstanding biocompatibility and excellent cells absorption effects, which have great potential in bioimaging application.