A series of N-substituted phenothiazine acrylate monomers for fluorescence nanoparticles: Synthesis, structure-fluorescence relationship and drugs delivery systems of paclitaxel

Aggregation-induced emission (AIE) materials can emit fluorescence with higher photoluminescence efficiency when aggregated or in the solid state, making them widely used in many fields recently. In this study, several novel N-substituted phenothiazine (PhT) derivatives HPMAD (HPMAC, HPMAN, HPMAP) with D-A structure were prepared by chemoenzymatic transesterification , Vilsmeier-Haack reaction and Knoevenagel condensation reaction , etc. Subsequently, the effects of functional groups with different natures on the optical properties of fluorescent molecules were investigated in detail. As compared with FPMA with an emission wavelength at 543 nm, the emission wavelengths of HPMAC, HPMAN and HPMAP were significantly red-shifted with the increase of electron-withdrawing and conjugation degree, and their maximum emission wavelengths were respectively at 595 nm, 599 nm and 649 nm. The quantum calculations also indicated that energy band gaps ΔE of HPMAC, HPMAN and HPMAP were obviously lower than that of the substrate FPMA, among which HPMAP had low ΔE of 3.04 eV due to the conjugation structure. Afterwards, amphiphilic copolymers PEG-HCC1, PEG-HCC2 and PEG-HCN were prepared by RAFT polymerization using PEGMA , HPMAC and HPMAN as monomers with different molar ratios, and their molar ratios in the copolymers were respectively about 23.7 %, 31.4 % and 30.8 %. Among them, PEG-HCN copolymers were easily dispersed in H 2 O solutions through self-assembly with a diameter of 100–200 nm, and exhibit significant aggregation-induced emission enhancement (AEE) phenomenon. Moreover, PEG-HCN FONs had excellent biocompatibility , lower toxicity, and good cellular endocytosis, which can be further used as a carrier for the anticancer drug of paclitaxel (PTX). Thus, drugs-carrying nanoparticles HCN-PTX FONs were constructed for drugs release and simultaneous imaging to track intracellular drug delivery , which demonstrates the potential for development in bioimaging, drugs delivery and medical diagnostics.