【摘要】 依次采用开环聚合(ROP)和原位引发聚合方法，分别在四苯乙烯(TPE)分子的不同苯环位置上共价键合嵌段共聚物PCL-b-PNIPAM(PCL=聚己内酯，PNIPAM=聚(N-异丙基丙烯酰胺))，并通过与Eu配位，合成含有单、双、四臂的3种双亲性嵌段共聚物-Eu配合物，再自组装构筑出粒径分别为4.8、4.3和2.7 nm的小尺寸非半导体型聚合物量子点(Pdots)。测试结果表明：单、双、四臂Pdots均具有蓝光(430 nm)和红光(615 nm)的双荧光发射性能，且由TPE发射的蓝光具有聚集诱导发光性能和温度响应特性，最低临界溶解温度分别为32、36和37℃，接近人体正常体温。同时，3种Pdots均表现出极低的细胞毒性，并展现出优异的蓝/红双色荧光成像能力和可逆双色荧光切换功能。此外，对3种Pdots进行对比发现，四臂Pdots具有最小的粒径、最优的双荧光性能和最佳的细胞成像效果。更多还原

【Abstract】 Three amphiphilic block copolymers 1s-TPE-PCL-b-PNIPAM, 2s-TPE-PCL-b-PNIPAM, and 4s-TPE-PCL-b-PNIPAM(PCL=polycaprolactone, PNIPAM=poly(N-isopropylacrylamide)) were synthesized by in situ polymerization with tetraphenylethylene(TPE) fluorescent small molecules as the center. Then, the rare earth element Eu(Ⅲ)was coordinated with the hydrophilic fragment PNIPAM to synthesize block copolymer-Eu(Ⅲ) complexes(1s-TPEPCL-b-PNIPAM-Eu(Ⅲ) for one-arm, 2s-TPE-PCL-b-PNIPAM-Eu(Ⅲ) for two-arm, and 4s-TPE-PCL-b-PNIPAM-Eu(Ⅲ)for four-arm). Finally, non-semiconductor polymer dots(Pdots) were prepared by self-assembly of the complexes in water. The three kinds of Pdots had excellent water solubility and ultra-small particle size below 5 nm(average particle sizes were 4.8, 4.3, and 2.7 nm, respectively). The optical test results showed that the single, double, and fourarm Pdots mainly emitted blue light at 430 nm under the excitation of 360 nm, and exhibited excellent aggregationinduced emission characteristics. At 395 nm, the red emission was mainly at 615 nm, and there had little mutual interference because of blue-red emission wavelength spacing was as high as 195 nm, showing excellent double fluorescence properties. The four-arm Pdots aqueous solution had a wider range of color changes and a better double fluorescence effect. In addition, the lower critical solution temperatures(LCSTs) of the three Pdots were 32, 36, and37 ℃, respectively. While the LCSTs of the four-arm Pdots were closer to the normal body temperature. At the same time, the conformation of the PNIPAM chain in Pdots changed from expansion state to contraction state along with the increase of temperature. As a result, the aggregation degree of TPE on the chain was enhanced, which caused the temperature response of Pdots aqueous solution fluorescence. Ultimately, cytotoxicity and cell imaging studies showed that the three Pdots had low cytotoxicity and could enter HeLa, A549, and HepG2 tumor cells by endocytosis. Under different excitation wavelengths, strong blue or red fluorescence signals could be received in the cells,exhibiting blue/red dual-color fluorescence imaging ability and reversible dual-color fluorescence switching function. In addition, the comparison of the three Pdots found that the four-arm Pdots had the smallest particle size, the best dual fluorescence performance, and the best cell imaging effect.更多还原