摘要/Abstract
远红/近红外(FR/NIR)发射荧光材料因其在生物成像领域的巨大应用潜力而受到广泛关注. 然而, 根据“能隙”规则, 电子带隙减小时, 非辐射失活途径占据能量耗散主导地位, 因此制备高量子产率、长发射波长的有机FR/NIR材料仍然是一个挑战. 本文通过引入扭曲构象基团(四苯基乙烯)对分子聚集态进行调控, 合成了一系列基于苯并硒二唑的供体-受体-供体(D-A-D)型化合物. 化合物TPE-DPA-Se在纳米粒子状态下表现出明亮的荧光发射, 其量子产率可高达16.48%, 证明其在水体系中仍具有良好的发射性能, 适用于多个领域. 本研究进一步证实了其优秀的细胞成像能力, 并将其成功地应用于荧光成像引导的手术导航, 特别是微小转移瘤的术中检测.
关键词: 聚集诱导发光, 远红/近红外, 纳米粒子, 细胞成像, 手术导航
Far red/near infrared (FR/NIR) materials have attracted wide attention due to their great potential in various applications, particularly in bio-imaging. However, it is still a challenge to manufacture organic FR/NIR materials with quite high efficiency and long emission wavelength, owing to the dominance of non-radiative deactivation in the dissipation of absorbed light excitation energy when the electronic bandgap decreases. Herein, a series of donor-acceptor-donor (D-A-D) type compounds based on benzoselenidazole are developed through the regulation of molecular aggregation states by twisted conformation groups. In one hand, the compound TPE-DPA-Se (tetraphenylethylene-diphenylamine-benzoselenidazole) exhibits the best aggregation-induced emission (AIE) properties among these compounds. In another hand, the obtained TPE-DPA-Se showed over 150 nm Stokes shift, which can be used to avoid the interference between excitation and emission light, as well as the near-infrared emission spectrum away from the organism auto-fluorescence, which was beneficial for the bio-application. Next, density functional theory (DFT) calculation was carried out with Gaussian 09W program at B3LYP/6-31G** level to determine the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) distributions and the optimized structures of these compounds. Then TPE-DPA-Se was formulated into nanoparticles by nanoprecipitation method with an amphiphilic co-polymer 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N- [methoxy(polyethylene glycol)-2000] (MPEG2000-DSPE) as the doping matrix. TPE-DPA-Se exhibited excellent aqueous diameter stability in nanoparticle-state, as well as impressive luminescence in aqueous system with higher efficiency of up to 16.48%, which are suitable for many fields. To evaluate the biocompatibility of the TPE-DPA-Se NPs, we further carried out 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity assay. The result indicated their negligible toxicity. Encouraged by the excellent performance of these luminogens in nanoparticle state, a successful 4T1 cells imaging was demonstrated. Next, to set up the tumor-bearing mouse model, the luciferase-expressed 4T1 cancer cells were injected into the healthy mice via intraperitoneal injection. After about 7 days, the abdominal metastatic tumors were formed with many nodules in the abdominal cavity. The fluorescent image can merged with bioluminescence image completely and image-guided tumor resection is verified in this work, particularly for the micro-sized tumor of intraoperative detection.
Key words: aggregation-induced emission, far red/near-infrared, nanoparticles, cell imaging, surgical navigation
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