LAUSR

Hydrophilic dendrimers, especially poly(amidoamine) (PAMAM) dendrimers are widely applied in modifying fluorescent dyes to endow them with water solubility and biocompatibility for biologic fluorescence imaging. Common preparation strategies of fluorescent dendrimers including encapsulating dyes or attaching dyes at periphery of dendrimers might cause uncertain constituent and lower biocompatibility. Here, we have developed a series of watersoluble fluorescent dendrimers with dye as core and fanshaped PAMAM as arms. Carboxylated perylene bisimides (PBI) dye and squarylium indocyanine (SICy) dye were conjugated with PAMAM dendrons by amidation to obtain a series of fluorescent dendrimers with enhanced water-solubility. Two PBI based dendrimers (PBI-G2.5 and PBI-G1.5) were chosen as model compounds for further optical, selfassembly and biological studies. In aqueous environment, PBI-G2.5 exhibited strong fluorescence, small size (~30 nm) and slightly positive surface charge (~2.46 mV), which are ideal for biomedical applications. In vitro assays demonstrated that PBI-G2.5 nanoparticles accumulated in the cytoplasm of HeLa cells with rapid cellular uptake. The strong fluorescence in HeLa cells remained for over 48 h. To conclude, our study provides an effective strategy for preparing water-soluble fluorescent dendrimers towards long-term live cell imaging.摘要亲水聚酰胺-胺型(PAMAM)树枝状分子能够提高荧光染料水溶性和生物相容性, 被广泛应用于生物荧光成像、药物、基因递送等 领域. 本文报道了一系列以扇形PAMAM为树枝, 以荧光染料为核的水溶性荧光树枝状分子. 扇形PAMAM树枝可通过酰胺化反应与羧基 化的苝酰亚胺(PBI)和吲哚方酸菁(SICy)染料相连. 随后, 我们进一步研究了PBI系列树枝状分子的物理性质及生物性能. PBI-G2.5具有良 好的水溶性, 强荧光发射, 并能在水中自组装形成30 nm的纳米粒子. 细胞实验表明, PBI-G2.5被细胞摄取后在细胞质富集, 且48小时后仍 可检测到强的荧光. 因此, 本合成方法可以有效制备水溶性、生物相容性良好的荧光树枝状分子, 并在长效活细胞荧光成像中有应用前景.