Nanocarriers protect the payload from degradation and enable specific targeting of the diseased tissue, thus reducing systemic toxicity. So, it is crucial and desirable to design a nanocarrier with specific nano-architectures that possess those essential characteristics. Considering the above aspects, we report the one-pot synthesis and self-assembly of oligoglycerol-based amphiphilic dendronized polythiourethanes consisting of an aliphatic or aromatic linker. During the ring opening of cyclodithiocarbonate, the generated thiols were utilized to conjugate first or zeroth-generation oligoglycerol dendrons (containing four or two hydroxyl groups) in one pot. Among them, the aromatic linker containing polymer ARM-PTU-G₁-OH had a higher encapsulation ability for hydrophobic dyes (pyrene and Nile red) than the other aliphatic linker containing polymer ALP-PTU-G₁-OH. Both the polymers had hydrodynamic diameters of 167 nm with PDI = 0.314–0.326. In addition, AFM results showed that ALP-PTU-G₁-OH and ARM-PTU-G₁-OH formed spherical aggregates with diameters of 136 ± 28 nm and 161 ± 35 nm, respectively. The formation of polymersomes was probed by encapsulating the hydrophilic dye calcein. Both the polymers were able to encapsulate calcein. Among them, the aromatic linker-containing polymer had 31% encapsulation efficiency, whereas the aliphatic linker-containing polymer had 14% encapsulation efficiency. To understand the stability of the polymersomes, a FRET study was performed by encapsulating DiO and DiI dyes individually in both the polymersomes, and then mixing and studying the evolution of FRET with time. The results showed that the mechanism of dye exchange was different for both polymers, and the aromatic linker containing polymersome had better stability during dye exchange. A few parameters were calculated by fitting the change in donor emission intensity with time, and it showed that in ARM-PTU-G₁-OH dye exchange occurred via a slow merging and splitting mechanism. In contrast, in ALP-PTU-G₁-OH, a fast expulsion and insertion mechanism was mainly operative.

中文翻译：

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芳香族与脂肪族接头：对寡甘油衍生的树枝状化聚合物体中染料负载量和稳定性的影响


纳米载体保护有效载荷不被降解，并能够特异性靶向病变组织，从而降低全身毒性。因此，设计具有具有这些基本特性的特定纳米结构的纳米载体至关重要且可取。考虑到上述方面，我们报道了由脂肪族或芳香族接头组成的基于寡甘油的两亲性树枝化聚硫脲烷的单锅法合成和自组装。在环二硫代碳酸酯的开环过程中，生成的硫醇被用来在一个罐中偶联第一代或第九代寡甘油树枝状（包含四个或两个羟基）。其中，含有聚合物 ARM-PTU-G_1-OH 的芳香族接头对疏水性染料（芘和尼罗红）的包封能力高于其他含有聚合物 ALP-PTU-G_1-OH 的脂肪族接头。两种聚合物的流体动力学直径均为 167 nm，PDI = 0.314–0.326。此外，AFM 结果表明，ALP-PTU-G_1-OH 和 ARM-PTU-G_1-OH 形成直径分别为 136 ± 28 nm 和 161 ± 35 nm 的球形聚集体。通过封装亲水性染料钙黄绿素来探测聚合物体的形成。两种聚合物都能够封装钙黄绿素。其中，含芳香族接头的聚合物的包埋效率为 31%，而含脂肪族接头的聚合物的包埋效率为 14%。为了了解聚合物体的稳定性，通过将 DiO 和 DiI 染料分别封装在两个聚合物体中，然后混合并研究 FRET 随时间的演变，进行了 FRET 研究。 结果表明，两种聚合物的染料交换机制不同，含有聚合物体的芳香族接头在染料交换过程中具有更好的稳定性。通过拟合供体发射强度随时间的变化计算了一些参数，结果表明在 ARM-PTU-G_中，1-OH 染料交换是通过缓慢的合并和分裂机制发生的。相比之下，在 ALP-PTU-G_1-OH 中，主要起作用的是快速排出和插入机制。