To enhance the bioavailability of carborane as a potential pharmacophore for BNCT, we labeled the modified o-carborane with the near-infrared dye IR775 and encapsulated it using two types of Eudragit^® (pH-sensitive and osmotic). Consequently, four separate fluorescent complexes containing carborane were acquired. To confirm the nido-carborane presence within these complexes, the distinct peak at 2510 cm⁻¹ was detected using infrared spectroscopy as a first step. The photophysical properties were observed in phosphate buffer with different pH. The UV and fluorescence spectra of the four fluorescent complexes were very similar, with the maximum absorption wavelengths centered in the range of 773–789 nm and the emission wavelengths centered in the range of 796–811 nm. Subsequently, a stable and releasing complex L100-C-IR775 was screened through zeta potential testing and simulated release experiments in the gastrointestinal environment, and spherical shape was observed by transmission electron microscopy. AFM imaging showed a relatively smooth surface with a uniform distribution of protrusions. The L100-C-IR775 was then applied to tumor cell imaging, and it was observed that it could enter into three kinds of tumor cells, A549, HCT116 and HeLa, and distribute around the nucleus. Finally, it was shown by a cell proliferation toxicity assay (CCK8) that the compound inhibited HeLa and PC-3 cells by 50 and 51% at concentrations up to 10 µg/mL. In conclusion, the carborane fluorescent complexes prepared in this paper have good biocompatibility and demonstrate toxicity toward tumor cell proliferation. Furthermore, they have the potential to serve as a carbon borane anti-tumor prodrug.

Graphical abstract

An acrylic encapsulated ionic polymer IR775@nido-carborane simulates release in the gastrointestinal environment, tumor cells imaging, and schematics of therapeutic mechanisms.

中文翻译：

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基于Eudragit®封装离子聚合物IR775@nido-carborane策略：模拟胃肠环境中的释放、生物活性和肿瘤细胞成像研究

为了提高碳硼烷作为 BNCT 潜在药效团的生物利用度，我们用近红外染料 IR775标记修饰的邻碳硼烷，并使用两种类型的 Eudragit ^®（pH 敏感型和渗透型）将其封装。因此，获得了四种单独的含有碳硼烷的荧光复合物。为了确认这些复合物中是否存在尼基碳硼烷，第一步使用红外光谱检测到2510 cm ^-1处的明显峰。在不同pH的磷酸盐缓冲液中观察其光物理性质。四种荧光配合物的紫外和荧光光谱非常相似，最大吸收波长集中在773-789 nm范围内，发射波长集中在796-811 nm范围内。随后，通过zeta电位测试和胃肠道环境模拟释放实验筛选出稳定释放的复合物L100-C-IR775，并通过透射电镜观察球形形状。 AFM 成像显示出相对光滑的表面和均匀分布的突起。随后将L100-C-IR775应用于肿瘤细胞成像，观察到它可以进入A549、HCT116和HeLa三种肿瘤细胞，并分布在细胞核周围。最后，细胞增殖毒性测定（CCK8）显示，该化合物在浓度高达 10 µg/mL 时，对 HeLa 和 PC-3 细胞的抑制分别为 50% 和 51%。总之，本文制备的碳硼烷荧光配合物具有良好的生物相容性，并且对肿瘤细胞增殖具有毒性。此外，它们有潜力作为碳硼烷抗肿瘤前药。

图形概要

丙烯酸封装的离子聚合物 IR775@nido-carborane 模拟胃肠道环境中的释放、肿瘤细胞成像和治疗机制示意图。