Ophthalmic formulation of methotrexate: a strategy of using the self-assembled LacAC4A nanoparticles for non-invasive drug delivery to the ocular posterior segment

Drug delivery to ocular posterior segment remains difficult due to the challenges imposed by dynamic and static ocular barriers, lesion point targeting, and off-target effect. In this study, a novel approach is demonstrated for non-invasive drug delivery to the ocular posterior segments using lactose-modified azocalix[4] arene (LacAC4A) as a supramolecular ocular drug delivery platform. LacAC4A contains azo groups and is covalently modified by lactose groups, which confers active targeting to the retina, and induces a hypoxic response. The immunomodulator methotrexate (MTX), which is commonly used in ophthalmology to treat immune system diseases such as uveitis, was also selected as a guest to prepare MTX@LacAC4A. The prepared LacAC4A and MTX@LacAC4A systems were characterized, then the internalization mechanisms and hypoxia response abilities were determined through flow cytometry and fluorescence imaging, respectively. Besides, the delivery route and efficiency were verified, and the safety profile of MTX@LacAC4A was evaluated in multiple dimensions. Importantly, it was found that the prepared MTX@LacAC4A exhibits good biocompatibility, can effectively reach the posterior segment, and demonstrates potential ophthalmic applications. These findings lay the grounds for the future development of non-invasive ocular posterior segment disease treatments based on the advanced use of LacAC4A as a drug delivery platform.

由于眼部动态与静态屏障、病灶靶向难题以及脱靶效应带来的多重挑战，眼后段药物递送始终面临诸多难点。本研究报道了一种无创眼后段药物递送的新型策略，以乳糖修饰偶氮杯[4]芳烃（lactose-modified azocalix[4]arene，LacAC4A）作为超分子眼部药物递送平台。LacAC4A含有偶氮基团，并经乳糖基团共价修饰，可赋予其视网膜主动靶向能力并诱发缺氧响应。本研究选取眼科领域常用于治疗葡萄膜炎等免疫性疾病的免疫调节剂甲氨蝶呤（methotrexate，MTX）作为客体分子，制备得到MTX@LacAC4A复合物。对所制备的LacAC4A及MTX@LacAC4A体系进行了表征，并分别通过流式细胞术（flow cytometry）与荧光成像（fluorescence imaging）探究了其细胞内化机制与缺氧响应能力。此外，本研究验证了该递送体系的转运路径与递送效率，并从多维度评估了MTX@LacAC4A的安全性。重要研究结果表明，所制备的MTX@LacAC4A具备良好的生物相容性，可有效抵达眼后段，展现出可观的眼科应用潜力。本研究成果为后续以LacAC4A作为药物递送平台开发无创眼后段疾病治疗手段奠定了坚实基础。