Enhancing ocular uptake of thiol antioxidants with nanodiamonds

项目总结/摘要 手术是治疗白内障的唯一有效方法，白内障是世界上最常见的致盲原因。虽然 白内障手术是常规的，通常被认为是安全的，它是昂贵的，并带来严重并发症的风险 (e.g.,囊混浊或破裂）。因此，对有效的局部治疗存在很高的需求， 预防这种使人衰弱的疾病。白内障是由透镜蛋白聚集引起的，这与 一个人一生中所积累的氧化损伤。谷胱甘肽（GSH），最重要的 内源性氧化还原调节剂，高度集中在透镜中并保护免受氧化损伤。然而，在这方面， 透镜中的GSH水平随着年龄的增长而降低，使得透镜易受氧化损伤。的抗氧化剂 可以穿透眼组织，具有保护透镜蛋白和恢复GSH的潜力。2- 巯基丙酰甘氨酸（MPG），也称为硫普罗宁，是一种巯基抗氧化剂药物， 抗白内障活性。然而，当以滴眼剂形式给药时，其渗透眼组织的能力是有限的。 为了克服这个问题，我们将研究一种新型的纳米金刚石（ND）眼部给药载体， MPG的管理使用ND的原因有三个方面：（1）ND可以改善局部药物的眼部摄取， 通过在角膜表面提供持续释放来施用药物，（2）ND已显示出增强 抗氧化活性，并抑制吸附分子的光降解，从而保护MPG免受 过早氧化和失活，和（3）ND是极好的药物递送平台：它们无毒， 化学稳定，同时还表现出大的表面积质量比和高度可定制的表面化学， 优化与药物和组织在其预期目的地的相互作用。 该项目的长期目标是开发一种局部应用的制剂，可以停止或显着延迟 白内障的进展。这项拟议研究的具体目的是（1）确定最佳表面 用于增强MPG的角膜渗透的新型纳米金刚石（ND）药物递送平台的化学，（2） 以确定NDs是否可以保持或促进MPG的抗氧化功效，以及（3）调查 ND促进MPG体内抗白内障作用的功效。我们将用各种不同的 表面化学性质，并使用角膜和透镜上皮的体外模型测试它们递送MPG的能力。我们 还将研究单独的ND和与MPG复合物的抗氧化性能和光稳定性， 体外模型。为了实现第三个目标，我们将使用Emory小鼠，一种与年龄相关的核 白内障，将在白内障发展之前用含有吸附到ND的MPG的滴眼剂治疗。 我们将评估ND-MPG滴眼液预防白内障的能力，方法是通过裂隙- 在治疗过程中进行灯显微镜检查。MPG及其代谢产物2-巯基丙酸（MPA）的水平将在 在泪液和眼组织中测量以确定药物释放和渗透的程度。各种 包括GSH/GSSG比值、抗氧化酶活性和脂质过氧化在内的氧化应激标志物将 在眼组织中进行测量，以确定ND是否提高MPG的抗氧化活性。

Project Summary/ Abstract Surgery is the only effective treatment for cataract, the most common cause of blindness worldwide. Although cataract surgery is routine and generally considered safe, it is costly and carries risks of serious complications (e.g., capsular opacification or rupture). Thus, there is a high demand for an effective topical treatment that can prevent this debilitating disease. Cataract is caused by the aggregation of lens proteins, which is associated with accumulated oxidative damage that occurs throughout one’s lifetime. Glutathione (GSH), the most important endogenous redox regulator, is highly concentrated in the lens and protects against oxidative damage. However, levels of GSH in the lens decrease with age, leaving the lens vulnerable to oxidative damage. Antioxidants that can penetrate ocular tissue have the potential to protect the lens proteins and to restore GSH. 2- Mercaptopropionylglycine (MPG), also known as tiopronin, is a thiol antioxidant drug that appears to exhibit anticataract activity. However, its ability to penetrate ocular tissues when administered in eye drop form is limited. To overcome this problem, we will investigate a novel nanodiamond (ND) drug delivery vehicle for ocular administration of MPG. The reasons for ND use are three-fold: (1) NDs can improve ocular uptake of topically administered drugs by providing sustained release on the corneal surface, (2) NDs have been shown to enhance antioxidant activity and suppress photodegradation of the adsorbed molecules, thereby protecting MPG from premature oxidation and inactivation, and (3) NDs are excellent drug delivery platforms: they are non-toxic and chemically stable, while also exhibiting large surface area-to-mass and highly tailorable surface chemistry for optimization of interactions with drugs and tissues at their intended destination. The project’s long-term goal is to develop a topically applied formulation that can halt or significantly delay progression of cataracts. The Specific Aims of this proposed research are (1) to determine the optimal surface chemistry of the novel nanodiamond (ND) drug delivery platform for enhancing corneal penetration of MPG, (2) to determine whether NDs can preserve or promote the antioxidant efficacy of MPG, and (3) to investigate the efficacy of NDs for promoting the anticataract effects of MPG in vivo. We will characterize NDs with various surface chemistries and test their ability to deliver MPG using in vitro models of corneal and lens epithelium. We will also investigate antioxidant properties and photostability of NDs alone and in complexes with MPG in both in vitro models. To accomplish the third aim, we will use the Emory mouse, a model of age-related nuclear cataracts, which will be treated with eye drops containing MPG adsorbed to NDs prior to cataract development. We will evaluate the ability of ND-MPG eye drops to prevent cataracts by monitoring cataract formation via slit- lamp microscopy during treatment. Levels of MPG and its metabolite 2-mercaptopropionic acid (MPA), will be measured in tear fluid and ocular tissues to determine the extent of drug release and penetration. Various markers of oxidative stress including GSH/GSSG ratio, antioxidant enzyme activities, and lipid peroxidation will be measured in the ocular tissues to determine if ND improve antioxidant activity of MPG.