Using Pulsed-Field Gradient Spin-Echo NMR to Determine Permeation Mechanisms in Human Stratum Corneum

使用脉冲场梯度自旋回波核磁共振确定人体角质层的渗透机制

• 批准号: 0854343
• 负责人: Annette Bunge
• 金额: $ 32万
• 依托单位: Colorado School of Mines
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-15 至 2013-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0854343&HistoricalAwards=false
• 关键词: Using; Pulsed; Field; Gradient; Spin

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).0854343BungeThe goal of this research is to study how lipophilic chemicals penetrate through the outermost layer of human skin, which is called the stratum corneum. The stratum corneum is a thin (20 to 40 um thick), composite membrane containing layers of flattened, dead skin cells called corneocytes surrounded by lipid (oily) molecules that are also organized into layers. The stratum corneum controls the rate at which many chemicals enter the body through the skin. Chemicals can penetrate the stratum corneum by two different paths: (1) through only the lipid layers, or (2) through the corneocytes and lipid layers in series. The prevailing opinion in the skin literature is that chemical penetration is restricted to the lipid layers alone, although no direct proof for this presently exists. Moreover, most arguments offered to support the claim that transport is through the lipid layers exclusively are equally applicable to the case of permeable corneocytes. The results of this research will provide direct evidence to answer the question: Can chemicals penetrate the stratum corneum through the corneocytes? The model chemical chosen for study, 2-(trifluoromethyl) benzonitrile, was selected to simulate chemicals that can penetrate the skin to produce either therapeutic or toxic effects in humans. The diffusion of this molecule in the stratum corneum will be studied using a method called pulsed-field gradient spin-echo nuclear magnetic resonance (NMR). This method measures translational molecular motion (i.e., diffusion) over short periods of time (i.e., millisecond to seconds). It also provides information about restrictive boundaries over short distances (i.e., 0.1-100 um), which will be used to distinguish diffusion through corneocytes and the lipid layers. Although this method has been used widely to study colloids and solid-state engineered materials, its use in the study of biological membranes has been limited. The new data generated in this project will improve our understanding of chemical permeation mechanisms in the stratum corneum, including how it changes with variations in water content. If diffusion within the corneocytes is shown to be a significant route for the absorption of lipophilic chemicals in human skin, the paradigm of skin science will shift, which will change existing strategies for transdermal drug delivery, treatment of skin diseases, and methods for predicting absorption of toxic chemicals through skin. The scientific challenges of using pulsed-field gradient spin-echo nuclear magnetic resonance to study diffusion in a composite medium like the stratum corneum arise in many other materials, both biological and non-biological, and the techniques used here will be applicable to these systems as well. The proposed studies of diffusion in the stratum corneum will be used to train graduate and undergraduate student researchers in the fundamentals of chemical transport in heterogeneous membranes and in applications of the pulsed-field gradient spin-echo nuclear magnetic resonance technique to materials from either biological or engineered systems that contain multiple phases. Women and other underrepresented minorities will be actively recruited into the project, which is designed to develop strong communication and organizational/management skills through experiences that are uniquely available in a research environment. In collaboration with an existing and successful outreach program at the Colorado School of Mines, the research team will develop educational modules on the topic of barrier membranes for elementary, middle and high school students and teachers.

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。0854343 Bunge这项研究的目标是研究亲脂性化学物质如何渗透到人体皮肤的最外层，这是所谓的角质层。 角质层是一层薄的（20至40 μ m厚）复合膜，包含多层扁平的死皮细胞，称为角质细胞，周围环绕着脂质（油性）分子，这些分子也组织成层。角质层控制着许多化学物质通过皮肤进入人体的速度。化学物质可以通过两种不同的途径渗透角质层：（1）仅通过脂质层，或（2）连续通过角质细胞和脂质层。皮肤文献中的流行观点是，化学渗透仅限于脂质层，尽管目前还没有直接证据证明这一点。此外，大多数支持转运仅通过脂质层的论点同样适用于渗透性角质细胞的情况。这项研究的结果将为回答这个问题提供直接的证据：化学物质能否通过角质细胞渗透到角质层？选择用于研究的模型化学品2-（三氟甲基）苯甲腈来模拟可以渗透皮肤以在人体中产生治疗或毒性作用的化学品。 将使用称为脉冲场梯度自旋回波核磁共振（NMR）的方法研究这种分子在角质层中的扩散。该方法测量平移分子运动（即，扩散）在短时间内（即，毫秒到秒）。它还提供了关于短距离限制性边界的信息（即，0.1-100 μ m），其将用于区分通过角质细胞和脂质层的扩散。虽然这种方法已被广泛用于研究胶体和固态工程材料，它的使用在生物膜的研究一直是有限的。 该项目产生的新数据将提高我们对角质层化学渗透机制的理解，包括它如何随着含水量的变化而变化。如果角质细胞内的扩散被证明是人体皮肤中亲脂性化学物质吸收的重要途径，皮肤科学的范式将发生转变，这将改变现有的经皮给药策略，皮肤疾病的治疗，以及预测有毒化学物质通过皮肤吸收的方法。使用脉冲场梯度自旋回波核磁共振来研究角质层等复合介质中扩散的科学挑战出现在许多其他材料中，包括生物和非生物材料，这里使用的技术也将适用于这些系统。角质层中扩散的拟议研究将用于培训研究生和本科生研究人员在异质膜中化学运输的基本原理和脉冲场梯度自旋回波核磁共振技术应用于包含多个阶段的生物或工程系统的材料。妇女和其他代表性不足的少数群体将积极参与该项目，该项目旨在通过研究环境中独特的经验来发展强大的沟通和组织/管理技能。该研究小组将与科罗拉多矿业学院现有的成功推广计划合作，为小学、初中和高中学生和教师开发关于屏障膜主题的教育模块。