蛇床子素在人皮肤角质层和去角质层皮肤中的分布测定

目的:研究抗银屑病蛇床子素贴剂经皮渗透后蛇床子素在人皮肤角质层和去角质层皮肤中的分布。方法:采用了胶带剥离、皮肤萃取法分别获取了人皮肤角质层、去角质层皮肤样本,用HPLC法测定了样本中的蛇床子素含量。结果:蛇床子素在人皮肤角质层的滞留量远大于去角质层皮肤的量。结论:蛇床子素在人皮肤内的滞留量与贴剂使用的时间呈线性,药物可以缓慢地扩散到皮肤的更深层而产生缓释效果。

高良姜素的体外透皮吸收特性研究

目的:考察高良姜素的体外透皮吸收特性及不同促透剂对其透皮行为的影响,为开发以高良姜素为原料药的治疗白癜风的皮肤给药制剂提供参考。方法:采用高效液相色谱法测定高良姜素的含量。以高良姜素的累积透过量(Q)和透皮速率(J)为指标,考察接收液[20%、40%聚乙二醇400(PEG400)溶液和30%乙醇溶液]、转速(200、300、400 r/min)对高良姜素在小鼠完整皮肤中吸收的影响,考察氮酮(1%、3%、5%)、丙二醇(10%、20%、40%)单用或者联用对其促透作用。同时,考察高良姜素在大鼠和小鼠的完整皮肤、去角质层皮肤、真皮层皮肤的透过特性。结果:以接收液为40%PEG400溶液、转速为300 r/min、5%氮酮单用时,高良姜素在小鼠完整皮肤中的透过性最好,J为3.257 0μg/(cm2·h)。小鼠完整皮肤、去角质层皮肤、真皮层皮肤的J分别为2.7199、34.016、33.874μg/(cm2·h),大鼠3种皮肤的J分别为0.499 6、9.512 4、17.406μg/(cm2·h)。结论:高良姜素可以透过小鼠和大鼠的完整皮肤,但是透过量远低于去角质层皮肤和真皮层皮肤。

Lithium-assisted exfoliation of pristine graphite for few-layer graphene nanosheets

A lithium-assisted approach has been developed for the exfoliation of pristine graphite, which allows the large-scale preparation of few-layer graphene nanosheets. The process involves an unexpected physical insertion and exfoliafion, and the graphene nanosheets prepared by this method reveal undisturbed sp2-hybridized structures. A possible two-step mechanism, which involves the negative charge being trapped around the edges of the graphite layers and a subsequent lithiation process, is proposed to explain the insertion of lithium inside the graphite interlayers. If necessary, the present exfoliation can be repeated and thinner （single or 2-3 layer） graphene can be achieved on a large scale. This simple process provides an efficient process for the exfoliation of pristine graphite, which might promote the future applications of graphene.