驻极体在药物经皮给药中的应用及研究进展

药物经皮吸收的独特优势使其具有良好的应用前景,并成为目前药物制剂的研究热点之一。为了克服皮肤的天然屏障功能,药学工作者研究了很多物理学、化学和药剂学促渗技术,以提高药物的经皮渗透和经皮吸收。 驻极体是一类具有永久保持电极化状态的功能电介质材料,其产生的静电场和微电流可以作为物理促渗源用于提高药物经皮吸收。本文主要综述驻极体经皮促渗作用、机制、影响因素和目前研究进展。     

Heat-treated membranes with bioelectricity promote bone regeneration

The barrier membranes maintain a secluded space to prevent the ingrowth of connective tissue and direct the growth of new bone into a desired site; however, they do not stimulate or induce bone regeneration. To enhance the bone bioactivities of membranes, we developed chitosan electret membranes with bioelectricity by grid-controlled constant voltage corona charging. The electret membranes charged with heat treatment (HT electret membranes) exhibited superior electret charge storage stability than the ones charged without heat treatment (RT electret membranes). Human bone marrow stromal cells (hBMSCs) demonstrated better growth on HT electrets membrane. Moreover, hBMSCs osteoblastic differentiation was enhanced on HT electret membranes, as evidenced by osteocalcin and osteopontin expression as assessed by immunocytochemistry, quantitative RT-PCR and western blot analysis. The rabbit calvarial defect model demonstrated that HT electret membranes induced a significantly enhanced bone regeneration compared with RT electret membranes. New bone formation was found at both the periphery and in the center of the defects four weeks after implantation. These results indicated that the chitosan electret membrane has osteogenic potential and could be applied as a novel barrier membrane.     

负极性驻极体对胰岛素介电特性及降糖效果的影响

目的 研究负极性驻极体外静电场对胰岛素介电特性和结构的影响,观察经电场作用的胰岛素的降糖效果。方法 采用栅压电晕充电系统将聚丙烯膜制备成－500、－1 000、－1 500 V的负极性驻极体,分别作用于胰岛素,使用补偿法测量实验各驻极体在48 h内的等效表面电位,通过介电常数d₃₃测量胰岛素的极化规律与外静电场的关系,采用核磁共振和凝胶电泳检测外静电场对胰岛素分子结构的影响。将经不同表面电位负极性驻极体作用12 h的胰岛素溶液注入糖尿病大鼠体内,观察驻极体作用后胰岛素的降糖效果。结果 不同表面电位负极性驻极体作用胰岛素溶液48 h时,0～4 h内胰岛素溶液两侧的电位差均随时间延长呈指数规律上升,4 h后逐渐趋于恒定。－500、－1 000和－1 500 V驻极体作用胰岛素贴剂12 h时d₃₃值相比无驻极体静电场作用分别提高了14.7倍、26.7倍和45.0倍,12 h后趋于稳定。经外电场作用后胰岛素的空间结构没有发生明显变化,而大部分基团的氢键含量减少;胰岛素结构中单聚体的比例提高,主要以单聚体和二聚体的形式存在。－500 V和－1 000 V驻极体作用胰岛素治疗组处理8 h时大鼠的血糖含量与无驻极体作用胰岛素组相比分别下降了50.9%和22.1%（P<0.05）,具有良好的降糖效果。结论 负极性驻极体可进一步改善胰岛素的降糖效果。     

驻极体改善小鼠皮肤微循环的研究

本文通过聚丙烯(PP)驻极体对小鼠局部皮肤微循环进行研究,结果表明,驻极体能使微静脉扩张,微动脉和微静脉的血流速度加快,毛细血管及微动脉血流改善。驻极体具有改善局部微循环的作用,用于改善局部支肤微循环的最佳注极电位在700伏左右。     

Folding of electrostatically charged beads-on-a-string as an experimental realization of a theoretical model in polymer science

The “beads-on-a-string” model for folding of polymers is a cornerstone of theoretical polymer science. This communication describes a physical model of beads-on-a-string, based on the folding of flexible strings of electrostatically charged beads in two dimensions. The system comprises millimeter-scale Teflon and Nylon-6,6 (spherical or cylindrical) beads (≈ 6 mm in diameter) separated by smaller (≈3 mm) poly(methyl methacrylate) (PMMA) spherical beads, threaded on a flexible string. The smaller, uncharged beads define the distances between the larger beads, and control the flexibility of the string. During agitation of the sequence of beads on a planar, horizontal paper surface, tribocharging generates opposite electrostatic charges on the larger Nylon and Teflon beads, but leaves the smaller PMMA beads essentially uncharged; the resulting electrostatic interactions cause the string to fold. Examination and comparison of two models—one physical and one theoretical—may offer a new approach to understanding folding, collapse, and molecular recognition at an abstract level, with particular opportunity to explore the influence of the flexibility of the string and the shape of the beads on the pattern and rate of folding. The physical system is, thus, an analog computer, simulating the theoretical beads-on-a-string model in two dimensions; this system makes it possible to test hypotheses connecting “sequence” to “folding”, rapidly and conveniently, while exploring nonlinearities and other complexities omitted from the theoretical model.