Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA.
Ann Biomed Eng. 2011 Aug;39(8):2242-51. doi: 10.1007/s10439-011-0323-4. Epub 2011 May 10.
There is growing recognition that lipids play key roles in ion channel physiology, both through the dynamic formation and dissolution of lipid ion channels and by indirect regulation of protein ion channels. Because existing technologies cannot rapidly modulate the local (bio)chemical conditions at artificial bilayer lipid membranes used in ion channel studies, the ability to elucidate the dynamics of these lipid-lipid and lipid-protein interactions has been limited. Here we demonstrate a microfluidic system supporting exceptionally rapid perfusion of reagents to an on-chip bilayer lipid membrane, enabling the responses of lipid ion channels to dynamic changes in membrane boundary conditions to be probed. The thermoplastic microfluidic system allows initial perfusion of reagents to the membrane in less than 1 s, and enables kinetic behaviors with time constants below 10 s to be directly measured. Application of the platform is demonstrated toward kinetic studies of ceramide, a biologically important lipid known to self-assemble into transmembrane ion channels, in response to dynamic treatments of small ions (La(3+)) and proteins (Bcl-x(L) mutant). The results reveal the broader potential of the technology for studies of membrane biophysics, including lipid ion channel dynamics, lipid-protein interactions, and the regulation of protein ion channels by lipid micro domains.
越来越多的人认识到，脂质在离子通道生理学中起着关键作用，既可以通过动态形成和溶解脂质离子通道，也可以通过间接调节蛋白质离子通道来实现。由于现有的技术无法快速调节用于离子通道研究的人工双层脂质膜中的局部（生物）化学条件，因此限制了阐明这些脂质-脂质和脂质-蛋白质相互作用的动态性。在这里，我们展示了一种支持对芯片上双层脂质膜进行极快试剂灌注的微流控系统，从而能够探测脂质离子通道对膜边界条件动态变化的响应。热塑性微流控系统允许在不到 1 秒的时间内将试剂初始灌注到膜中，并能够直接测量时间常数低于 10 秒的动力学行为。该平台的应用通过对生物上重要的脂质神经酰胺的动力学研究得到了证明，神经酰胺在响应于小离子（La3+）和蛋白质（Bcl-xL突变体）的动态处理时，会自组装成跨膜离子通道。结果表明，该技术具有更广泛的研究膜生物物理学的潜力，包括脂质离子通道动力学、脂质-蛋白质相互作用以及脂质微区对蛋白质离子通道的调节。
