Donsmark Jesper, Jorgensen Lene, Mollmann Susanne, Frokjaer Sven, Rischel Christian
Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
Pharm Res. 2006 Jan;23(1):148-55. doi: 10.1007/s11095-005-8636-3. Epub 2006 Nov 30.
The adsorption of insulin at an oil-water interface was studied with fluorescence correlation spectroscopy (FCS). FCS is able to measure diffusion properties of insulin at nanomolar concentrations, making it possible to detect the very early steps in the adsorption process. Below 20 nM bulk insulin concentration, the insulin molecules adsorbed to the surface diffuse freely at all times during the experiment (a few hours). At higher concentrations, a surprisingly abrupt transition to a slow diffusion phase is observed. Based on the information about both diffusion times and molecular brightness derived from the FCS experiments, we suggest that the transition represents the formation of a fractal network. FCS may be a valuable tool in pharmaceutical formulation science, because it provides information about concentration buildup and phase changes at interfaces formed in drug delivery systems.
采用荧光相关光谱法（FCS）研究胰岛素在油水界面的吸附情况。FCS能够测量纳摩尔浓度下胰岛素的扩散特性，从而能够检测吸附过程中非常早期的步骤。在本体胰岛素浓度低于20 nM时，吸附到表面的胰岛素分子在实验过程（数小时）中始终自由扩散。在较高浓度下，观察到向缓慢扩散阶段的惊人突然转变。基于FCS实验得出的扩散时间和分子亮度信息，我们认为这种转变代表了分形网络的形成。FCS可能是药物制剂科学中的一种有价值的工具，因为它提供了有关药物递送系统中形成的界面处浓度积累和相变的信息。
