Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Langmuir. 2011 Mar 1;27(5):1599-609. doi: 10.1021/la103469s. Epub 2011 Feb 3.
An aqueous solution containing photosynthetic reaction centers (RCs), membrane scaffold proteins (MSPs), phospholipids, and single-walled carbon nanotubes (SWCNTs) solubilized with the surfactant sodium cholate (SC) reversibly self-assembles into a highly ordered structure upon dialysis of the latter. The resulting structure is photoelectrochemically active and consists of 4-nm-thick lipid bilayer disks (nanodisks, NDs) arranged parallel to the surface of the SWCNT with the RC housed within the bilayer such that its hole injecting site faces the nanotube surface. The structure can be assembled and disassembled autonomously with the addition or removal of surfactant. We model the kinetic and thermodynamic forces that drive the dynamics of this reversible self-assembly process. The assembly is monitored using spectrofluorimetry during dialysis and subsequent surfactant addition and used to fit a kinetic model to determine the forward and reverse rate constants of ND and ND-SWCNT formation. The calculated ND and ND-SWCNT forward rate constants are 79 mM(-1) s(-1) and 5.4 × 10(2) mM(-1) s(-1), respectively, and the reverse rate constants are negligible over the dialysis time scale. We find that the reaction is not diffusion-controlled since the ND-SWCNT reaction, which consists of entities with smaller diffusion coefficients, has a larger reaction rate constant. Using these rate parameters, we were able to develop a kinetic phase diagram for the formation of ND-SWCNT complexes, which indicates an optimal dialysis rate of approximately 8 × 10(-4) s(-1). We also fit the model to cyclic ND-SWCNT assembly and disassembly experiments and hence mimic the thermodynamic forces used in regeneration processes detailed previously. Such forces may form the basis of both synthetic and natural photoelectrochemical complexes capable of dynamic component replacement and repair.
含有光合反应中心 (RCs)、膜支架蛋白 (MSPs)、磷脂和用表面活性剂胆酸钠 (SC) 溶解的单壁碳纳米管 (SWCNTs) 的水溶液在透析后者时可逆地自组装成高度有序的结构。所得结构具有光电化学活性，由 4nm 厚的脂质双层盘 (纳米盘，NDs) 组成，这些盘平行于 SWCNT 的表面排列，RC 位于双层内，使其注孔部位朝向纳米管表面。该结构可以通过添加或去除表面活性剂自主组装和解体。我们对驱动这种可逆自组装过程动力学的动力学和热力学力进行建模。在透析过程中以及随后添加表面活性剂时，使用荧光光谱法监测组装，并用于拟合动力学模型以确定 ND 和 ND-SWCNT 形成的正向和反向速率常数。计算得出的 ND 和 ND-SWCNT 正向速率常数分别为 79mM(-1)s(-1)和 5.4×10(2)mM(-1)s(-1)，并且在透析时间尺度上，反向速率常数可以忽略不计。我们发现该反应不是扩散控制的，因为 ND-SWCNT 反应由具有较小扩散系数的实体组成，具有更大的反应速率常数。使用这些速率参数，我们能够为 ND-SWCNT 复合物的形成开发一个动力学相图，该相图表明 ND-SWCNT 复合物的最佳透析速率约为 8×10(-4)s(-1)。我们还拟合了模型进行循环 ND-SWCNT 组装和拆卸实验，从而模拟了先前详细描述的再生过程中使用的热力学力。这些力可能构成能够进行动态组件替换和修复的合成和天然光电化学复合物的基础。
