Supramolecular Formation, Complexation and Dynamics in Colloidal Polyelectrolyte-Surfactant Complexes

本项目将重点研究可溶性胶体聚电解质表面活性剂配合物（CPSCs）。胶体颗粒与浓缩和封装的聚电解质（如DNA片段）的复杂形成和超分子组装需要引入更具挑战性的表面活性剂性质和表面活性剂分子拓扑结构的设计。提出了星形三臂表面活性剂，它由亲水性块、带电可溶性块和附加的可生物降解和柔性疏水块(B)组成，具有在疏水和亲水环境中都具有胶束形成特性的通用表面活性剂的潜力。动力学处理是操纵由于强静电相互作用而形成的络合物的基本要素。结合过程的时间分辨观察对于更好地理解C-PSC超分子形成机制具有重要作用。表面活性剂中可生物降解的疏水块(B)将被设计成具有多种有用的功能。它可以修饰PSC片段的疏水表面。因此，CPSC可以设计成可溶于水和疏水环境。PSC表面疏水和亲水二元链的存在可以增加对CPSC中聚电解质（例如DNA）的保护。此外，可生物降解的块将被设计成使CPSCs不稳定，以最终释放聚电解质。星形三臂表面活性剂已合成。基础研究将侧重于(i)这种新型表面活性剂在选择性溶剂中的胶束化，（ii）它们与聚电解质在水和疏水环境中的定向络合物形成，以及（iii） CPSCs的分解，根据(a)表面活性剂的形态和结构，包括三个块的化学组成，总块长度和块比，(b) pH值，(c)离子强度，(d)反离子的性质，以及溶剂的质量、浓度和温度。本研究涉及利用表面活性剂进行疏水和静电相互作用，对聚电解质缩合和包封的微相行为进行科学研究。这一发现将为设计更好的多电解质载体，特别是DNA片段载体提供新的途径。这可能会对嵌段共聚物作为基因和药物传递载体的使用产生影响，基于线圈到球体的转变以及更复杂的嵌段共聚物与相反电荷的聚电解质的自组装。从聚合物科学的角度来看，它对体外非病毒基因治疗应用的生物学意义尤其丰富。更广泛的影响该方法在药物和基因传递以及组织工程方面具有实际应用的潜力。这些都是重要的主题，可以利用我们在材料科学方面的知识，将其应用于生物学和医学。此外，该项目在聚合物合成（化学）、聚合物加工（工程）和表征（物理）以及具有特定时点目标的聚合物理论等学科之间有着独特而自然的联系。这片肥沃的土地吸引着从高中生到博士后的下一代科学家和工程师。

The emphasis in this project will be on soluble colloidal polyelectrolyte-surfactant complexes (CPSCs). The complex formation and supra-molecular assembly of colloidal particles with condensed and encapsulated polyelectrolytes, e.g., DNA fragments, require the introduction of more challenging designs on the nature of the surfactant and the surfactant molecular topology. Star tri-arm surfactants are proposed which consist of a hydrophilic block , a charged soluble block, and an additional biodegradable and flexible hydrophobic bloc (B), and which have the potential of being universal surfactants having micelle formation properties in both hydrophobic and hydrophilic environments. Kinetic processing is an essential element to manipulate the complex formation due to strong electrostatic interactions. Time-resolved observation of the binding process should play an important role in reaching a better understanding of the mechanism of C-PSC supra-molecular formation. The biodegradable hydrophobic block (B) in the surfactant will be designed to serve several useful functions. It can modify the hydrophobic surface of the PSC segments. The CPSC can thus be designed to be soluble in both the aqueous and hydrophobic environments. The presence of a duality of hydrophobic and hydrophilic chains on the PSC surface could increase the protection for the polyelectrolyte (e.g., DNA) in the CPSC. Furthermore the biodegradable block will be designed to destabilize the CPSCs for eventual release of the polyelectrolyte. Star tri-armed surfactants have synthesized . Fundamental studies will be carried out with emphasis on (i) the micellization of this new type of surfactants in selective solvents, (ii) their directed complex formation with polyelectrolytes in aqueous and hydrophobic environments, and (iii) the disassembly of CPSCs, in terms of (a) surfactant morphology and architecture, including chemical composition of the three blocks, total block length, and block ratio, (b) pH, (c) ionic strength, (d) the nature of counter ions, as well as solvent quality, concentration and temperature. Intellectual MeritThe proposed study deals with scientific investigations on the micro-phase behavior of polyelectrolyte condensation and encapsulation, using surfactants that can undergo hydrophobic and electrostatic interactions. The findings should provide new pathways on the design of better carriers for polyelectrolytes in general and for DNA fragments in particular. It could have an impact on the use of block copolymers as vehicles for gene and drug delivery, based on the coil-to-globule transition and the self-assembly of more complex block copolymers with oppositely charged polyelectrolyte. Its biological implication for in-vitro non-viral gene therapy applications could be especially fruitful from the polymer science viewpoint.Broader ImpactsThe proposed approach has potential for practical applications to drug and gene delivery, as well as tissue engineering. These are important topics that can take advantage of our knowledge in materials science for applications to biology and medicine. Furthermore, the project has unique and natural connections among the disciplines of polymer synthesis (chemistry), polymer processing (engineering) and characterization (physics), as well as polymer theory with specific timely objectives. The fertile grounds are appealing subject matters for the next generation of scientists and engineers, from high school to post-doctoral students.