Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, Maryland 20850, United States.
University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250, United States.
Mol Pharm. 2024 Feb 5;21(2):791-800. doi: 10.1021/acs.molpharmaceut.3c00916. Epub 2024 Jan 11.
Studies on the biological performance of nanomedicines have been increasingly focused on the paradigm shifting role of the protein corona, which is imminently formed once the formulation is placed in a complex physiological environment. This phenomenon is predominantly studied in the context of protein adsorption science, while such interactions for water-soluble systems remain virtually unexplored. In particular, the importance of plasma protein binding is yet to be understood for pharmaceuticals designed on the basis of supramolecular architectures, which generally lack well-defined surfaces. Water-soluble ionic polyphosphazenes, clinically proven immunoadjuvants and vaccine delivery vehicles, represent an example of a system that requires supramolecular coassembly with antigenic proteins to attain an optimal immunopotentiating effect. Herein, the self-assembly behavior and stability of noncovalently bound complexes on the basis of a model antigen─hen egg lysozyme─and polyphosphazene adjuvant are studied in the presence of plasma proteins utilizing isothermal calorimetry, asymmetric flow field flow fractionation, dynamic light scattering, and size exclusion chromatography methods. The results demonstrate that although plasma proteins, such as human serum albumin (HSA), show detectable avidity to polyphosphazene, the strength of such interactions is significantly lower than that for the model antigen. Furthermore, thermodynamic parameters indicate different models of binding: entropy driven, which is consistent with the counterion release mechanism for albumin versus electrostatic interactions for lysozyme, which are characterized by beneficial enthalpy changes. In vitro protein release experiments conducted in Franz diffusion cells using enzyme-linked immunoassay detection suggest that the antigen-adjuvant complex stability is not adversely affected by the presence of the most physiologically abundant protein, which confirms the importance of the delivery modality for this immunoadjuvant. Moreover, HSA shows an unexpected stabilizing effect on complexes with high antigen load─an important consideration for further development of polyphosphazene adjuvanted vaccine formulations and their functional assessment.
纳米医学的生物性能研究越来越关注蛋白质冠的范式转变作用，一旦制剂置于复杂的生理环境中，就会立即形成这种现象。这种现象主要在蛋白质吸附科学的背景下进行研究，而对于水溶性体系的这种相互作用则几乎没有探索。特别是，对于基于超分子结构设计的药物，其血浆蛋白结合的重要性尚待理解，因为这些药物通常缺乏明确的表面。水溶性离子型聚膦嗪，已在临床上被证明是免疫佐剂和疫苗递送载体，是一个需要与抗原性蛋白质进行超分子共组装以达到最佳免疫增强效果的系统的例子。在此，利用等温量热法、不对称流场流分离、动态光散射和尺寸排阻色谱法，研究了基于模型抗原——鸡卵溶菌酶和聚膦嗪佐剂的非共价结合复合物在血浆蛋白存在下的自组装行为和稳定性。结果表明，尽管血浆蛋白（如人血清白蛋白（HSA））对聚膦嗪表现出可检测的亲和力，但这种相互作用的强度明显低于模型抗原。此外，热力学参数表明存在不同的结合模型：熵驱动，这与白蛋白的抗衡离子释放机制一致，而对于溶菌酶，则是由有利的焓变特征的静电相互作用。在 Franz 扩散细胞中进行的体外蛋白释放实验，使用酶联免疫吸附检测法进行，表明抗原-佐剂复合物的稳定性不受最生理丰富的蛋白质的存在的不利影响，这证实了这种免疫佐剂的递药方式的重要性。此外，HSA 对高抗原负载的复合物表现出出乎意料的稳定作用——这是进一步开发聚膦嗪佐剂疫苗制剂及其功能评估的重要考虑因素。
