Wilcox Kathryn G, Yamagami Kai R, Roopnarine Brittany K, Linscott Adam, Morozova Svetlana
Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States.
ACS Polym Au. 2023 Dec 26;4(2):109-119. doi: 10.1021/acspolymersau.3c00027. eCollection 2024 Apr 10.
Gels are key materials in biological systems such as tissues and may control biocondensate formation and structure. To further understand the effects of elastic environments on biomacromolecular assembly, we have investigated the phase behavior and radii of complex coacervate droplets in polyacrylamide (PAM) networks as a function of gel modulus. Poly-l-lysine (PLL) and sodium hyaluronate (HA) complex coacervate phases were prepared in PAM gels with moduli varying from 0.035 to 15.0 kPa. The size of the complex coacervate droplets is reported from bright-field microscopy and confocal fluorescence microscopy. Overall, the complex coacervate droplet volume decreases inversely with the modulus. Fluorescence microscopy is also used to determine the phase behavior and concentration of fluorescently tagged HA in the complex coacervate phases as a function of ionic strength (100-270 mM). We find that the critical ionic strength and complex coacervate stability are nonmonotonic as a function of the network modulus and that the local gel concentration can be used to control phase behavior and complex coacervate droplet size scale. By understanding how elastic environments influence simple electrostatic assembly, we can further understand how biomacromolecules exist in complex, crowded, and elastic cellular environments.
凝胶是诸如组织等生物系统中的关键材料，可能控制生物凝聚物的形成和结构。为了进一步了解弹性环境对生物大分子组装的影响，我们研究了聚丙烯酰胺（PAM）网络中复合凝聚液滴的相行为和半径与凝胶模量的关系。在模量从0.035到15.0 kPa变化的PAM凝胶中制备了聚-L-赖氨酸（PLL）和透明质酸钠（HA）复合凝聚相。通过明场显微镜和共聚焦荧光显微镜报告复合凝聚液滴的大小。总体而言，复合凝聚液滴体积与模量成反比减小。荧光显微镜还用于确定复合凝聚相中荧光标记的HA的相行为和浓度与离子强度（100 - 270 mM）的关系。我们发现临界离子强度和复合凝聚稳定性作为网络模量的函数是非单调的，并且局部凝胶浓度可用于控制相行为和复合凝聚液滴尺寸尺度。通过了解弹性环境如何影响简单的静电组装，我们可以进一步了解生物大分子如何存在于复杂、拥挤和有弹性的细胞环境中。
