Cobb Jared S, Zai-Rose Valeria, Correia John J, Janorkar Amol V
Department of Biomedical Materials Science, School of Dentistry and Department of Cell and Molecular Biology, School of Medicine, University of Mississippi Medical Center, 2500 North State Street, Jackson, Mississippi 39216, United States.
ACS Omega. 2020 Apr 3;5(14):8403-8413. doi: 10.1021/acsomega.0c00271. eCollection 2020 Apr 14.
Previously, we found that elastin-like polypeptide (ELP), when dried above the lower critical solution temperature on top of a hydrophilic fused silica disk, exhibited a dynamic coalescence behavior. The ELP initially wet the silica, but over the next 12 h, dewett the surface and formed aggregates of precise sizes and shapes. Using Fourier-transform infrared (FT-IR) spectroscopy, the present study explores the role of secondary structures present in ELP during this progressive desiccation and their effect on aggregate size. The amide I peak (1600-1700 cm) in the ELP's FT-IR spectrum was deconvoluted using the second derivative method into eight subpeaks (1616, 1624, 1635, 1647, 1657, 1666, 1680, 1695 cm). These peaks were identified to represent extended strands, β-turns, 3(10)-helix, polyproline I, and polyproline II using previous studies on ELP and molecules similar in peptide composition. Positive correlations were established between the various subpeaks, water content, and aggregate size to understand the contributions of the secondary structures in particle formation. The positive correlations suggest that type II β-turns, independent of the water content, contributed to the growth of the aggregates at earlier time points (1-3.5 h). At later time points (6-12 h), the aggregate growth was attributed to the formation of 3(10)-helices that relied on a decrease in water content. Understanding these relationships gives greater control in creating precisely sized aggregates and surface coatings with varying roughness.
此前，我们发现，当类弹性蛋白多肽（ELP）在亲水性熔融石英盘上方的下临界溶液温度以上干燥时，会表现出动态聚结行为。ELP最初会润湿二氧化硅，但在接下来的12小时内，会使表面去湿并形成精确尺寸和形状的聚集体。本研究使用傅里叶变换红外（FT-IR）光谱，探讨了ELP在这种渐进干燥过程中二级结构的作用及其对聚集体尺寸的影响。使用二阶导数方法将ELP的FT-IR光谱中的酰胺I峰（1600 - 1700 cm）解卷积为八个子峰（1616、1624、1635、1647、1657、1666、1680、1695 cm）。利用先前对ELP和肽组成相似分子的研究，确定这些峰分别代表伸展链、β-转角、3(10)-螺旋、多聚脯氨酸I和多聚脯氨酸II。在各个子峰、含水量和聚集体尺寸之间建立了正相关关系，以了解二级结构在颗粒形成中的作用。正相关表明，与含水量无关，II型β-转角在早期时间点（1 - 3.5小时）有助于聚集体的生长。在后期时间点（6 - 12小时），聚集体的生长归因于依赖于含水量降低的3(10)-螺旋的形成。了解这些关系有助于更好地控制创建具有精确尺寸的聚集体以及具有不同粗糙度的表面涂层。
