FT-IR Spectroscopic Analysis of the Secondary Structures Present during the Desiccation Induced Aggregation of Elastin-Like Polypeptide on Silica
FT-IR Spectroscopic Analysis of the Secondary Structures Present during the Desiccation Induced Aggregation of Elastin-Like Polypeptide on Silica
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DOI：
10.1021/acsomega.0c00271
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发表时间：
2020-04-14
期刊：
影响因子：
4.1
通讯作者：
Janorkar, Amol, V
中科院分区：
文献类型：
--
作者：
Cobb, Jared S.;Zai-Rose, Valeria;Janorkar, Amol, V
在此之前，我们发现弹性蛋白样多肽（ELP），当在亲水熔融硅片上高于较低临界溶液温度干燥时，表现出动态聚结行为。ELP首先湿润二氧化硅，但在接下来的12小时内，湿润表面并形成精确大小和形状的聚集体。利用傅里叶变换红外（FT-IR）光谱，本研究探讨了ELP中二级结构在这种渐进干燥过程中的作用及其对骨料尺寸的影响。利用二阶导数法将ELP的FT-IR光谱中的酰胺I峰（1600-1700 cm(-1)）解卷积为8个子峰（1616、1624、1635、1647、1657、1666、1680、1695 cm(-1)）。根据先前对ELP和肽组成相似的分子的研究，这些峰被确定为代表延伸链、β -匝、3(10)-螺旋、脯氨酸I和脯氨酸II。各子峰、含水量和团聚体大小之间建立了正相关关系，以了解二级结构在颗粒形成中的贡献。正相关表明，与含水量无关的II型β -转体在较早的时间点（1-3.5 h）促进了团聚体的生长。在较晚的时间点（6-12 h），骨料生长归因于3（10）螺旋的形成，这依赖于含水量的减少。了解这些关系可以更好地控制创建精确尺寸的骨料和具有不同粗糙度的表面涂层。
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(-1)) 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(-1)). These peaks were identified to represent extended strands, beta-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 beta-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.