Kumar Krishan, Umapathi Reddicherla, Ramesh Kalyan, Hwang Seung-Kyu, Lim Kwon Taek, Huh Yun Suk, Venkatesu Pannuru
Department of Chemistry, University of Delhi, Delhi 110 007, India.
NanoBio High-Tech Materials Research Center, Department of Biological Engineering, Inha University, Incheon 22212, Republic of Korea.
Langmuir. 2021 Feb 9;37(5):1682-1696. doi: 10.1021/acs.langmuir.0c02900. Epub 2021 Jan 25.
The beguiling world of functional polymers is dominated by thermoresponsive polymers with unique structural and molecular attributes. Limited work has been reported on the protein-induced conformational transition of block copolymers; furthermore, the literature lacks a clear understanding of the influence of proteins on the phase behavior of thermoresponsive copolymers. Herein, we have synthesized poly(-isopropylacrylamide)--poly(-vinylcaprolactam) (PNIPAM--PNVCL) by RAFT polymerization using -isopropylacrylamide and -vinylcaprolactam. Furthermore, using various biophysical techniques, we have explored the effect of cytochrome (Cyt c), myoglobin (Mb), and hemoglobin (Hb) with varying concentrations on the aggregation behavior of PNIPAM--PNVCL. Absorption and steady-state fluorescence spectroscopy measurements were performed at room temperature to examine the copolymerization effect on fluorescent probe binding and biomolecular interactions between PNIPAM--PNVCL and proteins. Furthermore, temperature-dependent fluorescence spectroscopy and dynamic light scattering studies were performed to get deeper insights into the lower critical solution temperature (LCST) of PNIPAM--PNVCL. Small-angle neutron scattering (SANS) was also employed to understand the copolymer behavior in the presence of heme proteins. With the incorporation of proteins to PNIPAM--PNVCL aqueous solution, LCST has been varied to different extents owing to the preferential, molecular, and noncovalent interactions between PNIPAM--PNVCL and proteins. The present study can pave new insights between heme proteins and block copolymer interactions, which will help design biomimetic surfaces and aid in the strategic fabrication of copolymer-protein bioconjugates.
功能聚合物的迷人世界由具有独特结构和分子特性的热响应聚合物主导。关于嵌段共聚物的蛋白质诱导构象转变的报道有限；此外，文献中对蛋白质对热响应共聚物相行为的影响缺乏清晰的认识。在此，我们使用异丙基丙烯酰胺和乙烯基己内酰胺通过可逆加成-断裂链转移（RAFT）聚合合成了聚（N-异丙基丙烯酰胺）-聚（N-乙烯基己内酰胺）（PNIPAM-PNVCL）。此外，我们使用各种生物物理技术，研究了不同浓度的细胞色素c（Cyt c）、肌红蛋白（Mb）和血红蛋白（Hb）对PNIPAM-PNVCL聚集行为的影响。在室温下进行吸收和稳态荧光光谱测量，以检查共聚对荧光探针结合以及PNIPAM-PNVCL与蛋白质之间生物分子相互作用的影响。此外，进行了温度依赖性荧光光谱和动态光散射研究，以更深入地了解PNIPAM-PNVCL的低临界溶液温度（LCST）。还采用小角中子散射（SANS）来了解血红素蛋白存在下的共聚物行为。由于PNIPAM-PNVCL与蛋白质之间的优先、分子和非共价相互作用，将蛋白质加入PNIPAM-PNVCL水溶液后，LCST发生了不同程度的变化。本研究可以为血红素蛋白与嵌段共聚物相互作用提供新的见解，这将有助于设计仿生表面，并有助于共聚物-蛋白质生物共轭物的战略制造。
