Interaction of Amino Acids and Graphene Oxide: Trends in Thermodynamic Properties
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- 作者：Subrata PanditMrinmoy De
- 刊名：Journal of Physical Chemistry C
- 出版年：2017
- 出版时间：January 12, 2017
- 年：2017
- 卷：121
- 期：1
- 页码：600-608
- 全文大小：608K
- ISSN：1932-7455
文摘
Recent studies on interaction of graphene oxide with proteins and peptides has attracted a lot of attention in biomedical applications. Hence, fundamental and experimental estimation of binding thermodynamics between various amino acids and graphene oxide is highly significant for many aspects. In this study, the interaction of graphene oxide (GO) with amino acids bearing variable charge, hydrophobicity, and aromatic moieties are studied by using isothermal titration calorimetry. To explore the effect of lateral size and degree of oxidation in GO, we employ two different sizes of GO. The results show that the interactions of GO with amino acids are mainly governed by electrostatic and π–π interaction with variable enthalpy and entropy values. The highest complex stability is observed in the case of tryptophan and arginine followed by other amino acids containing either positive charge or aromatic moieties. Amino acids bearing other functional groups either exhibit very weak interaction or did not show any detectable binding. This trend and origin of interaction is further confirmed by zeta potential (for cationic amino acids) and fluorescence titration assay (for aromatic amino acids). Furthermore, there is a significant enthalpy–entropy correlation between GO and amino acids that is observed with near unit slope (α = 0.87) and positive intercept (TΔS0 = 18.65). This indicates the flexible nature of GO as a receptor against small molecules. In the future, this investigation will help in designing the peptide-based receptors for GO and understanding the nature of the interaction of proteins and peptides with GO-based receptors.