Quantifying Temperature-, Pressure-, and Nuclear Quantum Effects on Hydrophobic and Hydrophilic Water-Mediated Interactions

Author

Justin T. Engstler, The Graduate Center, City University of New YorkFollow

Date of Degree

9-2023

Document Type

Thesis

Degree Name

M.S.

Program

Nanoscience

Advisor

Nicolas Giovambattista

Advisor

Michele Vittadello

Committee Members

Gustavo Lopez

Emilio Gallicchio

Subject Categories

Computational Chemistry | Nanoscience and Nanotechnology | Other Engineering Science and Materials | Physical Chemistry | Statistical, Nonlinear, and Soft Matter Physics

Abstract

Water-mediated interactions (WMIs) are responsible for diverse processes in aqueous solutions, including protein folding and nanoparticle aggregation. WMI may be affected by changes in temperature and pressure, and hence, they can alter chemical/physical processes that occur in aqueous environments. Traditionally, attention has been focused on hydrophobic interactions while, in comparison, the role of hydrophilic and hybrid (hydrophobic–hydrophilic) interactions have been mostly overlooked. Here, we study the role of T and P on the WMI between nanoscale (i) hydrophobic–hydrophobic, (ii) hydrophilic–hydrophilic, and (iii) hydrophilic–hydrophobic pairs of (hydroxylated/non-hydroxylated) graphene-based surfaces. We find that hydrophobic, hydrophilic, and hybrid interactions are all sensitive to P. However, while hydrophobic interactions [case (i)] are considerably sensitive to T variations, hydrophilic [case (ii)] and hybrid inter- actions [case (iii)] are practically T-independent. An analysis of the entropic and enthalpic contributions to the potential of mean force for cases (i)–(iii) is also presented. This study is then extended to include (via a similar analysis) the role played by nuclear quantum effects (NQE) on WMI involving the surfaces in (i) and (ii). NQE are known to bring about significant differences in different thermodynamic properties of water (e.g., compressibility, thermal expansion coefficient, density), particularly at low temperatures. However, we find that although accounting for NQE leads to little or no difference in the strength of WMI, the presence of hydrophobic or hydrophilic solutes influences ring-polymer delocalization due to NQE. Our results are important in understanding T- and P-induced protein denaturation and the interactions of biomolecules in solution, including protein aggregation and phase separation processes. From the computational point of view, the results presented here are relevant in the design of implicit water models for the study of molecular and colloidal/nanoparticle systems at different thermodynamic conditions.

Recommended Citation

Engstler, Justin T., "Quantifying Temperature-, Pressure-, and Nuclear Quantum Effects on Hydrophobic and Hydrophilic Water-Mediated Interactions" (2023). CUNY Academic Works.
https://academicworks.cuny.edu/gc_etds/5539