Janel Rivera-Cancel1,2,3,Nicolas Giovambattista1,2,Gustavo Lopez2,4,Xi Chen3,5,Rein Ulijn3,2
Brooklyn College1,The City University of New York Graduate Center2,Advanced Science Research Center3,Lehman College of the City University of New York4,The City College of New York5
Janel Rivera-Cancel1,2,3,Nicolas Giovambattista1,2,Gustavo Lopez2,4,Xi Chen3,5,Rein Ulijn3,2
Brooklyn College1,The City University of New York Graduate Center2,Advanced Science Research Center3,Lehman College of the City University of New York4,The City College of New York5
Water responsive (WR) materials, which can undergo reversible changes in their conformation in response to a change in the relative humidity (RH), have recently gained attention due to the opportunities for them to be used as an energy source. For example, evaporation-driven engines can be powered by WR materials to directly harvest energy from the natural evaporation of water and convert it into mechanical work and electricity. However, little is known about the mechanisms involved in these WR materials or the role of water in these systems. In particular, the effects of deuterium oxide (D<sub>2</sub>O) on the mechanical properties of WR materials and the interactions between water and biomolecules is still an open question. In this study, we compared the responsiveness of histidine-tyrosine-phenylalanine (HYF) peptide crystals to H<sub>2</sub>O and D<sub>2</sub>O and the role of nanoconfined water in the water-peptide interactions. We investigated the changes in the mechanical properties of HYF due to isotope substitution (H<sub>2</sub>O and D<sub>2</sub>O). We performed experiments using powder x-ray diffraction (PXRD), atomic force microscopy (AFM), and Fourier-transform infrared spectroscopy (FTIR) in a humidity-controlled environment with both, H<sub>2</sub>O and D<sub>2</sub>O vapor to study its RH responsiveness. We plan to complement our experiments by performing classical and path-integral molecular dynamics simulations.