abstract
We investigate the intricate relationship among temperature, pH, and Brownian velocity in a range of differently sized upconversion nanoparticles (UCNPs) dispersed in water. These UCNPs, acting as nanorulers, offer insights into assessing the relative proportion of high-density and low-density liquid in the surrounding hydration water. The study reveals a size-dependent reduction in the onset temperature of liquid-water fluctuations, indicating an augmented presence of high-density liquid domains at the nanoparticle surfaces. The observed upper-temperature threshold is consistent with a hypothetical phase diagram of water, validating the two-state model. Moreover, an increase in pH disrupts the organization of water molecules, similar to external pressure effects, allowing simulation of the effects of temperature and pressure on hydrogen bonding networks. The findings underscore the significance of the surface of suspended nanoparticles for understanding high- to low-density liquid fluctuations and water behavior at charged interfaces.
authors
Fernando Eduardo Maturi
our authors
Carlos Brites
Associate Professor
Fernando Eduardo Maturi
Research Fellowship
Luís Carlos
Full professor
Ramon da Silva Raposo Filho
PhD StudentProjects
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
acknowledgements
This work was partially developed within the scope of Project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 (DOI 10.54499/UIDB/50011/2020), UIDP/50011/2020 (DOI 10.54499/UIDP/50011/2020), and LA/P/0006/2020 (DOI 10.54499/LA/P/0006/2020), financed by national funds through the FCT/MCTES (PIDDAC). This work was also financially supported by the project Shape of Water (PTDC/NAN-PRO/3881/2020) through Portuguese funds. F.E.M. acknowledges funding from the European Union’s Horizon 2020 research and innovation program under Marie Sklodowska-Curie Grant Agreement 823941 (FUNGLASS) and financial support from the FCT through Grant UI/BD/151445/2021. The authors thank Ricardo Longo (Federal University of Pernambuco), Christoph Rose-Petruck (Brown University), and Artemov Vasily (EPFL) for fruitful discussions.