Spin-lattice relaxation time in water/graphene-oxide dispersion

We present the results of the calculations of the spin-lattice relaxation time of water in contact with graphene oxide by means of all-atom molecular dynamics simulations. We fully characterized the water-graphene oxide interaction through the calculation of the relaxation properties of bulk water and of the contact angle as a function of graphene oxide oxidation state and comparing them with the available experimental data. We then extended the calculation to investigate how graphene oxide alters the dynamical and relaxation properties of water in different conditions and concentrations. We show that, despite the diamagnetic nature of the graphene oxide, the confining effects of the bilayers strongly affect the longitudinal relaxation properties of interfacial water, which presents a reduced dynamics due to hydrogen bonds with oxygen groups on graphene oxide. This property makes graphene oxide an interesting platform to investigate water dynamics in confined geometries and an alternative contrast-agent for magnetic resonance imaging applications, especially in view of the possibility to functionalize graphene oxide from theranostic perspectives.

Automated summary

We calculate the spin-lattice relaxation time of water in contact with graphene oxide using molecular dynamics simulations. The water-graphene oxide interaction is characterized by calculating the relaxation properties of bulk water and the contact angle, and comparing them with experimental data. The effect of graphene oxide on the dynamics and relaxation properties of water in different conditions and concentrations is investigated. Despite the diamagnetic nature of graphene oxide, the confined bilayers strongly affect the longitudinal relaxation properties of interfacial water due to hydrogen bonds with oxygen groups, making it a promising platform for studying water dynamics in confined geometries and a potential contrast-agent for MRI applications.