In Situ Measurement of Surface Functional Groups on Silica Nanoparticles Using Solvent Relaxation Nuclear Magnetic Resonance

Abstract

In situ analysis and study on the surface of nanoparticles (NPs) is a key to obtain their important physicochemical properties for the subsequent applications. Of them, most works focus on the qualitative characterization whereas quantitative analysis and measurement on the NPs under their storage and usage conditions is still a challenge. In order to cope with this challenge, solvation relaxation-based nuclear magnetic resonance (NMR) technology has been applied to measure the wet specific surface area and, therefore, determine the number of the bound water molecules on the surface of silica NPs in solution and the hydrophilic groups of various types grafted on the surface of the NPs. By changing the surface functional group on silica particles, the fine distinction for the solvent-particle interaction with different surface group can be quantitatively differentiated by measuring the number of water molecules absorbed on the surface. The results show that the number of the surface hydroxyl, amine, and carboxyl group per nm is 4.0, 3.7, and 2.3, respectively, for the silica particles with a diameter of 203 nm. The method reported here is the first attempt to determine in situ the number of bound solvent molecules and any solvophilic groups grafted on nanoparticles.

Synergetic effect of the surface ligand and SiO2 driven photoluminescence stabilization of the CH3NH3PbBr3 perovskite magic-sized clusters

“…It is worth to noting that the α resonances has been shifted from 1.474 ppm from the CH 3 NH 3 PbBr 3 PMSCs to 1.490 ppm for CH 3 NH 3 PbBr 3 PMSCs/SiO 2 , indicating the amine-groups on the perovskite surface interact with the silica surfaces 51 . Furthermore, we have evaluated the 1 H spin–spin (T 2 ) relaxation measurement that is sensitive to the dynamically dipole–dipole interaction between molecules in solvent 46 , 52 , 53 . The T 2 relaxation time attributes to the required time of the molecules in the solution to return to an initial equilibrium state after a dynamic motion by an electromagnetic radiation 52 .…”

Plasma polymerized nanoparticles effectively deliver dual siRNA and drug therapy in vivo

“…Chemical characterization of PPNs was consistent with our previous reports on PP-derived materials 33 , 34 , confirming incorporation of elemental carbon and nitrogen into the nanoclusters followed by surface restructuring due to oxidation (Figure S1 a) and the presence of amine and carboxyl functional moieties (Figure S1 b). These surface functional groups improve surface hydrophilicity 35 , 36 , significantly increase surface reactivity and can be readily protonated (or de-protonated) in solution by changing pH 37 , allowing fine tuning of surface charge and stability in solution 27 . The versatile surface properties of PPNs facilitate robust tethering of clinically relevant molecules of various sizes, charge and chemical structures using a simple one-step incubation in aqueous solution 27 .…”

Green earth pigments dispersions: Water dynamics at the interfaces

“…aqueous suspensions of various green earth materials in the absence of any organic binder and try to better assess the links between green earth nature and the interaction of water with pigment surfaces. For reaching such an aim, we use NMR relaxometry that has proven to be an efficient tool to evaluate particle dispersions [15], [16], [17], their stability [18], [19], [20], [21], [22] and especially the interaction of the solvent with the colloidal surfaces [19], [23], [24], [25]. The sensitivity of NMR relaxation rates of the solvent to the interaction with interfaces makes it even possible to evidence the counterion specific effect with charged surfaces [26], [27].…”