Nondestructive Monitoring of the Dispersion State of Titanium Dioxide Nanoparticles in Concentrated Suspensions Using Magnetic Resonance Imaging

Abstract

The purpose of the present study is to demonstrate the applicability of magnetic resonance imaging, especially T relaxation time mapping, for nondestructive monitoring of the dispersion state of nanoparticles (NPs) in concentrated suspensions. TiO 15-nm-diameter NPs, for use in sunscreen lotion products, were examined as a test NP. First, this study investigated whether T is sensitive to the NP concentration. In experiments with pulsed nuclear magnetic resonance on TiO NP suspensions with different organic solvents (ethanol, acetone, and decamethylcyclopentasiloxane), the T of each solvent varied in the suspensions according to the NP concentration. This study also confirmed that T mapping was effective for visualizing differences in NP concentration. Subsequently, gravitational sedimentation of the test suspensions was investigated. T mapping exhibited better detection sensitivity to sedimentation occurring in concentrated suspensions than visual observation, as it enabled the detection of changes in NP distributions that could not be visible to the naked eye. In addition, measurements of backscattered light enabled the full understanding of the dispersion stability of the TiO NPs in each solvent. Finally, the present study evaluated the centrifuge sedimentation of a commercial TiO NP suspension. T mapping clearly showed the complicated sedimentation behavior induced by the centrifugation treatment. The simulated fluid flow was consistent with the particle distribution in the centrifuged sample; thus, the sedimentation was believed to have developed in accordance with the vorticity generated by the centrifugation.

Determination of Hardness of a Pharmaceutical Oral Jelly by Using <i>T</i>₂ Relaxation Behavior Measured by Time-Domain NMR

“…The applications have also expanded into the fields of chemistry, 14,15) food, [16][17][18] and plants. 19,20) We applied TD-NMR analysis to evaluate characteristics of pharmaceuticals such as the crystalline state of active pharmaceutical ingredients in solid dosage forms, 12,21) the state of water incorporated in wet granules, 22) the dispersion state of pharmaceutical nanosuspensions, 23,24) and the hygroscopic behavior of disintegrants. 25) The jellies tested in this study were prepared with different compositions using ternary gel-forming agents.…”

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].…”

A Time-Domain NMR Study of the State of Water in Wet Granules with Different Fillers and Its Contribution to the Wet Granulation Process and to the Characteristics of Granules

“…10,11,23) Recently, we have demonstrated the usefulness of TD-NMR for the evaluation of physicochemical properties of pharmaceuticals. These studies include characterization of the crystalline state of APIs 24) and the dispersion state of nanoparticles in concentrated suspensions. 25) In this study, wet granules were prepared using different fillers [cornstarch (CS), microcrystalline cellulose (MCC), and D-mannitol (MAN)], and then tested using TD-NMR.…”