2020 Volume 56 Issue 4 Pages 133-141
Magnetic resonance imaging（ MRI） is one of the most popular molecular imaging methods especially in medical fields. As well as nondestructive monitoring of a sample, MRI enables to visualize the molecular mobility of a sample using magnetic resonance（ MR） parameters, including T2 relaxation time and apparent diffusion coefficient（ ADC）. From this perspective, the present study demonstrated the applicability of magnetic resonance imaging for evaluation of the dispersion state of nanoparticles（ NPs） in concentrated suspensions. Titanium dioxide（ TiO2） 15-nm-diameter NPs, for use in sunscreen lotion products, were examined as a test NP. As a result of the series of experiments, the MRI technique was proven to have a great capacity to visualize the slight change in dispersion state which is not detectable by the visible observation. Thus, this study succeeded in offering a new approach: that of nondestructive monitoring of the dispersion stability of NPs in concentrated suspensions. In the next phase of this study, we expanded the applicability of the MRI technique to the evaluation of emulsion state. Emulsions, for use in milky lotion and skin cream, were employed as test samples, and then their creaming behaviors were monitored by T2 and ADC maps. From the findings, it was confirmed that MRI was also powerful for monitoring the emulsion state of pharmaceutical emulsions. In conclusion, MRI is a promising tool for evaluation of dispersion states of suspensions and emulsions.
