LAUSR

Abstract This study proposes a single platform tool to capture aggregation and dissolution behaviour of copper oxide nanoparticles in acellular conditions using spin-spin nuclear relaxation time data. The spin-spin nuclear relaxation time gathered from pulsed 1H Nuclear magnetic resonance (NMR) spectroscopy can be mathematically translated to the wetted surface area of nanoparticles. The effect of suspension media (artificial lung fluid, algal growth media, and 1 mM NaNO3) and CuO nanoparticle concentrations (500 mg/L, 250 mg/L, and 100 mg/L) on dissolution, hydrodynamic size, and wetted surface area were determined for seven days. The data obtained through 1H NMR spectroscopy was compared with conventional techniques used for measuring dissolution (atomic absorption spectroscopy) and agglomeration (Centrifugal particle sedimentation, Dynamic light scattering). Dissolution experiments showed CuO nanoparticles to have a range of dissolution from 6% to 90%, based on the nature of media. Hydrodynamic size measurements captured the increment in the size of nanoparticles (73% increase) due to aggregation, and reduction in the size of the nanoparticles (88% decline) due to dissolution. Similarly, the temporal variation in the spin-spin nuclear relaxation time of the nanoparticles ranging from 0.25% to 72% detected dissolution and agglomeration of nanoparticles in three different media conditions. The temporal variation in the wetted surface area with respect to concentration and suspension media ranged from 2 m2/g to 380 m2/g. We have determined experimentally the complex interplay between size reduction-wetted surface area-dissolution of nanoparticles and how it evolves over 7 days period for CuO nanoparticles.