A New Freezedrying Technique for Nanoparticle Sample Preparations

Sandwich freeze-drying, a unique and novel technique, offers a new way to create an aggregate-free, high-density dispersion of nanoparticles on a silicon substrate, perfect for microscopy. All you need is a freeze-dryer and an －80℃ freezer. If you can prepare a suspension in water, the precise nature of the particles is no longer a concern. This article will introduce the technique's history, mechanisms, and outcomes, piquing your curiosity. The scheme of sample preparations with sandwich freeze-drying and atomic-force microscopy measurements could provide comprehensive particle statistics, even in the case of a wide particle-size distribution. It even detected the Ostwald ripening of a bimodal mixture of spherical silica nanoparticles, a feat that would be challenging with other measurement methods.