A Dynamic Temperature Control System for the Optimized Production of Liquid Metal Nanoparticles

Nanoparticles (NPs) of gallium-based liquid metal (LM) alloys have potential applications in flexible electronics, drug delivery, and molecular imaging. They can be readily produced using top-down methods such as sonication. However, the sonication process generates heat that can cause dealloying of NPs through hydrolysis and oxidation of gallium. This limits the sonication power and period that can be applied for disrupting LM into smaller particles with high concentrations. Also, it remains challenging to achieve long-term colloidal stability of NPs in biological buffers. Here, we develop a dynamic temperature control system for improving the production performance of LM NPs. The enhanced performance is reflected by the significantly increased particle concentration, the decreased overall particle size, the prevention of the formation of oxide nanorods, and the versatility of producing NPs of different types of alloys. In addition, we design a brushed polyethylene glycol polymer with multiple phosphonic acid groups for effectively anchoring the NPs. More importantly, we discover that phosphate can effectively passivate the surface of NPs to further improve their stability. Using these strategies, the produced NPs remain stable in biological buffers for at least six months. Thus, the proposed methods can unleash the vast potential of LM NPs for biomedical applications.