Biocompatible Gold Submicrometer Spheres with Variable Surface Texture Fabricated by Pulsed Laser Melting in Liquid

This paper highlights a strategy on how totally ligand-free biocompatible gold submicrometer spheres (Au-SMSs) can be synthesized by aggregating laser-fabricated nanoparticles (NPs) with NaCl followed by subsequent post-irradiation using pulsed lasers at a moderate fluence. Interestingly, we observed significant changes in the surface structure of the SMSs, caused by the adsorption of smaller particles following a disaggregation-melting-redeposition-sintering-mechanism. Here, utilization of low fluences yielded perfectly smooth textures while higher fluences lead to wrinkled textures. Furthermore, we elucidate that prior to aggregation, the particle size distribution of the source AuNPs may significantly interfere with the surface texture of the resulting Au-SMSs, indicated by predominant formation of rough surface structures in the presence of smaller source NPs. These findings may highlight novel synthesis strategies for Au-SMSs with rough surface textures, particularly beneficial for SERS applications.