Microfluidic device-based synthesis of highly monodispersed dumbbell-shaped gold nanorods and their biocompatibility evaluation

Abstract

Anisotropic gold nanomaterials have always fascinated the scientific community; however, controlling their synthesis to achieve desired properties and monodispersity is challenging in a conventional batch reactor. Here, we report the synthesis of highly monodispersed dumbbell-shaped gold nanorods (Ds-Au NRs) in a droplet microfluidic device. The device comprises a tapered T-junction for reagent droplet production, a winding structure to promote nucleation, and lengthy parallel microchannels to support the slow growth required for dumbbell shape morphology. After optimising the flow parameters and device geometry for uniform droplet production, the aspect ratio of Ds-Au NRs was tuned by controlling the total reagent flow rate, reagent flow rate ratio, and concentration of shaping reagent and reducing agent. Compared to batch counterparts, reaction time was reduced to one-fifth and revealed higher monodispersity. The cytotoxicity analysis showed that microfluidic synthesised Ds-Au NRs are non-toxic and have great potential for usage in biomedical applications.