Serially diluting centrifugal microfluidics for high-throughput gold nanoparticle synthesis using an automated and portable workstation

Abstract

We report a novel high-throughput (HTP) synthetic platform for gold (Au) nanoparticles (NPs), consisting of a HTP centrifugal microfluidic device and a portable automatic workstation. The proposed platform is capable of performing 60 different reactions, and can produce a variety of Au NP types on a single device in one run without any human interference. In the microdevice, a zigzag aliquoting microchannel was designed to facilitate the loading of each reactant in a single injection shot. Besides, we developed serially diluting microfluidic structures by pairing the ascorbic acid (AA) solution-loaded microchannel with the water-loaded microchannel, and gradually varying the depths of the two microchannels in reverse, thereby generating the serially diluted concentration-gradient of the AA solution. The morphology of the Au NPs in the triplicate experiments changed from spherical to triangle/ quadrangular/ polyhedron to star shapes in the end, as the concentration of the reducing agent AA increased. Among them, the hexapod star morphology of Au NP was the most effective substrate for surface-enhanced Raman spectroscopy (SERS). In addition, we constructed a portable automatic workstation, which enables on-demand injection of the designated solution onto a microfluidic centrifugal device, the programmed chip rotation, and the multiplex NP synthesis on a chip in a completely automatic manner. Therefore, we could obtain the desired nanomaterials using a HTP automatic screening platform that is cost-, time-, and labor-effective.