Droplet based synthesis, screening, sensing

Nanoparticle synthesis in droplets

Droplet generation.mov

Microfluidic droplets provide the advantage of better controlling over the concentration of reagents and avoiding the contamination of channel walls in continuous flow based microfluidic devices where nanoparticles are likely to deposit onto channel walls.

In this work, CdS nanoparticles with narrow size distribution were synthesized in droplets that were generated by a microfluidic device integrated with mechanical cutting valves that can independently control size and composition of droplets. The microfluidic platform offers the capability of controlling nanoparticle synthesis through varying reagent concentrations in droplets.

  • J. Dai et al, Particle size controlled synthesis of CdS nanoparticles on a microfluidic chip, Chemical Engineering Journal, 280, 385-390, (2015)

Droplet-based high-throughput screening

detection and sorting for website.pptx

Droplet microfluidics enables single cell compartmentalization, millions of independent picoliter reactions, and is capable of processing hundreds of samples at a high-throughput rate.

We are developing an integrated droplet-based high-throughput screening system consisting of several functional modules including droplet generation, incubation, detection, sorting, trapping, lysis, and preservation. We are using this system to screen a large number of microbial transformant library and performing subsequent on-chip sample preparation&preservation of targeted mutant. I developed an on-chip first-in first-out droplet incubation chamber to provide constant droplet incubation time for 106 droplets .

  • J. Dai et al., A large-scale on-chip droplet incubation chamber enables equal microbial culture time, RSC Advances, 6, 20516-20519 (2016)

  • J. Dai et al., Growth phenotype based reporter-free screening of filamentous fungi in microfluidic droplets, Proceeding of MicroTAS Annual Meeting, Basel, Switzerland, October, pp. 260-261, 2019.

Impedance detection of filamentous fungal cells in droplets

Droplet-based screening system has become a standard platform for high-throughput cell analysis. Although cell labeling by fluorescence is commonly used for detecting cell of interest, this technique requires genetic engineered cells and may not work for certain environmental microbes. Impedance spectroscopy is a label-free method to detect cells in droplets and it has high capability of integration.

We are developing a microsystem that integrates impedance spectroscopy and droplet microfluidics to detect and discriminate microbial cells, e.g. filamentous fungi, in droplets. This system can be readily to be integrated into a droplet-based screening system.

  • N. Sobahi, J. Dai et al., Discrimination of droplets containing single filamentous fungal cell using impedance spectroscopy, Proceeding of MicroTAS conference, Dublin, Ireland, pp.1168-1169, 2016