Picoliter droplet array based on bioinspired microholes for in situ single-cell analysis

摘要

The division of aqueous samples into microdroplet arrays has many applications in biochemical and medical analysis. Inspired by biological features, we propose a method to produce picoliter droplet arrays for single-cell analysis based on physical structure and interface. A 0.9-pL droplet array with an RSD (relative standard deviation) less than 6.3% and a density of 49,000 droplets/cm2 was successfully generated on a PDMS chip (polydimethylsiloxane) from a micromachined glass mold. The droplet generation principle of the wetting behavior in the microholes with splayed sidewalls on the PDMS chip by liquid smearing was exploited. The feasibility of the picoliter droplets for bacterial single-cell analysis was verified by the separation of mixed bacteria into single droplets and isolated in situ bacteria propagation. Researchers in China have developed a method to rapidly and reliably separate a solution into an array of picoliter-scale droplets. A team led by Jia Zhou of Fudan University first made a negative image of the surface of a lotus leaf. This served as the basis for a micromachined glass mold which was then used to manufacture PDMS chips. The structure of these chips-a series of microholes with angled walls-causes liquid smeared across the surface to form droplets within the holes. The droplets have an average volume of 0.9-pL. The team tested their approach by using it to isolate single-cell droplets of bacteria from a mixed solution. The ability to rapidly, reliably, and affordably generate picoliter microdroplets will prove valuable for studies in single-cell genomics and proteomics, as well as other fields.