A novel micro-injection droplet microfluidic system for studying locomotive behavior responses to Cu²⁺ induced neurotoxin in individual C.elegans

Analysis of C.elegans by droplet microfluidics has been widely used in study of locomotive behavior responses to neurotoxicity due to the capacity of high-throughput manipulating single cells. However, it has been difficult to manipulate droplets flexibly and actively on account of the limitation of the dimension of individual C. elegans droplets. In this study, a novel MiDMS (Micro-injection Droplet Microfluidic System) was proposed, which consisted of three parts: single C. elegans droplet generator, droplets drug micro-injection channels and drug-incubation observation array. Individual C.elegans droplets were produced initially by regulating the flow rates between oil and water phase as well as the concentration of C.elegans in suspension. Then, the drug solution was precisely injected into each C.elegans droplet, which by electricity induced surface tension of droplet changing. In addition, the effect of neurotoxic Cu²⁺ on locomotive behavior of C. elegans was evaluated at single cell resolution. The results showed that the neurotoxicity induced behavioral disorder of the C. elegans was more obvious with the increase of Cu²⁺ concentration or treatment time, and these dose-effect and time-effect relationship in MiDMS were similar as in petri dish. This study will provide a powerful platform for the study of the response of C. elegans to quantitative drug at single cell resolution.