Applications Of Responsive Hydrogel In Envelop, Culture And Release Of Single Cell

Compared with traditional research based on a large amount of cells, research onsingle cell level provides much more precise and abundant information. The research onsingle cell level is very important in biology, medicine and pharmacy because it relatesto the basic understanding of life. To study single cell, scientists often trap single cell ona surface by technologies, such as microfluidics, cell pattern, microwell and so on.However, these technologies have some disadvantages, especially cross contamination,low cell viability after culture for a long time, being hard to release and manipulatesingle cells.To solve these problems, we used responsive and biocompatible hydrogel toenvelop single cell. By enveloping single cell, cross contamination can be avoided.Single cells can be released on demand because of the responsiveness of hydrogel. Thebiocompatibility of hydrogel can ensure the high viability of cell for a long time.Firstly, we used chitosan hydrogel, a chemical hydrogel to make a chitosanhydrogel gate, which could envelop and release single cell on demand. Utilizing gravity,we trapped single cell in poly(dimethylsiloxane)(PDMS). We got a single cell arraywith single cell occupancy of95%after optimization experiments. After applying twocomponents of chitosan hydrogel on the PDMS microwell chip trapping single cells, theformed chitosan hydrogel could envelop the single cells, which could be confirmed withphosphate buffer solution (PBS) washing and scanning electronic microscopy (SEM).We explored the behavior and viability of the single cells enveloped in the microwells.We used lysin to trigger chitosan hydrogel to solution, thus, cells in microwells werereleased on demand.Next, considering the better permeability of DNA hydrogel, a physical hydrogel,we designed an enzyme triggered DNA hydrogel gate to envelop, culture and releasesingle cells. After applying two building blocks of DNA hydrogel on the PDMSmicrowell chip trapping single cells, the formed DNA hydrogel gate can envelop thesingle cells. We explored its morphology and thickness with SEM and confocalmicroscopy, respectively. We used specific restriction enzyme to turn DNA hydrogelinto solution, and cells were released as a result. We tested the permeability of DNA hydrogel and found that DNA hydrogel gate was of high permeability，which ensuredhigh viability of cells after culture of24hours.At last, we used microfluidic technique to prepare DNA microgel, which wasintended to encapsulate single cell. We designed and optimized the microfluidic chip tomake it to form microdroplet. We used alginate hydrogel as a model to explore how toprepare microgel. In the end, we could prepare DNA microgel with a defined diameterfrom50-300μm.