ABSTRACT
There is a great demand for blood and stem cells in clinic. It is difficult to achieve high throughput and to increase the cooling rate at the same time during vitrification. In this paper, a micro-droplet spray system with a container collection device was fabricated, and HepG2 cells were sprayed by this system for high-throughput vitrification. First, the container collection device and a cryo-paper were used to receive micro-droplets in the spray vitrification system. The results showed that the cell survival rate and 24h adhesion rate in container collection vitrification group were significantly higher than those in cryo-paper collection group. Second, HepG2 cells were sprayed and vitrified at increased cell density, and it was found that the results of micro-droplet spray vitrification did not change significantly. Finally, micro-droplet spray vitrification is compared with slow freezing. Cell processing capacity in the vitrification group increased, meanwhile, the cell survival rate and 24h adhesion rate in the vitrification group were significantly higher than those in slow freezing group. The results indicated that the micro-droplet spray vitrification system with container collection device designed in this paper can achieve high-throughput cell vitrification, which is of great significance for mass preservation of small cells.
Subject(s)
Humans , Cell Adhesion , Cell Survival , Cryopreservation , Hep G2 Cells , VitrificationABSTRACT
Novel compartment microparticles produced with double emulsion droplets as templates provide a protected internal space for material encapsulation. The effect of three-phase flow rate on the micro-droplet generation of double emulsion mechanism is available for reference to produce precise size and highly monodisperse particles. The influence of three-phase flow rate on the formation mode and size of the emulsion droplets was mainly investigated by making use of experiment and numerical simulation. The size of compound droplets decreases and the frequency increases with the increasing outer fluid flow rate. The monodispersity of the double emulsion reduces due to transition from dripping to narrowing jetting regime. Outer droplet size increases with the increasing flow rate of the middle fluid, whereas inner droplet size is the opposite. The frequency increases and then stabilizes,which leads to a widening regime. When Q2/Q1>6, multi-core type double emulsion droplets are produced. Droplet coalescence occurs when surfactant is not considered. As Q1 increases,there is an increasing tendency for inner drop size. The outer drop size is proportional to the sum of the inner and middle flow rate,and that is regardless of Q1/Q2. For drop size,ratio of core-shell and internal structure are precisely controlled by adjusting three-phase flow rate respectively.
ABSTRACT
Micro-droplets are widely used in the fields of drug controlled release,virus detection,synthetic of particulate materials,catalysts and so on due to their small size,large surface area,high speed,high throughput,uniform size,closed system,internal stability and other characteristics.The emergence and development of microfluidics technology provide a new platform for the generation and precise manipulation of size-controlled microdroplets with different structures and functional characteristics.The fundamentals,generation and manipulation of droplet-based microfluidics technology are introduced.Similarities and differences of droplets'conventional preparation methods and droplet-based microfluidics technology are compared and analyzed.Finally,the applications of droplet-based microfluidics for the synthesis of functional materials,bio-medicine and design of food structure etc.are comprehensively presented.In addition,the potential value and development direction of drop-based microfluidics are discussed and forecasted.