چكيده به لاتين
Three-dimensional (3D) bioprinting is a powerful approach to produce 3D tissue structures with suitable biological function. However, the dense hydrogel network formed after the gelation process of the printed bioink usually restricts the migration and proliferation of encapsulated cells. Therefore, a sacrificial microgel-laden bioink technique was designed for directly bioprinting constructs with mesoscale pore networks (MPNs) to enhance nutrient delivery and cell growth. After bioprinting and gelation process of bioink, encapsulated sacrificial microgels start to degrade subsequently and so, MPNs inside the printed constructs are formed. These MPNs allowed for effective oxygen/nutrient diffusion, facilitating the generation of bioactive tissues. However, traditional method for synthesize microgels have some issues such as control on fabrication process, small size and round shape with narrow distribution of microgels. Hence, our novelty is using microfluidics system to synthesize sacrificial alginate microgels which gelled by ionic crosslinking method. In this study, the concentration of alginate as a disperse phase and span80 in mineral oil as a continues phase was 2% (w/v%) and 0.5% (v/v%). Calcium chloride with 2.5% (w/v%) concentration was used as a crosslinking agent by off-chip gelation method. After the process of making microgels, in order to evaluate their performance to become MPNs, alginate microgels produced by microfluidic method were compared with the traditional method. The effect of calcium chloride concentration, gelling time, microgel size, gauge, and flow rate on the physico-chemical properties of alginate microgels were also investigated. According to the results of characterization tests, microgels with an average size of 130 microns produced by microfluidic chip were selected as optimal BSM. With the help of microfluidics system, we succeeded in producing microgels controlled in terms of size, physico-chemical properties, narrow and uniform distribution with a completely spherical shape. According to the results obtained from the tests, the microfluidic method as a state-of-the-art, efficient and cost-effective tools can be a good alternative to the traditional method for the production of BSMs. This novelty and also, ioinic crosslinking method in this project can control the count, size and degradation time of sacrificial microgels which is so important to enhance biological functions of cells and engineered tissues.
