Multi-well plate-based versatile platform for online fabricating alginate hydrogel microspheres and in-situ 3D cell...

Hydrogel microspheres with monodisperse and homogeneous dimensions have potential application in the field of three-dimensional (3D) cell culture due to its ability to provide a similar microenvironment. Currently, alginate hydrogel microspheres (AHMs) have received much attention due to the favorable properties of alginate such as biocompatibility, inexpensiveness, nontoxicity, and biodegradability. The fabrication methods of AHMs mainly include extrusion, electrostatic dripping and microfluidic chip techniques. These current methods suffer trade-offs between operational complexity, fabrication cost and practical application.

We proposed a novel and versatile multi-well plate-based platform for online fabricating AHMs and in-situ 3D cell culture. The AHMs could be easily fabricated based on gravity-driven gelation combined with our recently developed bent-capillary-centrifugal-driven (BCCD) system. Ca-EDTA complex was used as Ca²⁺ source for crosslinking reaction of the alginate chains. The whole preparation process of AHMs included four steps: emulsification, pre-gelation, spontaneous demulsification and further solidification. The gravity-driven hydrogel microsphere gelation could produce the AHMs with good sphericity (Φ = 0.96) and monodispersity (PDI% = 0.94 %). The rapid drug susceptibility testing and single-cell encapsulation in the AHMs were well demonstrated. It also provided a novel in-situ 3D cell culture strategy, which demonstrated more than 85 % cell viability in practice.

The proposed platform avoided the complex and laborious microfabrication. Moreover, cell-encapsulated AHMs could be directly produced in the multi-well plate, which could facilitate the subsequent cultivation and observation. It is expected to be a versatile in-situ 3D cell culture tool in the fields of biomedicine and tissue engineering.