Ionically annealed zwitterionic microgels for bioprinting of cartilaginous constructs

Ionically annealed zwitterionic microgels for bioprinting of cartilaginous constructs

16 January 2024 | František Surman, Maryam Asadikarayem, Patrick Weber, Daniel Weber, Marcy Zenobi-Wong
This study presents a novel method for producing zwitterionic microgel bioinks for high-resolution extrusion bioprinting. The bioink is made from alginate methacrylate (AlgMA) as a dual crosslinker, enabling both primary photocrosslinking of the bulk hydrogel and secondary ionic crosslinking of the microgels. The zwitterionic microgels are fabricated by mechanically fragmenting a photocrosslinked hydrogel of zwitterionic carboxybetaine acrylamide (CBAA) and sulfobetaine methacrylate (SBMA) through meshes with aperture diameters of 50 and 90 μm. The resulting microgels are then mixed with cells and crosslinked with calcium ions to form cell-laden microporous scaffolds. The scaffolds exhibit high porosity (≈20%) and support the viability and chondrogenesis of encapsulated human primary chondrocytes. A meniscus model was bioprinted to demonstrate the bioink's ability to print large, cell-laden constructs that are stable for further in vitro culture to promote cartilaginous tissue production. The zwitterionic microgel bioink allows for direct cell encapsulation in a microporous scaffold and has potential for in vivo biocompatibility due to the zwitterionic nature of the bioink. The study shows that the microgel bioink has excellent rheological properties, enabling high-resolution printing of complex structures without the need for a support structure or support bath. The microgels also exhibit shear-thinning and shear-recovery properties, which are essential for extrusion printing. The scaffolds produced have high porosity and support cell viability and chondrogenesis. The study demonstrates that the zwitterionic microgel bioink is a versatile and scalable strategy for high-resolution extrusion bioprinting of cartilaginous constructs.This study presents a novel method for producing zwitterionic microgel bioinks for high-resolution extrusion bioprinting. The bioink is made from alginate methacrylate (AlgMA) as a dual crosslinker, enabling both primary photocrosslinking of the bulk hydrogel and secondary ionic crosslinking of the microgels. The zwitterionic microgels are fabricated by mechanically fragmenting a photocrosslinked hydrogel of zwitterionic carboxybetaine acrylamide (CBAA) and sulfobetaine methacrylate (SBMA) through meshes with aperture diameters of 50 and 90 μm. The resulting microgels are then mixed with cells and crosslinked with calcium ions to form cell-laden microporous scaffolds. The scaffolds exhibit high porosity (≈20%) and support the viability and chondrogenesis of encapsulated human primary chondrocytes. A meniscus model was bioprinted to demonstrate the bioink's ability to print large, cell-laden constructs that are stable for further in vitro culture to promote cartilaginous tissue production. The zwitterionic microgel bioink allows for direct cell encapsulation in a microporous scaffold and has potential for in vivo biocompatibility due to the zwitterionic nature of the bioink. The study shows that the microgel bioink has excellent rheological properties, enabling high-resolution printing of complex structures without the need for a support structure or support bath. The microgels also exhibit shear-thinning and shear-recovery properties, which are essential for extrusion printing. The scaffolds produced have high porosity and support cell viability and chondrogenesis. The study demonstrates that the zwitterionic microgel bioink is a versatile and scalable strategy for high-resolution extrusion bioprinting of cartilaginous constructs.
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