3D printing of hydrogel containing PHBV microparticles

PACHECO, EVELINA; PÉREZ RECALDE, MERCEDES; ARAOZ, BEATRIZ; HERMIDA, ÉLIDA BEATRIZ

Dresden

Conferencia; 7th International Conference on Cellular Materials; 2022

DGM (Sociedad Alemana de Materiales)

3D printing has widely increased the development of cellular materials that emulate theextracellular matrix of different tissues [1]. Inks for 3D printing must fulfill certain biological andmechanical requirements: to be biocompatible and biodegradable, to have a shear-thinningbehavior, to show at least 0,90 of printability, and to give scaffolds with similar mechanicalproperties to the tissue to be replaced. Furthermore, the addition of a drug delivery systems (DDS)to a scaffold is under development, seeking potential applications in pharmacology [2]. In thiswork, a sodium alginate-gelatin hydrogel with poly (hydroxybutyrate-co-hydroxyvalerate) (PHBV)microparticles was employed to produce 3D printed scaffolds.The hydrogel was a blend made of 9% sodium alginate and 4.5% gelatin 4.5%; its liquid-likebehavior led to a poor printability (Pr=0.81). This value could be improved to 0,94 by the addition15 mM of CaCl 2 . This ink, called Ink-Ca, was filled with PHBV spherical microparticles (MP) from 5mg to 100 mg every 10 ml of ink. The MP were prepared by an emulsification/solvent technique[3]; their mean size, determined by microscopy, was 14+6 µm. Interestingly, the viscosity of the inkfilled with MP decreased as the concentration increases: 1498, 1178 and 840 Pa.s for 0, 30 and100 mg of MP/10 mL of ink.Samples made of the Ink-Ca loaded with MP (5 mg, 15 mg, 30 mg, 50 mg and 100 mg) andcrosslinked with CaCl 2 0,5 M for 3 h at 25°C and overnight at 4°C showed an increase in thecompression modulus from 400 kPa (without MP) to 550 kPa with 30 mg of MP. Higherconcentrations of MP particles did not increase the compression modulus. Thus, 30 mg MP/10 mLenhances the compression modulus and higher concentrations could be suitable for drug deliverywithout loss in the mechanical behaviour.When evaluated for 3D-printing, Ink-Ca/30 mg presented the same Pr (0,94) that the Ink-Ca. Wemanufactured scaffolds with infill 30% and 8 layers, by 3D printing, with the Ink-Ca and Ink-Ca/30mg MP, to compare mechanical properties. These scaffolds were also crosslinked overnight withCaCl 2 0,5M. In this case, again, the sample with MP increased the compression modulus (Ink-Ca172±30 kPa, Ink-Ca/30 mg MP 270±30 kPa).The results suggest that microparticles with alginate-gelatine hydrogel can be combined giving inksaccurate for the application in 3D printing, and the microparticles produce changes in themicrostructure both in ink form and in the scaffold form. 30 mg MP in this system is highlighted forDDS application for soft tissues.