Jonas Röder (Erlangen, DE), Stephan Hauschild (Jülich, DE), Chien-Hsin Yu (Jülich, DE), Dr. Rainer Detsch (Erlangen, DE), Prof. Dr. Aldo R. Boccaccini (Erlangen, DE), Prof. Dr. Stephan Förster (Jülich, DE)
Abstract text (incl. figure legends and references)
Introduction:
Microgels consist of colloidal gel particles built from a crosslinked polymer network.1 Such gels allow to generate structures by 3D printing with interconnected pore networks and embedded cells.
Objectives:
Aim of this study was to fabricate a microgel from oxidized-alginate (OA) and to characterize obtained particles considering potential applications in biofabrication strategies.
Materials and Methods:
Alginate PH163S2 was oxidized with NaIO4 to a degree of 13%.2 3 Syringes with 1.25% (w/v) OA-solution (in phosphate-buffered saline) and 2 syringes with crosslinker (1-Undecanol saturated with Calcium-2-ethylhexanoat) were connected to a flow-focusing microfluidics-chip.3 Using syringe pumps flowrates were adjusted until a steady stream of uniform, spherical particles was obtained. Changes in flowrates allowed for accurate control over particle size.
Results:
Oxidizing reduced molecular weight of alginate by 45% (to 120 kDa) while maintaining the M/G block ratio of 1.19.2 Using a chip with a 50 µm tapering, it was possible to generate OA-microgels with diameters between 45 and 110 µm. Mixing ratios of 6:1 up to 13:1 (oil to OA-solution) were used. Flow rates for the OA-solution ranged from 30 to 105 µl/h and for the crosslinker from 300 to 600 µl/h.
Conclusions:
In this study OA-microgels of sizes from 45 to 110 µm were successfully generated. Particle size can easily be controlled by varying flowrates and tapering size. The Influence of OA oxidation degree on microgel characteristics should be investigated. OA-microgel has promising properties for further investigation as hydrogel filler to modify rheology, porosity and cell behavior in the context of biofabrication.
Acknowledgments:
This project is funded by the German Research Foundation (DFG) project number 326998133-TRR-225 (subproject A01, A06).
1L. Zifu, et al; Nanoscale, 2013, 5, 1399-1410.
2E. Karakaya et al; Biomacromolecules, 2023, Article ASAP.
3B. Reineke, et al;ChemRxiv, 2021.