GELLAN GUM AND ELASTIN-BASED HYDROGELS WITH TUNABLE MECHANICAL AND PHYSICAL PROPERTIES

Engineered hydrogels from natural polymers such as gellan gum (GG) have been widely proposed for use in tissue engineering and regenerative medicine applications. Although GG hydrogels can be tailored to reach the appropriated stiffness to support cutaneous wound healing, they still do not show proper flexibility and resilience to be used as a skin dressing. To overcome this limitation, we combined GG with elastin (EL), once elastin is one of the proteins present in the extracellular matrix having the particularity to provide elasticity to tissues.

Hence, this study describes the production and characterization of novel hydrogels combining different concentrations of GG and EL from bovine neck ligament. The developed hydrogels were submitted to morphological analysis using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). Furthermore, the elastic performance was investigated through the mechanical properties of hydrogels using confined compression tests after incubation with PBS azide at 37 ºC for 0, 7 and 14 days. Results obtained from SEM and TEM confirmed the presence of elastin in the hydrogels, as well as the protein’s characteristic fibrils, responsible for the increase in the elasticity of biological tissues. The EDS revealed clear peaks of sulphur in the hydrogels with elastin fibrils, further confirming those results. The mechanical properties showed the nonlinear mechanical behaviour of the hydrogels and an increase of the compressive modulus and compressive strength as the amount of polymer in the hydrogel increased. Incorporation of elastin resulted in increased compressive modulus within a range of 16.10 kPa to 49.48 kPa, while the values for GG hydrogels spanned from 14.36 kPa to 43.00 kPa. The elongation capacity of the hydrogels was also increased due to the presence of elastin. The measurements performed demonstrated that the hydrogels are stable along the time. Our results indicate that the mechanical properties of GG/EL hydrogels can be tuned to develop new biomaterials to address the required mechanical properties of elastic tissues.

Acknowledgements:

This research was supported by the Portuguese Foundation of Science and Technology (FCT) under the research project Dressing4Scars (ERA-NET/CSA/JPI/M-ERANET). The authors would like to acknowledge The Discoveries Centre for Regenerative and Precision Medicine and the funds for POCI-01-0145-FEDER-007038-UMINHO/BPD/44/2016 (LPS), FCT/MCTES PD/BD/135248/2017 (DPR) and M-ERA-NET2/0013/2016 (MGF) grants. The authors thank Dr Santiago Sevillano (Leica Nanotechnology) the hydrogels preparation for SEM experiments.