Speaker
Description
Introduction:
Gelatin is a biocompatible polymer derived from natural sources. Its low cost and non toxicity make it an attractive alternative in tissue engineered scaffolds. Chitosan, a biodegradable polymer obtained from chitin, is widely used due to its antimicrobial properties and chemical similarity to glycosaminoglycans (GAGs) found in native tissue. Cellulose nanocrystals (CNCs) are 10 nm wide, 150 - 300 nm long crystals derived from cellulose, and can function as a reinforcement to improve the mechanical properties of scaffolds. As well as being naturally derived, they exhibit no cytotoxicity.
When combined, gelatin and chitosan can produce biocompatible and biodegradable scaffolds, with applications in various tissues, however, crosslinking is a vital step in the production of these scaffolds. Not only is it a way of improving their biodegradation behavior, it also allows them to reach the appropriate values of strength and stiffness for tendon tissue applications.
The aim of this work is to analyze and compare the performance of a novel, all-natural polymer scaffold crosslinked using three different methods. Gelatin-chitosan scaffolds reinforced with cellulose nanocrystals (CNCs) are made via freeze drying and treated with the one of the following crosslinking agents: 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), genipin and microbial transglutaminase (mTG).
Methodology:
10% gelatin solution and 3% chitosan solution are mixed in a 1:1 ratio, after which CNCs are added. The solution is cast into molds, cooled slowly to allow for gel formation and subsequently freeze dried. Crosslinking with genipin and EDC is carried out by soaking the scaffolds in a crosslinking solution for 24 hours, washing and freeze drying; crosslinking with mTG is carried out by adding the crosslinking agent to the polymeric solution[1].
Scaffolds are characterized via Scanning Electron Microscopy for pore size and contact angle for wettability. Tensile and compressive strength of the scaffolds are measured with an Instron Universal Testing system, after soaking the samples for 5 minutes in phosphate buffered solution. Porosity and water uptake measurements methodologies are described elsewhere[2].
Results:
Results show scaffolds with very high porosity (>90%) when non crosslinked, and slightly lower when crosslinked (>70% for all crosslinkers). Average pore sizes are found to be in the 150 - 300 µm range. Scaffolds exhibit hydrophilicity with contact angles lower than 80°; tensile strength is highest for scaffolds crosslinked with genipin, followed by EDC.
Conclusions:
All-natural polymeric scaffolds were successfully produced and crosslinked with 3 different agents. Chemical crosslinking was achieved, as demonstrated by an increase in the material’s mechanical properties. Scaffolds crosslinked with genipin and EDC showed encouraging values of tensile strength. Further analysis is required to determine the feasibility of these crosslinked scaffolds for tendon engineering.
Acknowledgments: This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under the Maria Skłodowska-Curie Grant Agreement N° 955685
References:
[1] Yang, G, et al. Sci Rep. 8(1):1616 (2018).
[2] Alizadeh, M et al. Mat. Sci. and Eng. C. 33, 3958-3967 (2013).
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