Influence of crosslinkers and stabilization methods on porous chitosan-bioglass networks

Chitosan bioglass networks can be used as biomaterials in medicine, for example, as bone implants. Their physiochemical and mechanical properties can be improved by crosslinkers and various stabilization methods. In the presented study, six of them were compared with each other.

Biernat, M.; Woźniak, A.; Chraniuk, M.; Panasiuk, M.; Tymowicz-Grzyb, P.; Pagacz, J.; Antosik, A.; Ciołek, L.; Gromadzka, B.; Jaegermann, Z. Effect of Selected Crosslinking and Stabilization Methods on the Properties of Porous Chitosan Composites Dedicated for Medical Applications. Polymers 2023, 15, 2507. https://doi.org/10.3390/polym15112507

EFFECT OF SELECTED CROSSLINKING AND STABILIZATION METHODS ON THE PROPERTIES OF POROUS CHITOSAN COMPOSITES DEDICATED FOR MEDICAL APPLICATIONS

The most important requirements for biomaterials are biocompatibility, bioactivity and easy availability. Furthermore, for certain applications, biomaterials have to fulfill additional requirements, e.g. for bone implants, biomaterials should have good biodegradability, an optimal pore size and sufficient mechanical strength.

Chitosan (CTS) has many applications in tissue engineering and regenerative medicine. It is biocompatible, biodegradable and non-toxic. In addition, CTS has antimicrobial and osteoconductive properties. However, chitosan networks often suffer from a lack of mechanical stability, which is why chitosan is often mixed with ceramic particles such as hydroxyapatite and bioglass (BG). This enables the production of reinforced and biologically active scaffolds.

Another way to improve mechanical strength and chemical resistance is to use polymeric crosslinkers. These also allow the gain of other properties such as elasticity, insolubility and uniform swelling behavior. Various crosslinking methods are described in the literature. Popular crosslinkers for chitosan in porous structures include genipin, vanillin, L-aspartic acid, sodium alginate, di-sodium-β-glycerol phosphate, or sodium tripolyphosphate (TPP). It has been shown that different crosslinkers prefer certain structures. For example, genipin and vanillin allow scaffolds with higher mechanical strength and better structural reproducibility. Crosslinking as a whole occurs either via ionic bonds (e.g., TTP and di-sodium-β-glycerol phosphate) or covalent bonds (genipin, vanillin).

In the presented study, the preparation of a new porous CTS-BG network was investigated using different crosslinkers and stabilization methods (genipin, vanillin, di-sodium-β-glycerolphosphate, TPP, ethanol, thermal degradation). Depending on these, the obtained networks were studied in terms of preserved microstructure and physiochemical properties. In addition, it was looked to what extent the crosslinker itself has an influence. A chitosan with a DDA of 95 and a viscosity of 2000 mPas from Heppe Medical Chitosan GmbH (95/2000) was used for the study.

RESULTS

Tab.1 : Comparison of the fabricated CTS-BG scaffolds with different crosslinkers and stabilization methods when the properties were evaluated with points, Thermal stability: 5 points for highest thermal stability, Microstructure: 5 points for highest pore diameter, Pycnometric density: 5 points for lowest pycnometric density, Specific surface area: 5 points for lowest specific surface area, Compressive strength: 5 points for highest compressive strength, Swelling behavior: 5 points for lowest swelling, Stability: 5 points for highest stability, Cytotoxicity: 5 points for lowest cytotoxicity, Cell proliferation: 5 points for best cell growth

Conclusions: In the presented study, all crosslinking methods allowed the preparation of stable, non-cytotoxic porous composites of CTS and BG. Genipin showed the best properties in terms of physiochemical and mechanical properties in comparison, while networks stabilized in ethanol were very swell stable and promoted cell proliferation. The composites generated by thermal dehydrogenation exhibited the most specific surface area.

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