Hydrogels have many applications in medicine and biomedical research, including the controlled release of drugs and as tissue growth scaffolds. Fibrin based hydrogels in particular have found use as glues for reattaching tissues during and after surgery. They have several properties which make them well-suited to this application: a setting time on the order of seconds, biocompatibility and biodegradability, and degradation time that is tunable by covalent crosslinking. One property which is lacking in fibrin hydrogels, however, is electrical conductivity, which may facilitate fast wound healing and improve the integration of synthetic cardiac tissue. In order to enhance this property of fibrin hydrogels, it was hypothesized that interspersing metallic MoS₂ nanosheets within the fibrin matrix would allow electrical conduction through the hydrogel while maintaining the aforementioned desirable properties for biomedical applications. The composite hydrogels were created by suspending freeze dried 1T-MoS₂ nanosheets in fibrinogen solution, followed by the addition of thrombin solution. Electrical conductivity of the composite hydrogels was measured by a four point probe method. Degradation of the composites in various solutions modeling the oxidative and proteolytic conditions of the human body was measured gravimetrically and by ICP-OES. Covalent crosslinking of the fibrin network was performed by incubation with the molecule genipin, and showed a substantial improvement in the material’s resistance to degradation, especially by proteases. At sufficiently high weight percentages of MoS₂ in the composite, significant increases in the conductivity of the hydrogel were observed. In purely oxidative conditions the degradation of MoS₂ nanosheets tended to occur faster than that of the fibrin matrix, whereas in purely proteolytic conditions the degradation of fibrin tended to occur faster than that of MoS₂. The use of covalent crosslinkers was able to slow the fibrin degradation sufficiently that MoS₂ nanosheet degradation was almost always faster.

Robert Hurt

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