Modeling the Electromobility of Type-I Collagen Molecules in the Electrochemical Fabrication of Dense and Aligned Tissue Constructs

Electrochemical control of the enzymatic polymerization of PEG hydrogels: formation of spatially controlled biological microenvironments

Control of pH gradient profile at the electrode-electrolyte interfaces allows the control of the enzymatic PEG-hydrogel polymerization. By tuning the solution pH, buffer capacity, and the applied current, the extent of the local inhibition and confinement of the Factor XIII-mediated polymerization of PEG are controlled. This technology opens new perspectives for the production of 3D-structured biological microenvironments.

Coding for hydrogel organization through signal guided self-assembly

Complex structured soft matter may have important applications in the field of tissue engineering and biomedicine. However, the discovery of facile methods to exquisitely manipulate the structure of soft matter remains a challenge. In this report, a multilayer hydrogel is fabricated from the stimuli-responsive aminopolysaccharide chitosan by using spatially localized and temporally controlled sequences of electrical signals. By programming the imposed cathodic input signals, chitosan hydrogels with varying layer number and thickness can be fabricated. The inputs of electrical signals induce the formation of hydrogel layers while short interruptions create interfaces between each layer. The thickness of each layer is controlled by the charge transfer (Q = ∫idt) during the individual deposition step and the number of multilayers is controlled by the number of interruptions. Scanning electron micrographs (SEMs) reveal organized fibrous structures within each layer that are demarcated by compact orthogonal interlayer structures. This work demonstrates for the first time that an imposed sequence of electrical inputs can trigger the self-assembly of multilayered hydrogels and thus suggests the broader potential for creating an electrical "code" to generate complex structures in soft matter.

Genipin crosslinking elevates the strength of electrochemically aligned collagen to the level of tendons

Collagen-based tissue mimics are important in clinical research because collagen is the main structural element in tendons. The current study aimed to improve the mechanical strength of Electronically Aligned Collagen (ELAC) threads by optimizing several crosslinking parameters. The results indicated that elevating the concentration of genipin to 2% and the solvent to 90% ethanol significantly enhanced the wet ultimate tensile stress of ELAC threads to 109 MPa with a crosslinking degree of 65%. Furthermore, significantly higher adhesion and proliferation of hMSCs was observed in ELAC threads crosslinked with 2% genipin in 90% ethanol compared to 0.625% genipin in 1X PBS. In conclusion, ELAC threads with mechanical strength on par with native tendon have significant potential to be used as scaffolds in tendon tissue engineering applications.