Calcium alginate/dextran methacrylate IPN beads as protecting carriers for protein delivery.

In the present study, mechanical and protein delivery properties of a system based on the interpenetration of calcium-alginate (Ca-Alg) and dextran-methacrylate (Dex-MA) networks are shown. Interpenetrated hydrogels beads were prepared by means of the alginate chains crosslinking with calcium ions, followed by the exposure to UV light that allows the Dex-MA network formation. Optical microscope analysis showed an average diameter of the IPN beads (Ca-Alg/Dex-MA) of 2 mm. This dimension was smaller than that of Ca-Alg beads because of the Dex-MA presence. Moreover, the strength of the IPN beads, and of their corresponding hydrogels, was influenced by the Dex-MA concentration and the crosslinking time. Model proteins (BSA and HRP) were successfully entrapped into the beads and released at a controlled rate, modulated by changing the Dex-MA concentration. The enzymatic activity of HRP released from the beads was maintained. These novel IPN beads have great potential as protein delivery system.

Hyaluronic acid and dextran-based semi-IPN hydrogels as biomaterials for bioprinting.

Bioprinting is a recent technology in tissue engineering used for the design of porous constructs through layer-by-layer deposition of cell-laden material. This technology would benefit from new biomaterials that can fulfill specific requirements for the fabrication of well-defined 3D constructs, such as the preservation of cell viability and adequate mechanical properties. We evaluated the suitability of a novel semi-interpenetrating network (semi-IPN), based on hyaluronic acid and hydroxyethyl-methacrylate-derivatized dextran (dex-HEMA), to form 3D hydrogel bioprinted constructs. The rheological properties of the solutions allowed proper handling during bioprinting, whereas photopolymerization led to stable constructs of which their mechanical properties matched the wide range of mechanical strengths of natural tissues. Importantly, excellent viability was observed for encapsulated chondrocytes. The results demonstrate the suitability of hyaluronic acid/dex-HEMA semi-IPNs to manufacture bioprinted constructs for tissue engineering.

In situ forming IPN hydrogels of calcium alginate and dextran-HEMA for biomedical applications.

In situ forming hydrogels, which allow for the modulation of physico-chemical properties, and in which cell response can be tailored, are providing new opportunities for biomedical applications. Here, we describe interpenetrating polymer networks (IPNs) based on a physical network of calcium alginate (Alg-Ca), interpenetrated with a chemical one based on hydroxyethyl-methacrylate-derivatized dextran (dex-HEMA). IPNs with different concentration and degree of substitution of dex-HEMA were characterized and evaluated for protein release as well as for the behavior of embedded cells. The results demonstrated that the properties of the semi-IPNs, which are obtained by dissolution of dex-HEMA chains into the Alg-Ca hydrogels, would allow for injection of these hydrogels. Degradation times of the IPNs after photocross-linking could be tailored from 15 to 180 days by the concentration and the degree of substitution of dex-HEMA. Further, after an initial burst release, bovine serum albumin was gradually released from the IPNs over approximately 15 days. Encapsulation of expanded chondrocytes in the IPNs revealed that cells remained viable and, depending on the composition, were able to redifferentiate, as was demonstrated by the deposition of collagen type II. These results demonstrate that these IPNs are attractive materials for pharmaceutical and biomedical applications due to their tailorable mechanical and degradation characteristics, their release kinetics and biocompatibility.