ascorbic-acid and ammonium-peroxydisulfate

Hydrogels composed of methylcellulose are candidate materials for soft tissue reconstruction. Although photocrosslinked methylcellulose hydrogels have shown promise for such applications, gels crosslinked using reduction-oxidation (redox) initiators may be more clinically viable. In this study, methylcellulose modified with functional methacrylate groups was polymerized using an ammonium persulfate (APS)-ascorbic acid (AA) redox initiation system to produce injectable hydrogels with tunable properties. By varying macromer concentration from 2% to 4% (w/v), the equilibrium moduli of the hydrogels ranged from 1.47 ± 0.33 to 5.31 ± 0.71 kPa, on par with human adipose tissue. Gelation time was found to conform to the ISO standard for injectable materials. Cellulase treatment resulted in complete degradation of the hydrogels within 24h, providing a reversible corrective feature. Co-culture with human dermal fibroblasts confirmed the cytocompatibility of the gels based on DNA measurements and Live/Dead imaging. Taken together, this evidence indicates that APS-AA redox-polymerized methylcellulose hydrogels possess properties beneficial for use as soft tissue fillers.

Topics: Ammonium Sulfate; Ascorbic Acid; Biocompatible Materials; Biomechanical Phenomena; Drug Stability; Fibroblasts; Humans; Hydrogels; Materials Testing; Methylcellulose; Oxidation-Reduction; Polymerization; Tissue Engineering

The crosslinking characteristics of an injectable poly(propylene fumarate-co-ethylene glycol) [P(PF-co-EG)]-based hydrogel were investigated. A water-soluble crosslinking system was used, consisting of poly(ethylene glycol) diacrylate (PEG-DA), ammonium persulfate (APS), and ascorbic acid (AA). The effects of PEG block length of the P(PF-co-EG), APS concentration, AA concentration, and PEG-DA concentration on equilibrium water content, sol fraction, onset of gelation, mechanical properties, and endothelial cell adhesion were studied. The equilibrium water content of the hydrogels ranged from 57.1 +/- 0.3 to 79.7 +/- 0.2% whereas the sol fraction ranged from 2.5 +/- 0.0 to 3.33 +/- 5.4%. The onset of gelation times varied from 1.1 +/- 0.1 to 4.3 +/- 0.2 min. For all hydrogel formulations, the tensile strength fell between 61.7 +/- 18.2 and 401.3 +/- 67.5 kPa and tensile moduli ranged from 0.4 +/- 0.0 to 3.3 +/- 0.3 MPa. Endothelial cells attached to the hydrogels in a range of 3.9 +/- 1.4 to 31.1 +/- 14.1% of cells seeded. These findings suggest that injectable poly(propylene fumarate-co-ethylene glycol) hydrogel formulations in conjunction with a novel water-soluble crosslinking system may be useful for in situ crosslinkable tissue-engineering applications.

Topics: Ammonium Sulfate; Ascorbic Acid; Biocompatible Materials; Cell Adhesion; Cells, Cultured; Cross-Linking Reagents; Endothelium, Vascular; Humans; Hydrogels; Injections; Molecular Weight; Polyethylene Glycols; Polypropylenes; Solubility; Tensile Strength; Time Factors; Viscosity; Water