A protocol for rheological characterization of hydrogels for tissue engineering strategies

Abstract

Hydrogels are studied extensively for many tissue engineering applications, and their mechanical properties influence both cellular and tissue compatibility. However, it is difficult to compare the mechanical properties of hydrogels between studies due to a lack of continuity between rheological protocols. This study outlines a straightforward protocol to accurately determine hydrogel equilibrium modulus and gelation time using a series of rheological tests. These protocols are applied to several hydrogel systems used within tissue engineering applications: agarose, collagen, fibrin, Matrigel™, and methylcellulose. The protocol is outlined in four steps: (1) Time sweep to determine the gelation time of the hydrogel. (2) Strain sweep to determine the linear-viscoelastic region of the hydrogel with respect to strain. (3) Frequency sweep to determine the linear equilibrium modulus plateau of the hydrogel. (4) Time sweep with values obtained from strain and frequency sweeps to accurately report the equilibrium moduli and gelation time. Finally, the rheological characterization protocol was evaluated using a composite Matrigel™-methylcellulose hydrogel blend whose mechanical properties were previously unknown. The protocol described herein provides a standardized approach for proper analysis of hydrogel rheological properties.

Tunable controlled release of bioactive SDF-1α via specific protein interactions within fibrin/nanoparticle composites

“…Rheological studies further supports that fibrin clot integrity was maintained upon addition of NPs (Figure 7C and D). The low-frequency plateau in the storage modulus (G′) of both 3 & 30mg/mL fibrin groups indicate polymerization of fibrinogen to form viscoelastic fibrin (Figure 7C) 59 . Additionally, the overall characteristics of the storage and loss moduli was not altered upon adding 10mg/mLNPs in either 3 or 30mg/mL fibrin matrices (Figure 7C).…”

The dramatic effect of small pH changes on the properties of chitosan hydrogels crosslinked with genipin

“…During the tests, a solvent trap filled with distilled water and an annular cover were used to avoid evaporation throughout the experiment. The time sweep experiments were conducted according to a protocol published by Zuidema, Rivet, Gilbert, and Morrison (2013). It should be noted that the slowest curing gels displayed a gelation point of more than 4.5 h and did not reach equilibrium even after 7 h; therefore, the LVR was determined for the fastest curing hydrogel (pH = 5.5 after 3 h of gelation on the rheometer plates).…”

Viscoelastic behaviour of hydrogel-based composites for tissue engineering under mechanical load

“…The sample holder was preheated to 90°C and the exact amount of the sample in the form of a solution/ suspension was pipetted and dropped onto the fixture. This assures a good contact between the sample and the fixture [18]. To prevent evaporation of water from the sample, paraffin oil was poured around the perimeter of the sample, and the insulating chamber was closed.…”