Curing kinetics and mechanical properties of a composite hydrogel for the replacement of the nucleus pulposus

Abstract

a b s t r a c tA polymer material system has been developed to propose an injectable, UV and in situ curable hydrogel with properties similar to the native nucleus pulposus of intervertebral disc. Neat hydrogels based on Tween Ò 20 trimethacrylates (T3) and N-vinyl-2-pyrrolidone (NVP) and composite hydrogels of same composition reinforced by nano-fibrillated cellulose were synthesized with different T3 concentrations and their curing kinetics was investigated by photorheology using UV light. The T3 concentration has an influence on the time of curing and final shear stiffness of the material. NFC does not alter the time of curing but increases the final mechanical performance of the hydrogels for a same chemical composition. Hydrogel samples, neat and composite, were then tested in unconfined compression at different hydration stages and in confined compression and their elastic modulus was determined. The amount of fluid present in the network is mostly responsible for the mechanical properties and NFC fibres proved to be an efficient reinforcement. The elastic modulus ranged from 0.02 to 8 MPa. Biocompatibility studies showed that cells are confluent at 90% and do not show any morphology change when in contact with the hydrogel. The present hydrogel can therefore be considered for NP replacement.

Synthesis and Photopolymerization of Tween 20 Methacrylate/N-vinyl-2-Pyrrolidone Blends

“…The water content of the NP ranges from 65 to 90% [22], which is similar to the values of 60 to 85% obtained in the present case and is crucial for the overall mechanical response of disc [23,24]. As described in detail elsewhere [25][26][27], the present T3/NVP hydrogels have been demonstrated to be biocompatible, and compression tests on hydrated specimens indicate viscoelastic behavior comparable with that of human nucleus pulposus, confirming this system to be an excellent candidate for intervertebral disc repair. (Table 1).…”

Photochemically crosslinked cell‐laden methacrylated collagen hydrogels with high cell viability and functionality

“…Stress and strain were computed from the load and displacement data. Compressive modulus was determined by taking the slope of the linear region of the stress–strain curve between the 0 and 10% strain …”

Photocross-linking of glycerol diglycidyl ether with reactive diluents

“…During the late stage, G 0 and G 00 continue to increase with time due to gel aging. The smaller values of G 00 compared to G 0 show the dominant elasticity of the system and indicate the existence of a permanent three-dimensional network formed by the interconnection of polymeric chains [25][26][27].…”