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Original Article

Vol. 3 No. 1 (2020): March-September

Synthesis and Characterization of S-IPN Hydrogels of Chitosan/PVA/PNIPAm to be Used in the Design of Nucleus Pulposus Prosthesis



Hydrogels (HG) have been widely used in biomedical applications due to their high-water content which improves their biocompatibility with living tissue. In this study, Chitosan (CS) hydrogels cross-linked with Genipin and semi interpenetrated network (S-IPN) with PVA/PNIPAm were prepared to be used in the design of nucleus pulposus (NP) prosthesis. Chemical structure, morphology, swelling ratio (SR), mechanical properties and cytotoxicity were evaluated through a variation of the Genipin percentage and CS/PVA/PNIPAm proportions. Those experiments were carried out through Fourier-Transform Infrared Spectroscopy, Scanning Electron Microscopy, swelling studies, dynamic rheology, and hemocompatibility tests. The results showed that regardless of the Genipin percentage or polymers proportions, all HGs had interconnective porous structure. What did change microstructurally, was the pore size, its size distribution and the wall thickness. Firstly, an increment in the Genipin percentage and in the CS proportion concluded in an augmentation of the pore size. Secondly, an augmentation in the PVA proportion ended up producing smaller pores, with larger wall thickness and more homogeneous pore size distribution. The variation in PNIPAm proportion didn´t influence the morphology, but did have an impact on the SR and storage modulus (G´) augmenting in both cases as the PNIPAm proportion. The swelling ratio turned out to be related to the pore morphology; as smaller the pore size, smaller the SR. Likewise, the storage modulus rose insofar the SR diminished. In these S-IPN HGs, G´ varied between 77 Pa and 27000 Pa, values below and above G´ reported for human NP. Also, ? varied between 1.4° and 13.17° while the ? reported for NP is 23°-31°. Finally, the hemocompatibility tests did not show cellular lysis for any formulation. These outcomes demonstrated that from the rheological and hemocompatibility point of view, this kind of as semi interpenetrated networks (S-IPNs) HGs can be tailored to attain the NP´s properties


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