Poly(vinyl alcohol)-poly(vinyl pyrrolidone) hydrogel for herniated nucleus pulposus: Synthesis, characterization, and in vitro study.

Hydrogel as a highly hydrophilic polymer is suitable for nucleus pulposus substitute. Poly(Vinyl Alcohol)-Poly(Vinyl Pyrrolidone) hydrogels are prepared through a cross-linking mechanism using sodium trimetaphospate (STMP). The synthesis method was carried out by mixing variations of the molar ratio between PVA to PVP consist 1:0, 1:0.5, 1:1, and 1:1.5. FTIR spectra for hydrogels revealed the formation of a new bond at 1292 cm-1 (O-P = O stretching). Bonding occurred between the functional group of cross-linking and STMP. The setting time value increased in agreement with the addition of the PVP molar ratio. Compressive strength test results obtained in samples 1:1 and 1:1.5 molar ratio is 5.65 and 4.47 kPa, respectively. Cytotoxicity test showed that sample 1:1.5 produced the highest cell viability with 69.68%. In the in vitro model test, the higher amount of PVP in the hydrogel, the better capability to follow the agarose mold details. Swelling test using phosphate buffer saline (PBS) approaching the ideal value for HNP replacement in the sample with a variation of 1:1 and 1:1.5 respectively 78.44% and 81.86%. The degradation test at a variation of 1:1.5 molar ratio showed a degradation mass of 20.27% for 21 days. PVA-PVP hydrogels have the potential to be applied to HNP replacement based on their compressive strength, biocompatibility status, mold filling ability test, swelling data, and degradation rate.