Polyvinyl Alcohol-Hydrogel (PVA-H) is a biomaterial used for manufacturing contact lenses as well as for the medium of drug delivery. Previous studies have also showed that PVA-H exhibits superior biocompatibility with hydrophilic elastic nature. The aim of this study is to examine the possible usage of the PVA-H as cartilage replacement material by determining the static and dynamic mechanical properties of PVA-H with different ratios of polyvinyl alcohol (PVA) and phosphate buffered saline (PBS) compositions.
Three different types of PVA-H specimens were made by changing the ratio of PVA (Sigma-Aldrich) and PBS (Sigma-Aldrich) compositions (PVA-H1: 10 wt% PVA and 90 wt% PBS; PVA-H2: 20 wt% PVA and 80 wt% PBS; PVA-H3: 25 wt% PVA, 45 wt% PBS and DMSO 30 wt%). Static and dynamic tensile tests under the loading frequencies of 0.001, 0.01, 0.1, and 1 Hz were carried out to measure the biomechanical properties of PVA-H1, -H2 within PBS solution and -H3 within PBS/ DMSO solution.
The equilibrium Young’s moduli (EY) of PVA-H1, -H2 and -H3 evaluated from the static displacement control were 84.2±35.1 kPa (n=10), 254±32.2 kPa (n=10) and 588±38.9 kPa (n=5), respectively. The amplitudes of dynamic tensile moduli were varied from 86.3±33.4 kPa (n=10) at 0.001 Hz to 96.9±42.0 kPa (n=10) at 1 Hz for PVA-H1, from 282.7±26.4 kPa (n=10) at 0.001 Hz to 309.1±32.2 kPa (n=10) at 1 Hz for PVA-H2 and from 643.8±49.8 kPa (n=10) at 0.001 Hz to 747.7±67.7 kPa (n=5) at 1 Hz for PVA-H3. According to the current results, the frequency dependence of the magnitude of the dynamic modulus confirms the viscoelastic nature of PVA-H material. However, it can be noted that the dynamic modulus increases by up to a factor of 1.15 for PVA-H1, 1.22 for PVA-H2 and 1.27 for PVA-H3, showing insignificant viscoelasticity compared with that for cartilage. The result that static and dynamic moduli of PVA-H3 are larger than those of PVA-H1 and PVA-H2 also suggests that the amount of PVA composition in PVA-H plays an important role in improving both static and dynamic mechanical strengths of PVA-H material. The phase angle decreased from 5.2±2.1 ° at 0.001 Hz to −0.3±1.7 ° at 1 Hz for PVA-H1, from 5.6±0.6 ° at 0.001 Hz to −0.3±0.7 ° at 1 Hz for PVA-H2 and from 8.2±1.1 ° at 0.001 Hz to 0.7±0.7 ° at 1 Hz for PVA-H3.