Studies on the Impact of the Photoinitiator Amount Used during the PVP-Based Hydrogels' Synthesis on Their Physicochemical Properties.

In recent times, a great interest is directed to developing biomaterials incorporated with various therapeutical substances which may enhance them with new properties and thus increase their application potential. In this work, polyvinylpyrrolidone (PVP)-based hydrogels modified with juice and vitamin C and differing in the amount of the photoinitiator used during their synthesis were developed. Analysis of hydrogels included characterization of their chemical structure via FT-IR spectroscopy, sorption properties, wettability, surface morphology, behavior in simulated physiological liquids and mechanical properties. Finally, hydrogels' cytotoxicity towards L929 murine fibroblasts using MTT reduction assay was additionally verified. It was demonstrated that as the amount of the photoinitiator used during the synthesis of hydrogels increased, the smoother their surface and the higher their hydrophilicity. Next, the greater the amount of the photoinitiator, the lower is the percentage elongation of the hydrogel and the greater the hardness. In turn, the swelling ability of hydrogels depended strongly on the type of the absorbed liquid-swelling ratios of samples in distilled water were 24% higher than in SBF, 18% higher than in Ringer liquid, and 32% higher than in hemoglobin wherein the amount of the photoinitiator did not affect this property. Additionally, hydrogels were stable and did not degrade in simulated physiological liquids. The only changes in pH of the incubation media were probably caused by the active substances release from hydrogels which was also confirmed via a lesser intensity of the absorption band on FT-IR spectra corresponding to the functional group occurring in compounds included in juice. Importantly, the viability of fibroblasts incubated with developed materials was at least 86%. Thus the hydrogels, due to their properties, seem to show application potential to be used for biomedical purposes, e.g., as innovative dressing materials.