Abstract

Cytotoxicity presents one of the required criteria in the biological evaluation of medical devices. In this study, the semi-direct contact test was used to evaluate the potential cytotoxicity of hydrogel wound dressings compared to the conventional extract test. Three types of hydrogel sheets were fabricated from poly(vinyl alcohol) (PVA) by gamma irradiation: Bare sheets, silver (Ag)-coated sheets, and Aloe vera (AV)-coated sheets. In the extract test, L929 cells were cultured in the extract derived from the elution of hydrogel samples. For the semi-direct contact test, the cells were cultured in situ with the hydrogel samples placed inside transwell inserts above the cell monolayers. At the endpoint of both tests, MTT assay was performed, and the cell viability was determined from the absorbance of formazan. Only the bare and AV-coated hydrogel sheets showed cell viability above the 70 % threshold that ensured the non-cytotoxicity by both tests. For Ag-coated sheets, less than 70 % cell viability occurred when Ag coating was². Interestingly, the formazan-depleted area underneath the Ag-coated sample could be clearly observed by the semi-direct contact test. The release of Ag in the form of nanoparticles was confirmed by UV-Vis absorption at 420 nm. In conclusion, the semi-direct contact test can serve as a reliable alternative to the conventional extract test in evaluating the potential cytotoxicity of hydrogel wound dressings.