Fig. 4

Protein adsorption and cell reactions of alginate-based t-ZnO bioinks. A: Protein loading efficiency plot of five different proteins on t-ZnO. The first two, filled bars show proteins with an IEP above 10 and high loading efficiency. In comparison the unfilled bars represent proteins with an IEP below 6. These exhibit a much lower loading efficiency than the first two proteins, hinting at a relation between loading efficiency and IEP. B-C: Antibacterial activity of t-ZnO-laden alginate hydrogels against S. aureus. The number of surviving bacteria of S. aureus cultured on t-ZnO-laden alginate hydrogels with different structures and containing differing amounts of ZnO (n = 4, *p ≤ 0.05, ***p ≤ 0.0005). In these experiments, B represents a closed structure, C represents an open lattice structure. D-H: Ex vivo skin explants were covered with or without wound dressings (WD) containing different t-ZnO concentrations (0; 5 or 15% respectively) and incubated for 48 h. Skin explants without WD served as a control. D shows the Schematic experimental setup (created in biorender.com). E: Lactate dehydrogenase (LDH)-release was measured in the surrounding supernatant. Skin explant in medium with Triton-X 100 0.1% served as high control. Measurement shows cytotoxicity (%) relative to Triton-X 100. F–H: After RNA isolation and reverse transcription from the remaining parts of skin explants real-time PCR analysis of FLG, hBD-3 and TGM-1 was performed. Shown are means ± s.e.m. of three independent ex vivo skin explants from different patients consisting of two to four stimulations (*p < 0.05; **p < 0.01; ns = not significant; paired t test)