Cytocompatibility of PEG/GBM composite hydrogels’ extracts. (A) Metabolic activity, expressed in relation to 24 h medium (positive control of cell viability), of HUVEC incubated for 24 h with extracts of neat PEG, GO and FLGO composites, TCPET (reference material), fresh medium and 0.1% Triton X-100 (negative control). Five technical replicates and two independent experiments: one-way ANOVA and Tukey’s multiple comparisons test, * p < 0.05. (B) Fluorescence images of HUVEC morphology after incubation with extracts from the aforementioned materials; actin filaments stained with phalloidin (green) and nuclei counterstained with DAPI (blue); scale bar: 200 μm.