English: Original caption (also CC-BY 4.0)ː (a,b) The gel stiffness increased after crosslinking and can be easily picked up with a pair of forceps, while remaining optically transparent. (c) LK6C + CRGD [peptide description] gels (99% water) were clear, transparent and easily handled. Phenol red was added to aid visualisation. d) FESEM [field emission scanning electron microscopy] analysis revealed a dense mesh of fibrous network. The thickness of the fibers was on the order of tens of nm, mimicking the fibrous microenvironment found in the ECM [extracellular matrix].