All chemicals and solvents were purchased from Merck, except for 2-chlorotrityl chloride resin that was acquired from GL Biochem (Shanghai, China). The 1 H and C NMR spectra were acquired at 400 and 100 MHz, respectively, on a Varian spectrometer, using deuterated solvents as indicated in the Supporting Information. The dipeptides were synthesized in solid phase using Fmoc-protection strategy, purified by reverse-phase HPLC (Agilent 1260), and visualized by microscopy, using standard protocols previously applied to similar dipeptides. Cell culture on peptide hydrogels and MTT assays were performed using standard protocols that have been previously described.