QP5 was synthesized by GL Biochem (Shanghai, China) using standard Fmoc solid-phase chemistry on an Apex 396 multiple peptide synthesizer (AAPPTec, Louisville, KY, USA). The peptide sequence and integrity were confirmed using electrospray ionization mass spectrometry (Shimadzu, Kyoto, Japan) and reverse-phase high-performance liquid chromatography (RP-HPLC; CHTH Sci. and Tech, Beijing, China). Peptide purity was determined to be >95.0% by using RP-HPLC. Chitosan of medium molecular weight (75–85% deacetylated) was purchased from Sigma-Aldrich (MI, USA).
The CS-QP5 hydrogel was prepared using the protocol developed by Ruan et al. [34 ] with some modifications. In total 1 ml of a Chitosan calcium phosphate solution (960 µl of 1% Chitosan, 25 µl of 0.1 M CaCl2 and 15 µl of 0.1 M Na2HPO4) was mixed with QP5 to obtain the final concentration of 25 µM, followed by stirring overnight at room temperature. The pH value was adjusted to 6.0 by using dilute NaOH.
The CS-QP5 hydrogel was prepared using the protocol developed by Ruan et al. [34 ] with some modifications. In total 1 ml of a Chitosan calcium phosphate solution (960 µl of 1% Chitosan, 25 µl of 0.1 M CaCl2 and 15 µl of 0.1 M Na2HPO4) was mixed with QP5 to obtain the final concentration of 25 µM, followed by stirring overnight at room temperature. The pH value was adjusted to 6.0 by using dilute NaOH.