Fig. 2
Preparation and characterization of WPV-CuO NPs. a Schematic diagram of WPV-CuO generation. Chemically synthesized CuO NPs were coated with PAA to obtain CuO-COOH NPs. A functional peptide (termed WPV) consisting of an outer COL2-targeting sequence (WYRGRL), intermediate MMP-2-sensitive sequence (PLGLA), inner MSC-targeting sequence (VTAMEPGQ), and NH2-rich linker was conjugated with CuO-COOH NPs via EDC/NHS reaction to obtain WPV-CuO NPs. b, c TEM images of CuO NPs. Hydrodynamic diameter distribution (d), Zeta potential (e), UV–vis spectra and FTIR spectra (g) of NPs. Bars represent mean ± SD (n = 3). h HPLC traces of WPV (MMP-2 cleavable) and WGV (MMP-2 uncleavable control) peptides treated with 30 ng mL−1 MMP-2. Peaks of the WPV peptide changed with time while no changes were observed for the WGV peptide, supporting MMP-2 sensitivity of the WPV peptide