Fig. 2: Characterizations of clickable peptide and Zn²⁺ and BMP-2 peptide co-modified surface.

A, B The molecular structures of (DOPA)₆-PEG₅-DBCO and (2-Azido)-PEG₅-BMP-2. C, D ESI-MS spectra of the two synthetic peptides. E AFM images of different surfaces and (F) quantitation of the suface roughess with the different modified surfaces (n = 3 independent samples per group, by a one-way ANOVA with a Tukey’s post hoc test for multiple comparisons). Data are reported as mean ± SD, *p < 0.05, **p < 0.01). G The water contact angles of different surfaces and (H) the quantitative results (n = 3 independent samples per group, by a one-way ANOVA with a Tukey’s post hoc test for multiple comparisons. Data are reported as mean ± SD, **p < 0.01). I SEM-EDS elemental mapping for the Zn²⁺ and BMP-2 peptide co-modified surface (Zn/BMP-2) (scar bar = 5 μm, three independent experiments). J–L XPS analysis of the bare and modified TiO₂ surface (DBCO-TiO₂, Zn, BMP-2 and Zn/BMP-2. M Quantitative elemental analysis according to XPS. N Changes of N 1 s signal in the XPS spectrum of the Zn/BMP-2 surface after incubated in DMEM for 2 weeks. O Zn²⁺ release profiles of the Zn/BMP-² surface in PBS solution; red (left) and blue (right) represent the non-accumulative and accumulative Zn²⁺ release, respectively. Exact P values were given in the Source Data file.