Stepwise Surface Engineering of Sr10‐HA‐g‐PBLG Porous Microspheres: Precise Functionalization for In Situ Scaffold Formation via Dynamic Crosslinking

This study develops a sequential surface functionalization strategy for strontium‐substituted hydroxyapatite‐graft‐poly(γ‐benzyl‐L‐glutamate) (Sr10‐HA‐ g ‐PBLG) porous microspheres to enable in situ scaffold assembly. Hydrazine hydrate‐mediated aminolysis and alkaline hydrolysis introduced surface amino (2.87 × 10 −2 mol/g) and carboxyl (1.76 × 10 −2 mol/g) groups, respectively, while preserving structural integrity (verified by FT‐IR/XRD/SEM). Subsequent EDC/NHS‐activated grafting of 3‐amino‐1,2‐propanediol (AP) achieved 90% efficiency, followed by NaIO 4 oxidation to generate aldehyde functionalities (2.65 × 10 −3 mol/g). Through dynamic imine crosslinking between aldehyde‐ and amino‐functionalized microspheres, 3D scaffolds were formed in situ. The scaffolds exhibited hierarchical porosity (pore size: 40–60 μm, porosity: 85.4% ± 2.3%), exceptional hydration capacity (613.6% ± 24.1% water retention), and enhanced mechanical properties (storage modulus > 13,000 Pa, compressive strength: 0.53 ± 0.02 MPa, tensile strength: 0.068 ± 0.02 MPa). Controlled degradation in PBS (pH = 7.4) showed 46.24% mass loss over 31 weeks. This interfacial engineering approach provides a versatile platform for designing polymer‐ceramic hybrids with tailorable surface reactivity and structural adaptability. Adipose‐derived stem cells were cultured in vitro, and the dual‐fluorescence tracking strategy revealed spatially coordinated cellular colonization patterns, demonstrating porous microsphere scaffold's potential for precision‐controlled 3D cell delivery in tissue engineering applications.