Tethering peptides onto biomimetic and injectable nanofiber microspheres to direct cellular response.

Biomimetic and injectable nanofiber microspheres (NMs) could be ideal candidate for minimally invasive tissue repair. Herein， we report a facile approach to fabricate peptide-tethered NMs by combining electrospinning， electrospraying， and surface conjugation techniques. The composition and size of NMs can be tuned by varying the processing parameters during the fabrication. Further， bone morphogenic protein-2 (BMP-2) and vascular endothelial growth factor (VEGF) mimicking peptides have been successfully tethered onto poly(ε-caprolactone) (PCL):gelatin:(gelatin-methacryloyl) (GelMA)(1:0.5:0.5) NMs through photocrosslinking of the methacrylic group in GelMA and octenyl alanine (OCTAL) in the modified peptides. The BMP-2-OCTAL peptide-tethered NMs significantly promote osteogenic differentiation of bone marrow-derived stem cells (BMSCs). Moreover， human umbilical vein endothelial cells (HUVECs) seeded on VEGF mimicking peptide QK-OCTAL-tethered NMs significantly up-regulated vascular-specific proteins， leading to microvascularization. The strategy developed in this work holds great potential in developing a biomimetic and injectable carrier to efficiently direct cellular response (Osteogenesis and Angiogenesis) for tissue repair.