Titanium-Adhesive Polymer Nanoparticles as a Surface-Releasing System of Dual Osteogenic Growth Factors

A titanium (Ti)-adhesive nanoparticle is developed as a surface-releasing system for dual osteogenic growth factors. The Ti-adhesive nanoparticle is prepared by self-assembly of a poly(L-lactide-co-glycolide) (PLGA)-grafted hyaluronic acid (HA) copolymer, followed by conjugation of catechol groups on nanoparticle surfaces. The nanoparticles consist of Ti-adhesive peripheral catechol groups, anionic HA shells, and hydrophobic PLGA inner cores. The immobilization of the nanoparticles onto Ti substrates is successfully verified using various analytical tools including field-emission scanning electron microscopy (Fe-SEM), contact angle measurement, and X-ray photoelectron spectroscopy (XPS). Positively charged dual growth factors, bone morphogenetic protein-2 (BMP-2) and insulin-like growth factor-1 (IGF-1) are readily loaded onto the negatively charged HA shells of surface-immobilized nanoparticles, which is confirmed by fluorescence microscopy. The Ti substrates with dual growth factor-loaded nanoparticle-immobilized nanoparticles remarkably promote the attachment, proliferation, spreading, and alkaline phosphatase (ALP) activity of human adipose-derived stem cells (hADSCs).