| Inorganic-hyaluronic acid (HA) core-shell nano-particles posses the excellent properties of both inorganic nano-materials and HA, and may even have the special properties which the original components do not have. N-isopropyl acrylamide was introduced into the core-shell nano-particles and this caused the shell to be cross-linked resulting in the formation of microgels. These microgels maintained the properties of HA, such as the biocompatibility, good water retention, high-viscosity and had a temperature sensitivity of PNIPAM.In this paper, the nano-SiN particles, whose surface were positively charged, were fabricated by modifying nano-SiO2 through the sol-gel method in situ. HA was coated onto the particles by electrostatic adsorption to form core-shell nanoparticles (SiNHA), which were selected as nuclear. Furthermore, N-isopropylacylamide was polymerized on the surface to form thermo-sensitive core-shell microgels (SiNHA-PNIPAM). The shape and conformation of SiO2, SiNHA and SiNHA-PNIPAM was determined by Scanning electron microscope(SEM), Transmission electron micrograph(TEM) and Fourier transform infrared spectroscopy(FTIR). The corresponding changes in particle size and zeta potential were characterized by Dynamic light scattering (DLS). At last the AFM was used to observe the film-forming of microgel above the critical temperature. The results indicated that nano-SiO2 had good dispersion after modifiying by KH550 and the core-shell nanoparticles(SiNHA-PNIPAM) was negatively charged. By polymerizing NIPAM onto the shell of particles, the thermo-sensitive core-shell microgels were formed and their critical temperature was 32℃. AFM and SEM observation revealed that the microgels were spherical on the mica surface at 25℃, but there was a phase-change and a film was depositing on the mica surface above the critical temperature (37℃). These nano-particles are hoped to be used in the soft and hard tissue replacement implants.
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