In this work, the preparation of chitosan-poly(acrylic acid)-calcium phosphate hybrid nanoparticles (CS-PAA-CaP NP) based on the mineralization of calcium phosphate (CaP) on the surface of chito-san-poly (acrylic acid) nanoparticles (CS-PAA NPs) was reported. CS-PAA-CaP NPs were achieved by directly adding ammonia to the aqueous solution of CS-PAA nanoparticles or by thermal decomposi-tion of urea in the aqueous solution of CS-PAA nanoparticles, resulting in the mineralization of CaP on the surface of CS-PAA NPs. Through these two routes, especially using urea as a pH-regulator, the precipitation of CS-PAA NPs, a common occurrence in basic environment, was avoided. The size, morphology and ingredient of CS-PAA-CaP hybrid nanoparticles were characterized by dynamic light scattering (DLS), transmission electron microscope (TEM), scanning electron microscope (SEM), thermogravimetry analysis (TGA) and X-ray diffractometer (XRD). When urea was used as the pH regulator to facilitate the mineralization during the thermal urea decomposition procedure, regular CS-PAA-CaP hybrid nanoparticles with a porosity-structural CaP shells and 400―600 nm size were obtained. TGA result revealed that the hybrid NPs contained approximately 23% inorganic component, which was consistent with the ratio of starting materials. The XRD spectra of hybrid nanoparticles in-dicated that dicalcium phosphate (DCP: CaHPO4) crystal was a dominant component of mineralization. The porous structure of the CS-PAA-CaP hybrid NPs might be greatly useful in pharmaceutical and other medical applications.
In this work, gelatin-poly（acrylic acid） （GEL-PAA） nanospheres with diameter of around 35 nm were prepared using a polymermonomer （gelatin-AA） pair reaction system. These nanospheres can self-assemble into nanorods in aqueous solution at 4 ℃. Based on the observation that the intermediate state of the formation of the nanorods and the facts that the self-assembly can only occur at relatively low temperature and the gelatin molecules on the outermost layer of the GEL-PAA nanospheres can be renatured to triple helix conformation, it can be rationally inferred that the hydrogen bonding and electrostatic interactions between the gelatin molecules with the triple helix structure induce the one-dimensional self-assembly of the nanospheres into nanorods.
