Jun Shi

Hollow hybrid hydroxyapatite microparticles with sustained and pH-responsive drug delivery properties

The hybrid hydroxyapatite (HAP) hollow microparticles were achieved by combining HAP hollow microparticles and chitosan/sodium alginate (CHI/SA) multilayers via the layer-by-layer (LbL) self-assembly technique. Doxorubicin hydrochloride (DOX) loading and release investigation indicated that the prepared hybrid CHI/SA/HAP hollow microparticles with a hollow hydroxyapatite core and polymer multilayer shell exhibited high drug loading efficiency, sustained and pH-dependent drug release properties. The drug loading efficiency of CHI/SA/HAP hollow microparticles was 90.0%, which was much higher than that of solid HAP microparticles (39.6%). Compared to the solid HAP microparticles having a higher amount of released DOX over the initial 1 h (about 44.4% of total released drug over 24 h), CHI/SA/HAP hollow microparticles displayed sustained release properties with the value of only 28.4% with the same treatment. Moreover, the drug release of hybrid CHI/SA/HAP hollow microparticles was pH-dependent because of the different electrostatic interaction in the CHI/SA multilayers at different pH values and the dissolution of HAP hollow core under acidic conditions. The results indicate that the hybrid CHI/SA/HAP hollow microparticles show great potential as a novel drug carrier for controllable drug delivery.

Hollow hierarchical hydroxyapatite/Au/polyelectrolyte hybrid microparticles for multi-responsive drug delivery

In this study, hollow hierarchical hydroxyapatite (HAP)/Au/polyelectrolyte hybrid microparticles with a hollow HAP core and polymer multilayer/Au nanoparticle (AuNPs) shell for multi-responsive drug delivery have been prepared via a layer-by-layer (LbL) technique. Thermal-/pH-dual responsive aliphatic poly(urethane-amine) (PUA) was employed as the smart component. The aggregated AuNPs inside hybrid microparticles could potentially obstruct the diffusion of doxorubicin hydrochloride (DOX) from the hollow microparticles and assuage the initial burst release of DOX. Upon irradiation with near-infrared (NIR) laser, AuNP aggregates can effectively convert light to heat and result in the rapid release of DOX due to the partial collapse of the polyelectrolyte multilayers (PUA/sodium poly(styrenesulfonate) (PSS)). In addition, due to the dissolution of HAP in the acidic media and the shrinkage of aliphatic PUA above its lower critical solution temperature (LCST), the drug release of hollow hybrid carriers exhibits distinguished pH- and thermal-dependent properties. The results indicate that the hollow HAP/Au/PUA/PSS hybrid microparticles show great potential as novel smart drug carriers for controllable drug delivery.

Biomineralized organic–inorganic hybrids aiming for smart drug delivery

Abstract Organic–inorganic hybrid materials have received great interest in the last 10 years in the controlled drug delivery area because of their excellent biocompatible, biomimetic, and pH-sensitive properties. Biomineralization is a biomineral-inspired route to prepare novel organic–inorganic hybrids, which involves a diffusion-controlled deposition of inorganic minerals within porous polymeric matrices. Proper combination of controlled biomineralization technique with the rational choice of polymer templates would lead to the successful development of smart self-assembled drug carriers. The present work mainly summarizes our recent work about the biomineralized organic–inorganic hybrid materials aiming for smart drug delivery including hybrid beads, membranes, and micro/nano gels. Furthermore, prospect for future development of the smart organic–inorganic hybrids is also discussed.

Full functional photorefractive molecule with large two-beam coupling gain

We have synthesized two Carbazole-based monolithic monomers, 3-[9-(2-Ethyl-hexyl)-9H-carbazol-3-yl]-2-(4-nitro- phenyl)-acrylonitrile (M1) and (Z)-2-((9-(4-ethylhexyl)-9H-carbazol-6-yl)methylene)-4-oxopentanenitrile (M2), which contain both photoconductive and electro-optic chromophore. The melting point were measured to be 151 oC (M1) and 77 oC(M2) respectively, which are higher than the room temperature. No crystallization of their films is observed at room temperature. One of the monomers M1 exhibits good photorefractive performance. The two-beam coupling gain coefficient of M1 is measured to be 372 cm-1 at 50 V/um, while the two-beam coupling gain coefficient of M2 is only 17 cm-1 at 42 V/um. By applying ellipsometric technique, we deduced that the better PR performance of M1 was due that M1 has larger effective electro-optic coefficient. The photorefractive index modulation of M1 was measured to be 6x10-3 at an electric field of 48.3V/μm. Further investigation on the structure-property relationship has also been demonstrated.