Guan-Jun Ding

Porous hollow microspheres of amorphous calcium phosphate: soybean lecithin templated microwave-assisted hydrothermal synthesis and application in drug delivery

Calcium phosphate biomaterials are very promising for various biomedical applications owing to their excellent biocompatibility and biodegradability. Calcium phosphate nanostructured materials with a porous and hollow structure are excellent drug carriers due to their advantages such as high biocompatibility, large specific surface area, nanosized channels for drug loading and release, high drug loading capacity and pH-responsive drug release behavior. In this work, porous hollow microspheres of amorphous calcium phosphate have been successfully prepared by the microwave-assisted hydrothermal method using adenosine triphosphate disodium salt, CaCl2 and soybean lecithin in aqueous solution. This preparation method is facile, rapid, energy-saving and environment friendly. The effects of microwave hydrothermal temperature and concentrations of the reactants on the morphology and structure of the product were investigated. The as-prepared samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy. The as-prepared porous hollow microspheres of amorphous calcium phosphate are efficient for drug loading and release, and the drug delivery system shows a pH-responsive drug release behavior and high ability to damage tumor cells. Thus, the as-prepared porous hollow microspheres of amorphous calcium phosphate are promising for the applications in various biomedical fields.

α-Fe2O3 nanosheet-assembled hierarchical hollow mesoporous microspheres: Microwave-assisted solvothermal synthesis and application in photocatalysis.

α-Fe2O3 nanosheet-assembled hierarchical hollow mesoporous microspheres (HHMSs) were prepared by thermal transformation of nanosheet-assembled hierarchical hollow mesoporous microspheres of a precursor. The precursor was rapidly synthesized using FeCl3·6H2O as the iron source, ethanolamine (EA) as the alkali source, and ethylene glycol (EG) as the solvent by the microwave-assisted solvothermal method. The samples were characterized by X-ray powder diffraction (XRD), thermogravimetric (TG) analysis, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption-desorption isotherm. The effects of the microwave solvothermal temperature and EA amount on the morphology of the precursor were investigated. The as-prepared α-Fe2O3 HHMSs exhibit a good photocatalytic activity for the degradation of salicylic acid, and are promising for the application in wastewater treatment.

Porous microspheres of amorphous calcium phosphate: Block copolymer templated microwave-assisted hydrothermal synthesis and application in drug delivery

Amorphous calcium phosphate (ACP) microspheres with a porous and hollow structure have been prepared using an aqueous solution containing CaCl2 as a calcium source, adenosine triphosphate disodium salt (Na2ATP) as a phosphorus source in the presence of a block copolymer methoxyl poly(ethylene glycol)-block-poly(D,L-lactide) (mPEG-PLA) by the microwave-assisted hydrothermal method. The effects of microwave hydrothermal temperature and the concentrations of CaCl2 and Na2ATP on the crystal phase and morphology of the product are investigated. The as-prepared ACP porous hollow microspheres have a relatively high specific surface area of 232.9 m(2) g(-1) and an average pore size of 9.9 nm. A typical anticancer drug, docetaxel, is used to evaluate the drug loading ability and drug release behavior of ACP porous hollow microspheres in phosphate buffered saline (PBS) with different pH values of 4.5 and 7.4. The experiments reveal that the ACP porous hollow microspheres have a high drug loading capacity and favorable pH-responsive drug release property, and the ACP porous hollow microsphere drug delivery system shows a high ability to damage tumor cells. It is expected that the as-prepared ACP porous hollow microspheres are promising for the applications in various biomedical fields such as drug delivery.

Solvothermal synthesis of hydroxyapatite nanostructures with various morphologies using adenosine 5′-monophosphate sodium salt as an organic phosphorus source

In this paper, we report a simple and green strategy for the synthesis of hydroxyapatite (HAP) nanostructures with various morphologies (including nanoparticles, microtubes, nanorods and nanorod-assembled flower-like hierarchical structures) using adenosine 5′-monophosphate sodium salt (AMP) as an organic phosphorus source by solvothermal treatment in different solvents. The effects of the solvents and the reaction time on the morphology of the product as well as the formation mechanism of HAP nanostructures are investigated. In this strategy, the AMP biomolecules act as an organic phosphorus source for the formation of HAP nanostructures, and the solvents have effects on the morphology of the product. This strategy is environmentally friendly and surfactant-free. The as-prepared products are characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TG).

Amorphous calcium phosphate nanowires prepared using beta-glycerophosphate disodium salt as an organic phosphate source by a microwave-assisted hydrothermal method and adsorption of heavy metals in water treatment

Amorphous calcium phosphate nanowires (ACPNWs) were prepared using calcium chloride as the calcium source and β-glycerophosphate disodium salt (BGP) as the phosphate source by a microwave-assisted hydrothermal method. The effects of the hydrothermal temperature and concentrations of BGP and CaCl2 on the morphology and crystalline phase of the product were investigated. The as-prepared products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The possible formation mechanism of the ACPNWs is proposed. The experimental results indicate that the as-prepared ACPNWs exhibit large adsorption capacities for heavy metal ions (Cd2+, Cu2+, Pb2+, and Zn2+) and a highly selective adsorption activity for Pb2+ ions in an aqueous solution in the pH range from 4.5 to 8.5, implying that ACPNWs are a promising adsorbent for applications in water treatment.

Microwave-assisted rapid synthesis of magnesium phosphate hydrate nanosheets and their application in drug delivery and protein adsorption

Magnesium phosphate biomaterial, as an alternative to well-known calcium phosphate biomaterials, is an excellent candidate for biomedical applications, owing to its outstanding biocompatibility and biodegradability. Herein, we report a simple strategy for the rapid synthesis of magnesium phosphate hydrate nanosheets (MPHSs) using the microwave-assisted hydrothermal method. This method is facile, rapid, surfactant-free and environmentally friendly. The product shows an excellent ability to promote osteoblast MC-3T3 adhesion and spreading, which indicates high biocompatibility. Moreover, the as-prepared MPHSs are explored for potential applications in the loading and release of the anticancer drug and protein adsorption, using docetaxel as a model anticancer drug and hemoglobin (Hb) as a model protein. The experiments indicate that the as-prepared MPHSs have a relatively high protein adsorption capacity and a high ability to damage tumor cells after loading docetaxel. Thus, the as-prepared MPHSs are promising for applications in various biomedical fields such as drug delivery and protein adsorption.

A novel semiconductor compatible path for nano-graphene synthesis using CBr4 precursor and Ga catalyst

We propose a novel semiconductor compatible path for nano-graphene synthesis using precursors containing C-Br bonding and liquid catalyst. The unique combination of CBr4 as precursor and Ga as catalyst leads to efficient C precipitation at a synthesis temperature of 200°C or lower. The non-wetting nature of liquid Ga on tested substrates limits nano-scale graphene to form on Ga droplets and substrate surfaces at low synthesis temperatures of T ≤ 450°C and at droplet/substrate interfaces by C diffusion via droplet edges when T ≥ 400°C. Good quality interface nano-graphene is demonstrated and the quality can be further improved by optimization of synthesis conditions and proper selection of substrate type and orientation. The proposed method provides a scalable and transfer-free route to synthesize graphene/semiconductor heterostructures, graphene quantum dots as well as patterned graphene nano-structures at a medium temperature range of 400–700°C suitable for most important elementary and compound semiconductors.