Qi-Li Tang

Hydroxyapatite nanorods/poly(vinyl pyrolidone) composite nanofibers, arrays and three-dimensional fabrics: electrospun preparation and transformation to hydroxyapatite nanostructures.

Electrospinning has been recognized as an efficient technique for fabricating polymer nanofibrous biomaterials. However, the study of electrospun inorganic biomaterials with well-designed three-dimensional (3-D) structures is still limited and little reported. In this study hydroxyapatite (HAp) nanorods with an average diameter of approximately 7 nm and length of approximately 27 nm were synthesized through a simple precipitation method and used for the fabrication of inorganic/organic [poly(vinyl pyrolidone) (PVP)] composite nanofibers by electrospinning in ethanol solution. 3-D fabrics and aligned nanofiber arrays of the HAp nanorods/PVP composite were obtained as precursors. Thereafter, 3-D single phase HAp fabrics, tubular structures and aligned nanofiber arrays were obtained after thermal treatment of the corresponding composite precursors. Cytotoxicity experiments indicated that the HAp fabric scaffold had good biocompatibility. In vitro experiments showed that mesenchymal stem cells could attach to the HAp fabric scaffold after culture for 24h.

Europium-doped amorphous calcium phosphate porous nanospheres: preparation and application as luminescent drug carriers.

Calcium phosphate is the most important inorganic constituent of biological tissues, and synthetic calcium phosphate has been widely used as biomaterials. In this study, a facile method has been developed for the fabrication of amorphous calcium phosphate (ACP)/polylactide-block-monomethoxy(polyethyleneglycol) hybrid nanoparticles and ACP porous nanospheres. Europium-doping is performed to enable photoluminescence (PL) function of ACP porous nanospheres. A high specific surface area of the europium-doped ACP (Eu3+:ACP) porous nanospheres is achieved (126.7 m2/g). PL properties of Eu3+:ACP porous nanospheres are investigated, and the most intense peak at 612 nm is observed at 5 mol% Eu3+ doping. In vitro cytotoxicity experiments indicate that the as-prepared Eu3+:ACP porous nanospheres are biocompatible. In vitro drug release experiments indicate that the ibuprofen-loaded Eu3+:ACP porous nanospheres show a slow and sustained drug release in simulated body fluid. We have found that the cumulative amount of released drug has a linear relationship with the natural logarithm of release time (ln(t)). The Eu3+:ACP porous nanospheres are bioactive, and can transform to hydroxyapatite during drug release. The PL properties of drug-loaded nanocarriers before and after drug release are also investigated.

Calcium phosphate drug nanocarriers with ultrahigh and adjustable drug-loading capacity: One-step synthesis, in situ drug loading and prolonged drug release

UNLABELLED Calcium phosphates (CPs) are regarded as the most biocompatible inorganic biomaterials; however, they are limited in the drug-delivery applications, especially for hydrophobic drugs. Achieving high drug-loading capacity and a controllable drug-release property are two main challenges. In this study we report a strategy for the preparation of novel drug delivery systems based on a concerted process in which the formation of the CP nanocarriers and the drug storage are accomplished in one step in mixed solvents of water and ethanol. The key advantage of this strategy is that the formation of CP nanocarriers and in situ loading of the drug occur simultaneously in the same reaction system, which makes it possible to achieve ultrahigh drug-loading capacity and prolonged drug release due to ultrahigh specific surface area and numerous binding sites of the CP nanocarriers. A series of hydrophobic drug-delivery systems with adjustable drug-loading capacities and drug-release rates have been successfully synthesized. In addition, the drug-release kinetics of the as-prepared drug-delivery systems have been found in which the cumulative amount of drug release has a linear relationship with the natural logarithm of release time. FROM THE CLINICAL EDITOR Calcium phosphates (CPs) are highly biocompatible inorganic biomaterials with thus far limited drug-delivery applications. This study reports the preparation of a novel drug delivery system where the formation of CP nanocarriers and in situ loading of the drug occur simultaneously in the same reaction, enabling ultra-high drug-loading.

Preparation and sustained-release property of triblock copolymer/calcium phosphate nanocomposite as nanocarrier for hydrophobic drug.

The P123/ACP nanocomposite with sizes less than 100 nm consisting of triblock copolymer P123 and amorphous calcium phosphate (ACP) has been prepared by using an aqueous solution containing CaCl2, (NH4)3PO4, and P123 at room temperature. The P123/ACP nanocomposite is used as the nanocarrier for hydrophobic drug ibuprofen, based on the combined advantages of both amphiphilic block copolymer and calcium phosphate delivery system. The P123/ACP nanocomposite has a much higher ibuprofen loading capacity (148 mg/g) than the single-phase calcium phosphate nanostructures. The drug release percentage of the P123/ACP nanocomposite in simulated body fluid reaches about 100% in a period of 156 h, which is much slower than that of single-phase calcium phosphate nanostructures. It is expected that the P123/ACP nanocomposite is promising for the application in the controlled delivery of hydrophobic drugs.

Porous nanocomposites of PEG-PLA/calcium phosphate: room-temperature synthesis and its application in drug delivery

We report room-temperature preparation of poly(ethylene glycol)-block-polylactide (PEG-PLA)/calcium phosphate (CP) nanocomposites with a porous morphology. The reaction time and concentration of the inorganic ingredients play an important role in the morphology and chemical composition of the nanocomposite. Thermogravimetry analysis shows that there is approximately 8.5 wt.% of PEG-PLA block copolymer in the nanocomposite. A typical anti-inflammatory drug, ibuprofen, is used to evaluate the drug loading ability and the release behavior of the porous PEG-PLA/CP nanocomposite. The experiments reveal that the nanocomposite has a higher drug loading capacity and favorable drug release property. The drug release kinetics of the porous PEG-PLA/CP nanocomposite is discussed as a three-stage process. The as-prepared porous PEG-PLA/CP nanocomposite is promising for application in drug delivery.