Jian-Bo Qu

PEG-chitosan-coated iron oxide nanoparticles with high saturated magnetization as carriers of 10-hydroxycamptothecin: Preparation, characterization and cytotoxicity studies

A magnetic nano-sized carrier for 10-hydroxycamptothecin (HCPT) was prepared by using Fe(3)O(4) nanoparticles as cores and chitosan (CS) as a polymeric shell by a novel reverse ultrasonic emulsification method. Poly(ethylene glycol) (PEG) chains were then coupled onto the magnetic particles (CS-Fe(3)O(4)) to improve their biocompatibility (PEG-CS-Fe(3)O(4)). HCPT was loaded onto PEG-CS-Fe(3)O(4) by a subtle precipitation method. Under optimum conditions, the CS-Fe(3)O(4) was close to spherical in shape with an average size of 174 nm and a high saturated magnetization. After coupling PEG chains, the unspecific adsorption of bovine serum albumin (BSA) on PEG-CS-Fe(3)O(4) decreased significantly. The drug loading content and loading efficiency were 9.8-11.8% and 49-59% for magnetic composite nanoparticles, respectively. HCPT-loaded magnetic composite nanoparticles showed sustained release profiles up to 48 h, and the cumulative release amount of HCPT from nanoparticles at 45°C increased significantly compared to that at 37°C. Cytotoxicity assay suggests that CS-Fe(3)O(4) does not exhibit noteworthy cytotoxicity against HepG2 cells, but the antitumor activities of HCPT-loaded magnetic composite nanoparticles against HepG2 cells increased significantly in comparison with that of pristine HCPT powder. These results reveal the promising potential of PEG-CS-Fe(3)O(4) as a stable magnetic targeting drug carrier in cancer therapy.

A novel stationary phase derivatized from hydrophilic gigaporous polystyrene-based microspheres for high-speed protein chromatography

Using agarose coated gigaporous polystyrene microspheres as a base support, a novel anion exchanger (DEAE-AP) has been developed after functionalization with diethylaminoethyl chloride. The gigaporous structure, static adsorption behavior, and chromatographic properties of DEAE-AP medium were characterized and compared with those of commercially available resin DEAE Sepharose Fast Flow (DEAE-FF). The results implied that there existed some through pores in DEAE-AP microspheres, which effectively reduced resistance to stagnant mobile phase mass transfer by inducing convective flow of mobile phase in the gigapores of medium. As a consequence, the column packed with DEAE-AP exhibited low column backpressure, high column efficiency, high dynamic binding capacity and high protein resolution at high flow velocity up to 2600cm/h. In conclusion, all the results suggested that the gigaporous absorbent is promising for high-speed protein chromatography.

Galactosylated nanocrystallites of insoluble anticancer drug for liver-targeting therapy: an in vitro evaluation

AIM Low solubility in water has become an intrinsic property of many anticancer drugs, which poses a hurdle in the translation from the bench to the clinic. In this study, we developed a facile method to prepare 10-hydroxycamptothecin (HCPT) nanocrystallites and testified their feasibility for liver-targeting therapy. MATERIALS & METHODS HCPT nanocrystallites were prepared under the soft template effect of galactosylated chitosan. The internalization profile, intracellular trafficking, drug activity and cell viability were evaluated by exposing these nanocrystallites to human hepatocellular carcinoma HepG2 cells. RESULTS Galactosylated chitosan located on the HCPT nanocrystallites not only stabilized the formulation in aqueous medium, but also enhanced the cellular internalization through an asialoglycoprotein receptor-mediated pathway. These nanocrystallites also exhibited the advantages of nuclear entry and active HCPT delivery, and consequently better anticancer cytotoxicity could be achieved. CONCLUSION These data strongly support the superior properties of galactosylated HCPT nanocrystallites on liver-targeting therapy.

An Effective Way To Hydrophilize Gigaporous Polystyrene Microspheres as Rapid Chromatographic Separation Media for Proteins

To overcome the disadvantages of protein denaturation and nonspecific adsorption on poly(styrene-divinylbenzene) (PS) medium as a chromatographic support, gigaporous PS microspheres prepared in our previous study were coated with hydrophobically modified agarose (phenoxyl agarose, Agap). Both the modification of agarose and the gigaporous structure of PS microspheres provided an advantage that facilitated the coating of Agap onto PS microspheres. The amount of Agap adsorbed onto the PS surface was examined as a function of the polymer concentration, and various samples of microspheres, differing in surface Agap density, were prepared. The adsorbed layer was then stabilized by chemical cross-linking and its stability was evaluated in the presence of sodium dodecyl sulfate. Results showed that PS microspheres were successfully coated with Agap, while the gigaporous structure could be well maintained. After coating, the nonspecific adsorption of proteins on PS microspheres was greatly reduced. Flow hydrodynamics experiments showed that the Agap-co-PS column had low backpressure, good permeability, and mechanical stability. Such a procedure could provide a hydrophilic low-pressure liquid chromatographic support for different types of chromatography, since the Agap layer may be easily derivatized by classical methods, and because of their good permeability, the coated microspheres have great potential applications in high-speed protein chromatography.

A novel matrix derivatized from hydrophilic gigaporous polystyrene-based microspheres for high-speed immobilized-metal affinity chromatography

Agarose coated gigaporous polystyrene microspheres were evaluated as a novel matrix for immobilized-metal affinity chromatography (IMAC). With four steps, nickel ions were successfully immobilized on the microspheres. The gigaporous structure and chromatographic properties of IMAC medium were characterized. A column packed with the matrix showed low column backpressure and high column efficiency at high flow velocity. Furthermore, this matrix was used for purifying superoxide dismutase (SOD), which was expressed in Escherichia coli (E. coli) in submerged fermentation, on an Äkta purifier 100 system under different flow velocities. The purity of the SOD from this one-step purification was 79% and the recovery yield was about 89.6% under the superficial flow velocity of 3251 cm/h. In conclusion, all the results suggested that the gigaporous matrix has considerable advantages for high-speed immobilized-metal affinity chromatography.

Functional gigaporous polystyrene microspheres facilitating separation of poly(ethylene glycol)–protein conjugate

A novel sulfopropyl gigaporous polystyrene (SP-GP) microsphere enhancing the separation of poly(ethylene glycol)-protein (PEGylated protein) was first presented. The SP-GP microspheres were successfully prepared by introducing sulfopropyl groups into agarose-coated gigaporous polystyrene microspheres and used as chromatography media. Compared with a commercial medium, SP-GP microspheres exhibited improved column efficiency and reduced backpressure with increasing flow velocity, which could ensure its use in high-speed chromatography. Furthermore, a higher protein recovery and purity of the PEGylated protein could be obtained, even when SP-GP was applied at a flow velocity of 1224 cm h(-1). Additionally, the dynamic binding capacity (DBC) of SP-GP was significantly improved, which was higher than 10 mg mL(-1) medium even at a flow velocity of 306 cm h(-1). Further investigation using a laser scanning confocal microscope (LSCM) demonstrated that the static adsorption equilibrium of the PEGylated protein on SP-GP could be completed in 5 min, whereas a much longer period (ca. 60 min) was required for the commercial medium, indicating that the mass transfer of SP-GP was much faster with the gigaporous structure. All of these results strongly support that our developed SP-GP could serve as a promising cation exchange chromatography resin for high-speed separation, especially for biomolecules of high molecular weight.

Inherently fluorescent polystyrene microspheres for coating, sensing and cellular imaging

Commercially available polystyrene (PS) fluorescent microspheres are widely used in biological field for tracing, in vivo imaging and calibration of flow cytometry, among other applications. However, these particles do suffer from some drawbacks such as the leakage and photobleaching of organic dyes within them. In the present study, inherently fluorescent properties of PS based microspheres have been explored for the first time. Here we find that a simple chloromethylation reaction endows the polystyrene particles with inherent fluorescence without any subsequent conjugation of an external fluorophore. A possible mechanism for fluorescence is elucidated by synthesizing and investigating p-ethylbenzyl chloride, a compound with similar structure. Significantly, no photobleaching or leaking issues were observed owing to the stable structure of the microspheres. Chloromethylated PS (CMPS) microspheres can keep their perpetual blue fluorescence even in dry powder state making them attractive as a potential coating material. Furthermore, the chloromethyl groups on CMPS microspheres make them very convenient for further functionalization. Poly(ethylene glycol) (PEG) grafted microspheres showed good biocompatibility and negligible cytotoxicity, and could be used to image intracellular Fe3+ due to the selective fluorescence quenching effect of aqueous Fe3+ in cytoplasm.

Isolation of Immunoglobulin from Chicken Egg Yolk using Single-Stage Ultrafiltration with 100-kDa Regenerated Cellulose Membranes

The aim of this work is to develop a membrane-based cost-effective process for the rapid isolation of immunoglobulin from chicken egg yolk. It was found that a single-stage ultrafiltration using a 100 kDa molecular weight cut-off regenerated cellulose membrane could be employed to isolate immunoglobulin from the crude feedstock. The effects of operational parameters (solution pH, ionic strength, stirring speed and permeate flux) on the transmission of immunoglobulin and the presence of impurity protein with molecular weight close to immunoglobulin were quantified using the parameter scanning ultrafiltration technique. Under optimized conditions, the purity of immunoglobulin obtained was about 85 percent after the single-stage ultrafiltration process, and the recovery of immunoglobulin from the feedstock was 91 percent.