Hongying Su

Polypyrrole Nanofibers Supported Cr(III)(salen)Cl Catalyst: A Novel Polymer Supported Catalyst for Alternating Copolymerization of Cyclohexene Oxide with Carbon dioxide

Polypyrrole(PPy) supported Cr(III)(salen)Cl catalyst was prepared for alternating copolymerization of cyclohexene oxide and carbon dioxide. The supported catalyst and the copolymerization products were characterized by FTIR, XRD, XPS, ICP-MS, SEM, TEM, NMR, gel permeation chromatography, thermogravimetric analysis and differential scanning calorimetry. After the study, we concluded that the homogeneous Cr(III)(salen)Cl is successfully supported on the PPy, and its catalytic performance is much better than the homogeneous one. Moreover, the copolymerization product catalyzed by PPy-Cr(III)(salen)Cl exhibits higher molecular weight, narrower molecular weight distribution, superior thermal stability and selectivity.Graphical Abstract

Porous structured MIL-101 synthesized with different mineralizers for adsorptive removal of oxytetracycline from aqueous solution

In this work, highly porous MIL-101 materials using hydrochloric acid (HCl) or hydrofluoric acid (HF) as a mineralizer were synthesized. The products were characterized with X-ray diffraction, scanning electron microscopy, thermal gravimetric analysis, and N2 sorption analysis. The results proved that the mineralizers had an obvious effect on the microstructures and morphologies of MIL-101, and MIL-101(HCl) showed remarkable superiority in a higher specific surface area, smaller particle size and higher crystallinity to the HF counterpart. These materials were then used to adsorb and remove the oxytetracycline (OTC) antibiotics from a water solution and an effective fast adsorption of OTC in aqueous solution was observed in the adsorptive kinetics. Compared with MIL-101(HF), a higher adsorption capacity on the MIL-101(HCl) was obtained, which was probably attributed to the higher specific surface area for the MIL-101(HCl). The adsorption mechanism might be greatly ascribed to π–π interaction, and acid–alkaline interaction between the oxytetracycline molecule and the adsorbent.

Synthesis and characterization of Schiff base contained dextran microgels in water-in-oil inverse microemulsion.

Polysaccharide-based microgels with high water content, excellent biocompatibility and controllable particle size have been widely studied as ideal candidates for drug release and delivery. In this study, microgels based on dextran were developed via the Schiff base formation between aldehyded dextran and ethylenediamine in a water-in-oil (W/O) microemulsion. Particle size of the resulted microgel was controllable between 800 and 1100nm by modulating the amount of the employed co-surfactants (Span 80/Tween 80). Furthermore, fluoresceins (e.g., aminofluorescein) and drugs (e.g., doxorubicin) with free amino groups can be conjugated onto the network of the dextran-based microgel via Schiff base linkages. Since the Schiff base linkages are degradable via hydrolysis and their stability decreases with the environmental pH decreases, the resulted Schiff bases contained microgel showed a pH dependent degradation profile. These results indicated that the pH-sensitive microgel based on dextran could be used as promising drug delivery systems for biomedical applications.

Efficient alternating copolymerization of sulfur dioxide with cyclohexene oxide and a mechanistic understanding

The alternating copolymerization of sulfur dioxide with epoxides is rarely reported because of the low reactivity and polysulfite selectivity of the process. This work describes an efficient alternating copolymerization of sulfur dioxide with cyclohexene oxide using salenCrIIICl as the catalyst. The effect of temperature, time, and type of catalyst on the overall activity and selectivity was investigated in detail. The results proved that the reactivity and polysulfite selectivity of salenCrIIICl are better than those of amines and inorganic salts. The copolymer product poly(cyclohexene sulfite) was characterized by nuclear magnetic resonance spectroscopy, infrared spectroscopy, thermogravimetric analysis and gel permeation chromatography. We found that SO2 not only acts as reactant, but also acts as a co-catalyst to promote the copolymerization reaction in the presence of salenCrIIICl. On the basis of the copolymerization mechanism of CO2 and epoxide using a salen catalyst, and spectroscopic evidence, a mechanism to account for the results is proposed.

Schiff base-containing dextran nanogel as pH-sensitive drug delivery system of doxorubicin: Synthesis and characterization

Stimuli-responsive hydrogels have been widely researched as carrier systems, due to their excellent biocompatibility and responsiveness to external physiologic environment factors. In this study, dextran-based nanogel with covalently conjugated doxorubicin (DOX) was developed via Schiff base formation using the inverse microemulsion technique. Since the Schiff base linkages are acid-sensitive, drug release profile of the DOX-loaded nanogel would be pH-dependent. In vitro drug release studies confirmed that DOX was released much faster under acidic condition (pH 2.0, 5.0) than that at pH 7.4. Approximately 66, 28, and 9% of drug was released in 72 h at pH 2.0, 5.0, and 7.4, respectively. Cell uptake by the human breast cancer cell (MCF-7) demonstrated that the DOX-loaded dextran nanogel could be internalized through endocytosis and distributed in endocytic compartments inside tumor cells. These results indicated that the Schiff base-containing nanogel can serve as a pH-sensitive drug delivery system. And the presence of multiple aldehyde groups on the nanogel are available for further conjugations of targeting ligands or imaging probes.