Buning Zhang

Adsorption of Copper (II) and Lead (II) Ions onto Cottonseed Protein-PAA Hydrogel Composite

The adsorption behaviors of copper and lead ions in aqueous solution by cottonseed protein-poly (acrylic acid) copolymer (CP-PAA) hydrogel composite have been studied in single component sorption systems. The influence of cottonseed protein content in the copolymer composition on the adsorption capacity of the hydrogel is studied and the sorption of copper (II) and lead (II) ions is investigated in aqueous solution with different initial metal ion concentration and pH value, respectively. The results indicate that the hydrogel composite is a suitable sorbent for the two metal ions. The experimental data of the adsorption equilibrium from Cu(II) and Pb(II) solution correlated well with the Langmuir isotherm equation. The adsorption kinetics of the two metal ions has been analyzed and the pseudo–second-order equation provides good fits to experimental data of both metals. By treatment with aqueous HCl solution, the hydrogel can be regenerated and reused again to adsorb heavy metal ions. The characterization of the hydrogel after adsorption of metal ions by XRD, SEM and EDS reveals that the accumulation of metal ions occurs on the surface of the hydrogel composite.

Nano carriers for drug transport across the blood–brain barrier

Abstract Effective therapy lies in achieving a therapeutic amount of drug to the proper site in the body and then maintaining the desired drug concentration for a sufficient time interval to be clinically effective for treatment. The blood–brain barrier (BBB) hinders most drugs from entering the central nervous system (CNS) from the blood stream, leading to the difficulty of delivering drugs to the brain via the circulatory system for the treatment, diagnosis and prevention of brain diseases. Several brain drug delivery approaches have been developed, such as intracerebral and intracerebroventricular administration, intranasal delivery and blood-to-brain delivery, as a result of transient BBB disruption induced by biological, chemical or physical stimuli such as zonula occludens toxin, mannitol, magnetic heating and ultrasound, but these approaches showed disadvantages of being dangerous, high cost and unsuitability for most brain diseases and drugs. The strategy of vector-mediated blood-to-brain delivery, which involves improving BBB permeability of the drug–carrier conjugate, can minimize side effects, such as being submicrometre objects that behave as a whole unit in terms of their transport and properties, nanomaterials, are promising carrier vehicles for direct drug transport across the intact BBB as a result of their potential to enter the brain capillary endothelial cells by means of normal endocytosis and transcytosis due to their small size, as well as their possibility of being functionalized with multiple copies of the drug molecule of interest. This review provids a concise discussion of nano carriers for drug transport across the intact BBB, various forms of nanomaterials including inorganic/solid lipid/polymeric nanoparticles, nanoemulsions, quantum dots, nanogels, liposomes, micelles, dendrimers, polymersomes and exosomes are critically evaluated, their mechanisms for drug transport across the BBB are reviewed, and the future directions of this area are fully discussed.

Synthesis and Swelling Properties of Hydrolyzed Cottonseed Protein Composite Superabsorbent Hydrogel

A novel protein-based superabsorbent hydrogel was synthesized by graft copolymerization of hydrolyzed cottonseed protein (HCP) and acrylic acid (AA) monomer. This hydrogel was synthesized by solution-based copolymerization, using N,N-methylene bisacrylamide as a crosslinking agent, potassium persulphate and sodium sulfite as the initiators. The effects of the certain variables of the graft copolymerization on the swelling capacity of the hydrogel were measured and its swelling properties in different solutions were investigated as well. This new approach is a promising method in utilizing hydrolyzed cottonseed protein in the production of a superabsorbent polymer with excellent water absorbency and potential use in various applications.

Preparation and characterization of a dialdehyde starch crosslinked feather keratin film for food packaging application

Feathers, a byproduct of the poultry industry, have long been considered as a solid waste, posing a series of environmental and economic problems. However, feather keratin (FK) extracted from feathers is a valuable source of the biodegradable and biocompatible polymer. The aim of this study was to develop and characterize novel casting films based on feather keratin (FK) crosslinked by dialdehyde starch (DAS) and plasticized with glycerol for applications in biomedicine. The microstructure, crystallization behavior, light transmission, moisture content, solubility, tensile properties, water vapor barrier property, and cytotoxicity of the FK–DAS films were investigated. The fracture surface of the crosslinked film showed a more compact microstructure than that of the control film, and the crosslinked films were completely amorphous and very transparent (transparency value <2). These results indicate that the addition of DAS increased the transparency value and moisture content and decreased the solubility, indicating the crosslinking between the FK and DAS. The films with 2% DAS showed increased tensile elongation and water vapor permeability compared to the control films, whereas the tensile strength of the film decreased, most probably because the crosslinking effect was counterbalanced by the plasticization of DAS. DAS increased the water resistance of the FK films, thus expanding their potential application in food packaging.

Fabrication and characterization of electrospun feather keratin/poly(vinyl alcohol) composite nanofibers

Feathers, which contain more than 90% of keratin, are valuable natural protein resources. Moreover, recycling waste feathers to develop biomaterials contributes to environmental protection. The aim of this study was to fabricate and characterize both random and aligned feather keratin (FK)/PVA composite nanofibers through an electrospinning process. The morphology, molecular interaction, crystallization behavior, and tensile properties of the nanofibers were investigated. The electrospinning process appeared stable and successful for solutions containing no more than 40 wt% of FK. Smooth and bead-free FK/PVA random nanofibers were obtained for all the experimental samples. The fiber average diameter decreased for the random nanofibers and the degree of fiber orientation increased for the aligned nanofibers as the FK content increased. The crystallinity of the nanofibers reduced with the incorporation of FK but the orientation of nanofibers was favorable to crystallization. Random nanofibers exhibited an increased tensile strength when the FK to PVA ratio increased. Tensile strength and elongation at break in the direction of the aligned fibers were improved compared to the random nanofibers at the same FK content. This work demonstrates the potential of expanding the application of nanofiber-based products in the biomaterial field.

Preparation and Physicochemical Properties of Dialdehyde Starch Crosslinked Feather Keratin/PVA Composite Films

Feathers, as a by-product of the poultry industry, have long been treated as solid waste disposal which causes a series of environmental and economic problems. Feather keratin (FK) can be extracted from feathers and have very strong stretching resistance. A series blend films based on FK and poly (vinyl alcohol) (PVA) was prepared by solution casting, and dialdehyde starch (DAS) were introduced to achieve better physicochemical properties for the blend films. According to DSC analysis, the single glass transition temperature and single melting temperature of the blend films indicated the good compatibility among FK, PVA and DAS. With increasing PVA content, the tensile strength (σb), elongation at break (ϵb), and decomposition temperature increased, indicated that hydrogen bonds were formed between FK and PVA. With certain PVA content, the increase of DAS caused σb to increase and ϵb, decomposition rates, solubility and water vapor permeability (WVP) to decrease, suggesting the formation of crosslink network among FK, PVA and DAS, that is to say, the mechanical properties, thermal stability and water-resistance of FK/PVA blend film were improved by crosslinking with DAS. The blend film was uniform and translucent, and could be used in packing and bio-medical industries.

Synthesis of the polymerizable room temperature ionic liquid AMPS – TEA and superabsorbency for organic liquids of its copolymeric gels with acrylamide

A polymerizable room temperature ionic liquid (RTIL), 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) – triethylamine (TEA), was synthesized by neutralization of AMPS with TEA in acetone followed by evaporation of the solvent under a reduced pressure at room temperature. The RTIL was characterized with fourier transform infrared spectroscopy, differential scanning calorimetry (DSC), and 1H NMR. Co-polymeric gels of the RTIL with acrylamide (AAm) were prepared by aqueous solution polymerization using N,N′-methylenebisacrylamide as a crosslinker, and ammonium persulfate as an initiator. Superabsorbency of the gels in aqueous and a series of organic liquids was investigated gravimetrically. DSC data showed that the glass transition temperature of AMPS – TEA was −59.4 °C. Poly(AMPS – TEA-co-AAm) gels exhibited superabsorbency in both water and a series of organic solvents. The mechanism for swelling in aqueous and organic media of the gels was critically discussed.

Synthesis, Chloramphenicol Uptake, and In Vitro Release of Poly(AMPS–TEA-Co-AAm) Gels with Affinity for Both Water and Alcohols

Novel copolymeric gels of poly(AMPS–TEA-co-AAm) with superabsorbency in both water and alcohols were synthesized by neutralizing 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) with triethylamine (TEA) followed by copolymerizing the resulted salt with acrylamide (AAm) in aqueous solutions using N,N′-methylenebisacrylamide (MBAm) as a crosslinker, and ammonium persulfate (APS) as an initiator. By swelling the xerogel of poly(AMPS–TEA-co-AAm) in the drug solution followed by removing the solvent to give drug-polymer conjugate, the incorporation of a model drug, chloramphenicol, into the gels was investigated by using water and alcohols as solvent, respectively. The in vitro drug release profile of the drug-polymer conjugate was investigated in PBS. The results showed that poly(AMPS–TEA-co-AAm) gels exhibited superabsorbency in both water and a series of alcohols; and the alcohol-facilitated uploading of chloramphenicol into the gels was much greater than that achieved in water. The poly(AMPS–TEA-co-AAm) gels exhibited a similar drug release profile with conventional hydrogels; and only part of the drug uptaken by the gels was released as a result of poor aqueous solubility of chloramphenicol.

Synthesis of two AMPS-based polymerizable room temperature ionic liquids and swelling difference between their co-polymeric gels with HEMA

Abstract Two polymerizable room temperature ionic liquids (RTIL), AMPS-BA and AMPS-DMAEMA, were synthesized by neutralization of 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) with butylamine (BA) and 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA), respectively, in acetone, followed by evaporation of the solvent under a reduced pressure at room temperature. The RTILs were characterized by differential scanning calorimetry to determine their glass transition temperatures (Tg). Co-polymeric gels of the RTILs with 2-hydroxyethylmethacrylate (HEMA) were prepared by aqueous solution polymerization using N,N′-methylenebisacrylamide (MBAm) as a cross-linker and ammonium persulfate as an initiator. The superabsorbency of the gels in water and various organic solvents was gravimetrically investigated. The results showed that the Tg of AMPS-BA and AMPS-DMAEMA was -47.7°C and -45.8°C, respectively. Poly(AMPS-BA-co-HEMA) gels exhibited superabsorbency in both water and various organic solvents, while poly(AMPS-DMAEMA-co-HEMA) gels did not swell in any liquids. The mechanism for the swelling difference between poly(AMPS-BA-co-HEMA) gels and poly(AMPS-DMAEMA-co-HEMA) gels was critically discussed.

Effects of the Structure and Composition of Montmorillonite on the Dimerization of Unsaturated Fatty Acids

The effects of structure and composition of different montmorillonites on their catalytic performance in the dimerization of unsaturated fatty acids were investigated. The dimerization reaction was performed at 240 °C for 3 h, with montmorillonite as catalyst, and LiCl as the co-catalyst. The results showed that the specific surface areas of the different montmorillonites did not have a major effect on their catalytic performance, but the interlayer spacing and surface acidity of montmorillonite show significant effects on the product yield. After the organic modification through hexadecyl trimethyl ammonium bromide (CTAB) intercalation, the microenvironment of the montmorillonite layer changes. Moreover, the inner and outer surfaces change from being hydrophilic to lipophilic, which improves the dispersibility of montmorillonite in fatty acids. The xAl/xSi molar ratios of the three samples are similar and lie within the range of 0.4306-0.5010, thus the xAl/xSi molar ratio has little effect on the dimerization reaction.