Characterization of magnetic soluble starch-functionalized carbon nanotubes and its application for the adsorption of the dyes.

Soluble starch-functionalized multiwall carbon nanotube composites (MWCNT-starch) were prepared to improve the hydrophilicity and biocompatibility of MWCNTs. Characterization of the MWCNT-starch by Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, X-ray diffraction (XRD), transmission electron microscope (TEM) and thermogravimetric analysis (TG), showed that the starch component (about 14.3 wt%) was covalently grafted onto the surface of MWCNT. MWCNT-starch-iron oxide composites, intended for use as adsorbents for the removal of dyes from aqueous solutions, were prepared by synthesizing iron oxide nanoparticles at the surface of MWCNT-starch. Starch acts as a template for growth of iron oxide nanoparticles which are uniformly dispersed on the surface of the MWCNT-starch. MWCNT-starch-iron oxide exhibits superparamagnetic properties with a saturation magnetization (23.15 emu/g) and better adsorption for anionic methyl orange (MO) and cationic methylene blue (MB) dyes than MWCNT-iron oxide.

[Preparation and drug releasing property of curcumin nanoparticles].

OBJECTIVE: To prepare curcumin nanoparticles and evaluate the in vitro release of curcumin. METHODS: The chitosan-graft-vinyl acetate copolymers were synthesized by free radical polymerization. Curcumin nanoparticles were synthesized by ultrasonic irradiation. The encapsulation efficiency of the nanoparticles and the in vitro release of curcumin were studied. RESULTS: The nanoparticles were discrete and uniform spheres, covered with positive charges. The encapsulation efficiency of nanoparticles was up to 91.6%. The in vitro release profile showed the slower release rate of curcumin. CONCLUSION: The methods is simple. The nanoparticles possess good physical performance and sustained release character in vitro.

Preparation and characterization of glycerol plasticized-pea starch/ZnO-carboxymethylcellulose sodium nanocomposites.

Among natural polymers, starch is one of the most promising biodegradable materials because it is a renewable bioresource that is universally available and of low cost. However, the properties of starch-based materials are not satisfactory. One approach is the use of nano-filler as reinforcement for starch-based materials. In this paper, a nanocomposite is prepared using ZnO nanoparticles stabilized by carboxymethylcellulose sodium (CMC) as the filler in glycerol plasticized-pea starch (GPS) matrix by the casting process. According to the characterization of ZnO-CMC particles with Fourier transform infrared (FTIR), Ultraviolet-visible (UV-vis), X-ray diffraction (XRD), transmission electron microscope (TEM) and thermogravimetric analysis (TG), ZnO (about 60 wt%) is encapsulated with CMC (about 40 wt%) in ZnO-CMC particles with the size of about 30-40 nm. A low loading of ZnO-CMC particles can obviously improve the pasting viscosity, storage modulus, the glass transition temperature and UV absorbance of GPS/ZnO-CMC nanocomposites. When the ZnO-CMC contents vary from 0 to 5 wt%, the tensile yield strength increase from 3.94 MPa to 9.81 MPa, while the elongation at break reduce from 42.2% to 25.8%. The water vapor permeability decrease from 4.76 x 10(-10) to 1.65 x 10(-10) g m(-1) s(-1) Pa(-1).

Fabrication and characterization of citric acid-modified starch nanoparticles/plasticized-starch composites.

Starch nanoparticles (SN) were prepared by delivering ethanol as the precipitant into starch-paste solution dropwise. Citric acid (CA) modified SN (CASN) were fabricated with the dry preparation technique. According to the characterization of CASN with Fourier transform infrared, X-ray diffraction, rapid visco analyzer, and scanning electron microscopy (SEM), amorphous CASN could not be gelatinized in hot water because of the cross-linking, and most of CASN ranged in size from about 50 to 100 nm. The nanocomposites were also prepared using CASN as the filler in glycerol plasticized-pea starch (GPS) matrix by the casting process. SEM revealed that CASN was dispersed evenly in the GPS matrix. As shown in dynamic mechanical thermal analysis, the introduction of CASN could improve the storage modulus and the glass transition temperature of CASN/GPS composites. The tensile yield strength and Young's modulus increased from 3.94 to 8.12 MPa and from 49.8 to 125.1 MPa, respectively, when the CASN contents varied from 0 to 4 wt %. Moreover, the values of water vapor permeability decreased from 4.76 x 10(-10) to 2.72 x 10(-10) g m(-1) s(-1) Pa(-1). The improvement of these properties could be attributed to the good interaction between CASN filler and GPS matrix. The comprehensive application of green chemistry principles were demonstrated in the preparation of CASN and CASN/GPS composites.

The new insight on ultrastructure of C-type starch granules revealed by acid hydrolysis.

C-type starch granule could be considered as the mixture of A- and B-polymorphs. The ultrastructure of C-type starch granules has not been elucidated detailedly by comparison with that of A- or B-type starch. To better understand the ultrastructure of C-type starch granules, Environment Scanning Electron Microscope (ESEM) and Field Emission Gun Transmission Electron Microscope (FEG-TEM) have been used to analyze the conformation and ultrastructure of C-type starch granule from Rhizoma Dioscorea during acid hydrolysis. SEM results showed that the amorphous areas were mainly located interior part of C-type starch granules whereas the crystalline regions were found mostly in the peripheral region of the granules. The grain size can be confirmed to be about 4.5-9 nm from the HR-TEM micrographs. The nanocrystals from acid-thinned starch displayed the typical face-centered cubic structure. This selected area electron diffraction patterns showed that individual C-type starch granule consisted of A- and B-type polymorphs.

Fabrication and characterization of poly(lactic acid)/acetyl tributyl citrate/carbon black as conductive polymer composites.

By using acetyl tributyl citrate (ATBC) as the plasticizer of poly(lactic acid) (PLA) and carbon black (CB) as conductive filler, electrically conductive polymer composites (CPC) with different CB and ATBC contents were prepared. FTIR revealed that the interaction existed between PLA/ATBC matrix and CB filler and ATBC could improve this interaction. The rheology showed that ATBC could obviously decrease the shear viscosity and improve the fluidity of the composites but just the reverse for CB. With the increasing of CB contents, the enforcement effect, storage modulus, and glass-transition temperature increased but the elongation at break decreased. PLA/ATBC/CB composites exhibited the low electrical percolation thresholds of 0.516, 1.20, 2.46, and 2.74 vol % CB at 30, 20, 10, and 0 wt % ATBC. The conductivity of the composite containing 3.98 vol % CB and 30 wt % ATBC reached 1.60 S/cm. Scanning electron microscopy revealed that the addition of ATBC facilitated the dispersion of the CB in the PLA matrix. Water vapor permeability (WVP) showed that, at the same CB contents, the more ATBC contents there were, the less the values of WVP were.

Conformation and location of amorphous and semi-crystalline regions in C-type starch granules revealed by SEM, NMR and XRD.

The conformations and locations of amorphous and semi-crystalline regions in C-type starch granules from Chinese yam were evaluated by a combination of morphology and spectroscopy studies during acid hydrolysis. Scanning electron micrographs showed that amorphous or less crystalline areas were essentially located in the centre part of C-type starch granules, whereas the semi-crystalline and amorphous growth rings were found mainly in the outer part of the granules. (13)C cross-polarization magic angle spinning NMR ((13)C CP/MAS NMR) showed that amorphous regions were hydrolyzed faster than the crystalline ones. In addition, B-type polymorphs were shown to be hydrolyzed more rapidly than A-types. Powder X-ray diffraction (XRD) also revealed that the B-polymorph was hydrolyzed more rapidly than the A-type. XRD showed that the amorphous or less crystalline areas were mainly located in the core of starch granules, while the amorphous growth rings are distributed toward the outside of the granules and alternatively arranged with semi-crystalline growth rings. The amorphous or less crystalline areas predominantly consisted of the B-polymorph whereas the outer semi-crystalline and amorphous growth rings were mostly composed of the A-polymorph.

[Identification of Fritillaria herbal drugs by X-ray diffraction of starch grains].

OBJECTIVE: To provide a simple method to identify different of herbal drugs of Fritillaria. METHOD: The X-ray diffraction spectra of five Fritillaria powders were obtained by X-ray diffractometry (XRD). RESULT: By analyzing the diffraction peaks of starch over the 2theta diffraction angle in the range of 10 degrees-30 degrees, we concluded that the crystal type of starch in F. thunbergii, F. ussurensis, F. pallidifloca and F. hupehensis was B-type. However, the crystal type of starch in F. cirrhosa was CB-type. The degree of crystallinity of starch was 42.1%, 43.6%, 37.7%, 35.9% and 30.8%, corresponding to F. thunbergii, F. ussurensis, F. pallidiflcoca,F. cirrhosa and F. hupehensis. CONCLUSION: Based on the differences of crystallinity of starch and X-ray diffraction spectra of Fritillaria powders, different species of Fritillaria can be identified.

[Synthesis of a novel starch derivative and its adsorption property for creatinine].

AIM: To prepare a novel creatinine adsorbent with anti-renal failure activity. METHODS: A novel starch ester was prepared under heterogeneous condition by the reaction of starch (ST) and 3, 5-dinitrobenzoyl chloride (DNBZ-Cl). The products were characterized by means of elemental analysis, FTIR, 13CNMR and UV-Vis spectra. The adsorption properties of DNBZ-ST were examined. RESULTS: The adsorption equilibrium is reached after 4 h, the adsorption capacity increases with the degree of substitution (DS) of adsorbent and creatinine concentration. When creatinine concentration is higher than 300 mg.L-1, concentration showed no apparent effect on adsorption capacity. As the adsorption temperature varied from 19 degrees C to 49 degrees C, adsorption capacity first decreases and then increases, and is lowest at 37 degrees C. The adsorption capacity first increases and then decreases as the pH value increase from 4 to 11 and is highest at pH 8. The highest adsorption capacity reached 25 mg.g-1 at 37 degrees C pH 7 and the creatinine concentration is 100 mg.L-1. CONCLUSION: Starch 3,5-dinitrobenzoate showed a better adsorption property for creatinine, and it is worthy to be studied more deeply.