Cai Zhijiang

Poly(hydroxybutyrate)/cellulose acetate blend nanofiber scaffolds: Preparation, characterization and cytocompatibility.

Poly(hydroxybutyrate) (PHB)/cellulose acetate (CA) blend nanofiber scaffolds were fabricated by electrospinning using the blends of chloroform and DMF as solvent. The blend nanofiber scaffolds were characterized by SEM, FTIR, XRD, DSC, contact angle and tensile test. The blend nanofibers exhibited cylindrical, uniform, bead-free and random orientation with the diameter ranged from 80-680 nm. The scaffolds had very well interconnected porous fibrous network structure and large aspect surface areas. It was found that the presence of CA affected the crystallization of PHB due to formation of intermolecular hydrogen bonds, which restricted the preferential orientation of PHB molecules. The DSC result showed that the PHB and CA were miscible in the blend nanofiber. An increase in the glass transition temperature was observed with increasing CA content. Additionally, the mechanical properties of blend nanofiber scaffolds were largely influenced by the weight ratio of PHB/CA. The tensile strength, yield strength and elongation at break of the blend nanofiber scaffolds increased from 3.3 ± 0.35 MPa, 2.8 ± 0.26 MPa, and 8 ± 0.77% to 5.05 ± 0.52 MPa, 4.6 ± 0.82 MPa, and 17.6 ± 1.24% by increasing PHB content from 60% to 90%, respectively. The water contact angle of blend nanofiber scaffolds decreased about 50% from 112 ± 2.1° to 60 ± 0.75°. The biodegradability was evaluated by in vitro degradation test and the results revealed that the blend nanofiber scaffolds showed much higher degradation rates than the neat PHB. The cytocompatibility of the blend nanofiber scaffolds was preliminarily evaluated by cell adhesion studies. The cells incubated with PHB/CA blend nanofiber scaffold for 48 h were capable of forming cell adhesion and proliferation. It showed much better biocompatibility than pure PHB film. Thus, the prepared PHB/CA blend nanofiber scaffolds are bioactive and may be more suitable for cell proliferation suggesting that these scaffolds can be used for wound dressing or tissue-engineering scaffolds.

Preparation of amidoxime surface-functionalized polyindole (ASFPI) nanofibers for Pb( ii ) and Cd( ii ) adsorption from aqueous solutions

Amidoxime surface-functionalized polyindole (ASFPI) nanofibers were prepared by electrospinning of chemically synthesized poly(5-cyanoindole) followed by surface modification. The as-prepared ASFPI nanofibers were characterized with FTIR, SEM, BET surface areas and water contact angle measurement. Meanwhile, the adsorption properties and mechanism of ASFPI nanofibers towards Pb(II) and Cd(II) in aqueous solution were mainly investigated by a batch method. It was found that ASFPI nanofibers showed a high affinity towards Pb(II) and Cd(II). The maximum adsorption capacities were found to be 307.44 and 108.49 mg g−1 for Pb(II) and Cd(II), which are markedly high values compared to other fiber adsorbents reported. The adsorption isotherms were better fitted with the Langmuir model rather than Freundlich and Temkin models. The kinetics data analysis showed that the adsorption process could be described by a pseudo-second order kinetic model, suggesting a chemisorption process as the rate limiting step. Thermodynamic parameters revealed the spontaneity of the adsorption process and higher temperature favored adsorption. Regeneration tests showed that ASFPI nanofibers could be reused repetitively for 10 times with 80% of the initial adsorption capacity.

The effect of chitosan concentration on the electrical property of chitosan-blended cellulose electroactive paper

We studied the effect of chitosan blending on the electrical property of chitosan-blended cellulose electroactive paper (EAPap) under different humidity conditions. As the chitosan blending ratio increased, the real part of the dielectric constant of chitosan-blended cellulose EAPap increased while the dielectric loss factor decreased. From the curve fitting of the measured data using an electrode polarization model, it was found that increasing the chitosan ratio in the EAPap might promote a decrease in the relaxation time of the EAPap, resulting in an increase of the ion mobility and dc conductivity. Over 30% of the chitosan blending ratio, a gradual increment of the ion mobility of the EAPap was observed at 40% relative humidity, while a quadratic increment of the mobility was found at 60% relative humidity condition. This kind of ion-mobility-enhanced cellulose EAPap can be used not only for bending actuators but also for medical applications such as blood clotting patches.

Electrospun carboxyl multi-walled carbon nanotubes grafted polyhydroxybutyrate composite nanofibers membrane scaffolds: Preparation, characterization and cytocompatibility

Electrospun polyhydroxybutyrate (PHB)/carboxyl multi-walled carbon nanotubes grafted polyhydroxybutyrate (CMWCNT-g-PHB) composite nanofibers scaffolds were fabricated by electrospinning technology. The grafted product CMWCNT-g-PHB was prepared by condensation reactions between the carboxyl groups of CMWCNT and hydroxyl groups of PHB molecules and characterized by FTIR, XRD, XPS, TG and TEM measurements. The surface morphology, hydrophilicity and tensile mechanical properties of the electrospun PHB/CMWCNT-g-PHB composite nanofibers membrane scaffolds were investigated. The values of tensile strength, breaking elongation rate, initial modulus and fracture energy of the composite nanofibers scaffolds can reach to 4.64MPa, 255.59%, 88MPa and 109.73kJ/m2, respectively. The biodegradability and cytocompatibility of the electrospun composite nanofibers scaffolds were preliminarily evaluated. The as-prepared electrospun PHB/CMWCNT-g-PHB composite nanofibers scaffolds with the characteristics of large specific area, high porosity, good biodegradability and cytocompatibility as well as sufficient mechanical properties should be more promising in the field of tissue engineering scaffolds and biological medicine.

Bacterial Cellulose as a Template for the Formation of Polymer/Nanoparticle Nanocomposite

In this paper, we investigate a novel method using bacterial cellulose (BC) as template by in situ method to prepare BC/silver nanocomposites. We first introduce sonication procedure during immersion and reduction reaction process to make sure that the silver nanoparticles can be formed and distributed homogeneously throughout the whole bacterial cellulose network. The BC/silver nanocomposites were confirmed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). To examine the effect of varying solution concentrations on silver nanoparticles formation, the concentration of AgNO 3 Solution was increased from 0.01 M to 0.05 M and Ag + -ions were reduced by the same concentration of NaBH 4 . The effects of time and frequency of sonication on BC/silver nanocomposite preparation were also investigated by varying sonication time from 10 min to 60 min and sonication frequency from 20 kHz to 60 kHz. Compared with an ordinary process, ultrasound seems to be an effective way for ions to penetrate into BC and thus the weight percent of silver nanoparticles can be increased. Combined with TGA result, the weight percent of silver nanoparticles can be improved from 8.9% to 31.7% with simple sonication procedure performed by the same preparation condition. However, the average size of silver nanoparticles is around 15 nm, which is bigger than ordinary process. This may be due to the aggregation of small nanoparticles, especially at high AgNO 3 concentration.

Zein/Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) electrospun blend fiber scaffolds: Preparation, characterization and cytocompatibility

In the present work, a series of Zein/Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) blend fiber scaffolds have been prepared by electrospinning method. The electrospun fibers showed a circular and uniform morphology with random distribution. The blend fiber scaffolds possessed well interconnected porous fibrous network structure with high porosity and large aspect surface areas. The FTIR and XPS spectra of Zein/P(3HB-co-4HB) blend fibers demonstrated the same characteristics to that of pure Zein and P(3HB-co-4HB) electrospun fibers. However, Zein might hinder the crystallization of P(3HB-co-4HB) owing to the formation of weak intermolecular interactions, which can affect the preferential orientation of P(3HB-co-4HB) molecules. Only one glass transition temperature (Tg) can be detected for electrospun Zein/P(3HB-co-4HB) blend fiber scaffolds implying the miscibility of Zein and P(3HB-co-4HB) in the blend fibers. The Zein/P(3HB-co-4HB) blend fiber scaffolds showed about 50% of improvement in tensile strength and 400% of increase in elongation at break by increasing P(3HB-co-4HB) content from 20% to 80%. The cytocompatibility of the Zein/P(3HB-co-4HB) blend fiber scaffolds was preliminarily evaluated by cell culture in vitro. The as-prepared electrospun Zein/P(3HB-co-4HB) blend fiber scaffolds with the characteristics of good biocompatibility, excellent pore characteristic as well as sufficient mechanical properties should be more promising for applications as tissue engineering scaffold.