Chitosan Composite Nanofibers Research Articles

Development of Poly(vinyl alcohol)-Chitosan Composite Nanofibers for Dual Drug Therapy of Wounds.

Current trends in localized drug delivery are emphasizing the development of dual drug-loaded electrospun nanofibers (NFs) for an improved therapeutic effect on wounds, especially infected skin wounds. The objective of this study was to formulate a new healing therapy for an infected skin wound. To achieve this goal, this study involved the development and characterization of poly(vinyl alcohol) (PVA)/chitosan nanofibers loaded with ciprofloxacin and rutin hydrate. Polymers and drugs were used in different ratios. Nanofiber morphology was studied by scanning electron microscopy, thermal stability by thermogravimetric analysis, structural determination by the X-ray diffraction method, and integrity by Fourier transform infrared spectroscopy. Dissolution studies were performed to check the drug release behavior of the formulations. Antibacterial studies were performed against Staphylococcus aureus and Pseudomonas aeruginosa. The wound healing efficiency of dual drug-loaded nanofibers was measured by a full-thickness excisional wound model of rabbits. The fabricated nanofibers were smooth in morphology. According to FTIR findings, the drugs remained intact in the nanofibers. The results of swelling ratio and porosity revealed that the pore size was increased as the amount of chitosan was increased up to 30% but a further increase in chitosan concentration reduced the swelling ratio and porosity. Drug release studies of nanofibers depicted an initial burst effect and afterward controlled drug release behavior. Drug-loaded nanofibers showed better activity against S. aureus than P. aeruginosa. The antibacterial efficacy of rutin hydrate with ciprofloxacin was improved compared to that of the formulation having rutin hydrate only, likely due to the additive effect in activity. Based on wound healing studies, nanofibrous membranes acted as a promising wound dressing material as compared to the commercial wound healing formulation. Drug-loaded polymeric nanofibers were successfully fabricated by using an electrospinning method. These nanofibers showed an efficient ability to deliver drugs and treat infected wounds.

Correlation of adsorbed and embedded palladium species in chitosan composite nanofibers with their catalytic activities for Suzuki reactions

Heterogeneous palladium catalysts play an important role in the synthetic organic chemistry. Palladium species have been adsorbed on the surface of solid matrices or embedded inside solid matrices to prepare recyclable heterogeneous catalysts. Due to the different surrounding environment, these two type palladium species had different electronic properties and catalytic performances. In this study, we fabricated three series of chitosan composite nanofibers with adsorbed and embedded palladium species. Their fiber morphologies and chemical structures were characterized by SEM and FT-IR, respectively. Positron annihilation lifetime spectra (PALS) showed that the intensities (I3) of o-Ps annihilations were all linearly decreased with the increase of palladium contents in the chitosan composite nanofibers. Moreover, compared with the palladium adsorbed chitosan composite nanofibers, the palladium embedded chitosan composite nanofibers had stronger o-Ps annihilation ability, which could be ascribed to the stronger electron donating property of embedded palladium species and higher crosslinking of chitosan molecules by embedded palladium species. At last, the I3 values were successfully correlated with the rate constants of chitosan supported palladium composite nanofibers catalyzed Suzuki reactions of iodobenzene with phenylboric acid. Therefore, we have developed a facile method to distinguish the adsorbed and embedded palladium species by PALS, which can be further related with their catalytic performance.

Fabrication of chitosan composite nanofibers for the recovery of precious palladium cations from aqueous solution

Fabrication of chitosan composite nanofibers for the recovery of precious palladium cations from aqueous solution

Preparation of chitosan/poly(methacrylic acid) supported palladium nanofibers as an efficient and stable catalyst for Heck reaction

Homogeneous chitosan/poly(methacrylic acid) solution containing Pd2+ cations was successfully prepared by addition of pyridine-2-carboxaldehyde. Then, this homogeneous solution was smoothly electrospun into uniform composite nanofibers with mean diameter of 442 ± 163 nm, followed by annealing at elevated temperature to improve the solvent resistance. Scanning electron microscopy (SEM) analysis shows that the solvent resistance of the composite nanofibers was improved with the increment of annealing temperature. FT-IR spectra demonstrate that the chemical structure of the composite nanofibers was not oxidized after annealing process. Moreover, the palladium species were homogeneously incorporated inside the composite nanofibers. The catalytic performance of these novel composite nanofibers was evaluated by Heck reaction. The catalysis result shows that these composite nanofibers were very efficient to catalyze the Heck reaction of aromatic iodides with acrylates with yields over 86%. Moreover, these composite nanofibers can be reused for 10 times with little decrement of yield. A novel palladium embedded chitosan composite nanofiber mat has been prepared by electrospinning and thermal techniques. This novel fiber palladium catalyst exhibited high catalytic activity and stability for Heck reaction.

Palladium nanoparticles stabilized by chitosan/PAAS nanofibers: A highly stable catalyst for Heck reaction

Palladium chloride doped chitosan composite nanofibers were prepared by electrospinning with sodium polyacrylate (PAAS) as the co‐spinning agent. The composite nanofibers are subsequently treated at elevated temperature to improve their solvent resistance. The Pd (II) cations inside the composite nanofibers were reduced into uniform palladium nanoparticles (Pd NPs) with mean diameter of ~4.93 nm. These Pd NPs inside the chitosan composite nanofibers exhibited excellent catalytic activity for Heck reactions of aromatic iodides with alkenes with yields over 85%. Moreover, due to the fibrous structure, this novel fibrous palladium catalyst could be readily recovered by simple filtration and reused for 18 times without loss of initial catalytic activity. It was found that the reactants could readily diffuse from the reaction solution to the active Pd NPs inside the nanofibers and the products could departure from composite fibers into the reaction solution, while the Pd NPs were tightly restricted inside the chitosan composite nanofibers.

High Efficiency Fabrication of Chitosan Composite Nanofibers with Uniform Morphology via Centrifugal Spinning.

While electrospinning has been widely employed to spin nanofibers, its low production rate has limited its potential for industrial applications. Comparing with electrospinning, centrifugal spinning technology is a prospective method to fabricate nanofibers with high productivity. In the current study, key parameters of the centrifugal spinning system, including concentration, rotational speed, nozzle diameter and nozzle length, were studied to control fiber diameter. An empirical model was established to determine the final diameters of nanofibers via controlling various parameters of the centrifugal spinning process. The empirical model was validated via fabrication of carboxylated chitosan (CCS) and polyethylene oxide (PEO) composite nanofibers. DSC and TGA illustrated that the thermal properties of CCS/PEO nanofibers were stable, while FTIR-ATR indicated that the chemical structures of CCS and PEO were unchanged during composite fabrication. The empirical model could provide an insight into the fabrication of nanofibers with desired uniform diameters as potential biomedical materials. This study demonstrated that centrifugal spinning could be an alternative method for the fabrication of uniform nanofibers with high yield.

Removal of heavy metal chromium using cross-linked chitosan composite nanofiber mats

Uniform chitosan composite nanofiber mats (CS/PAAS) containing 4.0 wt% polyacrylic acid sodium loading have been prepared by electrospinning, followed by annealing at elevated temperature to improve solvent resistance and mechanical strength. The CS/PAAS nanofiber mats have been characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and tensile strength analysis. The prepared nanofiber mats have been shown to be much better than the pristine chitosan powder to adsorb the chromium (VI) ion. SEM-Energy dispersive X-ray spectroscopic (SEM-EDS) and positron annihilation lifetime spectroscopic (PALS) analysis show that Cr(VI) ion can freely permeate into the composite nanofiber and coordinate with the internal chitosan chain molecules. The adsorption abilities of these cross-linked CS/PAAS nanofiber mats are dependent on the chitosan contents as well as N-atom basicity of the chitosan chain. The adsorption capacity toward Cr(VI) ion was improved to 78.92 mg/g after modification of the chelating ligands for the cross-linked CS/PAAS composite nanofibers.

Cerium functionalized PVA–chitosan composite nanofibers for effective remediation of ultra-low concentrations of Hg(ii) in water

Functionalized PVA–chitosan composites nanofibers effective for removal of very low concentration of mercury.

Preparation of polyamide-6/chitosan composite nanofibers by a single solvent system via electrospinning for biomedical applications

This work was focused on preparation and characterizations of chitosan blended polyamide-6 nanofibers by a new single solvent system via electrospinning process for human osteoblastic (HOB) cell culture applications. The morphological, structural and thermal properties of the polyamide-6/chitosan nanofibers were analyzed by using field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform-infrared (FT-IR) spectroscopy, Raman spectroscopy, differential scanning calorimetry (DSC) and thermogravimetry (TGA). SEM images revealed that the nanofibers were well-oriented and had good incorporation of chitosan. FT-IR results indicated that the amino groups of chitosan existed in the blended nanofibers. TGA analysis revealed that the onset degradation temperature was decreased with increasing chitosan content in the blended nanofibers. The morphological features of the cells attached on nanofibers were confirmed by SEM. The adhesion, viability and proliferation properties of osteoblast cells on the polyamide-6/chitosan blended nanofibers were analyzed by in vitro cell compatibility test.

Preparation and electrical characterization of polyamide-6/chitosan composite nanofibers via electrospinning

We report on the preparation and electrical characterization of polyamide-6/chitosan composite nanofibers. These composite nanofibers were prepared using a single solvent system via electrospinning process. The resultant nanofibers were well-oriented and had good incorporation of chitosan. Current–voltage (I–V) measurements revealed interesting linear curve, including enhanced conductivities with respect to chitosan content. The electrical conductivity of the polyamide-6/chitosan composite nanofibers increased with increasing content of chitosan which was attributed to the formation of ultrafine nanofibers. In addition, the sheet resistance of composite nanofibers was decreased with increasing chitosan concentration.