Electrospun Cellulose Acetate Fibers Research Articles

Factors Influencing the Morphology of Cellulose Acetate Electrospun Fiber Mats

This study investigated the effect of solvent composition, spinning rate and spinning time on the morphology of electrospun cellulose acetate (CA) fiber mats. To fabricate the fibers, 17 %w/v CA solutions prepared in the solvent consisting of acetone/N,N-dimethylacetamide (DMAc) at the ratios of 2:1, 1:1 and 1:2 (v/v) were subjected to electrospinning process under the constant electric field of 1.17 kV/cm. Scanning electron microscope imaging revealed that different morphologies of fibers obtained were bead-free fibers, fibers with spherical beads, and fibers with spindles, when the acetone/DMAc ratios of 2:1, 1:1 and 1:2 were used, respectively. In the aspect of spinning rate, it was found that the diameter of electrospun CA fibers, spindles or beads increased with the increasing spinning rate from 0.2 to 1 ml h-1. In addition, the thickness of electrospun CA fiber mats was directly proportional to the spinning time from 2 to 6 h and spinning rate. Interestingly, by using the same spinning time and rate, the bead-free fiber mats were thicker than mats containing fiber with spherical beads or with spindles. These findings provide useful information for the selection of suitable electrospinning parameters in order to obtain the fiber mat with desired characteristics for the intended purpose.

Cellulose Acetate Electrospun Fiber Mats for Controlled Release of Silymarin

In this research, the silymarin-loaded electrospun cellulose acetate (CA) fibers were prepared which containing silymarin in various amounts (i.e., 2.5-20 wt.% based on the weight of CA powder). Incorporation of silymarin in the neat CA solution did not affect the morphology of the resulting fibers, as both the neat and the silymarin-loaded CA fibers were smooth. The average diameters of silymarin-loaded CA fiber ranged between 550-900 nm. No presence of the silymarin aggregates of any kind was observed on the surfaces of these fibers, suggesting that the silymarin was encapsulated well within the fibers. These results were confirmed by lowering the glass transition temperature and the melting temperature of the silymarin-loaded electrospun CA fibers which is determined by DSC technique. The release characteristic of silymarin from the silymarin-loaded CA fiber mats was investigated by the total immersion in the solution of 1/1 phosphate buffer/methanol medium pH 7.4 at 37 degrees C. The silymarin release from the silymarin-loaded electrospun CA fiber mat is monotonously increased to reach the maximum value at 480 min. The maximum amount of silymarin released from these materials increases with the increasing of initial silymarin loading in the spinning CA solutions. Since no aggregation of silymarin was found on the surface of the silymarin-loaded fibers, the release of the silymarin from fiber mats was mainly by the diffusion.

Gallic Acid-loaded Cellulose Acetate Electrospun Nanofibers: Thermal Properties, Mechanical Properties, and Drug Release Behavior

The gallic acid-loaded electrospun cellulose acetate fibers were successfully prepared. The fiber containing 2.5% gallic acid was smooth surface but observed drug flake on the surface of the fiber when increasing drug content. The thermal properties, mechanical properties and drug release behavior of the fibers were investigated comparing to the corres-ponding films.

Fabrication and Characterization of Regenerated Cellulose/TiO<sub>2</sub> Nanocomposite Hybrid Fibers

Nanocomposite fibers are one of the most fascinating materials with broad applications. In the present work，nanocomposite fibers were prepared by a low-cost, simple, and “green” process. The nanocomposite of cellulose acetate/TiO2 was realized by combining the functional oxide material TiO2 with the regenerating electrospun cellulose acetate fibers. The structural features were characterized by scan electron microcopy, transmission electron microscopy and infrared spectrum. The compositing mechanism was proposed. The surface functionalized hydroxyl by the regenerating process plays an important role for the formation of hybrid material.

2,6-Dichloro-4-nitroaniline –loaded Electrospun Cellulose Acetate Fiber Mats and Their Release Characteristics

Mats of cellulose acetate (CA) nanofibers containing 2,6-dichloro-4-nitroaniline (DCNA) were successfully fabricated by electrospinning from the neat CA solution (17% w/v in 2:1 acetone/dimethylacetamide) containing DCNA in various amounts (i.e. 5-15 wt. % based on the weight of CA). The morphological appearance of both the neat and the DCNA-loaded electrospun CA fibers were smooth and the incorporation of DCNA in the neat CA solution did not affect the morphology of the resulting fibers. The average diameters of the neat and the DCNA-loaded electrospun CA fibers ranged between 241-320 nm. The integrity of the as-loaded DCNA in the DCNA-loaded CA fiber mats was intact as verified by the 1H-nuclear magnetic resonance spectroscopic method. The amount of water retention, the amount of weight loss, and release characteristics of the DCNA-loaded CA fiber mats and the DCNA-loaded as-cast films in distilled water at 30°C were studied. The release characteristics were investigated by the total immersion method. The DCNA-loaded CA fiber mats exhibited greater amount of water retention, weight loss, and DCNA released than the DCNA-loaded as-cast films.

Randomly oriented and aligned cellulose fibres reinforced with cellulose nanowhiskers, prepared by electrospinning

The goal of this work was to prepare random and aligned cellulose fibres by electrospinning. Cellulose acetate (CA) was used as a matrix and a mixture of acetic acid and acetone (1∶1) was used as an solvent. Cellulose nanowhiskers (CNWs) with different concentrations (0–5 wt‐%) were used as reinforcement. Microscopy studies showed fibres with smooth surfaces, different morphologies and diameters ranging between 200 and 3300 nm. It was found that the fibre diameters decreased with increased CNW contents. The microscopy studies also indicated well aligned fibres. Results from dynamic mechanical thermal analysis indicated improved mechanical properties with the addition of CNWs. The storage modulus of electrospun CA fibres increased from 81 to 825 MPa for fibres with 1 wt‐% CNW at room temperature. X‐ray analysis showed that the electrospun CA fibres had a crystalline nature and that there was no significant change in crystallinity with the addition of CNWs.

Ester prodrug-loaded electrospun cellulose acetate fiber mats as transdermal drug delivery systems

Cellulose acetate (CA) fibers loaded with the ester prodrugs of naproxen, including methyl ester, ethyl ester and isopropyl ester, were prepared through electrospinning using acetone/N,N-dimethylacetamide(DMAc)/ethanol (4:1:1, v/v/v) as solvent. The chemical and morphological characterizations of the medicated fibers were investigated by means of SEM, DSC, XRD and FTIR, as well as the studies of the drug release properties. The results indicated that the morphology and diameter of the fibers were influenced by the concentration of spinning solution, applied voltage, electrospun solvent and the surfactants. The average diameters of the fibers ranged between 100 and 500 nm for three prodrugs. There was good compatibility between CA and three prodrugs in the blended fibers, respectively. In vitro release indicated that constant drug release from the fiber was observed over 6 days. The prodrugs were successfully encapsulated into the fibers, and this system was stable in terms of effectiveness in release.

Development of polyelectrolyte multilayer-coated electrospun cellulose acetate fiber mat as composite membranes

Abstract Electrostatic multilayers of chitosan (CHI)/sodium alginate (SA) and CHI/poly(styrene sulfonate) sodium salt (PSS) were alternatively coated on electrospun cellulose acetate (CA) fiber mat. Morphologies of the composite membranes were characterized by scanning electron microscopy. The morphology of the CHI/SA-coated membrane was denser than the CHI/PSS-coated one. The top layers consisted of carboxyl and sulfonic functional groups for SA and PSS layers, respectively. Amino groups of CHI were only presented in slight quantity. X-ray photoelectron spectroscopy (XPS) confirmed the deposition of the amino groups of CHI on the multilayer membrane surface. These composite membranes were characterized for its water permeability where the water flux decreased with an increase in the number of the bilayers. The water flux was in the range of 60 and 40 L m −2 h −1 for 15 and 25 bilayered membranes, respectively. The sodium chloride (NaCl) solution flux was lower than the pure water flux due to the effect of osmotic pressure, and it decreased with an increase in the NaCl concentration. The rejection of NaCl increased substantially with the number of the bilayers of the polyelectrolytes multilayers. The level of NaCl rejection from this work was in the range of 6% and 15% for 15 and 25 bilayered membranes, respectively.

Electrospun cellulose acetate fibers containing chlorhexidine as a bactericide

Submicron fibers with bactericidal properties were prepared from electrospinning of blends containing cellulose acetate (CA) as a polymer base, chlorhexidine (CHX) as a bactericidal agent, and organic titanate Tyzor® TE (TTE) as a cross-linker. A small amount of high molecular weight poly(ethylene oxide) (PEO) was incorporated into the blends to facilitate the electrospinning, and its effect on the extensional properties and spinnability of the N,N-dimethylformamide (DMF) solutions were evaluated. The CHX-containing fiber meshes were cured by TTE in the presence of water vapor, which created covalent links between the CA and CHX. The immobilization of CHX on or within the fibers was confirmed by FTIR, Raman and XPS measurements. The resulting fiber meshes exhibited bactericidal properties on contact, due to the CHX immobilized on the fibers, and within a zone of inhibition (ZoI), due to the release of unbound CHX. The relationship of ZoI for the gram-negative Escherichia coli and the gram-positive Staphylococcus epidermidis to the amount of unbound CHX in the fibers is described by a simple diffusion model. The contact bactericidal capacity against both E. coli and S. epidermidis was assayed after complete removal of unbound CHX from the fibers. A post-spin treatment to attach CHX onto CA–PEO fibers via TTE linkers was also shown to be effective.

Electrospun cellulose acetate fiber mats containing curcumin and release characteristic of the herbal substance

Ultra-fine cellulose acetate (CA; Mw≈30,000Da; degree of acetyl substitution≈2.4) fiber mats containing curcumin from the plant Curcuma longa L., widely known for its anti-tumor, antioxidant, and anti-inflammatory properties, were fabricated, for the first time, from the neat CA solution (17% w/v in 2:1 v/v acetone/dimethylacetamide) containing curcumin in various amounts (i.e., 5–20wt.% based on the weight of CA powder) by electrospinning. Incorporation of curcumin in the neat CA solution did not affect the morphology of the resulting fibers, as both the neat and the curcumin-loaded CA fibers were smooth. The average diameters of the curcumin-loaded CA fibers ranged between ∼314 and ∼340nm. The integrity of the as-loaded curcumin in the curcumin-loaded CA fiber mats was intact as indicated by the 1H nuclear magnetic resonance spectrometric results and the ability of the as-loaded curcumin in maintaining its free radical scavenging ability. Investigation of the release characteristic of curcumin from the curcumin-loaded CA fiber mats was carried out by the total immersion and the transdermal diffusion through a pig skin method in the acetate buffer solution containing Tween 80 and methanol or the B/T/M medium at 37°C. In the total immersion method, almost all of the curcumin loaded in the curcumin-loaded CA fiber mat specimens was released into the medium (∼90 to ∼95%), while considerably lower values were obtained when the curcumin-loaded CA fiber mats were placed on top of a piece of pig skin. Lastly, the curcumin-loaded CA fiber mats were proven non-toxic to normal human dermal fibroblasts.

Release characteristics of four model drugs from drug-loaded electrospun cellulose acetate fiber mats

Ultra-fine fiber mats of cellulose acetate (CA; Mw≈30 000Da; degree of acetyl substitution≈2.4) containing four different types of model drugs, i.e., naproxen (NAP), indomethacin (IND), ibuprofen (IBU), and sulindac (SUL), were successfully prepared by electrospinning from 16% w/v CA solutions in 2:1 v/v acetone/N,N-dimethylacetamide (DMAc). The amount of the drugs in the solutions was fixed at 20wt.% based on the weight of CA powder. The morphology of the drug-loaded electrospun (e-spun) CA fiber mats was smooth, with the average diameters of these fibers ranging between 263 and 297nm. No presence of the drug aggregates of any kind was observed on the surfaces of these fibers, suggesting that the drugs were encapsulated well within the fibers. After submersion in the acetate buffer solution at 37°C for 24h, the drug-loaded e-spun CA fiber mats swelled particularly well (i.e., 570–630%), while the corresponding solvent-cast film counterparts did not. The release characteristics of the model drugs from both the drug-loaded CA fiber mats and the drug-loaded as-cast CA films were carried out by the total immersion method in the acetate buffer solution at 37°C. At any given immersion time point, the release of the drugs from the drug-loaded e-spun CA fiber mats was greater than that from the corresponding as-cast films. The maximum release of the drugs from both the drug-loaded fiber mats and films could be ranked as follows: NAP>IBU>IND>SUL.

Electrospun cellulose acetate fibers: effect of solvent system on morphology and fiber diameter

This paper reports an investigation of the effects of solvent system, solution concentration, and applied electrostatic field strength (EFS) on the morphological appearance and/or size of as-spun cellulose acetate (CA) products. The single-solvent systems were acetone, chloroform, N,N -dimethylformamide (DMF), dichloromethane (DCM), methanol (MeOH), formic acid, and pyridine. The mixed-solvent systems were acetone–DMAc, chloroform–MeOH, and DCM–MeOH. Chloroform, DMF, DCM, MeOH, formic acid, and pyridine were able to dissolve CA, forming clear solutions (at 5% w/v), but electrospinning of these solutions produced mainly discrete beads. In contrast, electrospinning of the solution of CA in acetone produced short and beaded fibers. At the same solution concentration of 5% (w/v) electrospinning of the CA solutions was improved by addition of MeOH to either chloroform or DCM. For all the solvent systems investigated smooth fibers were obtained from 16% (w/v) CA solutions in 1:1, 2:1, and 3:1 (v/v) acetone–DMAc, 14–20% (w/v) CA solutions in 2:1 (v/v) acetone–DMAc, and 8–12% (w/v) CA solutions in 4:1 (v/v) DCM–MeOH. For the as-spun fibers from CA solutions in acetone–DMAc the average diameter ranged between 0.14 and 0.37 μm whereas for the fibers from solutions in DCM–MeOH it ranged between 0.48 and 1.58 μm. After submersion in distilled water for 24 h the as-spun CA fibers swelled appreciably (i.e. from 620 to 1110%) but the physical integrity of the fibrous structure remained intact.