Cellulose Acetate Fiber Mats Research Articles

Electrospun wound dressings containing bioactive natural products: physico-chemical characterization and biological assessment

BackgroundCurrent research on skin tissue engineering has been focusing on novel therapies for the effective management of chronic wounds. A critical aspect is to develop matrices that promote growth and uniform distribution of cells across the wound area, and at the same time offer protection, as well as deliver drugs that help wound healing and tissue regeneration. In this context, we aimed at developing electrospun scaffolds that could serve as carriers for the bioactive natural products alkannin and shikonin (A/S).MethodsA series of polymeric nanofibers composed of cellulose acetate (CA) or poly(ε-caprolactone) (PCL) and varying ratios of a mixture of A/S derivatives, has been successfully fabricated and their physico-chemical and biological properties have been explored.ResultsScanning electron microscopy revealed a uniform and bead-free morphology for CA scaffolds, while for PCL beads along the fibers were observed. The average diameters for all nanofibers ranged between 361 ± 47 and 487 ± 88 nm. During the assessment of physicochemical characteristics, CA fiber mats exhibited a more favored profile, while the assessment of the biological properties of the scaffolds showed that CA samples containing A/S mixture up to 1 wt.% achieved to facilitate attachment, survival and migration of Hs27 fibroblasts. With respect to the antimicrobial properties of the scaffolds, higher drug-loaded (1 and 5 wt.%) samples succeeded in inhibiting the growth of Staphylococcus epidermidis and S. aureus around the edges of the fiber mats. Finally, carrying out a structure-activity relationship study regarding the biological activities (fibroblast toxicity/proliferation and antibacterial activity) of pure A/S compounds – present in the A/S mixture – we concluded that A/S ester derivatives and the dimeric A/S augmented cell proliferation after 3 days, whereas shikonin proved to be toxic at 500 nM and 1 μM and alkannin only at 1 μM. Additionally, alkannin, shikonin and acetyl-shikonin showed more pronounced antibacterial properties than the other esters, the dimeric derivative and the A/S mixture itself.ConclusionsTaken together, these findings indicate that embedding A/S derivatives into CA nanofibers might be an advantageous drug delivery system that could also serve as a potential candidate for biomedical applications in the field of skin tissue engineering.

Enhancing mechanical properties of Electrospun Cellulose Acetate Fiber Mat upon Potassium Chloride exposure

Cellulose acetate (CA) based biomaterials are being used as substrates for bone ingrowth applications due to their non-toxic and non-irritant nature coupled with optimum morphology and stiffness. Electrospinning with additives and/or post-treatment has emerged as a viable protocol to improve the mechanical properties of CA further and expand its utility. Herein, we highlight the role of potassium chloride (KCl) in association with air-drying to enhance the elastic modulus and tensile strengths of CA fiber mats. Salt aggregation between fibers was observed through Scanning Electron Microscopy (SEM). However, Fourier-transform infrared (FTIR) analysis indicates the interactions between K+ ions and acetyl groups. X-ray diffraction (XRD) study suggests the retention of CA structure in the CA-KCl mats and the excess presence of KCl. The increase in KCl concentration (from 2 to 6%) boosts the elastic modulus to 176 MPa (52 times than pure CA) and tensile strength to 1.2 MPa (9 times than pure CA). Indeed, the presence of K+ ions offers osteoconduction to fiber mats, and thus the outcome has potential in bone tissue engineering.

Gallic acid‐loaded electrospun cellulose acetate nanofibers as potential wound dressing materials

Gallic acid (GA)–loaded cellulose acetate (CA) nanofiber mats with 10 to 40 wt.% GA contents (based on the weight of CA) were fabricated by electrospinning. The effects of GA contents and applied potential on the morphology and the average diameters of fibers were studied. The electrospun fiber mats containing 20 and 40 wt.% GA were investigated for their potential use as carrier of GA in wound dressing application. The GA‐loaded CA films were prepared by solvent casting technique for use in comparative studies. Determination of the release characteristics of GA from the GA‐loaded fiber mats and films was carried out by the total immersion and the transdermal diffusion through a pig skin method in acetate buffer solution (pH 5.5) or normal saline (pH 7.0) at either 32 or 37°C, respectively. In the total immersion method, the maximum amounts of the GA released from the fiber mats containing 20 and 40 wt.% GA in the acetate buffer were approximately 97% and 71% (based on the weight of initial GA), while those of the GA released into the normal saline were approximately 96% and 81%, respectively. Lower values were observed in the experiments of the transdermal diffusion through a pig skin method. The corresponding GA‐loaded CA films showed the lower amounts of GA released into media. The as‐loaded and the as‐released GA remained its antioxidant activity as investigated by 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) assay. Lastly, the GA‐loaded CA fiber mats exhibited antibacterial activity against Staphylococcus aureus, which showed the potential for use as wound dressing materials.

All cellulose electrospun water purification membranes nanotextured using cellulose nanocrystals

Cellulose acetate (CA) fibers were electrospun on a mesh template to create specific surface and pore structures for membrane applications. The mesh template CA fiber mats were impregnated with cellulose nanocrystals at varying weight percentages. The membranes showed nanotextured surfaces and improved mechanical properties post impregnation. More importantly, the hydrophilicity of the original CA fibers was increased from a hydrophobic contact angle of 102°–0° thereby creating an anti-fouling membrane surface structure. The membranes showed rejection of 20–56% for particles of 0.5–2.0 μm, indicating potential of these membranes in rejecting microorganisms from water. Furthermore, high rejection of dyes (80–99%) by adsorption and potential application as highly functional affinity membranes was demonstrated. These membranes can therefore be utilized as all-cellulose, green, scalable and low cost high flux membranes (> 20,000 LMH) for water cleaning applications in food industry where microorganisms and charged contaminants are to be removed.

Electrospun Cellulose Acetate Fiber Mats as Carriers for Crude Extracts From Phyllanthus Emblica Linn. Fruits

Fruit of Phyllanthus emblica Linn (PE) was extracted with methanol and then partitioned into diethyl ether, ethyl acetate, butanol, and water fractions. The diethyl ether fraction showed the highest antibacterial activity against two pathogenic bacteria including Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 25923). The PE extract from diethyl ether fraction was then loaded into 17%w/v cellulose acetate (CA) solution prepared in 2:1 v/v acetone/ N, N -dimethylacetamide at concentrations of 1, 3, and 5% w/w (based on the weight of CA). The PE extract-loaded electrospun CA fiber mats were fabricated by electrospinning. The morphological appearance of both the neat and the PE extract-loaded electrospun CA fibers were smooth with the average diameters in a range of 335-694 nm. The amounts of water retention and release characteristics of PE extract from fiber mats in an acetate buffer (pH 5.5) were studied and compared with the corresponding cast-films fabricated by the solvent casting method. The amount of water retention of the PE extract-loaded fiber mats was about 112-205% which was higher than that of the cast films (i.e. 25-35%). The study of release characteristics of PE extract from fiber mats and films was carried out by total immersion method in an acetate buffer at 32°C for 72 h. The PE extract-loaded fiber mats exhibited greater amount of extract released than those of the cast films. The maximum amounts of PE extract released from fiber mats and films were about 40-80% and 18-23%, respectively.

Asiaticoside/2-Hydroxypropyl-β-cyclodextrin 포접화합물 함유 셀룰로오스 아세테이트 섬유 매트의 전기방사: 창상피복제로서 사용가능성과 방출특성

Cellulose acetate (CA) fiber mats containing inclusion complexes of asiaticoside (AC) in 2-hydroxypropyl-<TEX>${\beta}$</TEX>-cyclodextrin (<TEX>$HP{\beta}CD$</TEX>) for potential usage as wound dressings were developed. The AC/<TEX>$HP{\beta}CD$</TEX> complex-loaded CA fibers at various <TEX>$HP{\beta}CD$</TEX> to AC molar ratios of 0.5, 1, and 2 were prepared in 90:10 v/v mixture of 80% (v/v) acetic acid and N,N-dimethylacetamide (DMAc) via electrospinning. The maximum released amounts of AC depended on the <TEX>$HP{\beta}CD$</TEX> content and were much greater than those released from the AC-loaded CA fiber mat. In the in vitro study, indirect cytotoxic evaluation with human dermal fibroblasts (HDFa) showed that these materials released no substances in the levels that were harmful to the cells and the cells appeared to attach and proliferate well on these substrates. However, only the CA fiber mats containing AC/<TEX>$HP{\beta}CD$</TEX> complexes at the <TEX>$HP{\beta}CD$</TEX> to AC molar ratio of 0.5 was effective in upregulating the production of collagen of the cultured cells.

Fabrication and properties of capsicum extract-loaded PVA and CA nanofiber patches

The aim of this study was to prepare, characterize and evaluate electrospun polyvinyl alcohol (PVA) and cellulose acetate (CA) nanofibers loaded with capsicum extract (CE) for use in topical skin treatments. CE, 0.5, 1 or 2 wt %, was loaded into PVA and CA electrospun fiber mats. Various properties of the CE-loaded fiber mats as well as release and skin permeation were investigated. The average diameters of these fibers ranged from 251–368 nm. The release rate of capsaicin from CE-loaded as-spun PVA was faster than that of the CA fiber mats and increased as the CE content in CE-loaded as-spun PVA and CA increased. The release kinetics of the CA and PVA fibers followed the Higuchi equation. The percentages of CE that permeated the shed snake skin with PVA and CA fiber mats containing 2 wt % CE after 24 h were 60% and 20%, respectively. The results suggest a potential use of PVA and CA nanofibers being used to control skin permeation of capsicum extract. Our research suggests the potential application of CE-loaded PVA electrospun mats as transdermal drug delivery systems.

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.

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.