Nanofibers – A Newer Technology

Nanofibers are the fibers having diameter in nanometer ranging from 50-1000nm.Nanofibers can be prepared by using polymers like cellulose, silk, fibroin, keratin, gelatin, polylactic acid, polyurethane etc. The chain of polymers are connected by covalent bonds. The diameter of nanofibers depends on the type of polymers used in preparation method. There are various methods are used to fabricate nanofibers like electrospinning, thermal induced phase separation, drawing, template synthesis, self-assembly. Nanofibers are widely used in various fields like in filtration, affinity membrane and recovery of metal ions, tissue engineering, wound dressing, catalyst s; enzyme, carriers, sensor, energy conversion and storage, sound absorbtive material etc. Nanofibers are the newer technology which is widely used than the others due to large surface area. It has high porosity and small pore size hence it does not allow to bacterial infection due to larger size of bacteria. It has higher mechanical strength hence it is easy to use as compare to other.

Changes of Mineralogical Properties and Biological Activities of Gypsum and Its Calcined Products with Different Phase Structures

Raw gypsum (RG) and calcined gypsum (CG) are widely used in traditional Chinese medicine (TCM). RG is usually taken orally to resolve heat and diminish inflammation, while CG is only used externally to treat ulcerations and empyrosis. Calcination at different temperatures, three phase CG structures, namely, bassanite, anhydrite III, and anhydrite II, may be generated. We herein investigated the relationship between the phase structure and the efficacy of CG and the optimum phase structure for CG. RG has a compact structure, small pore size, weak anti-inflammatory effect, but no antibacterial effect, and has almost no effect on the repair of scalds. CG150 (bassanite) has a loose texture, large pore size and specific surface area, and certain antibacterial and anti-inflammatory effects, but it has a poor repair effect on scalds. CG750 (anhydrite II) has a compact structure, small pore size and specific surface area, and low antibacterial and anti-inflammatory effects, but it has a certain repair effect on scalds. Only CG350 (anhydrite III) has good performance in texture, pore size, specific surface area, antibacterial, anti-inflammatory, and scald repair. Our research has proved that the mineral properties and biological activities of CG are different due to different phase structures. CG350, namely, anhydrite III, is considered by our research to be the optimal phase structure as CG.

Quaternary ammonium salt–modified polyacrylonitrile/polycaprolactone electrospun nanofibers with enhanced antibacterial properties

In this experiment, octadecyltrimethylammonium chloride (STAC), a cationic antibacterial agent, was designed to modify hydrolyzed polyacrylonitrile (PAN) through tight electrostatic attraction. Then, the modified PAN was successfully electrospun with polycaprolactone (PCL) to obtain PCL/PAN-STAC nanofibrous membranes with enhanced mechanical properties. The modified PAN was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis and elemental analysis. The morphological, mechanical and antibacterial properties of nanofibrous membranes were investigated. The blended nanofibrous membrane presented a uniform and stable structure with small pore size. Tensile tests indicated that the mechanical property of PCL/PAN-STAC nanofibrous membrane was obviously enhanced by blending. Disk diffusion tests showed that the inhibition zones of PCL/PAN-STAC against Escherichia coli and Staphylococcus aureus were 7.56 ± 0.05 mm and 15.37 ± 0.34 mm, respectively. Shaking method indicated that the antibacterial activity against E. coli was as high as 96.20 ± 0.89% when the use of PCL/PAN-STAC reached 9 mg. Therefore, this antibacterial nanofibrous membrane is very favorable for applications such as protective filtration masks and wound dressing.

Enhanced Air Filtration Performances by Coating Aramid Nanofibres on a Melt-blown Nonwoven

Nanofibre membranes with small diameter and large specific surface area are widely used in filtration fields due to their small pore size and high porosity. To date, aramid nanofibres (ANFs)...

Binary All-Nanoporous Composite Membrane Constructed via Vapor Phase Transformation for High-Permeance Gas Separation

The metal-organic framework (MOF) membranes with ultra-small pore size (< 4 Å) have shown a great perspective for the highly selective separation of small gas molecules such as hydrogen, while...

Osteochondral Tissue Regeneration Using a Tyramine-Modified Bilayered PLGA Scaffold Combined with Articular Chondrocytes in a Porcine Model

Repairing damaged articular cartilage is challenging due to the limited regenerative capacity of hyaline cartilage. In this study, we fabricated a bilayered poly (lactic-co-glycolic acid) (PLGA) scaffold with small (200–300 μm) and large (200–500 μm) pores by salt leaching to stimulate chondrocyte differentiation, cartilage formation, and endochondral ossification. The scaffold surface was treated with tyramine to promote scaffold integration into native tissue. Porcine chondrocytes retained a round shape during differentiation when grown on the small pore size scaffold, and had a fibroblast-like morphology during transdifferentiation in the large pore size scaffold after five days of culture. Tyramine-treated scaffolds with mixed pore sizes seeded with chondrocytes were pressed into three-mm porcine osteochondral defects; tyramine treatment enhanced the adhesion of the small pore size scaffold to osteochondral tissue and increased glycosaminoglycan and collagen type II (Col II) contents, while reducing collagen type X (Col X) production in the cartilage layer. Col X content was higher for scaffolds with a large pore size, which was accompanied by the enhanced generation of subchondral bone. Thus, chondrocytes seeded in tyramine-treated bilayered scaffolds with small and large pores in the upper and lower parts, respectively, can promote osteochondral regeneration and integration for articular cartilage repair.