Antimicrobial cellulose acetate nanofibers containing silver nanoparticles

It was found for the first time that polymer nanofibers containing Ag nanoparticles on their surface could be produced by UV irradiation of polymer nanofibers electrospun with small amounts of silver nitrate (AgNO₃). When the cellulose acetate (CA) nanofibers electrospun from CA solutions with 0.5 wt% of AgNO₃ were irradiated with UV light at 245 nm, Ag nanoparticles were predominantly generated on the surface of the CA nanofibers. The number and size of the Ag nanoparticles were continuously increased up to 240 min. The Ag⁺ ions and Ag clusters diffused and aggregated on the surface of the CA nanofibers during the UV irradiation. The Ag nanoparticles with an average size of 21 nm exhibited strong antimicrobial activity.     

Electrospun cellulose acetate phthalate nanofibrous scaffolds fabricated using novel solvent combinations biocompatible for primary chondrocytes and neurons

Electrospun nanofibres have been shown to exhibit extracellular matrix (ECM)-like characteristics required for tissue engineering in terms of porosity, flexibility, fibre organization and strength. This study focuses on developing novel cellulose acetate phthalate (CAP) scaffolds by electrospinning for establishing 3-D chondrocyte and neuronal cultures. Five solvent combinations were employed in fabricating the fibres, namely, acetone/ethanol (9:1), dimethylformamide/tetrahydrofuran/acetone (3:3:4), tetrahydrofuran/acetone (1:1), tetrahydrofuran/ethanol (1:1) and chloroform/methanol (1:1). The electrospun fibres were characterized by scanning electron microscopy (SEM) analysis and confirmed to be within the nanometre range. Based on the morphology of the fibers from SEM results, two solvent combinations such as acetone/ethanol and dimethylformamide/tetrahydrofuran/acetone were selected for stabilization as CAP exhibits a pH dependent solubility. Fourier-Transform Infrared (FTIR) analysis revealed the hydrolysis of CAP which was overcome by EDC [1-ethyl-3-(3-dimethylaminopropyl) carbodiimide] and EDC/NHS (N-hydroxysuccinimide) cross-linking resulting in its stability (pH of 7.2) for three months. MTT [3-(4, 5-dimethylthiazol-2-yl)-1, 5-diphenyltetrazolium bromide] assay performed using L6 myoblast confirmed the biocompatibility of the scaffolds. 3-D primary chondrocyte and neuronal cultures were established on the scaffolds and maintained for a period of 10 days. H&E staining and SEM analysis showed the attachment of the chondrocytes and neurons on CAP scaffolds prepared using dimethylformamide/tetrahydrofuran/acetone and acetone/ethanol respectively.     

Synthesis and properties of polyaniline–cellulose acetate blends: The use of sugarcane bagasse waste and the effect of the substitution degree

Membranes of blends of polyaniline (PANi) and cellulose acetate (CA) produced from sugarcane bagasse with different degrees of substitution were produced and characterized using various techniques. Results showed that incorporation of PANi into the CA matrices leads to significant alterations of the blend morphologies, with phase separation, and that these differences are less significant for PANi/cellulose triacetate blends. The blends also showed a significant increase in electrical conductivity, with that of PANi/cellulose diacetate demonstrating an almost 200-fold increase.     

The separation of Liriomyza huidobrensis (Diptera: Agromyzidae) from related indigenous and non-indigenous species encountered in the United Kingdom using cellulose acetate electrophoresis

The non-indigenous pest leaf miner Liriomyza huidobrensis and its close relatives L. bryoniae and L. strigata belong to a natural group. These species can be separated from one another by means of protein electrophoresis on a cellulose acetate membrane. The protocol for this diagnostic assay involves staining for two enzymes, glucose-6-phosphate dehydrogenase (G6PDH) and leucine-glycine peptidase (PEP). Other leaf miner species that might also be found under glass, Chromatomyia syngenesiae, C. horticola and the non-indigenous L. trifolii and L. sativae , are clearly distinguishable from the L. huidobrensis group of species by this assay. The effect of parasitism on L. huidobrensis by Dacnusa sibirica was investigated and shown unlikely to cause misidentification of the leaf miner host. Results obtained from practical use of the assay to identify unknown specimens from ports and nurseries are compared with those obtained from flies kept in laboratory culture and used during development of the assay. No new variation was found for G6PDH. New PEP variation was found for both L. huidobrensis and L. bryoniae but this did not affect the integrity of the assay. A biochemical key to these agromyzid leaf miners is presented.     

Biomaterials of PVA and PVP in medical and pharmaceutical applications: Perspectives and challenges

Poly(vinyl alcohol) (PVA) has attracted considerable research interest and is recognized among the largest volume of synthetic polymers that have been produced worldwide for almost one century. This is due to its exceptional properties which dictated its extensive use in a wide variety of applications, especially in medical and pharmaceutical fields. However, studies revealed that PVA-based biomaterials present some limitations that can restrict their use or performances. To overcome these limitations, various methods have been reported, among which blending with poly(vinylpyrrolidone) (PVP) showed promising results. Thus, our aim was to offer a systematic overview on the current state concerning the preparation, properties and various applications of biomaterials based on synergistic effect of mixtures between PVA and PVP. Future trends towards where the biomaterials research is headed were discussed, showing the promising opportunities that PVA and PVP can offer.