EMULSION ELECTROSPINNING OF POLYVINYLPYRROLIDONE (PVP)/PARACETAMOL NANOFIBERS

This study aimed to achieve Polyvinylpyrrolidone (PVP) nanofiber production including paracetamol (PCT) by oil-in-water emulsion electrospinning. At first, emulsions were prepared at 14 wt % PVP with various PCT concentrations (0, 0.1, 0.3, 0.5, 0.7, 0.9 wt %). Then, solution properties such as viscosity, conductivity, and surface tension were determined. The production of nanofiber samples was carried out by emulsion electrospinning under the optimum process parameters (voltage, distance between electrodes, feed rate, and atmospheric conditions). Finally, the morphological and structural characterization of the nanofiber surface was carried out with SEM and FT-IR. According to the results of emulsion properties, although the change is not remarkable, it tends to increase the viscosity with an increase in PCT concentration. On the other hand, it was observed that surface tension did not change significantly with PCT concentration increasement and while the conductivity of emulsions decreased slightly. When the fibre structure was investigated, average fibre diameter and fibre diameter uniformity were not affected prominently by PCT concentration. From the SEM images, it is possible to say that generally fine, uniform and bead-free drug-loaded nanofibers were obtained. The finest (326 nm) and most uniform (1.03) nanofibers were achieved from the sample N4 which included 0.5 wt % PCT. Also, the FT-IR results verified that PVP and PCT exist in the nanofiber structure.

PARACETAMOL DRUG LOADED MICROCAPSULE BASED NANOFIBER PRODUCTION

In this study, it was aimed to production and characterization of paracetamol (PCT) loaded microcapsules and microcapsule added electro spun PVA nanofibers. Eudragit RS 100 and PVA were used as the shell in the microcapsule structure, and PCT was used as the core material. First of all, the PCT loaded Eudragit RS 100/PVA microcapsules were produced by solvent evaporation method under the optimum process parameters. Then, properties such as conductivity, viscosity and surface tension of the microcapsule loaded PVA solution were measured and the effects of microcapsule concentration on the solution properties were determined. According to the solution results, while the viscosity increased with the microcapsule concentration, conductivity and surface tension did not change significantly except for the PVA-10 sample. After the electrospinning process, fibre morphology was determined by SEM and incorporation of microcapsules into the nanofibers was clearly demonstrated. It was calculated from the SEM images that average microcapsule size is 9.81μm, average fibre diameter is 550 nm and fibre diameter uniformity coefficient is 1.025. Finally, the incorporation of PCT loaded microcapsules into the nanofibers was chemically confirmed by FT-IR analysis. It is thought that the results of this study will be useful for controlled drug release, especially in medical textiles.

Evaluation of a new portable device that measures diameter of animal fibres

Increasing production of animal fibres has increased the need for a portable instrument that measures fibre diameter and associated characteristics with precision and accuracy. This research evaluated a new portable fibre tester (PFT) by measuring the diameter and related characteristics of tops and scoured fibres of wool, alpaca, and vicuña. The PFT was constructed with integrated mechanical, optical, electronic, and informatic components. Textile tops of sheep wool, alpaca fibres, and mohair goat fibres were used as standard references to calibrate the PFT and determine its accuracy and precision. The results were compared with those from a wool industry standard instrument (OFDA2000) that uses similar technology. The PFT had high accuracy (-0.01, -0.12, and -0.01 μm) for average fibre diameter (AFD) of wool, alpaca, and mohair fibres, respectively. Deviations of standard tops (ST) were within industry-accepted tolerance ranges. Standard errors, indicating precision, were low, ranging from 0.07 to 0.25 μm, 0.02 to 0.44 μm, and 0.09 to 0.024 μm, for wool, alpaca, and mohair fibre tops, respectively. The correlations of measurements of AFD from the two instruments were 0.99 for wool, alpaca, and mohair fibres, but lower for vicuña fibres (0.82). No evidence of bias was observed. Therefore, the PFT may be used as an alternative instrument for measuring fibre diameter and quantifying variation in diameter of wool, mohair, and alpaca fibres. The PFT has appeal for use in the field for practical animal selection and fleece classification based on fibre characteristics. Keywords: alpaca, fibre diameter, mohair, vicuña, wool

Fish Scale Collagen Functionalized Thermo-Responsive Nanofibres

Smart thermosensitive polymer such as poly (N-isopropyl acrylamide) (PNIPAM) and dominant fibrous protein of connective tissue such as collagen (CLG) possess great potential in biomedical and tissue engineering applications. The objectives of current work aim to explore potential of PNIPAM and collagen by (i) establish a stable procedure to extract collagen from fresh water Tilapia fish scale (TFS) and (ii) fabricate PNIPAM and hybrid PNIPAM-CLG nanofibrous scaffolds through electrospinning technique and investigate their material-process-structure behaviour. Type I collagen was derived through acid hydrolysis of TFS. Electrospinning of PNIPAM was carried out with 16, 18 and 20 wt% PNIPAM concentration in methanol (MeOH) while PNIPAM-CLG was prepared through blending measured quantity of PNIPAM dissolved in water with collagen dissolved in acetic acid. Material properties, viscosity, morphology and thermo-physical behaviors of the derived collagen, electrospun PNIPAM and PNIPAM-CLG scaffolds were characterized. Results from SDS-PAGE and FTIR confirmed that the isolated TFS collagen is of type I. EDX revealed that demineralization eliminated the aluminium, magnesium, silicon and phosphorus while significantly reduced the sulfur elements from raw TFS. SEM observation of the collagen morphology shown a fluffy and fibrillary lamellae structure. Electrospun scaffolds were successfully fabricated with 16 and 18 wt% PNIPAM in MeOH. Both homogeneity and average fibre diameter (Davg) were greater in the 18 wt% PNIPAM scaffold, in which the Davg for 16 and 18 wt% were ~110 and ~131.7 nm respectively. However, PNIPAM at 20 wt% failed to be electrospun owing to its excessively high viscosity. On the other hand, SEM observation revealed that the electrospun hybrid PNIPAM-CLG scaffold has Davg of ~105.5 nm amid the presence of numerous elongated beads.

Empirical modelling and optimization of pressure-coupled infusion gyration parameters for the nanofibre fabrication

Pressure-coupled infusion gyration (PCIG) is a novel promising technique for economical and effective mass production of nanofibres with desirable geometrical characteristics. The average diameter of spun fibres significantly influences the structural, mechanical and physical properties of the produced fibre mats. Having a comprehensive understanding of the significant effects of PCIG experimental variables on the spun fibres is beneficial. In this work, response surface methodology was used to explore the interaction effects and the optimal PCIG experimental variables for achieving the desired morphological characteristics of fibres. The effect of experimental variables, namely solution concentration, infusion (flow) rate, applied pressure and rotational speed, was studied on the average fibre diameter and standard deviations. A numerical model for the interactional influences of experimental variables was developed and optimized with a nonlinear interior point method that can be used as a framework for selecting the optimal conditions to obtain poly-ethylene oxide fibres with desired morphology (targeted average diameter and narrow standard deviation). The adequacy of the models was verified by a set of validation experiments. The results proved that the predicted optimal conditions were able to achieve the average diameter that matched the pre-set desired value with less than 10% of difference.

The effect of graphene–poly(methyl methacrylate) fibres on microbial growth

A novel class of ultra-thin fibres, which affect microbial growth, were explored. The microbial properties of poly(methyl methacrylate) fibres containing 2, 4 and 8 wt% of graphene nanoplatelets (GNPs) were studied. GNPs were dispersed in a polymeric solution and processed using pressurized gyration. Electron microscopy was used to characterize GNP and fibre morphology. Scanning electron microscopy revealed the formation of beaded porous fibres. GNP concentration was found to dictate fibre morphology. As the GNP concentration increased, the average fibre diameter increased from 0.75 to 2.71 µm, while fibre porosity decreased. Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa were used to investigate the properties of 2, 4 and 8 wt% GNP-loaded fibres. GNP-loaded fibres (0 wt%) were used as the negative control. The fibres were incubated for 24 h with the bacteria; bacterial colony-forming units were enumerated by adopting the colony-counting method. The presence of 2 and 4 wt% GNP-loaded fibres promoted microbial growth, while 8 wt% GNP-loaded fibres showed antimicrobial activity. These results indicate that the minimum inhibitory concentration of GNPs required within a fibre is 8 wt%.

Effect of Molecular Weight on Morphological Structure of Electrospun PVA Nanofibre

This work focuses on the preparation of electrospun Polyvinyl Alcohol (PVA) nanofibres of three different molecular weights. The electrospinning process parameters were varied in terms of the voltage and feed rate. Scanning Electron Microscopy technique was used to characterize the morphological structure of the electrospun PVA nanofibre. The results show that the average fibre diameter increased as the molecular weight of the polymer increased. The formation of beads occurs from the lowest molecular weight sample of 89K However, long, continuous and beaded-free fibres were obtained from the 125K and 205K polymer weight PVA. The results also suggest that higher spinning voltage and feed rate produce larger fibre diameter, respectively.Keywords : Polyvinyl Alcohol, nanofibres, molecular weight, electrospinningCorresponding Author:Khairunnadim Ahmad Sekak, Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), Shah Alam, 40450 Selangor Darul Ehsan.Email: [email protected]

OPTIMIZATION OF ELECROSPINNING OF PVDF SCAFFOLDS FABRICATION USING RESPONSE SURFACE METHOD

Poly(vinylidene fluoride) (PVDF) scaffolds were prepared via electrospinning. The response surface methodology (RSM) was used to optimize the parameters that influence the average fibre diameter. The objective is to produce fibres with small diameters. The factors considered for experimental design were the applied electric voltage, the PVDF solution concentration, and the distance between the needle tip and the collecting drum. The Central Composite Design (CCD) was used to generate the experimental design whilst the analysis of variance (ANOVA) was performed to obtain statistical validation of regression models and to study the interaction between input parameters. The optimum operating conditions that guaranteed PVDF scaffolds with small nanofibre diameter were in the voltage and concentration range of 16-20 kV and 10-14wt%.

Fibre quality of South American camelids in Argentina: a review

SummaryArgentina's annual camelid fibre production is estimated at 60 000 kg for llama (Lama glama), somewhat more than 2 000 kg for guanaco (Lama guanicoe) and about 845 kg for vicuña (Vicugna vicugna). The potential for increasing these amounts is huge considering that barely 30 percent of llamas are shorn and considering the size of the wild camelid population in the country. A compilation of published and unpublished work confirms that almost 50 percent of the llamas are single-coated, about 40 percent have white fleeces and that average fibre diameter is about 22 µm in the main llama production area. In general, there is a wide variation in fleece weights and fibre quality between and within herds. However, a llama fleece classing and pricing system is not yet in place to motivate implementation of breeding programmes. Guanaco and vicuña fleeces are double-coated but the fine undercoat represents more than 80 percent of the fleece weight. The proportion of down fibre remaining after mechanical dehairing is only 50 percent in guanacos and 70 percent in vicuñas. The guanaco undercoat fibre diameter is about 16 µm and vicuña fibre diameter is typically between 13 and 14 µm. Both fibres are relatively short. Research is needed to establish optimum shearing season and shearing frequency that results in fibre quality demanded for handcraft and industry in each of the three species.

Needleless Melt-Electrospinning of Polypropylene Nanofibres

Polypropylene (PP) nanofibres have been electrospun from molten PP using a needleless melt-electrospinning setup containing a rotary metal disc spinneret. The influence of the disc spinneret (e.g., disc material and diameter), operating parameters (e.g., applied voltage, spinning distance), and a cationic surfactant on the fibre formation and average fibre diameter were examined. It was shown that the metal material used for making the disc spinneret had a significant effect on the fibre formation. Although the applied voltage had little effect on the fibre diameter, the spinning distance affected the fibre diameter considerably, with shorter spinning distance resulting in finer fibres. When a small amount of cationic surfactant (dodecyl trimethyl ammonium bromide) was added to the PP melt for melt-electrospinning, the fibre diameter was reduced considerably. The finest fibres produced from this system were400±290 nm. This novel melt-electrospinning setup may provide a continuous and efficient method to produce PP nanofibres.