Budimir Mijović

Synthetic vs natural scaffolds for human limbal stem cells

Aim To investigate the impact of synthetic electrospun polyurethane (PU) and polycaprolactone (PCL) nanoscaffolds, before and after hydrolytic surface modification, on viability and differentiation of cultured human eye epithelial cells, in comparison with natural scaffolds: fibrin and human amniotic membrane. Methods Human placenta was taken at elective cesarean delivery. Fibrin scaffolds were prepared from commercial fibrin glue kits. Nanoscaffolds were fabricated by electrospinning. Limbal cells were isolated from surpluses of human cadaveric cornea and seeded on feeder 3T3 cells. The scaffolds used for viability testing and immunofluorescence analysis were amniotic membrane, fibrin, PU, and PCL nanoscaffolds, with or without prior NaOH treatment. Results Scanning electron microscope photographs of all tested scaffolds showed good colony spreading of seeded limbal cells. There was a significant difference in viability performance between cells with highest viability cultured on tissue culture plastic and cells cultured on all other scaffolds. On the other hand, electrospun PU, PCL, and electrospun PCL treated with NaOH had more than 80% of limbal cells positive for stem cell marker p63 compared to only 27%of p63 positive cells on fibrin. Conclusion Natural scaffolds, fibrin and amniotic membrane, showed better cell viability than electrospun scaffolds. On the contrary, high percentages of p63 positive cells obtained on these scaffolds still makes them good candidates for efficient delivery systems for therapeutic purposes.

The efficacy of electrospun polyurethane fibers with TiO2 in a real time weathering condition

This study focuses on the behavior of electrospun polyurethane fibers filled with nano, micro spheres and nanotube TiO2, thus nTiO2, mTiO2 or TiNT, under real time ultraviolet (UV) radiation. Analyses were conducted using scanning electron microscopy (SEM), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis and differential scanning calorimetry (DSC) techniques. Significant changes of thermoplastic polyurethane (TPU) + 0.5% nTiO2 and TPU + 0.5% mTiO2 fibers morphology, that is, agglomerated TiO2 particles, were observed on material surfaces due to TPU fiber degradation, also supported by FTIR spectra given as reduction in the peaks intensities after UV radiation, especially in the case of TPU + 0.5% nTiO2. Further, after UV radiation, the initial degradation temperature reduction of the hard segment for all materials was up to 40℃. A significant reduction in the final degradation temperature (from 397.8℃ to 274.1℃) was noticed for the mTiO2 filled fibers, suggesting their photocatalytic activity, while Tg was increased up to 20℃ for almost all fillers added to TPU, thus indicating lower molecular chain mobility upon UV radiation.

Nursing Student Remote Performance Assessment using a Novel Smartphone Application

Smartphone technologies have transformed the way people interact with each other around the world. The technology offers new approaches and opportunities for collecting, storing and sharing information. A novel smartphone technology application (app) originally developed for Patient Behavior Health applications was tested to determine if the proficiency of nursing students demonstrating a standardized seasonal influenza immunization protocol could be accurately recorded and subsequently evaluated remotely. The student performance was rated by four university instructors independently of each other. Each instructor used a standardized competency check-list to score these students. The study showed that by using the new smart-phone application, the remote evaluation of clinical nursing student proficiencies could be accomplished quickly and easily. However, the inter-rater agreement indicated that training of the evaluators in the use of the new app prior to scoring student performances will be needed. While the new smartphone application proved to be effective in documenting student performance, the technology promises to have practical uses in additional fields such as the secure monitoring of specialized training for paramedics, firefighters, police, skilled tradesmen, aircraft crews, etc.

Parameters Dependence of Fibers Diameter and Pores Area in Electrospinning

Electrospinning has become the most popular nanofibers production technique that many scientists around the world were intrigued by. It is based on electrostatic forces stretching a polymer solution that undergoes bending instability and eventually results in number of fine nanoscaled filaments. The study reports of four processing parameters effect on electrospun polyethylene oxide (PEO) fibers diameter and pores area. Fibers diameter increase results from the increase of time, volume flow rate and tip to collector distance with a critical value of the first two parameters. The pores area showed both decrease and increase after a critical value of the electrical voltage at 19 kV, while the mean pores area decreased with the time increase. Irregular trends of increasing and decreasing trends of the means pores area were noticed with the change of the volume flow rate and tip to collector distance..

11 – Electrospun nanofibers

With the rapid development of nanotechnology, research interest in nanofibers has grown exponentially, especially for those prepared by electrospinning. Electrospun nanofibers are light weight with high surface-to-volume ratio, adjustable fiber diameter/morphology, and well-controlled functionality, making them a very important nanomaterial for various applications. Considerable effort has been devoted to improving electrospinning efficiency, controlling nanofiber structure, and finding their unique property and novel application. From the initial study that used a simple needle-based electrospinning setup, electrospinning has entered a new era of mass production from needleless apparatus and nonweb fibrous structure-like nanofiber yarns. This chapter provides an overview of electrospinning, its brief history, physical principle, advanced electrospinning setups, and functional applications. The advantages of electrospinning and nanofibers, their structures, and functionalities are discussed in detail.