Title : Influence of electrospinning methods on characteristics of nanofibres essential for biological applications
Nanofibres may be generated using a number of techniques; however, electrospinning allows industrial-scale production. In this study, we examine different nanofibre properties resulting from five different electrospinning methods when using the same polymer solution (polyurethane and polyvinylbutyral) and environmental parameters within the given range (temperature, humidity, etc.). Specifically, for biological applications (scaffolds, biomass carriers) of nanofibrous structures, it is necessary to know their properties to estimate the behavior of bacteria (biofilm) on their surface respectively in the surface structure. The basic parameters for the determination of bacteria behavior on the surface of nanofibres are a surface charge, porosity, surface morphology, which is strongly related to cell adhesion and other specific physical mechanical properties. In this paper, we examine the effects of five different electrospinning methods on a range of nanofibre material properties while keeping solution and environmental parameters constant for all methods. Nanofibre characterization (surface integrity) is presently considered one of the most interesting areas of nanofibre research; hence, we undertook a detailed analysis of the nanofibres using modern analysis methods, with the aim of assessing the basic structural properties that affect the nanofibre product’s mechanical or physical properties (consequently important for biological interactions). The five electrospinning methods examined were based on (a) alternating current (AC Electrospinning) and (b) direct current (DC Rod Electrospinning, DC NanospiderTM Electrospinning, DC Needle Electrospinning and DC Centrifugal Electrospinning). Detailed analysis of nanofibre structural properties (total fibre length and diameter, pore size and porosity, linearity/curvature rating) was performed using scanning electron microscopy, with thermal properties assessed using differential scanning calorimetry, biodegradability using a respirometer and surface roughness using confocal microscopy. The results showed clear structural differences in the nanomaterials produced depending on the method used and open further possibilities for research in this area. Based on the results we can claim that DC methods are suitable for the preparation of well defined, compact nanofibre structures (depending on method productivity). Centrifugal electrospinning, on the other hand, may be more suitable for a narrow range of specialist applications, especially as regards medical use, e.g. tissue engineering or sensors, while the more productive AC method may be more suitable for applications requiring substrates with nanofibre coatings that are more thread-like, require thicker layers or rough surfaces. By tailoring the methods and equipment used, therefore, it should be possible to prepare customized nanofibre structures (larger/smaller pore size, specific fibre diameters, etc.) for specific biological applications.