Novel Biohybrid Materials by Electrospinning: Nanofibers of Poly(ethylene oxide) and Living Bacteria

Abstract

Electrospinning is a versatile method for the preparation of continuous fibers with diameters ranging from micrometers down to a few nanometers.[1] Nonwovens of electrospun fibers are obtained from polymer solution or melt when a materials jet moves from an electrode to the corresponding counter electrode under the influence of a strong electrical field (up to several kV cm -1 ) with simultaneous evaporation of solvent or solidification of melt. Although the experimental set-up is simple the process is complex since numerous parameters such as solution viscosity, electrical conductivity, surface tension, polymer molecular mass, molecular mass distribution, glass transition, distance of electrodes, shape of electrodes, strength of electrical field, nature of counter electrode, processing atmosphere etc. influence shape, yield, and dimensions of resulting fibers. Nevertheless, electrospinning of polymers offers unique opportunities for the preparation of manifold fibers since nearly every soluble or meltable polymer can be processed to fibers of different shapes, dimensions, and surface characteristics and composites can be prepared simply by addition of a composite component to the electrospinning solution. Thereby, composite fibers, functional fiber, and fibers with complex structure can be prepared by electrospinning of polymers with additional compounds like nanoparticles, carbon nanotubes, catalysts, and enzymes just to name a few. [2][3][4][5] Recently, dispersions of M13 viruses in watersoluble polyvinylpyrrolidon were processed to nanofibers by electrospinning. It was clearly shown that virus infection of bacterial host was possible by viruses coming form the electrospun virus-based nonwovens. [6] In another pioneering work Zussman et al. showed encapsulation of Escherichia (E.) coli and Staphylococcus albus by elctrospinning of bacteria suspensions with poly(vinyl alcohol) (PVA). [7] These remarkable findings clearly showed that nonwovens composed of polymer nanofibers and complex biological objects can be prepared directly without total loss of biological functionality. In extension of these encouraging results we have undertaken attempts to electrospin bacterial aqueous dispersions with water-soluble poly(ethylene oxide) and to compare survival rates of different bacteria at ambient temperatures.[8] Bacteria-modified nonwovens furnished with tailored complex biological functionalities such as virus or bacteria could be of great interest as novel biohybrid materials. These new biohybrid materials could be of interest as living membranes for a variety of application areas like filtration, separation membranes, sensors, catalysis, textiles etc. The removal of water by rapid evaporation upon electrospinning is anticipated to cause a drastic change of the bacterial osmotic environment. For our experiments we therefore chose a bacterium known to be adapted to life at low water activities and to survive rapid changes in osmotic pressure. Such an organism is Micrococcus (M.) luteus, which is an airborne non-path...

Nanofibrous solid dosage form of living bacteria prepared by electrospinning

“…In former studies bioactive ingredients such as proteins and DNA have been embedded successfully in nanofibers mainly for tissue engineering purposes, while living prokaryotic cells were encapsulated by this technique mainly for industrial application in bioreactors utilizing their metabolic activity [20][21][22]. Zussman [23] has recently reviewed the preparation methods of electrospun polymer fibers encapsulating cells and their potential applications.…”

Engineering of bio-hybrid materials by electrospinning polymer-microbe fibers

“…As described earlier, electrospinning is an efficient method for encapsulating bacteria in the polymer fiber. However, in the electrospinning process, the removal of water by rapid evaporation is anticipated to cause drastic changes in the osmotic environment of the organism (23). Furthermore, an electric field, which may be harmful to the bacteria, is generated by applying a high voltage between the metal capillary and the collector.…”

“…If these mechanical and biocompatible properties are combined with the high surface-to-volume ratios of fibers, the hydrogel can be used as an efficient support material both for enzymes and for immobilization of microorganisms (20). Lee and Belcher (21), Salalha et al (22), and Gensheimer et al (23) had investigated electrospinning as a possible method of encapsulating both bacteria and bacterial viruses. Although these studies are of great value and showed the promise of this emerging field, the electrospun polyvinyl alcohol, PEO, and polyvinyl pyrrolidone materials were water soluble, and thus their use was significantly limited.…”

Physics and Chemistry of Sol-Gel Nanocomposites Formation

“…As the composites obtained in other ways, these nanocomposites are classified by the nature of interaction between organic and inorganic phases: nanocomposites with interphase covalent bond [92][93][94] and nanocomposites with weak (for example, hydrogen) bonds between the phases [95][96][97]. There are quite many examples in which these types of nanocomposites are described and characterized, we shall confine just to some of them [98][99][100][101][102][103][104][105][106][107][108][109][110]. Class 5 by classification [49] from Table 4.2 belongs to this type of materials They include hard metal oxide polymer and organic polymer capable of binding metal ions, thus forming metal-polymer complex.…”