New project for the development of functionalized nanofiber filters

Nanofiber filters for filtration of vegetable oils, wine and other media

The processing of vegetable oils, in this case rapeseed, is a relatively complicated process that includes a number of technological steps, starting from pressing and filtration, through acid hydration to remove phospholipids, alkaline refining to remove fatty acids, bleaching to remove pigments, oxidation products and metal residues, and ending with deodorization. All of these process steps have a negative impact on the nutritional and, above all, sensory properties of the vegetable oil and are, of course, energy and material intensive. 

The initial idea was to replace conventional cotton bag filters with nanofiber filters, which would be more effective and do not require as frequent maintenance. After a series of experiments, this was indeed achieved. However, what was our surprise when the filtered oil also contained a significantly lower amount of sensory undesirable substances. This was followed by demanding testing and analytical evaluation, which proved that, thanks to the not yet fully understood, probably quantum - sorption phenomena on the nanofiber membrane, when filtering oil at the appropriate temperature, there is indeed a significant reduction in the content of phosphatides, fatty acids, oxidation products and pigments. In one process step, we obtain oil free of the vast majority of undesirable substances with nutritional and sensory properties corresponding to virgin oil. This eliminates the need for additional process steps, which has a very positive effect on both the quality of the oil and the energy intensity of the entire vegetable oil processing process. 

Encouraged by these successes, we tried to implement a similar technology in such a conservative and traditional technology as wine production. We replaced standard cellulose filters with nanofiber ones, however, initial results showed that our filters were too effective – they even removed pigments from red wine and turned it into white wine. After a series of experiments, we developed an optimal technological solution for filtering wine must, which removes only unwanted impurities, including bacterial pathogens. The presence of these pathogens in wine is the reason why winemakers have to stabilize wine by adding sulfites, which, however, have a negative sensory effect on the quality of wine. Thanks to our solution, the need to add stabilizing sulfur substances to wine is significantly reduced, and the result is the preservation of all nutritional and sensory properties of wine. 

Nanofibrous carriers of bacterial biomass for water and air purification

During 2014, we developed a unique technology for preparing nanofiber yarns. Through this technology, the required layer of nanofibers is continuously applied to the carrier fiber using AC spinning, thereby creating a solid fiber coated with an extremely complex nanostructure. These AC nanostructures very faithfully imitate the so-called extracellular matrix of cells and thus represent an ideal supporting environment for the growth and proliferation of various types of microorganisms. Communities of microorganisms, consisting mainly of bacterial and fungal biomass, are able to degrade contaminants in the aquatic environment, starting with nitrogenous substances and ending with pesticides and drug and hormone residues. This led us to the idea of ​​using these nanoyarns as carriers of microbial biomass for water purification. We have created various 3D versions of nanofibrous carriers, from small units in the order of centimeters, which can be used in the required amount according to the volume of purified water (tens to hundreds of units) to large carrier structures measuring many square meters, which can be used both in stationary treatment plants and in modular mobile purification systems for local applications at contaminated sites. For these carriers, we are able to very accurately identify the appropriate composition of the microbial community and specifically plant it with a culture of the desired microorganisms according to the specifics of the contamination, which will significantly support the formation and stabilization of the necessary microbial community. Tests at a number of sites have shown that these biomass carriers are capable of not only effectively removing nitrogenous substances, but also effectively reducing the concentrations of micropollutants, drug residues, hormonal substances and pesticides, which conventional water purification methods do not allow. We have adapted and successfully tested a similar concept for removing unwanted volatile substances from the air, which are generated, for example, in wastewater treatment plants, biogas stations, etc., where they create an annoying and sometimes dangerous odor.

Implantable nanofibrous carriers and wound covers

Nanostructures created using electrostatic spinning very closely imitate the so-called extracellular matrix of cells, which makes them an ideal supporting environment for cell growth and proliferation. This led us to the idea of ​​using our nanostructures as cell carriers in regenerative medicine and tissue engineering. We can prepare nanostructures from biocompatible and biodegradable polymers and, in addition, we can further functionalize them using biologically active substances. So, we created nanofibrous carriers from biopolymers, which we functionalized in several ways – with stem cells, stem cell extracts, growth factors and other biologically active substances. We experimentally implanted these carriers into several types of tissue defects – damaged cartilage, bone defects, and we are planning to also damage tendons. The nanofibrous structure at the site of implantation supports the growth of new tissue, and in addition, the gradual natural degradation of the biopolymer leads to the gradual release of the biologically active substance, which thus always reaches an optimal concentration at the site of the defect for maximum support of the regenerative effect. 

We have achieved similar results in the case of nanofibrous wound dressings, where the target therapeutic indication is difficult-to-heal skin damage, leg ulcers, burns, etc. Here, the functionalized planar nanostructure not only functions as a barrier, protecting the wound from pathogens while ensuring breathability, but in addition, the biodegradation of the polymer gradually releases the active substance into the site of damage, which further accelerates the regeneration process. 

The application of nanofibrous functionalized cell carriers and wound dressings in experimental and, to a limited extent, human models has demonstrated high effectiveness in supporting the regenerative healing process of damaged tissue as well as a significant reduction in undesirable complications.