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 oil—is a relatively complex process that involves a series of technological steps, beginning with pressing and filtration, followed by 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 vegetable oil and are, of course, energy- and material-intensive. 

The initial idea was to replace conventional cotton sleeve filters with nanofiber filters, which would be more efficient and require less frequent maintenance. After a series of experiments, we actually succeeded in doing so. But to our surprise, the filtered oil also contained significantly lower levels of substances that were undesirable from a sensory perspective. This was followed by rigorous testing and analytical evaluation, which demonstrated that—thanks to as-yet-not-fully-understood, likely quantum-sorption phenomena on the nanofiber membrane—filtering the oil at an appropriate temperature does indeed result in a significant reduction in the content of phosphatides, fatty acids, oxidation products, and pigments. In a single process step, we thus obtain oil stripped of the vast majority of undesirable substances, with nutritional and sensory properties corresponding to those of virgin oil. This eliminates the need for additional process steps, which has a very positive impact on both the quality of the oil and the energy intensity of the entire vegetable oil processing process. 

Encouraged by these successes, we attempted to implement similar technology in a field as conservative and traditional as winemaking. We replaced standard cellulose filters with nanofiber filters; however, initial results showed that our filters were too effective—they even removed the pigments from red wine, turning it into white wine. After a series of experiments, we developed an optimal technological solution for filtering grape must that removes only unwanted impurities, including bacterial pathogens. The presence of these pathogens in wine is the reason why winemakers must stabilize the wine by adding sulfites, which, however, have a negative sensory impact on the wine’s quality. Thanks to our solution, the need to add sulfites to the wine is significantly reduced, resulting in the preservation of all the wine’s nutritional and sensory properties. 

Nanofibrous carriers of bacterial biomass for water and air purification

During 2014, we developed a unique technology for the production of nanofiber yarns. Using this technology, the desired layer of nanofibers is continuously applied to a carrier fiber via AC spinning, resulting in a strong fiber coated with an extremely complex nanostructure. These AC nanostructures closely mimic the so-called extracellular matrix of cells and thus provide an ideal supportive environment for the growth and proliferation of various types of microorganisms. Microorganism communities, consisting primarily of bacterial and fungal biomass, are capable of degrading contaminants in aquatic environments, ranging from nitrogenous compounds to pesticides and residues of pharmaceuticals and hormones. This led us to the idea of using these nanofibers as carriers of microbial biomass for water treatment. We have created various 3D versions of nanofiber carriers, ranging from small units on the order of centimeters—of which the required quantity can be used depending on the volume of water being treated (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 treatment systems for local applications at contaminated sites. For these carriers, we are able to very precisely identify the appropriate composition of the microbial community and specifically seed it with a culture of the required microorganisms based on the specifics of the contamination, which significantly promotes the formation and stabilization of the necessary microbial community. Tests at a number of sites have demonstrated that these biomass carriers are capable not only of effectively removing nitrogenous substances but also of significantly reducing concentrations of micropollutants, pharmaceutical residues, hormones, and pesticides—something conventional water treatment methods cannot achieve. We have also adapted and successfully tested a similar concept for removing undesirable volatile substances from the air—substances that are generated, for example, in wastewater treatment plants, biogas plants, and similar facilities, where they produce unpleasant and sometimes even hazardous odors.

Implantable nanofibrous carriers and wound covers

Nanostructures created using electrostatic spinning closely mimic the so-called extracellular matrix of cells, making them an ideal supportive 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 are able to prepare nanostructures from biocompatible and biodegradable polymers, and we can further functionalize them using biologically active substances. We have therefore created nanofiber carriers from biopolymers, which we have 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 also plan to test them on tendon damage. The nanofiber structure at the implantation site promotes the ingrowth of new tissue; furthermore, the gradual natural degradation of the biopolymer leads to the slow release of the biologically active substance, which thus consistently maintains an optimal concentration at the defect site to maximize the regenerative effect. 

We achieved similar results with nanofiber wound dressings, where the target therapeutic indications include slow-healing skin lesions, leg ulcers, burns, and others. Here, the functionalized two-dimensional nanostructure not only acts as a barrier, protecting the wound from pathogens while ensuring breathability, but the biodegradation of the polymer also results in the gradual release of the active substance into the site of injury, which further accelerates the regeneration process. 

The use of nanofiber-based functionalized cell carriers and wound dressings in experimental models and, to a limited extent, in human models has demonstrated high effectiveness in promoting the regenerative healing process of damaged tissue, as well as a significant reduction in adverse complications.