Roksana Kurpanik

Antibiotic resistance poses a critical challenge in ocular medicine, where treatments must combine antibacterial potency with tissue compatibility. Electrospun core-shell nanofibers offer an attractive solution for ocular applications as they provide a biomimetic extracellular matrix structure with controlled drug release and surface functionality. In this work, polycaprolactone (PCL) was used as the mechanically robust, biodegradable core, while polyvinylpyrrolidone (PVP) formed a hydrophilic shell to enhance wettability and ocular compatibility. The nanofibers were further functionalized with N,S-doped carbon quantum dots, exhibiting light-switchable redox behavior. Compositional and spectroscopic analyses revealed that N,S-doped CQDs possessed a significantly narrowed bandgap (3.14 eV) relative to cysteine- and tryptophan-derived CQDs, attributable to heteroatom-induced defect states and the formation of π-π conjugated domains, confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). XPS measurements showed valence band energies suitable for superoxide generation under illumination, consistent with the reported redox potentials. As a result, illuminated nanofibers produced reactive oxygen species (ROS), reducing Escherichia coli and Staphylococcus aureus populations by 90% and 80%, respectively. In the dark, the same CQDs exhibited up to 90% radical-scavenging activity, increasing BJ human fibroblast viability by 35%. Additional mechanistic evidence indicated that light enhances the adhesion of CQDs to bacterial membranes, further promoting ROS-mediated inactivation. With a high quantum yield of 50% and strong blue fluorescence (λ_em = 445 nm, λ_ex = 380 nm), the CQDs also offer imaging and diagnostic potential. Together, these findings position N,S-doped CQDs-modified core-shell nanofibers as a biologically adaptive platform capable of photodynamic antibacterial action while supporting cytoprotection and tissue regeneration─an innovative approach for combating antibiotic-resistant ocular infections.

There is an urgent need to alleviate the symptoms of neurodegenerative diseases. The presented work includes the use of electrochemical polymerization (CV) to obtain active polypyrrole layers with incorporated molecules of a neurological drug substance—amantadine hydrochloride. The obtained films were characterized chemically, structurally, and functionally in terms of their use as a drug delivery systems which are neurologically active. FTIR spectra were recorded to identify the incorporation of drug substances into the matrix. The obtained results showed that amantadine and heparin were embedded to the polypyrrole matrix. Scanning electron microscopy (SEM) was used to examine the morphology of the films. The films deposited on the steel substrate showed a compact, smooth structure, where there was no visible organized structure. After release, the film became corrugated. Adhesive tests were conducted with the cross-cut Test Method B to determine the mechanical properties, and the results showed that amantadine improves adhesion for steel substrates. The films were potentially stimulated by chronoamperometry, and UV-Vis spectra were registered to calculate the concentration of AMA in the solution after release. The release curves indicate a 95% efficiency of AMA release over the studied time period and protocol. Later, antibacterial properties were tested. The proposed system was able to provide a daily dose of drugs that ensures a therapeutic effect. This is a significant step towards developing systems capable of delivering a wider range of doses, potentially in line with the full spectrum recommended for therapeutic efficacy. The antibacterial properties of the material allows it to be considered as a material with antibacterial potential in the presence of the Staphylococcus aureus (S. aureus) strain. The percentage reduction ratio indicates a 90–100% reduction of bacteria in the suspension.

The study examined the possibility of intercalation of montmorillonite with neomycin in an aqueous drug solution and the factors influencing the effectiveness of this process, such as the ion exchange capacity and process conditions, including the time and temperature of incubation with the drug. X-ray diffractometry (XRD), infrared spectroscopy (FTIR), thermal analysis (DSC/TG), and Zeta potential measurement were used to confirm drug intercalation as well as to investigate the nature of clay–drug interactions. The obtained conjugates with the most favorable physicochemical properties were also tested for antibacterial response against Gram-negative bacteria (Escherichia coli) to confirm that the bactericidal properties of neomycin were retained after intercalation and UV–VIS spectrophotometry was used to examine the kinetics of drug release from the carrier. The results of the conducted research clearly indicate the successful intercalation of neomycin in montmorillonite and indicate the influence of process parameters on the properties of not only the conjugates themselves but also the properties of the intercalated drug, particularly its bactericidal activity. Ultimately, a temperature of 50 °C was found to be optimal for effective drug intercalation and the conjugates obtained within 2 h showed the highest antibacterial activity, indicating the highest potential of the thus-obtained montmorillonite conjugates as neomycin carriers.

Materials based on polydimethylsiloxane have been developed with antibacterial activity and mechanical properties required for wound treatment. Sage herb (raw, modified, and polyphenol extract) was used as a filler in an amount of 5 and 10% by weight. Physicochemical, mechanical, and biological properties were examined. The results indicate a beneficial effect of sage modification on the tested properties.

Emulsion electrospinning is a method of modifying a fibers’ surface and functional properties by encapsulation of the bioactive molecules. In our studies, bovine serum albumin (BSA) played the role of the modifier, and to protect the protein during the electrospinning process, the W/O (water-in-oil) emulsions were prepared, consisting of polymer and micelles formed from BSA and anionic (sodium dodecyl sulfate–S) or nonionic (Tween 80–T) surfactant. It was found that the micelle size distribution was strongly dependent on the nature and the amount of the surfactant, indicating that a higher concentration of the surfactant results in a higher tendency to form smaller micelles (4–9 µm for S and 8–13 µm for T). The appearance of anionic surfactant micelles reduced the diameter of the fiber (100–700 nm) and the wettability of the nonwoven surface (up to 77°) compared to un-modified PCL polymer fibers (100–900 nm and 130°). The use of a non-ionic surfactant resulted in better loading efficiency of micelles with albumin (about 90%), lower wettability of the nonwoven fabric (about 25°) and the formation of larger fibers (100–1100 nm). X-ray photoelectron spectroscopy (XPS) was used to detect the presence of the protein, and UV-Vis spectrophotometry was used to determine the loading efficiency and the nature of the release. The results showed that the location of the micelles influenced the release profiles of the protein, and the materials modified with micelles with the nonionic surfactant showed no burst release. The release kinetics was characteristic of the zero-order release model compared to anionic surfactants. The selected surfactant concentrations did not adversely affect the biological properties of fibrous substrates, such as high viability and low cytotoxicity of RAW macrophages 264.7.

Electrospinning was used to obtain multifunctional fibrous composite materials with a matrix of poly-ɛ-caprolactone (PCL) and 2 wt.% addition of a nanofiller: montmorillonite (MMT), montmorillonite intercalated with gentamicin sulphate (MMTG) or gentamicin sulphate (G). In the first stage, the aluminosilicate gallery was modified by introducing gentamicin sulfate into it, and the effectiveness of the intercalation process was confirmed on the basis of changes in the clay particle size from 0.5 µm (for MMT) to 0.8 µm (for MMTG), an increase in the interplanar distance d₀₀₁ from 12.3 Å (for MMT) to 13.9 Å (for MMTG) and altered clay grain morphology. In the second part of the experiment, the electrospinning process was carried out in which the polymer nonwovens with and without the modifier were prepared directly from dichloromethane (DCM) and N,N-dimethylformamide (DMF). The nanocomposite fibrous membranes containing montmorillonite were prepared from the same polymer solution but after homogenization with the modifier (13 wt.%). The degree of dispersion of the modifier was evaluated by average microarray analysis from observed area (EDS), which was also used to determine the intercalation of montmorillonite with gentamicin sulfate. An increase in the size of the fibers was found for the materials with the presence of the modifier, with the largest diameters measured for PCL_MMT (625 nm), and the smaller ones for PCL_MMTG (578 nm) and PCL_G (512 nm). The dispersion of MMT and MMTG in the PCL fibers was also confirmed by indirect studies such as change in mechanical properties of the nonwovens membrane, where the neat PCL nonwoven was used as a reference material. The addition of the modifier reduced the contact angle of PCL nonwovens (from 120° for PCL to 96° for PCL_G and 98° for PCL_MMTG). An approximately 10% increase in tensile strength of the nonwoven fabric with the addition of MMT compared to the neat PCL nonwoven fabric was also observed. The results of microbiological tests showed antibacterial activity of all obtained materials; however, the inhibition zones were the highest for the materials containing gentamicin sulphate, and the release time of the active substance was significantly extended for the materials with the addition of montmorillonite containing the antibiotic. The results clearly show that the electrospinning technique can be effectively used to obtain nanobiocomposite fibers with the addition of nonintercalated and intercalated montmorillonite with improved strength and increased stiffness compared to materials made only of the polymer fibers, provided that a high filler dispersion in the spinning solution is obtained.

Despite high interest in the issues of hemocompatibility of titanium implants, particularly those made of the Ti-13Nb-13Zr alloy, the applied methods of surface modification still do not always guarantee the physicochemical properties required for their safe operation. The factors that reduce the efficiency of the application of titanium alloys in the treatment of conditions of the cardiovascular system include blood coagulation and fibrous proliferation within the vessel’s internal walls. They result from their surfaces’ physicochemical properties not being fully adapted to the specifics of the circulatory system. Until now, the generation and development mechanics of these adverse processes are not fully known. Thus, the fundamental problem in this work is to determine the correlation between the physicochemical properties of the diamond like carbon (DLC) coating (shaped by the technological conditions of the process) applied onto the Ti-13Nb-13Zr alloy designed for contact with blood and its hemocompatibility. In the paper, microscopic metallographic, surface roughness, wettability, free surface energy, hardness, coating adhesion to the substrate, impendence, and potentiodynamic studies in artificial plasma were carried out. The surface layer with the DLC coating ensures the required surface roughness and hydrophobic character and sufficient pitting corrosion resistance in artificial plasma. On the other hand, the proposed CrN interlayer results in better adhesion of the coating to the Ti-13Nb-13Zr alloy. This type of coating is an alternative to the modification of titanium alloy surfaces using various elements to improve the blood environment’s hemocompatibility.