Szewczyk, Piotr K.
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inżynieria materiałowa
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Item type:Article, Access status: Open Access , Comparative Physicochemical Characterization of Electrospun PCL, PLLA, and PLCL Scaffolds and Cell Responses for Tissue Engineering Applications(2026) Polak, Martyna; Neela, Nagalekshmi Uma Thanu Krishnan; Berniak, Krzysztof; Knapczyk-Korczak, Joanna; Szewczyk, Piotr K.; Marzec, Mateusz M.; Stachewicz, Urszula
Wydział Inżynierii Metali i Informatyki PrzemysłowejIn tissue engineering, electrospun scaffolds are valued for their tunable features, which direct cell behavior. Within this study, we electrospun scaffolds from three common polyesters: polycaprolactone (PCL), poly(L-lactic acid) (PLLA), and poly(lactide-co-caprolactone) (PLCL), to identify differences in cell–material interactions. PLLA fibers had the largest average diameter (2.6 ± 0.2 µm), PLCL fiber diameter was intermediate (2.2 ± 0.5 µm), and PCL was the smallest (1.1 ± 0.6 µm). Additionally, X-ray photoelectron spectroscopy (XPS) revealed distinct surface chemistries that are correlated with streaming potential results at pH 7.4. PLCL fibers showed the most negative zeta potential (−36.4 ± 0.7 mV), followed by PLLA (−28.4 ± 0.8 mV) and PCL (−24.0 ± 0.5 mV). Mechanical testing indicates the highest strength for PLCL mats (5.6 ± 0.9 MPa), then PLLA (3.5 ± 0.3 MPa) and PCL (1.9 ± 0.1 MPa). Cell studies indicated lower initial adhesion of osteoblasts on PLCL (∼53%↓) and PLLA (∼73.6%↓) vs. PCL, likely reflecting PCL scaffold morphology; however, viability at 3 and 7 days was significantly higher on PLCL and PLLA. Microscopy studies confirmed greater filopodia and cell spreading on PLCL and PLLA. Overall, all three are suitable scaffold materials, with PLCL and PLLA supporting cytoskeleton organization and viability better.Item type:Article, Access status: Open Access , Enhanced Electroactive Phases of Poly(vinylidene Fluoride) Fibers for Tissue Engineering Applications(2024) Zaszczyńska, Angelika; Gradys, Arkadiusz; Ziemiecka, Anna; Szewczyk, Piotr K.; Tymkiewicz, Ryszard; Lewandowska-Szumieł, Małgorzata; Stachewicz, Urszula; Sajkiewicz, Paweł
Wydział Inżynierii Metali i Informatyki PrzemysłowejNanofibrous materials generated through electrospinning have gained significant attention in tissue regeneration, particularly in the domain of bone reconstruction. There is high interest in designing a material resembling bone tissue, and many scientists are trying to create materials applicable to bone tissue engineering with piezoelectricity similar to bone. One of the prospective candidates is highly piezoelectric poly(vinylidene fluoride) (PVDF), which was used for fibrous scaffold formation by electrospinning. In this study, we focused on the effect of PVDF molecular weight (180,000 g/mol and 530,000 g/mol) and process parameters, such as the rotational speed of the collector, applied voltage, and solution flow rate on the properties of the final scaffold. Fourier Transform Infrared Spectroscopy allows for determining the effect of molecular weight and processing parameters on the content of the electroactive phases. It can be concluded that the higher molecular weight of the PVDF and higher collector rotational speed increase nanofibers’ diameter, electroactive phase content, and piezoelectric coefficient. Various electrospinning parameters showed changes in electroactive phase content with the maximum at the applied voltage of 22 kV and flow rate of 0.8 mL/h. Moreover, the cytocompatibility of the scaffolds was confirmed in the culture of human adipose-derived stromal cells with known potential for osteogenic differentiation. Based on the results obtained, it can be concluded that PVDF scaffolds may be taken into account as a tool in bone tissue engineering and are worth further investigation.Item type:Article, Access status: Open Access , Improving stability and mechanical strength of electrospun chitosan-polycaprolactone scaffolds using genipin cross-linking for biomedical applications(2025) Uma Thanu Krishnan Neela, Nagalekshmi; Szewczyk, Piotr K.; Karbowniczek, Joanna; Polak, Martyna; Knapczyk-Korczak, Joanna; Stachewicz, Urszula
WIMiIPElectrospun nanofiber scaffolds have become vital in biomedical applications due to their high surface area and tunable properties. Chitosan (CS) is widely used, but its rapid degradation limits its effectiveness. This study addresses this limitation by blending CS with polycaprolactone (PCL) and applying genipin cross-linking to enhance its stability and mechanical properties. Scanning electron microscopy indicated a uniform morphology of the electrospun fibers, and further, the crystallinity of the scaffolds before and after cross-linking is verified. Fourier-transform infrared spectroscopy is used to analyze the chemical structure, identifying the presence of trifluoroacetic acid residues in the as-spun fibers. These residues are successfully eliminated through neutralization and cross-linking, which are critical for enhancing stability and cell viability in in-vitro studies. Mechanical testing revealed that cross-linked CS+PCL scaffolds exhibit a 350% increase in tensile strength compared to pure CS, and zeta potential reaches the favorable for cell development -26.27 mV. The cytotoxicity assay results with murine NIH 3T3 fibroblast cells indicate the suitability of CS+PCL scaffolds for targeted tissue engineering and wound healing. This work establishes the potential for fine-tuning scaffold properties to create stable, functional, and biocompatible substrates for extended biomedical use.Item type:Article, Access status: Open Access , Flexible and thermally insulating porous materials utilizing hollow double-shell polymer fibers(2024) Knapczyk-Korczak, Joanna; Szewczyk, Piotr K.; Berniak, Krzysztof; Marzec, Mateusz M.; Frąc, Maksymilian; Pichór, Waldemar; Stachewicz, Urszula
Wydział Inżynierii Metali i Informatyki PrzemysłowejThe global climate change is mainly caused by carbon dioxide ($CO_{2}$) emissions. To help reduce $CO_{2}$ emissions and conserve thermal energy, sustainable materials based on flexible thermal insulation are developed to minimize heat flux, drawing inspiration from natural systems such as polar bear hairs. The unique structure of hollow double-shell fibers makes it possible to achieve low thermal conductivity in the material while retaining exceptional elasticity, allowing it to adapt to insulation systems of any shape. The layered system of porous mats reaches a thermal conductivity coefficient of $0.031 W∙m^{−1}∙K^{−1}$ and enables to reduce the heat transfer. The results achieved using scanning thermal microscopy (SThM) correlate with the simulated heat flow in the case of individual fibers. This research study brings new insights into the energy efficiency of domestic environments, thereby addressing the growing demand for sustainable and high-performance insulation materials for saving energy loss and reducing pollution footprint.Item type:Article, Access status: Open Access , Interfacial blending in co-axially electrospun polymer core-shell fibers and their interaction with cells via focal adhesion point analysis(2024) Polak, Martyna; Ura, Daniel Paweł; Berniak, Krzysztof; Szewczyk, Piotr K.; Marzec, Mateusz M.; Stachewicz, Urszula
Wydział Inżynierii Metali i Informatyki PrzemysłowejElectrospun polymer scaffolds have gained prominence in biomedical applications, including tissue engineering, drug delivery, and wound dressings, due to their customizable properties. As the interplay between cells and materials assumes fundamental significance in biomaterials research, understanding the relationship between fiber properties and cell behaviour is imperative. Nevertheless, altering fiber properties introduces complexity by intertwining mechanical and surface chemistry effects, challenging the differentiation of their individual impacts on cell behaviour. Core-shell fibers present an appealing solution, enabling the control of mechanical properties of scaffolds, flexibility in material and drug selection, efficient encapsulation, strong protection of bioactive drugs against harsh environments, and controlled, prolonged drug release. This study addresses a key challenge in core-shell fiber design related to the blending effect between core and shell polymers. Two types of fibers, PMMA and core-shell PC-PMMA, were electrospun, and thorough analyses confirmed the desired core-shell structure in PC-PMMA fibers. Surface chemistry analysis revealed PC diffusion to the PMMA shell of the core-shell fiber during electrospinning, subsequently prompting an investigation of the fiber’s surface potential. Conducting cellular studies on osteoblasts by super-resolution confocal microscopy provided insights into the direct influence of interfacial polymer blending and, consequently, altered fiber surface and mechanical properties on cell focal adhesion points, bridging the gap between material attributes and cell responses in core-shell fibers.Item type:Article, Access status: Open Access , Hybrid piezo-, pyro-, and triboelectric nanogenerator based on PVDF and rGO composite fibers for a multifunctional approach to energy harvesting applications(2025) Sukumaran, Sunija; Szewczyk, Piotr K.; Bajda, Tomasz; Stachewicz, Urszula
Wydział Inżynierii Metali i Informatyki PrzemysłowejRecently, wearable nanogenerators have gained interest in energy harvesting and sensors, driven by smart electronics and Internet of Things (IoT) advancements. Here, we have developed a multifunctional nanogenerator that can convert mechanical and thermal energy into electrical energy via piezoelectric, triboelectric, and pyroelectric effects. The electrospun nanogenerator was fabricated to investigate the effect of reduced graphene oxide (rGO) on the energy generation of polyvinylidene fluoride (PVDF) fibers. The highest amount of electroactive β phase (81 %) and crystallinity (48.58 %) were obtained for 7 wt% rGO/PVDF fiber composite. Then, the 7 wt% rGO/PVDF composite was taken to prepare the piezo, tribo, and pyroelectric nanogenerator, and characterized using piezoresponse force microscopy (PFM), Kelvin probe microscopy (KPFM), and scanning thermal microscopy (SThM). Furthermore, the nanogenerator was made using the composite mat, illustrating its potential for powering small electronic devices using piezoelectric power and an enormous triboelectric power density of 3.37 ± 0.72 mWcm−2. We also demonstrate the device’s multifunctionality under thermal fluctuations. The results show the synergetic tribo and pyroelectric current of 33nA from 7 wt% rGO/PVDF. The present work indicates the significance of rGO inclusion into a PVDF matrix, resulting in enhanced multifunctional properties for energy harvesting, thereby enabling self-powering capabilities for microelectronic devices.Item type:Article, Access status: Open Access , Comparative Analysis of Electrophoretic Deposition and Dip Coating for Enhancing Electrical Properties of Electrospun PVDF Mats Through Carbon Nanotube Deposition(2025) Kopacz, Michał; Szewczyk, Piotr K.; Długoń, Elżbieta; Stachewicz, Urszula
Wydział Inżynierii Metali i Informatyki PrzemysłowejIntegrating carbon nanotubes (CNTs) into electrospun polyvinylidene fluoride (PVDF) fibers is a promising approach for developing conductive and multifunctional materials. This study systematically compared two CNT deposition techniques, electrophoretic deposition (EPD) and dip coating (DC), in terms of their effectiveness in modifying the surface of aligned electrospun PVDF mats. Morphological characterization revealed that EPD produced more homogeneous and compact CNT coatings. In contrast, DC resulted in discontinuous and irregular layers regardless of deposition time. A key distinction between the two methods was the tunability of the coating: EPD allowed for precise control over CNT layer thickness and mass accumulation by adjusting the deposition time. In contrast, DC showed no significant changes in thickness with longer immersion. These structural differences translated into distinct electrical behaviors. Resistance measurements showed that EPD samples exhibited a substantial decrease in resistance with increasing deposition time, from 5.9 ± 2.5 kΩ to 0.2 ± 0.1 kΩ, indicating the formation of well-connected conductive pathways. On the other hand, DC samples maintained relatively constant, higher resistance values across all conditions. Additionally, EPD-coated mats demonstrated enhanced touch sensitivity, generating higher and more stable current responses compared to DC-deposited samples. These results confirm that EPD is a more effective, tunable method for fabricating conductive CNT coatings on electrospun PVDF mats, particularly for applications in flexible electronics and wearable sensors.Item type:Article, Access status: Open Access , Poly(L-lactide)/nano-hydroxyapatite piezoelectric scaffolds for tissue engineering(2025) Zaszczyńska, Angelika; Gradys, Arkadiusz; Kołbuk, Dorota; Zabielski, Konrad; Szewczyk, Piotr K.; Stachewicz, Urszula; Sajkiewicz, Paweł
Wydział Inżynierii Metali i Informatyki PrzemysłowejThe development of bone tissue engineering, a field with significant potential, requires a biomaterial with high bioactivity. The aim of this manuscript was to fabricate a nanofibrous poly(L-lactide) (PLLA) scaffold containing nano-hydroxyapatite (nHA) to investigate PLLA/nHA composites, particularly the effect of fiber arrangement and the addition of nHA on the piezoelectric phases and piezoelectricity of PLLA samples. In this study, we evaluated the effect of nHA particles on a PLLA-based electrospun scaffold with random and aligned fiber orientations. The addition of nHA increased the surface free energy of PLLA/nHA (42.9 mN/m) compared to PLLA (33.1 mN/m) in the case of aligned fibers. WAXS results indicated that at room temperature, all the fibers are in an amorphous state indicated by a lack of diffraction peaks and amorphous halo. DSC analysis showed that all samples located in the amorphous/disordered alpha' phase crystallize intensively at temperatures just above the Tg and recrystallize on further heating, achieving significantly higher crystallinity for pure PLLA than for doped nHA, 70 % vs 40 %, respectively. Additionally, PLLA/nHA fibers show a lower heat capacity for PLLA in the amorphous state, indicating that nHA reduces the molecular mobility of PLLA. Moreover, piezoelectric constant d33 was found to increase with the addition of nHA and for the aligned orientation of the fibers. In vitro tests confirmed that the addition of nHA and the aligned orientation of nanofibers increased osteoblast proliferation.Item type:Article, Access status: Open Access , Optimizing Piezoelectric Coefficient in PVDF Fibers: Key Strategies for Energy Harvesting and Smart Textiles(2023) Sukumaran, Sunija; Szewczyk, Piotr K.; Knapczyk-Korczak, Joanna; Stachewicz, Urszula
Wydział Inżynierii Metali i Informatyki PrzemysłowejWith the advancement in smart electronic devices and self-powered devices, the demand for piezoelectric polymers found potential research interest. Among these, electrospun polyvinylidene fluoride (PVDF) fibers have gained attention for energy harvesting due to their flexibility and higher piezoelectric coefficient. We compare various methods to enhance PVDF's piezoelectric properties, including different solvents (DMAc, DMF), conductive filler (rGO), and annealing as post-treatment. Our results indicate that PVDF/rGO fibers in DMAc solvent exhibit the highest β phase fraction and crystallinity. Moreover, for the first time, we present the piezoelectric properties of PVDF/rGO electrospun single fiber using high voltage switching spectroscopy piezoelectric force microscopy (HVSS-PFM). The highest piezoelectric coefficient (d33) was measured for PVDF/DMAc-rGO composite fibers. Notably, PVDF/rGO in DMAc solvent significantly improves the piezoelectric coefficient, leading to a remarkable fourfold increase in power density compared to pure PVDF, making it a promising material for energy harvesting applications.Item type:Article, Access status: Open Access , Photoresponsive Electrospun Fiber Meshes with Switchable Wettability for Effective Fog Water Harvesting in Variable Humidity Conditions(2023) Parisi, Gregory; Szewczyk, Piotr K.; Narayan, Shankar; Stachewicz, Urszula
Wydział Inżynierii Metali i Informatyki PrzemysłowejThe global water supply worsens yearly with climate change; therefore, the need for sustainable water resources is growing. One of them is fog water collectors with variable surface wettability, with multifunctional designs for utilization worldwide and to address regions with low humidity levels. Therefore, we created fiber meshes with a photoresponsive switchable surface. This study uses electrospun polyvinylidene fluoride (PVDF) meshes, whose wettability is controlled by adding $TiO_{2}$. The fog water collection performance is studied at high and low humidity levels. With $TiO_{2}-PVDF$, the electrospun mesh can be converted from hydrophobic to hydrophilic under UV irradiation and transformed back to a hydrophobic state with heat treatment. The switchable meshes were found to be more effective at water collection after UV irradiation at lower fog rates of 200 $mL·h^{–1}$. The ability to switch between hydrophobic and hydrophilic properties as needed is highly desired in fog collection applications using electrospun meshes, as it can improve overall efficiency after UV irradiation.
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