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Streszczenie:
The development of advanced poly(vinyl alcohol) (PVA)-based biomedical materials is often hindered by the reliance on toxic chemicals and energy-intensive processes, raising sustainability and safety concerns. This work addresses these challenges by presenting a low-temperature, “green” approach for fabricating PVA-based nanofibrous hydrogels cross-linked with natural lemon juice (Citrus limon) and enriched with bromelain derived from pineapple (Ananas comosus) extract. Electrospun nanofibers containing fruit components were stabilized via mild thermal treatment at 60 °C, enabling covalent ester bond formation while avoiding harmful cross-linkers and preserving the enzymatic activity of bromelain. Analysis results confirmed the successful formation of hydrogel, its reduced solubility in aqueous environments, improved mechanical properties, and tunable pH-responsive swelling behavior. Bromelain incorporation altered cross-linking density, enhancing multifunctionality. The dual-bioactive hydrogel could release incorporated substances, demonstrating strong antioxidant capacity and antibacterial activity. Moreover, the developed nanofibrous hydrogel showed photothermal response under near-infrared (NIR) irradiation. In vitro assays using L929 fibroblasts demonstrated high biocompatibility and stimulated cell proliferation over extended culture periods. Moreover, the developed hydrogel supported early-stage wound closure, highlighting its importance in promoting the initial phases of the healing process, which are critical for effective tissue regeneration. By combining the natural bioactivities of lemon juice and bromelain with the structural advantages of electrospun PVA fibers, the developed nanoplatform offers a promising, environmentally friendly solution for advanced wound healing, bacterial elimination, and infection control applications.

Słowa kluczowe:
“Green” cross-linking, Lemon juice, Pineapple-derived bromelain, Electrospun nanofibers, Antibacterial hydrogel

Streszczenie:
Cross-linking bonds adjacent polymer chains into a three-dimensional network. Cross-linked poly(vinyl alcohol) (PVA) turns into a hydrogel, insoluble structure exhibiting outstanding sorption properties. As an electrospinnable polymer, PVA enables the creation of nanofibrous hydrogels resembling biological tissues, thus ideal for nature-inspired platforms. PVA properties are easily adjustable through additives and an appropriate cross-linking method. Drawing inspiration from environmentally safe approaches, this work developed a new “green” method of low-temperature PVA cross-linking. Nanofibers were electrospun from a precursor solution of PVA dissolved in fresh lemon juice, stabilized by heating at 60 °C for 7 days, and thoroughly characterized. The obtained nanoplatform demonstrated long-term stability and enhanced mechanical properties. Its biocompatibility was confirmed, and its antibacterial and health-promoting effects were attributed to lemon juice-rich in vitamin C, a potent antioxidant with anti-inflammatory properties. The developed system has future potential for use in the biomedical engineering field as a dressing accelerating wound healing.

Streszczenie:
Cross-linking of poly(vinyl alcohol) (PVA) creates a three-dimensional network by bonding adjacent polymer chains. The cross-linked structure, upon immersion in water, turns into a hydrogel, which exhibits unique absorption properties due to the presence of hydrophilic groups within the PVA polymer chains and, simultaneously, ceases to be soluble in water. The properties of PVA can be adjusted by chemical modification or blending with other substances, such as polymers, e.g., conductive poly[3-(potassium-5-butanoate)thiophene-2,5-diyl] (P3KBT). In this work, PVA-based conductive semi-interpenetrating polymer networks (semi-IPNs) are successfully fabricated. The systems are obtained as a result of electrospinning of PVA/P3KBT precursor solutions with different polymer concentrations and then cross-linking using “green”, environmentally safe methods. One approach consists of thermal treatment (H), while the second approach combines stabilization with ethanol and heating (E). The comprehensive characterization allows to evaluate the correlation between the cross-linking methods and properties of nanofibrous hydrogels. While both methods are successful, the cross-linking density is higher in the thermally cross-linked samples, resulting in lower conductivity and swelling ratio compared to the E-treated samples. Moreover, the H-cross-linked systems have better mechanical properties─lower stiffness and greater tensile strength. All the tested systems are biocompatible, and interestingly, due to the presence of P3KBT, they show photoresponsivity to solar radiation generated by the simulator. The results indicate that both methods of PVA cross-linking are highly effective and can be applied to a specific system depending on the target, e.g., biomedical or electronic applications.

Słowa kluczowe:
poly(vinyl alcohol),poly[3-(potassium-5-butanoate)thiophene-2.5-diyl],electrospun nanofibers,cross-linking,fibrous hydrogel,semi-IPN