پوشش‌هاي هوشمند ضد باكتري پلي‌يورتاني آب‌پايه تابش‌پز فرابنفش حاوي نانوذرات نقره احياء شده با تانيك اسيد اصلاح شده با گليسيديل متاكريلات

Microorganisms are widely present in all different environments and, after attaching to each other, form biofilms, which are one of the main causes of bacterial infections. In this context, one of the promising solutions is the use of antibacterial coatings. Among polymers, polyurethanes are of particular importance due to characteristics such as the possibility of using diverse raw materials, desirable mechanical properties, biocompatibility, and good adhesion. However, conventional polyurethanes have disadvantages, such as the use of toxic and expensive organic solvents. In recent years, waterborne polyurethanes have been introduced as a suitable alternative. However, the presence of hydrophilic groups in the structure of waterborne polyurethanes can negatively affect water resistance, leading to a reduction in their long-term performance. One approach to improving the properties of waterborne polyurethane coatings is the creation of crosslinking through UV-induced photopolymerization. The presence of crosslinks increases chemical stability, tensile strength, and abrasion resistance. In this study, tannic acid, a natural and biocompatible compound, was modified with glycidyl methacrylate to participate in the polymerization reaction. The modification of tannic acid with glycidyl methacrylate was examined using FTIR, 1H NMR, XRD, and XPS tests. The stability of WPUA, WTG, and WTGAg dispersions was eva‎luated over one month, and their stability without coagulation or agglomeration was confirmed. The prepared nanocomposites exhibited elongation and char residue of 44.47% and 13.18%, respectively, compared to pure polyurethane. Furthermore, the presence of silver nanoparticles in the polymer matrix was confirmed using UV-VIS, XRD, FESEM, and EDS tests. The presence of catechol groups of tannic acid in the synthesized polyurethane structure resulted in the rapid reduction of silver ions in less than 1 minute. The release of silver nanoparticles did not occur due to the presence of crosslinks in the polymer matrix, and hence, no toxicity was observed in the synthesized films in the scratch, MTT, and cell adhesion tests. The results obtained from these tests demonstrated that 100% scratch resistance and proliferation of fibroblast cells occurred on the WTGAg sample. It is noteworthy that silver nanoparticles possess photothermal properties, which enhance antibacterial properties. The effect of photothermal properties on antibacterial activity was investigated using antibacterial tests under both light and dark conditions. The prepared coatings were able to eliminate 100% of both Gram-negative and Gram-positive bacterial species.

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