https://scidar.kg.ac.rs/handle/123456789/8220 Thu, 12 Mar 2026 13:02:31 GMT 2026-03-12T13:02:31Z https://scidar.kg.ac.rs/handle/123456789/22887 Title: Formulation of Alginate–Gelatin Hydrogels within a Circular Economy Framework: Controlled Release of Grape Skin Extract via Gelatin Content Modulation Authors: Bradic, Jovana V.; Kocovic, Aleksandar G.; Petrovic, Anica M.; Simic, Marko Z.; Jakovljevic, Vladimir; Avdović, Edina; Ugrinovic, Vukasin Dj. Abstract: Hydrogels, as cross-linked polymer networks, are increasingly utilized in biomedical applications due to their high water absorption, biocompatibility, and capability to deliver bioactive substances. Compared to synthetic hydrogels, natural polymers such as alginate and gelatin provide advantages including biodegradability, low toxicity, and the formation of stable matrices suitable for biomedical use. Grape skins from the Šumadija region in Serbia, a byproduct of winemaking, are abundant in polyphenolic compounds with potent antioxidant and anti-inflammatory effects, making them suitable for incorporation into bioactive hydrogel systems. In this study, alginate–gelatin hydrogels were prepared and loaded with grape skin extract (GSE) to evaluate their physicochemical characteristics and in vitro release behavior. Three formulations with different alginate-to-gelatin ratios (3:1, 3:2, and 1:1) were produced, mixed with GSE (8 mg/mL), frozen, and cross-linked with CaCl₂. Organoleptic assessment confirmed uniform, coherent gels, with color imparted by the extract. In vitro release studies in PBS (pH 7.4, 37 °C) demonstrated a biphasic release, with an initial rapid phase during the first 5–10 h followed by sustained release up to 24 h. Gelatin content influenced release kinetics by altering network density and hydrogel porosity. These findings underscore the importance of optimizing alginate-to-gelatin ratios and indicate that GSE-loaded hydrogels are promising candidates for controlled delivery of natural antioxidants in biomedical applications. Wed, 01 Jan 2025 00:00:00 GMT https://scidar.kg.ac.rs/handle/123456789/22887 2025-01-01T00:00:00Z https://scidar.kg.ac.rs/handle/123456789/22886 Title: Grape Skin Extract Hydrogel Restores Systemic Redox Balance in Diabetic Rats Authors: Simic, Marko Z.; Bradic, Jovana; Kocovic, Aleksandar; Petrovic, Anica; Jakovljevic, Vladimir; Avdović, Edina Abstract: Chronic diabetic wounds are difficult to heal due to prolonged inflammation and oxidative stress, often leading to severe complications. This study aimed to evaluate the systemic redox status in diabetic rats treated with grape skin extract (GSE)-loaded alginate-gelatin hydrogels. Hydrogels were prepared with 8 mg/mL GSE and applied topically to full-thickness skin wounds in streptozotocin-induced diabetic Wistar rats. Redox biomarkers including TBARS, H₂O₂, O₂⁻, SOD, CAT and GSH were analyzed in blood samples on days 3, 7, and 15 post-treatment. Results showed that untreated diabetic rats exhibited significantly elevated prooxidative markers and reduced antioxidant enzyme activities. In contrast, rats treated with GSE-loaded hydrogels showed progressive normalization of all redox parameters, particularly by day 15, suggesting both early and sustained antioxidant effects. These findings indicate that GSE, which is rich in polyphenols, contributes to systemic redox balance restoration, making these hydrogels a promising therapeutic agents for diabetic wound management. Wed, 01 Jan 2025 00:00:00 GMT https://scidar.kg.ac.rs/handle/123456789/22886 2025-01-01T00:00:00Z https://scidar.kg.ac.rs/handle/123456789/22885 Title: Grape Skin Extract–Enriched Hydrogels for Wound Healing: An Antioxidant- Based Approach Authors: Kocovic, Aleksandar; Bradic, Jovana; Petrovic A.; Simic, Marko; Jakovljevic, Vladimir; Avdović, Edina Abstract: Gelatin–alginate hydrogels incorporating grape skin extract (GSE) from the Šumadija region were prepared by blending alginate and gelatin (3:1, 3:2, 1:1), casting, freezing, and CaCl₂ cross-linking. Organoleptic properties, total phenolic content (TPC, Folin–Ciocalteu), and antioxidant activity (DPPH and ABTS microplate assays with Trolox) were evaluated. GSE-loaded hydrogels formed uniform, solid gels. Compared with blank matrices, GSE increased TPC by approximately 46–79% and produced modest but consistent reductions in SC50 values: 0.3–1.8% in ABTS and 0.5–1.6% in DPPH (Trolox 6.909 and 5.034 μg/mL, respectively). Across GSE formulations, higher gelatin fractions correlated with higher TPC and lower ABTS SC50, suggesting protein–polyphenol interactions that enhance aqueous availability, whereas DPPH responses were minimally affected. These findings indicate that GSE incorporation preserves antioxidant functionality and yields small in-assay gains, with composition exerting a stronger effect in ABTS than in DPPH. The platform is a sustainable route to bioactive wound dressings and merits further optimization and biological validation. Wed, 01 Jan 2025 00:00:00 GMT https://scidar.kg.ac.rs/handle/123456789/22885 2025-01-01T00:00:00Z https://scidar.kg.ac.rs/handle/123456789/22884 Title: Data mining from oscillatory reactions perturbed by Usnic acid Authors: Maksimović, Jelena; Manojlovic, Nedeljko; Ivanović-Šašić, Ana; Maćešić, Stevan; Čupić, Željko Abstract: The influence of Usnic acid was investigated in two iodate based oscillatory reactions: Bray Liebhafsky and Briggs-Raucher with the aim of possible application in determining the reactivity of this acid in complex reaction systems. Obtained results show that Usnic acid added in similar concentration has different influence on these two oscillatory systems. Wed, 01 Jan 2025 00:00:00 GMT https://scidar.kg.ac.rs/handle/123456789/22884 2025-01-01T00:00:00Z