School of Natural Sciences

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Now showing 1 - 5 of 5
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    PublicationEmbargo
    Kinetic study of in vitro release of curcumin from chitosan biopolymer and the evaluation of biological efficacy
    (Elsevier B.V., 2024-09) Wijayawardana, S; Thambiliyagodage, C; Jayanetti, M
    Sustained release of curcumin from the polymeric carrier system chitosan, a natural biopolymer material derived from chitin originated from natural shrimp shell waste, was studied. Six kinetic models, zero order, first order, Korsmeyer–Peppas (KP), Peppas – Sahlin (PS), Higuchi, and Hixson–Crowell, were applied to study the drug release kinetics. The release mechanism of the drug from the curcumin-chitosan composite was evaluated by changing the pH, ionic strength of the release media, and drug concentration. KP and PS models were selected among the studied models to investigate the drug release mechanism from the chitosan biopolymer based on the R2 values (R2 > 0.99). The model constants m in the PS model and n in the KP model stand for the case II relaxation and Fickian diffusion contribution, respectively. The n being < 0.43 in the KP model suggests that the Fickian diffusion governs the drug release. Furthermore, there is a noticeable difference between the values obtained for model parameters m and n in the PS and KP models, indicating that Case II relaxation and Fickian diffusion play crucial roles in the curcumin release mechanism from chitosan. Polymer relaxation has been proven to play a predominant role in releasing curcumin from the composite at lower ionic strengths and higher pH values. Anti-inflammatory activity was tested using the egg-albumin denaturation assay, and the diphenyl-2-picrylhydrazyl assay was carried out to determine the antioxidant activity of the composite. The composite material showed IC50 values of 0.29 mg/ mL and 1.08 mg/ mL for anti-inflammatory and anti-oxidant activities, respectively. The drug composite has shown antibacterial activity against Pseudomonas aeruginosa, Klebsiella pneumoniae, and Staphylococcus aureus, which are highly effective against S.aureus. The resulting inhibition zones for S.aureus were 13.34 ± 0.34 mm, 16.34 ± 0.60 mm, and 13.34 ± 0.73 mm for 5, 10, and 20 mg/ml concentrations, respectively. The drug composite’s minimum inhibitory concentration/ minimum bactericidal concentration ratio for S.aureus, K. pneumoniae, and P.aeruginosa was greater than 4, suggesting that they cause bacteriostatic effects.
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    PublicationOpen Access
    Unlocking plant defense: Exploring the nexus of biochar and Ca2+ signaling
    (Elsevier, 2024-12) Sarfraz, Rubab; Priyadarshani, S.V.G.N; Fakhar, Ali; Khan, Muhammad Israr; Hassan, Zohaib Ul; JooKimae, Pil; WonKimabe, Gil
    The interaction between biochar application and calcium ions (Ca2+) in plants, in terms of activating plant defense mechanism would be useful to improve plant resilience and sustainable agriculture. This review aims to highlight the possible connection between biochar-induced changes in soil physicochemical properties, microbial interactions, and Ca2+ dynamics, ultimately leading to promote the plant defense mechanisms. We are also interested to discuss the role of Ca2+ signaling in coordinating plant responses to various biotic and abiotic stresses such as pathogen and insects attacks, cold or heat stress and drought stress as well as how Ca2+ fluxes, calcium-binding proteins, and ion channels are influenced by biochar application in the soil environment. Furthermore, we examine the impact of biochar on plant Ca2+ signaling pathways and how it can prime defense genes and strengthen call wall barriers to improve plant immunity. Despite significant progress, there is a need for interdisciplinary collaboration to fully sort out the mechanism of Ca2+ signaling in plants and induction of Ca2+ ions by biochar induction in soil environment. Advanced imaging techniques, proteomics and omics approaches could be helpful to unlock the complex interaction between biochar application and Ca2+ signaling. Overall, this review contributes substantially to the literature by describing the relationship between biochar and Ca2+ signaling and providing insights into novel approaches for enhancing plant defense mechanisms and development of sustainable agricultural solutions.
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    PublicationOpen Access
    Persulfate assisted photocatalytic and antibacterial activity of TiO2–CuO coupled with graphene oxide and reduced graphene oxide
    (https://www.nature.com, 2024-05-31) Thambiliyagodage, C; Liyanaarachchi, H; Jayanetti, M; Ekanayake, G; Mendis, A; Samarakoon, U; Vigneswaran, S
    Photocatalysts of TiO2–CuO coupled with 30% graphene oxide (GO) were hydrothermally fabricated, which varied the TiO2 to CuO weight ratios to 1:4, 1:2, 1:1, 2:1 and 4:1 and reduced to form TiO2–CuO/reduced graphene oxide (rGO) photocatalysts. They were characterized using XRD, TEM, SEM, XPS, Raman, and DRS technologies. TiO2–CuO composites and TiO2–CuO/GO degrade methylene blue when persulfate ions are present. Persulfate concentration ranged from 1, 2, 4 to 8 mmol/dm−3 in which the highest activity of 4.4 × 10–2 and 7.35 × 10–2 min−1 was obtained with 4 mmol/dm−3 for TiO2–CuO (1:4) and TiO2–CuO/GO (1:1), respectively. The presence of EDTA and isopropyl alcohol reduced the photodegradation. TiO2–CuO coupled with rGO coagulates methylene blue in the presence of persulfate ions and such coagulation is independent of light. The catalyst dosage and the concentration of the dye were varied for the best-performing samples. The antibacterial activity of the synthesized samples was evaluated against the growth of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumonia. Ti:Cu (1:2)-GO and Ti:Cu (1:4)-GO had the highest antibacterial activity against K. pneumoniae (16.08 ± 0.14 mm), P. aeruginosa (22.33 ± 0.58 mm), E. coli (16.17 ± 0.29 mm) and S. aureus (16.08 ± 0.88).
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    PublicationEmbargo
    Exploring the evolving landscape: Urban horticulture cropping systems–trends and challenges
    (Elsevier, 2024-03-01) Sashika, M.A.N; Gammanpila, H.W; Priyadarshani, S.V.G.N.
    Urban horticulture cropping systems offer a promising solution for food security and sustainable agriculture in rapidly urbanizing areas. This paper explores their evolving landscape, emphasizing trends and challenges shaping their development and impact on urban environments. Vertical farming, rooftop gardens, hydroponics, aeroponics, Internet of Things (IoT), integration of optimized space, resources, and year-round cultivation are considered as key trends in urban horticulture. These innovations reflect the growing interest in sustainable urban agriculture and technology's role in boosting productivity and resilience. However, urban horticulture faces challenges that demand attention. Limited space requires creative land-use solutions, while soil quality and contamination concerns necessitate remediation strategies for crop safety. Similarly, access to water is crucial, driving the adoption of water-saving technologies. The urban heat island effect poses another challenge, urging heat stress mitigation for crop health. Zoning and regulations play a vital role, requiring supportive policies and secure land tenure. High costs must be managed with innovative financial approaches to ensure urban farming's viability. Finally, public perception and awareness play a critical role. Advocacy, education, and community engagement are vital to dispel misconceptions, garner support, and encourage involvement in urban horticulture. Even with challenges, urban horticulture helps to provide food for the growing population, creates business opportunities, and contributes to a greener environment for sustainable development.
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    PublicationOpen Access
    In vitro influence of PEG functionalized ZnO–CuO nanocomposites on bacterial growth
    (PubMed ID, 2024-01-14) Thambiliyagodage, C; Jayanetti, M; Liyanaarachchi, H; Ekanayake, G; Mendis, M; Usgodaarachchi, L
    Polyethyleneglycol-coated biocompatible CuO–ZnO nanocomposites were fabricated hydrothermally varying Zn:Cu ratios as 1:1, 2:1, and 1:2, and their antibacterial activity was determined through the well diffusion method against the Gram-negative Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and the Gram-positive Staphylococcus aureus. The minimum inhibitory concentration and the minimum bactericidal concentration values of the synthesized samples were determined. Subsequently, the time synergy kill assay was performed to elucidate the nature of the overall inhibitory effect against the aforementioned bacterial species. The mean zone of inhibition values for all four samples are presented. The inhibitory effect increased with increasing concentration of the nanocomposite (20, 40 and 60 mg/ml) on all the bacterial species except for S. aureus. According to the MBC/MIC ratio, ZnO was found to be bacteriostatic for E. coli and P. aeruginosa, and bactericidal for S. aureus and K. pneumoniae. Zn:Cu 2:1 was bactericidal on all bacterial species. A bacteriostatic effect was observed on E. coli and P. aeruginosa in the presence of Zn:Cu 1:1 whereas, it showed a bactericidal effect on S. aureus and K. pneumoniae. Zn:Cu 1:2 exhibited a bacteriostatic effect on E. coli while a bactericidal effect was observed for E. coli, P. aeruginosa, and K. pneumoniae. The metal oxide nanocomposites were found to be more sensitive towards the Gram-positive strain than the Gram-negative strains. Further, all the nanocomposites possess anti-oxidant activity as shown by the DPPH assay.