Fabrication of electrospun nanofibers made of watermelon peel extract and PVA and investigating their antioxidant and antibacterial activities
Food waste has become a huge problem globally since thousands of different food items are wasted all over the world which affects our environment severely due to the emissions of greenhouse gas due to anaerobic decomposition and leakage at the garbage. Fruit wastes like the peels and seeds are a major contribution to the waste products thrown everyday especially in juice industries. The antioxidant and antimicrobial activities of food wastes have been of great interest nowadays due to oxidative stress and antibiotic resistance problems. However the stability of the fruits or vegetables wastes was a challenge to perform these activities under controlled release and remains stable for long period of time. Therefore, the purpose of this study is to extract watermelon peel using different solvents and examines its total phenolic content using Folin & Ciocalteu's method. The best solvent showed the highest TPC was methanol and selected for the tests below. The watermelon peel extract (WPE) was mixed with polyvinyl alcohol (PVA) and used to fabricate nanofibers (WPE/PVA). To the best of our knowledge WPE/PVA nanofibers have never been reported before. The main motivation behind this fabrication process is to enhance the antioxidant and antibacterial activities of WPE and more importantly is to effectively use such fruit waste at nanoscale that gives the WPE higher stability and controlled release that reached 72 hours. After successful preparation of WPE/PVA nanofibers several parameters were carefully controlled such as applied voltage, solution flow rate, and distance from the needle to the collector and needle diameter. The WPE/PVA nanofibers were fabricated at different concentrations 0.1%, 0.5%, 1% and 2.5% of the PVA weight. All the concentrations showed 100% Â± 5 entrapment efficiency. The antioxidant and antibacterial activities were effectively enhanced in WPE/PVA nanofibers where the IC50 of the WPE/PVA nanofibers was 0.12 mg/mL while the IC50 of the WPE alone was 0.55 mg/mL so the activity was increased approximately 22% in the WPE/PVA nanofibers. While in the antibacterial activity the WPE/PVA nanofibers showed 83.5 Â± 0.9% inhibition of the E.coli, however it showed in the WPE 70.3 Â± 4.2% inhibition of the E.coli therefore the WPE/PVA nanofibers is 1.2 folds higher activity that WPE. While for S. aureus the WPE/PVA nanofibers showed 94 Â± 0.8% inhibition, however it showed in the WPE 83.5 Â± 1.12% inhibition of the therefore, the WPE/PVA nanofibers is 1.12 folds higher activity than that of WPE. The PVA fibers (unloaded) showed no significant inhibition activity in both E.coli and S. aureus. Characterization of the waste content like phenolics, FTIR, SEM... etc before and after Nano-formulation were done.
MS in Chemistry
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(2019).Fabrication of electrospun nanofibers made of watermelon peel extract and PVA and investigating their antioxidant and antibacterial activities [Master's Thesis, the American University in Cairo]. AUC Knowledge Fountain.
Soliman, Wafaa. Fabrication of electrospun nanofibers made of watermelon peel extract and PVA and investigating their antioxidant and antibacterial activities. 2019. American University in Cairo, Master's Thesis. AUC Knowledge Fountain.
Foremost, I would like to dedicate this work to me beloved father Yassin Soliman who passed away before he can see this moment. He guided me throughout my life to be a successful woman and mother, he always encouraged me to do my best in everything and I hope that he would be proud of me in every step of my life. Also my mother Eman abdelrahman who helped me a lot in order to reach this moment and took care of me and my son when I wasnâ€™t around working in this project. First of all I would like to express how thankful I am to Dr. Wael Mamdouh, my supervisor, for his valuable guidance and support during working. He gave me unlimited support and a lot of his precious time and advice. I am thankful also to my research colleagues for their help, the time and support I spent with them Sherine Saad, Sara Omar, Amro Shetta, Fatma Nabil, Khadija Sadek, Jailan Badawyâ€¦etc Also, I feel grateful to all my professors whom I have learnt a lot at through their courses at the AUC chemistry department. Special thanks to the colleagues and researchers at AUC who taught me research skills and during my work; for their care and guidance during my research work, Ahmed Omaia and Mr. Mahmoud AbdelMoez for the FTIR experiments James kegere for helping me in the SEM imaging and antibacterial testing. I would like to express my heartfelt thanks my family the support they always provide me my uncle Mohamed Soliman, my aunt Mona Abdelrahman my sister, Eman Soliman, my brother Ahmed Soliman, my sister in law Hadeer Abdelbasset and my cousin Mohamed Nabil for their great support and encouragements. Moreover, I am thankful to my close friends Nada, Menna, Yara, Rana, Heba, Marwa, Mariam, Safa and Yasmin their friendship that played crucial role in my life and for their warm support, strength and advice throughout the Masters. Last, but by no means least, I thank God.