Abstract

Polylactic acid (PLA) is a versatile biopolymer that is widely used as a biomaterial. However, one of the major issues which limits its further application in tissue engineering purposes is its hydrophobic nature and poor cellular interaction. Modification of PLA properties can be achieved by polymer blending techniques. Polymer blending is a simple yet attractive method to combine and optimize polymeric physical properties of interest. In this study, an antibacterial electrospun nanofibrous scaffolds, with diameters around 400–1000 nm, were prepared by physical blending PLA with a hydrophylic biopolymer, cellulose acetate (CA). In this stage, PLA was used as the main polymer, blended with CA, at two main ratios (9:1 and 7:3 w/w), to achieve desirable properties such as better hydrophilicity, excellent cell attachment and proliferation. For preventing common clinical infections, an antimicrobial agent, Thymoquinone, TQ was incorporated into the electrospun fibers. TQ is the active ingredient of Nigella sativa and it is well known for its antibacterial properties. The potentiality of the prepared scaffolds, regarding being used as an interactive wound dressing, has been investigated including, swelling behavior, WVP and porosity. The release profile of TQ from the prepared scaffolds was also examined at the physiological pH (7.4) and temperature (37 οC). The antimicrobial efficiency of the prepared scaffolds against gram negative and gram positive bacteria were determined by the agar diffusion assay. The interaction between fibroblasts and the TQ-loaded PLA: CA scaffolds such as viability, proliferation, and attachment were characterized. TQ-loaded PLA: CA scaffolds showed burst TQ release after 24 h, compared with medicated PLA scaffolds, followed by a sustained release rate for 9 successive days. The results also indicated that medicated PLA: CA nanocomposite scaffolds showed a significant antibacterial activity against both gram positive and gram negative bacteria. Furthermore, the prepared scaffolds enhanced cell viability, attachment and proliferation, as compared to medicated PLA nanofibers. The presence of CA in the nanofiberous scaffolds improved its hydrophilicity, bioactivity, and water uptake capacity. Furthermore, it created a moist environment for the wound, which can accelerate wound recovery. A preliminary in vivo study performed on normal full thickness mice skin wound models demonstrated that TQ-loaded PLA: CA (7:3) scaffolds significantly accelerated the wound healing process by promoting angiogenesis, increasing re-epithelialization and controlling granulation tissue formation. Our results suggest that TQ-loaded PLA: CA nanocomposite mat could be an ideal biomaterial for wound dressing applications.

Department

Chemistry Department

Degree Name

MS in Chemistry

Graduation Date

2-1-2016

Submission Date

January 2016

First Advisor

Madkour, Tarek Madkour

Committee Member 1

Ramadan, Adham Ramadan

Committee Member 2

El-sherbiny, Ibrahium Mohamed

Extent

125 p.

Document Type

Master's Thesis

Rights

The author retains all rights with regard to copyright. The author certifies that written permission from the owner(s) of third-party copyrighted matter included in the thesis, dissertation, paper, or record of study has been obtained. The author further certifies that IRB approval has been obtained for this thesis, or that IRB approval is not necessary for this thesis. Insofar as this thesis, dissertation, paper, or record of study is an educational record as defined in the Family Educational Rights and Privacy Act (FERPA) (20 USC 1232g), the author has granted consent to disclosure of it to anyone who requests a copy.

Institutional Review Board (IRB) Approval

Not necessary for this item

Comments

I would like to express my special gratitude to my supervisor; Dr. Tarek Madkour, as this project would not have been done without his continuous support and unconditional help. Actually, I can’t find words to thank Dr. Tarek for his patience, encouragement, motivation, and immense knowledge. I could not have imagined having better advisor and mentor for my Master study than Dr. Tarek. Also, I would like to thank Dr. Ibrahium El-sherbiny for giving me the chance to work in his lab, providing me with all the facilities I need. I consider it an honor to have been able to work with him. Besides my advisors, I would like to acknowledge the American University in Cairo for the financial support through the graduate student research grant and the fellowship. I would like to acknowledge Zewail City for science and technology for allowing me to be a part of its community for a whole year. Special thanks to VACSERA center for their contribution in the biological analysis. Also, I would like to highlight the help from my sincere manager at Savola group, Eng. Shahat Saber. I would also like to express my sincere thanks to all the staff in the Chemistry department, especially Mr. Ahmed Omia for his great effort, I am very gratitude for his support, and Mr. Emad for their valuable technical help. I am extremely thankful to my lab-colleagues Samar, Ghada, Sara and Ahmed. And very special thanks to my dear friends; AlShaimaa, Woroud, Sara Omar, Ruaa, Ayat, Yomna, Nada, and Ali for their encouragement, help, love and support and for the good times we spent together. Last but not least, I cannot find words to express my feeling toward my parents. I am extremely grateful to them for being always by my side and providing me with all the love, care and support that made me capable of achieving my goals. Also, I would like to thank my beloved sisters for their kindness and love, and my elder brother, Dr. Mustafa for his guidance, encouragement and support throughout my life

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