Abstract

In an attempt to develop novel natural nanofibers with enhanced antimicrobial activities, polymer composites and nanomaterials play a vital role and exhibit superior properties. Among the different types of nanomaterials, nanofibers have attracted a lot of attention in various fields due to their large surface area per unit mass and advanced mechanical performance. Nanofibers are potential candidates to be used in many fields such as drug delivery systems, nano-sensors, filtration media, and medical applications, etc. Among theses applications is the use of these nannanofibers in wound management. The development of novel approaches that can enhance wounds healing is always in focus of research. Here in our research, we're trying to develop an effective, safe and economic composite nanofibers with an antimicrobial activity that can have an application as a novel wound dressing that can enhance healing. The main objectives of this thesis are: (i) to prepare and optimize the fabrication of Cellulose Acetate (CA) nanofibers by Electrospinning technique, (ii) to add Citric acid (CIT) as an antimicrobial material to the formed electrospun CA nanofibers and (iii) to finally investigate a possible enhancement in the antibacterial activity of the electrospun composite CA/CIT nanofibers against two different bacterial strains; Escherichia coli (E. Coli) and Staphylococcus aureus (S. aureus). In this study, electrospinning technique was used and the experimental parameters were optimized to fabricate uniform CA electrospun nanofibers as well as CA/CIT composite nanofibers to be tested for their antimicrobial activities. Electrospinning parameters (such as applied voltage, and solution flow rate, distance from the spinneret tip-to-the collector and the solvent system) of CA and CA/CIT blend solutions were varied to be electrospun to choose the most acceptable electrospinning conditions. The most uniform nanofibers were obtained with 5% (w/v) for CA dissolved in acetone at voltage 15 KV, at a tip-collector distance of 5 cm and a solution flow rate of 5mL/hr. Thereafter, these parameters were used with CA/CIT blend solution (5% CA and 10% CIT in acetone) in order to obtain uniform and bead free electrospun CA/CIT composite nanofibers. After successful preparation of electrospun CA and CA/CIT composite nanofibers, full characterization of the morphology and chemical structural characteristics by using scanning electron microsopy (SEM) and Fourier Transform Infrared (FT-IR) spectroscopy were carried out. After characterization of the produced CA and CA/CIT Electrospun nanofibers, they were tested for their antibacterial activity with E. coli and Staphylococcus aureus (S. aureus) bacteria, by the dynamic contact method. Amazingly, the negative control (E.coli) showed an increase in the bacterial growth from zero to 48 hours by 26.5% (i.e. from 1.06 x 108 to 2.8 x 109 CFU), respectively, while on the other hand, the electrospun CA nanofibers showed only 2.2% increase in the bacterial growth at the same time interval (from 1.09 x 108 to 2.4 x 108 CFU), respectively. Similarly, the negative control (S. aureus) showed an increase in the bacterial growth from zero to 48 hours by 28% (i.e. from 1.09 x 108 to 3.08 x 109 CFU), respectively, while on the other hand, the electrospun CA nanofibers showed only 2.1% increase in the bacterial growth at the same time interval (from 1.1 x 108 to 2.34 x 108 CFU), respectively. Moreover, CA/CIT electrospun composite nanofibers showed much higher antibacterial activities (i.e. lower growth rate) than CA electrospun nanofibers and also the negative control against both bacterial strains. So, in case of E-coli, the CA/CIT electrospun composite nanofibers showed only 1.5% increase in the bacterial growth at the same time interval (from 1.3 x 108 to 1.98 x 108 CFU), respectively. Similarly, in case of S-aureus, the CA/CIT electrospun composite nanofibers showed only 1.46% increase in the bacterial growth at the same time interval (from 1.15 x 108 to 1.69 x 108 CFU), respectively. These results open new avenues for fabricating antibacterial products from semi synthetic materials with superior biomedical activities. Additionally, trials to electrospin other composites of CA, namely CA/CS & CA/CS/CIT were done, however no nanofibers could be obtained.

Department

Biotechnology Program

Degree Name

MS in Biotechnology

Date of Award

2-1-2015

Online Submission Date

January 2016

First Advisor

Mamodouh, Wael

Committee Member 1

Elsayed, Mayyada

Committee Member 2

Ghobashy, Medhat

Document Type

Thesis

Extent

114 p.

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.

IRB

Not necessary for this item

Comments

I would like to thank my supervisor, Dr. Wael Mamdouh, for his support during this research work. I've learnt too much from him. His limitless support and close guiding was a cornerstone to accomplish this work, without which it wouldn’t be done at this level of professionalism and perfection. I would like also to thank all my professors in AUC during this program for their great effort in teaching us. I'm proud being a student of you. I'd like to specially thank Dr. Rania Siam for her endless support during the whole program. "First impression lasts" and if I'm proud of being an AUC student, a major part of this is because you were my first impression about AUC. I also like to thank my colleagues and research group for their support and the time we spent together. Special thanks for Walaa Wahby, for her time & support in this research work. I'd like to thank Rami Wasfi for helping me in the SEM imaging, Mr. Mahmoud AbdelMoez, Ahmed Omaia for the FTIR experiments and Mohamed Rabiee for the antimicrobial assessment. My deep thanks for all my family, specially my father Mr. Adly Saied and my mother Mrs. Samia Hassan. I wouldn’t achieve any good thing in my life without your encouragement, support and prayers. I still remember the little stories you kept buying me to make me like reading and learning. Grown as me, those little stories are now references and textbooks. Not only I and my stories have grown, my love to you and my honor you’re my parents is the ever growing inside me. I would also like to thank my beloved wife Amira Hamdy for her support and understanding of this period of my life. I apologize being a too busy husband with full loaded agenda that has too limited time to spend with you and with our kids. I wish to enjoy our time together soon. This is extended to my cute daughter, Roqayyah, and my brave son, Hamzah. I know you are missing your dad and missing the play zones, too. When you grow and read this, I want you to know I'm trying doing my best for a better future for you and your generation. I wish you too, will keep it up. I would like also to dedicate this work for youth people in Egypt and everywhere who strive for shaping a better future for their countries and the whole humanity and I'm fully confident they'll do. Last but not least, my deep thanks to Allah the Almighty for all his blessings on me and all are from him. Without your grace I can't ever do anything or achieve anything. I wish this work will be for the welfare of his creatures and that he accepts it.

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