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Hsieh, Chung-Jen (2006) STUDIES ON SURFACE MODIFICATIONS OF MATERIALS FOR TISSUE ENGINEERING APPLICATIONS. Master's Thesis, University of Pittsburgh. (Unpublished)

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Peripheral nerve injury (PNI) is a serious health problem for the society today. It affects 2.8% of trauma patients, many of whom acquire life-long disability. Approximately 360,000 people in the United States suffer from upper extremity paralytic syndromes yearly. Two current clinical approaches: end-to-end surgical reconnection and autologous nerve graft are used to cure the patients suffered PNI. However, both approaches have some disadvantages such as loss functions of donor site and two surgeries, at least, are needed. Therefore, various synthetic materials for bridging the injured nerve gap and surface modifications for enhancing the outgrowth of nerve cells have been reported. The objectives of this research were: 1) To investigate ways of modifying the surface of some biomaterials; 2) To investigate the influence of surface properties, such as the types of functional groups, wettability, and surface morphology on the cell culture; 3) To investigate the possibility of differentiating between male and female stem cells in the cells via surface modification. Three materials, mica, glass, and polycaprolactone (PCL) were used as substrates in this study. Mica substrates were prepared and modified using PAMAM dedrimer polymers. The optical microscopy images showed that neurites started to sprout and considerable neuron cell adhesion on the mica substrates coated with multilayer PAMAM dendrimers but uncoated and monolayer coated mica substrates showed no cell adhesion after a 12 hr cell culture. Similarly, the surfaces of gold and titanium coated glass substrates were modified so that the surface was terminated with different functional groups. Atomic force microscopy (AFM) measurements showed that the average surfaces roughness increased from 4.663 to 5.328 nm after gold-coated surface reacted with 1-dodecanethiol. The average surface roughness (Ra) increased after gold-coated surface reacted with 11-mercaptoundecanoic acid (Ra= 0.190 nm) and 11- mercapto-1-undecanol( Ra= 0.394 nm). The contact angle (ƒá) increased from 76.56 ¡Ó 4.6¢X to 107.43 ¡Ó 4.6¢X after gold-coated surface reacted with 1-dodecanethiol. The surfaces became more hydrophilic after gold-reaction with 11-mercaptoundecanoic acid (ƒá=37.24 ¡Ó 2.2¢X) and 11- mercapto-1-undecanol (ƒá= 28.42 ¡Ó 2.0¢X). Based on the cell culture data on PCL, the carboxyl terminated surface showed more cell attachment than methyl and hydroxyl terminated surface. The numbers of cells adhering to each modified surface after a 12 hr cell culture in an ascending order is as follow: NH2 < COOH < CH3 , Control PCL. In the surface modifications we investigated, the behavior of male and female adult fat derived stem cells was essentially identical.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Hsieh, Chung-Jenchh30@pitt.eduCHH30
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairFulay, Pradeep Pfulay@engr.pitt.eduPPP
Committee MemberNettleship, Iannettles@pitt.eduNETTLES
Committee MemberMarra, Kacey Gmarrak@upmc.eduKGM5
Date: 2 June 2006
Date Type: Completion
Defense Date: 28 March 2006
Approval Date: 2 June 2006
Submission Date: 6 April 2006
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Materials Science and Engineering
Degree: MSMSE - Master of Science in Materials Science and Engineering
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: adipose derived stem cells; advancing contact angle; cell attachments; cell culture; contact angles; glass coverslips; hysterese; mica; neuron; PC12 cells; polycaprolactone; receding contact angle
Other ID:, etd-04062006-135500
Date Deposited: 10 Nov 2011 19:34
Last Modified: 19 Dec 2016 14:35


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