Date of Award

2009-01-01

Degree Name

Master of Science

Department

Metallurgical and Materials Engineering

Advisor(s)

Ryan B. Wicker

Second Advisor

Lawrence E. Murr

Abstract

One of the challenges in tissue engineering is to have spatial and temporal control over the biological elements within a scaffold used to guide regeneration for example of transected nerves. Some of the physical and chemical characteristics to regulate include incorporation of bioactive domains and release of chemical signals. This study presents the use of stereolithography (SL) to incorporate localized domains for cell adhesion in addition to include releasable nerve growth factor (NGF) in the process of building poly(ethylene glycol)diacrylate (PEGda) hydrogel scaffolds. Besides providing sites for cell attachment, an ideal nerve guidance conduit (NGC) should be able to release growth factors to promote the axons´ growth. NGF is a neurotrophin known to enhance survival, growth and differentiation of nerve cells. This protein was either encapsulated or conjugated to the polymer of varying concentrations of two molecular weights, PEGda 3.4 and 6 kDa. PEG hydrogels released the neurotrphin into RPMI-1640 cell culture medium. An NGF release profile was determined by enzyme-linked immunosorbent assay (ELISA). Results showed that protein release increased with increasing molecular weight of the matrix´s mesh and diminished with decreased concentration within the same PEG´s mw. The total amount of trapped NGF diffused after one week from PEG 20 wt% 3.4 kDa, 30 wt% 3.4 kDa and 10 %(w/v) 6 kDa was 93±1.9, 46±2ng and 292.23±6.5ng, respectively. Gels with the conjugated protein released 254.6±21.1 from 6kDa PEG matrix and 19.2±0.4 from 3.4kDa PEG gels after 15 days. The hydrogels´ supernatants were added to pheochromocytoma (PC-12) cells to demonstrate bioactivity by observing neurite extension of in response to NFG. Ultimately, SL shows as a promising tool for producing bioactive synthetic PEG guides for peripheral nerve regeneration.

Language

en

Provenance

Received from ProQuest

File Size

154 pages

File Format

application/pdf

Rights Holder

Nubia Zuverza

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