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Synthesis and recovery characteristics of branched and grafted PNIPAAm–PEG hydrogels for the development of an injectable load-bearing nucleus pulposus replacement

Paper ID Volume ID Publish Year Pages File Format Full-Text
2506 114 2010 10 PDF Available
Title
Synthesis and recovery characteristics of branched and grafted PNIPAAm–PEG hydrogels for the development of an injectable load-bearing nucleus pulposus replacement
Abstract

A family of injectable poly(N-isopropyl acrylamide) (PNIPAAm) copolymer hydrogels has been fabricated in order to tune mechanical properties to support load-bearing function and dimensional recovery for possible use as load-bearing medical devices, such as a nucleus pulposus replacement for the intervertebral disc. PNIPAAm–polyethylene glycol (PEG) copolymers were synthesized with varying hydrophilic PEG concentrations as grafted or branched structures to enhance dimensional recovery of the materials. Polymerizations were confirmed with attenuated total reflectance-Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy studies. Incorporation of PEG was effective in raising water content of pure PNIPAAm hydrogels (29.3% water for pure PNIPAAm vs. 47.7% for PEG branches and 39.5% for PEG grafts). PNIPAAm with 7% grafted as well as 7% branched PEG had significantly reduced compressive modulus compared to that of pure PNIPAAm. Initially recovered compressive strain was significantly increased for 7% PEG branches after pre-testing immersion in PBS for up to 33 days, while 7% PEG grafts decreased this value. Sample height recovery for pure PNIPAAm was limited to 31.6%, while PNIPAAm with 7% branches was increased to 71.3%. When mechanically tested samples were allowed to recover without load over 30 min, each composition was able to significantly recover height, indicating that the time to recovery is slower than the unloading rates typically used in testing. While the incorporation of hydrophilic PEG was expected to alter the mechanical behavior of the hydrogels, only the branched form was able to significantly enhance dimensional recovery.

Keywords
Hydrogel; Mechanical properties; Intervertebral disc; PNIPAAm; Recovery
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Synthesis and recovery characteristics of branched and grafted PNIPAAm–PEG hydrogels for the development of an injectable load-bearing nucleus pulposus replacement
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Publisher
Database: Elsevier - ScienceDirect
Journal: Acta Biomaterialia - Volume 6, Issue 4, April 2010, Pages 1319–1328
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us