Abstract/Details

Influence of hydrophobic modification in alginate-based hydrogels for biomedical applications


2010 2010

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Abstract (summary)

Alginate has been exploited commercially for decades in foods, textiles, paper, pharmaceutical industries, and also as a detoxifier for removing heavy metals. Alginate is also popular in cell encapsulation because of its relatively mild gelation protocol and simple chemistry with which biological active entities can be immobilized. Surface modification of alginate gels has been explored to induce desired cell interactions with the gel matrix. These modifications alter the bulk properties, which strongly determine on how cells feel and response to the three-dimensional microenvironment. However, there is a need to develop strategies to engineer functionalities into bulk alginate hydrogels that not only preserve their inherent qualities but are also less toxic.

In this thesis, our main focus was to optimize the mechanical properties of alginate-based hydrogels, and by doing so control the performance of the biomaterials. In the first scheme, we used alginate and hydrophobically modified ethyl hydroxy ethyl cellulose as components in interpenetrating polymer network (IPN) gels. The second network was used to control gelation time and rheological properties. We believe these experiments also may provide insight into the mechanical and structural properties of more complex biopolymer gels and naturally-occurring IPNs. Next, we worked on incorporating a hydrophobic moiety directly into the alginate chain, resulting in materials for extended release of hydrophobic drugs. We successfully synthesized hydrophobically modified alginate (HMA) by attaching octylamine groups onto the alginate backbone by standard carbodiimide based amide coupling reaction. Solubility of several model hydrophobic drugs in dilute HMA solutions was found to be increased by more than an order of magnitude. HMA hydrogels, prepared by crosslinking the alginate chains with calcium ions, were found to exhibit excellent mechanical properties (modulus ∼100 kPa) with release extended upto 5 days. Ability to vary the hydrophobic tails, degree of substitution, and crosslinker density gave us handles to tune the properties of the materials. Finally we will show how modulus of the alginate gels can be used to influence the proliferation and differentiation of encapsulated neural stem cells. A preliminary attempt was also made to develop three dimensional “life-like” vasculature network made from alginate tubes and other biomaterials.

Indexing (details)


Subject
Biomedical engineering;
Chemical engineering;
Materials science
Classification
0541: Biomedical engineering
0542: Chemical engineering
0794: Materials science
Identifier / keyword
Applied sciences, Alginate, Amphiphillic polymer, Drug delivery systems, Hydrogels, Interpenetrating polymer network, Microfluidic devices
Title
Influence of hydrophobic modification in alginate-based hydrogels for biomedical applications
Author
Choudhary, Soumitra
Number of pages
148
Publication year
2010
Degree date
2010
School code
0118
Source
DAI-B 71/12, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
9781124319698
Advisor
Bhatia, Surita R.
Committee member
Roberts, Susan C.; Rothstein, Jonathan P.
University/institution
University of Massachusetts Amherst
Department
Chemical Engineering
University location
United States -- Massachusetts
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3427510
ProQuest document ID
814734744
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/814734744
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