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Publication Date

Fall 2012

Degree Type

Thesis - Campus Access Only

Degree Name

Master of Science (MS)


Biomedical, Chemical & Materials Engineering


Maryam Mobed-Miremadi


biomedical engineering, biophysics, hollow microfiber, mathematical modeling, stent, tissue engineering

Subject Areas

Biomedical engineering


Hydrogels like alginate and chitosan have proven potential in drug delivery systems. Their advantageous qualities such as biocompatibility, biodegradability, non-toxicity, and structural tunability make them excellent drug carriers. Alginate-chitosan-alginate (ACA) hollow fibers (i.e., stents) were fabricated with a semi-permeable membrane to allow release of drugs by diffusion into a desired lumen of the body. A solution of 2% (w/v) medium molecular weight alginate crosslinked with 10% CaCl2 was used to fabricate hollow stents (od~1300 µm, id~900 µm, t~300 µm, L=3.5cm). For empty stents, solutes with Stokes radii ranging from 0.36 to 3.5 nm were determined to have diffusivities between 2.93x10-12 and 5.2x10-14 m2/s for uncoated and ACA membranes, as determined by spectrophotometry and mathematical modeling in Matlab 7.10.0(R2010a). A comparative technique with fluorescence microscopy was used to validate the diffusivity range of 3.78x10-10 - 3.94x10-13 m2/s for FITC-dextrans with molecular weights ranging from 4-500 kDa. Mechanical testing on bare hollow alginate stents showed that as CaCl2 concentration and cross-linking duration was increased, the tensile strength and elastic modulus increased. Bare alginate and ACA stents cross-linked with 10% CaCl2 for 60 min had the following tensile properties: E=0.24 MPa, UTS=0.097MPa and E=0.053MPa, UTS=1.03x10-01 MPa.