| 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 2.93×10 -12 and 5.2×10-14 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 3.78×10-10 – 3.94×10-13 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% CaCl 2 for 60 min had the following tensile properties: E=0.24 MPa, UTS=0.097MPa and E=0.053MPa, UTS=1.03×10-01 MPa. |
