Concentration characterization of encapsulated macromolecules in electrospun alginate fibers using image analysis

Electrospun fibers made of biocompatible polymers have been used as scaffolds in tissue engineering to mimic the fibrous environment found in the extracellular matrix (ECM) of biological tissue; and bioactive macromolecules can also be encapsulated in the electrospun fibers. In order to control the release of these encapsulated macromolecules, it is of great interest to understand how the release rate is affected by the sizes of molecules, cross-linking as well as electrospinning configuration (single axial versus co-axial). Fluorescein imaging technique has been applied in quantifying molecular transport phenomena. This paper presents an image analysis method to establish a baseline correlation between the fluorescent intensity and the macromolecule concentration in the electrospun fibers. In this study, alginate and Poly(ethylene oxide) (PEO) blend polymer aqueous solution (1:1 ratio, 3%w/v) was used to electrospin fibers and fluorescein-isothiocyanate dextran (FITC-dextran) with different molecular weights was chosen as the encapsulated macromolecule. Linear correlation was established based on the statistical analysis of electrospun fiber images, and imaging parameters effects were also identified.