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M. E. Smith, G. E. Wnek; Incorporation and Release of Immunoglobulin G as a Model Protein System From Biphasic Polymeric Tissue Engineering Scaffolds Produced Through Electrospinning. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4807.
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© ARVO (1962-2015); The Authors (2016-present)
Electrospun polymers represent an excellent example of multi-functional ocular biomaterials, affording a micro- or nanofibrous mechanical support for cell and tissue growth, a high surface area and controllable surface chemistry, tailored porosity to promote vascularization and innervation, and a matrix for the delivery of bioactive molecules. Incorporation of water-soluble molecules into otherwise hydrophobic polymers represents an interesting challenge. One viable approach involves using ‘biphasic’ electrospinning, where dispersions of water droplets in a polymer/organic solvent are first prepared and then electrospun, encapsulating the aqueous pockets within polymer fibers. Molecules initially dissolved in the water droplets are sequestered in aqueous domains in the fibers, and can be released via a variety of mechanisms. The purpose of this study was to investigate the incorporation and release of Immunoglobulin G as a model protein from various biodegradable polymer scaffolds, to asses and control delivery kinetics and to determine the impact of the processing and release on the activity of bioactive compounds from these ocular tissue engineering scaffolds.
Biphasic electrospinning was carried out with biocompatible and biodegradable polymers, including poly(lactic-co-glycolic acid) and poly(ε-caprolactone). Mats were characterized via scanning electron microscopy for fiber diameters, and by dynamic mechanical analysis to evaluate thermal and mechanical properties. Fluorescent labeling and microscopy was used to locate the proteins within the fibers. ELISA was performed to quantify release rates and to assess the activity of the protein upon delivery.
Scaffolds containing the model protein were successfully produced from a multitude of polymer systems, and were fabricated in thicknesses ranging from fifteen to hundreds of microns. The model protein was found to be fully encapsulated within aqueous pockets in the core of the fiber, providing isolation from the external environment. Release profiles for the various scaffolds were obtained, with greater than 85% of the total protein being delivered. Also, it was found that protein activity was not negatively affected by the fabrication or release.
Using biphasic electrospinning, proteins can be readily encapsulated in aqueous domains within polymer fibers, and controlled delivery of the active protein can be achieved, providing a multifunctional ocular tissue engineering scaffold.
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