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Description: TOPIC:USE OF SUB-MICRON SIZED ELECTROSPUN FIBERS TO ENHANCE THE SURFACE FUNCTIONALITY: CHARACTERIZATION AND APPLICATIONS
Abstract: Functionalization of polymeric fibers can be used as a multipotent tool to facilitate their application in different research fields such as tissue engineering, drug delivery and ion-exchange. In tissue engineering and drug delivery, biodegradable polymer-based textile structures (woven, knitted, or non-woven) are becoming more popular as their specific chemical composition, mechanical properties and morphological features can be controlled and modified according to the required application. Most bio-inert polymers lack the functional motifs for specific bioactivity; however, functionalization of scaffolds can provide biological functions to actively induce tissue regeneration and promote cell adhesion by targeting specific cell-matrix interactions. Functionalization is also a powerful tool to incorporate specific drug molecules which can then be released in a sustained manner at the target site. In the current study, poly(caprolactone) (PCL) fibers were fabricated by electrospinning, and functionalized through wet chemical techniques that are preferable for complex 3D structure of these fibrous scaffolds. The functionalized electrospun PCL fibers were characterized through scanning electron microscopy, x-ray photoelectron spectroscopy and gel permeation chromatography. Results from this study showed the favorable effect of functionalization on altering cellular behavior. Next, the functional groups introduced via hydrolysis (-COOH) were ionized to impart a negative charge to the fiber surface and doxorubicin hydrochloride (DOX), an FDA approved anticancer drug, was ionized to impart a positive charge at a certain pH. The pH-sensitivity of both the materials was utilized to bind DOX electrostatically to the functionalized PCL fibers, with an aim to create pH-responsive drug delivery vehicle for the site-specific delivery of DOX. Results indicate successful electrostatic binding of DOX to functionalized electrospun PCL fibers and a high drug payload was achieved. The drug delivery response can be modulated by introduction of suitable stimuli (pH in this case) by utilization of a composite scaffold system comprising of drug-loaded scaffolds and hydrogels that release acid in the vicinity of scaffolds. Finally, polymer functionalization was used to obtain fibers with ion-exchange properties that could be used in environmental engineering as well as drug delivery applications. This study again emphasized the role of fiber diameter and surface area in enhancing the surface functionality of polymers. In summary, this research enabled us to gain a basic understanding of the functionalization process of electrospun fibers and how this functionalization process could be exploited to suit various end use applications. The current research established the fact that appropriately functionalized submicron to nanometer fibrous assemblies are promising candidates for next generation tissue-engineered 3D scaffolds/drug delivery vehicles.