Simultaneous contrast agent and drug delivery in colon-targeted MRI using pH sensitive electrospun theranostic fibers

Abstract

We report the first use of coaxial electrospinning to prepare core-shell fibers encapsulating therapeutic, diagnostic and targeting agents. Eudragit S100 formed the shell and the core comprised polyethylene oxide (PEO) loaded with the MRI contrast agent Gd(DTPA) and indomethacin as a model therapeutic agent. Swollen PEO adheres strongly to colonic mucosa, Eudragit S100 polymer coating is stable at the acid stomach pH but dissociates at the basic pH values of the later parts of the intestine, co-delivering the imaging agent and the drug at the colon. The fibers were prepared by coaxial electrospinning and their morphology and structure studied by SEM, TEM, DSC, XRD and FTIR. Gd3+ leaching from the fibers and drug release were followed by UV. Ex vivo fiber mucoadhesion and imaging of delivery of rhodamine B to porcine colon pieces allowed visualization of the dye release only at pH 7.4. The fibers can selectively deliver Gd(DTPA) and the drug to the colon, allowing successful imaging the colon wall. The new platform reported herein can deliver therapeutic and imaging agents simultaneously to the colon, allowing theranostic studies by imaging the progression of inflammatory lesions or colon cancer as they are treated.