Enabling magnetic resonance imaging of hollow-core microstructured optical fibers via nanocomposite coating

Optical fibers are widely used in bioimaging systems as flexible endoscopes that are capable of low-invasive penetration inside hollow tissue cavities. Here, we report on the technique that allows magnetic resonance imaging (MRI) of hollow-core microstructured fibers (HC-MFs), which paves the way for combing MRI and optical bioimaging. Our approach is based on layer-by-layer assembly of oppositely charged polyelectrolytes and magnetite nanoparticles on the inner core surface of HC-MFs. Incorporation of magnetite nanoparticles into polyelectrolyte layers renders HC-MFs visible for MRI and induces the red-shift in their transmission spectra. Specifically, the transmission shifts up to 60 run have been revealed for the several-layers composite coating, along with the high-quality contrast of HC-MFs in MRI scans. Our results shed light on marrying fiber-based endoscopy with MRI to open novel possibilities for minimally invasive clinical diagnostics and surgical procedures in vivo. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement