PEGylated Superparamagnetic Iron Oxide Nanoparticles as Contrast-Enhancing Agents for Swept-Source Optical Coherence Tomography of Biological Tissue.

In this work, the effect of surface modification of superparamagnetic iron oxide nanoparticles (SPIONs) with polyethylene glycol (PEG) on contrast enhancement in swept-source optical coherence tomography (SS-OCT) is investigated. The bare and PEGylated SPIONs were prepared by the co-precipitation method from an aqueous solution of an Fe(III) salt. They were characterized by UV-DRS, Raman spectroscopy, FTIR, TEM, and VSM to determine their physicochemical properties. The performance of ex vivo imaging was evaluated in chicken breast tissue with B-scan SS-OCT at various exposure times (0, 10, 20, 30, 40, and 50 min), and the contrast enhancement was investigated by measuring the scattering coefficient. The brightness of bare SPIONs was low, and the penetration into tissues was slow. PEG-SPIONs, on the other hand, showed better optical stability, penetration, enhanced scattering, and brighter SS-OCT images. The scattering coefficient (mm-1) of PEG-SPION-treated tissue increased with exposure time, indicating its effectiveness as a tissue contrast agent.