Dual Nanoparticle Conjugates for Highly Sensitive and Versatile Sensing Using <sup>19</sup>F Magnetic Resonance Imaging
Daniel J. Cooke, Esther Y. Maier, Tyler L. King, Haoding Lin, Santiago Hendrichs, S. K. Lee, Noushaba Nusrat Mafy, Kathleen M. Scott, Yi Lu, Emily L. Que
Abstract
Abstract Fluorine magnetic resonance imaging ( 19 F MRI) has emerged as an attractive alternative to conventional 1 H MRI due to enhanced specificity deriving from negligible background signal in this modality. We report a dual nanoparticle conjugate ( DNC ) platform as an aptamer‐based sensor for use in 19 F MRI. DNC consists of core–shell nanoparticles with a liquid perfluorocarbon core and a mesoporous silica shell ( 19 F‐MSNs), which give a robust 19 F MR signal, and superparamagnetic iron oxide nanoparticles (SPIONs) as magnetic quenchers. Due to the strong magnetic quenching effects of SPIONs, this platform is uniquely sensitive and functions with a low concentration of SPIONs (4 equivalents) relative to 19 F‐MSNs. The probe functions as a “turn‐on” sensor using target‐induced dissociation of DNA aptamers. The thrombin binding aptamer was incorporated as a proof‐of‐concept ( DNC Thr ), and we demonstrate a significant increase in 19 F MR signal intensity when DNC Thr is incubated with human α‐thrombin. This proof‐of‐concept probe is highly versatile and can be adapted to sense ATP and kanamycin as well. Importantly, DNC Thr generates a robust 19 F MRI “hot‐spot” signal in response to thrombin in live mice, establishing this platform as a practical, versatile, and biologically relevant molecular imaging probe.