Fe-T1 Sensor Based on Coordination Chemistry for Sensitive and Versatile Bioanalysis

The main challenge of paramagnetic ions-mediated magnetic sensors is their relatively low sensitivity. In this study, we observe the amplification of longitudinal relaxation time (T1) signal when Fe2+ transforms into Fe3+ followed by the coordination of potassium thiocyanate (KSCN) and develop a sensitive Fe-T1 sensor based on the coordination chemistry between KSCN and Fe3+ to amplify the T1 signal for detecting a series of targets, such as hydrogen peroxide, glucose, and antigen/antibody. We justify the practicability of our assay by successfully detecting tetracycline in milk samples and hepatitis C virus in clinical samples with satisfactory accuracy. This KSCN-mediated Fe-T1 sensor not only realizes biochemical analysis and immunoassay with higher sensitivity but also retains many advantages of paramagnetic ions-mediated magnetic sensors (good stability and straightforward operation), which holds great promise for the detection of a range of targets of interest in complex samples.