Versatile T1-Based Chemical Analysis Platform Using Fe3+/Fe2+ Interconversion

We report a versatile analytical platform for assaying multiple analytes relying on changes in longitudinal relaxation time (T-1) as a result of Fe3+/Fe2+ interconversion. The T-1 of water protons in Fe3+ aqueous solution differs significantly from that of Fe2+, allowing for the development of a generally applicable Trbased assay since many redox reactions enable the interconversion between Fe' and Fe3+ that can result in the change of Ti. Compared with conventional magnetic biosensors, this T-1-based assay is free of magnetic nanoparticles (MNPs), and the stability of T-1 based assay is better than conventional magnetic sensors that suffer from nonspecific adsorption and aggregation of MNPs. This T-1-based assay simultaneously enables one-step mixing assays (such as saliva sugar) and multiple-washing immunoassays with good stability and sensitivity, offering a promising platform for convenient, stable, and versatile biomedical analysis