fig9

Figure 9. Principle of MNP-enhanced NMR bioassay. When monodispersed MNPs cluster upon binding to targets, the self-assembled clusters become more efficient at dephasing nuclear spins of many surrounding water protons, leading to a decrease in T2 relaxation time. The bottom panel shows an example of the proximity assay measured by the DMR system. Avidin was added to a solution of biotinylated magnetic nanoparticles, causing T2 to decrease from 40 to 14 ms (A); schematic diagram of the DMR system (B); the microcoil generates rf pulses (C); the microfluidic network (D); schematic of the NMR electronics (E)^[89] (reprinted with permission from Springer Nature)