Observation of Brownian Relaxation of Magnetic Nanoparticles using HTS SQUID

We analyzed the sensitivity of a separationless immunoassay scheme using functionalized magnetic nanoparticles (MNPs) and a sensitive HTS SQUID magnetometer. The signal of a 100 mu L sample at a concentration of 1 mg/mL and field of 7.5 nT was 20 m Phi(0). This makes it possible for the sensitivity to be within the range of 50 ng/mL at the required time of up to 100 s per a point in the frequency spectrum