Abstract
A magnetic sensor, called MIAplex®, has been developed by the company Magnisense. This instrument measures a signal, which is proportional to the second derivative of a magnetization curve. We show that this sensor is able to discriminate between the signature of small superparamagnetic nanoparticles produced chemically and that of larger ferromagnetic nanoparticles produced by magnetotactic bacteria. The reason why this distinction is possible comes from the different magnetization curves of these two types of nanoparticles. These results pave the way for the simultaneous detection of different types of biological molecules or living organisms.
