Scanning force microspy study of biogenic nanoparticles for medical applications

We present a combined atomic force microscopy (AFM) and magnetic force microscopy (MFM) study of bacterial magnetosomes, consisting of membrane-covered magnetite particles. AFM imaging unambiguously demonstrates the existence of single isolated magnetosomes with a size of about 40 nm, in addition to various clusters of magnetosomes. With MFM we have particularly addressed the magnetic properties of single magnetosornes. These nanoparticles behave like single mono-domain nanomagnets, as shown by the comparison of the MFM data to simple simulations. These simulations also provide information on the size of the magnetic kernel of the magnetosomes. Moreover, the invasiveness of the MFM tip is addressed. (c) 2004 Elsevier B.V. All rights reserved.