Magnetic Langmuir-Blodgett films of ferritin with different iron loadings

Magnetic Langmuir-Blodgett multilayers of two ferritin molecules 1 and 2, containing, respectively, 4220 and 3062 Fe atoms have been prepared by using the adsorption properties of a 6/1 mixed monolayer of dioctadecyldimethylammonium bromide (DODABr) and methyl stearate (SME). Transfer ratios close to unity were reached giving rise to LB films with a strong red colour. Infrared and UV-vis spectroscopy indicates that ferritin molecules are incorporated within the LB films. Magnetic measurements show that the superparamagnetic properties of these molecules are preserved. Thus, a marked hysteresis loop of magnetisation is obtained for LB films of 1 and 2 with a coercive field of 3400 and 2400 G, respectively.