Surface plasmon resonance method: new applications to sorption kinetics analysis

In our previous work was showed that the SPR technique is very effective for in situ observation of the lipase interaction with MNFcP (9 merkaptononyl - 5' - ferrocenylpentanoate). However, the investigation was performed with only monochromatic 633nm light at the beginning and at the end of the reaction. In this work, the results of the investigation of the reaction kinetics using a tunable light source (&lgr;=600÷1400nm) are presented. Spectral measurements were accomplished with a commercial spectral ellipsometer GES-5 (SOPRA, France). It was demonstrated that this method is sufficiently sensitive for lipase interactions with a thin MNFcP layer (d=3.65nm). It was concluded that the experimental plasmon minimum shift is due to lipase sorption on the MNFcP and, as a result, causes an increase in the effective layer thickness. These results are important in understanding the interaction of these molecules and in determing their size and distribution on the surface.