Study of hemoglobin-octadecylamine LB film formation and deposition by compressibility analyse, QCM and AFM

Hemoglobin (Hb)-octadecylamine (ODA) Langmuir–Blodgett film was formed by spreading Hb solution directly onto subphase covered with a layer of ODA. The optimum equilibrium time of HSA interacted with ODA layer, the optimum amount of protein spread on subphase’s interface and the optimum ionic strength and pH of subphase were obtained according to the experimental results. The compressibility of Hb–ODA film in compressing process indicated that at least two types of phase transition occurred. The complex LB film is very stable and can be used to modify electrode surface. AFM images of complex monolayer deposited on Au (1 1 1) surface under different surface pressures indicated that rearrangement and reorientation of Hb molecules in ODA film on Au (1 1 1) surface occurred during the phase transition process by compressing monolayer. The well ordered Hb–ODA LB film on solid surface can be obtained by depositing it under surface pressure range of 35–40 mN/m.