Chitosan polymer as support to IgG immobilization for piezoelectric applications

Immunoenzymatic assays using gold plates and quartz crystal microbalance (QCM) analysis were carried out in order to evaluate chitosan/IgG interaction. Two chitosan solutions (S1 and S2) were prepared with different concentrations of NaOH (0.8% – S1 and 8% – S2). Absorbances 3-fold higher were obtained when chitosan (S2) was used as support when compared with direct IgG adsorption on gold. S1 on gold showed a better stability (at 22 °C, for 72 h) for IgG immobilization when compared with S2. However, S1 was used on QCM analysis and the IgG adsorption led to a non-Sauerbrey response, in which the mass on the electrode surface promote a proportional increase in the crystal resonant frequency. Direct IgG adsorption on gold electrode led to a 14.19% (±2.43) increase in crystal frequency. When S1 was used as a support for IgG, a better immobilization occurred, causing a 24.34% (±0.75) variation in crystal frequency. The structure of chitosan was shown to be efficient for IgG immobilization both in the immunoenzymatic method and in the QCM system.