Novel Siloxane Derivatives as Membrane Precursors for Lactate Oxidase Immobilization

Abstract

We report new enzyme-containing siloxane membranes for biosensor elaboration. Lactate oxidase immobilization from water-organic mixtures with a high concentration of organic solvent (90%) leads to advanced lactate biosensors. The use of the new alkoxysilane monomers-(3-aminopropyl)trimethoxysilane (APTMS) and trimethoxy[3-(methylamino)propyl]silane (MAPS)-as the base for enzyme-containing membrane construction resulted in a biosensor with up to a two times higher sensitivity (0.5 A·M^-1·cm^-2) compared to the biosensor based on (3-aminopropyl)triethoxysilane (APTES) we reported previously. The validity of the elaborated lactate biosensor for blood serum analysis was shown using standard human serum samples. The developed lactate biosensors were validated through analysis of human blood serum.

Keywords: Prussian blue; immobilization from water–organic mixtures; lactate biosensor; siloxane.

Figure 1

(a) The calibration curve for the lactate biosensor with a 1 _vol% of MAPS in an enzyme-containing membrane solution; (b) calibration graph for the lactate biosensor in the batch mode (E = 0.00 V, phosphate buffer, pH 6.0). The zoomed initial parts of the correspondent dependencies are shown in the insets.

Figure 2

Dependence of the lactate biosensor sensitivity on the siloxane concentration in the membrane solution. Siloxanes: MAPS (■) and APTMS (●).

Figure 3

Residual sensitivity of the lactate biosensor after storage in the refrigerator (4 °C).