Properties of modified amperometric biosensors based on methanol dehydrogenase and cells Methylobacterium nodulans

The properties of amperometric biosensors based on methanol dehydrogenase (MDH) Methylobacterium nodulans , cells, and the ferrocene-modified carbon paste electrode were investigated. It was shown that the addition of hydroxyapatite (HA) to a carbon paste increased the sensitivity and operating stability of MDH biosensors. The linear range of the electrode was 0.0135–0.5 and 0.032–1.5 mM for methanol and formaldehyde, respectively. The detection limit of methanol and formaldehyde was 4.5 and 11.0 μM, respectively. The loss of activity of the electrode within 10 days of storage in the presence of 2.0 mM KCN did not exceed 12%. Cyanide (10 mM) completely inhibited the sensor responses to formaldehyde (1.0 mM), which allowed for the selective determination of methanol in the presence of formaldehyde. The biosensor based on cells exhibited lower stability and sensitivity toward methanol and formaldehyde; the sensitivity coefficients were 980 and 21 nA/mM, respectively.