Impedimetric Biosensor for the Determination of Phospholipase A₂ Activity in Snake Venom

ABSTRACT

An impedimetric biosensor to determine the activity of phospholipase A₂ has been developed for the first time. This biosensor is based on the immobilization of enzyme phospholipase A₂ (PLA₂) from snake venom on the surface of a gold electrode. The enzymatic reaction takes place in the presence of L-α-phosphatidylcholine (lecithin) substrate, in 10 mM pH 7.4 phosphate buffer. The impedance of enzymatically modified electrode/electrolyte interface increased as the concentration of lecithin increases. A detection limit of 10⁻¹¹ M and a linear range of 10⁻¹⁰ to 10⁻⁵ M were obtained. At a fixed concentration of lecithin (10⁻³ mM), when the PLA₂ enzyme with a certain level of activity is injected, the impedance of the enzymatically modified electrode/electrolyte interface changed in the inverse direction, due to the competitive effect of injected PLA₂ enzyme. A linear range of 10 to 400 ng/L (corresponding to 16 to 640 U/L) was obtained for commercial naja mossambica mossambica snake venom. The activity of PLA₂ from naja cobra snake venom (Origin Thailand) was determined to be 75% of that of naja mossambica mossambica snake venom.

KEYWORDS:

• Honey bee venom
• nonfaradaic electrochemical impedance spectroscopy
• phospholipase A₂ enzymatic activity
• polarization resistance
• snake venom

Additional information

Funding

The authors thank Halal Food Science Center, Faculty of Science and Technology, Prince of Songkla University, Pattani Campus, Thailand for grant No. 11400.