AMPEROMETRIC NITRIC OXIDE BIOSENSOR BASED ON THE IMMOBILIZATION OF HEMOGLOBIN ON A NANOMETER-SIZED GOLD COLLOID MODIFIED AU ELECTRODE.

A novel reagentless NO biosensor based on hemoglobin (Hb) immobilized on nanometer-sized gold colloid particles associated with a cysteamine monolayer on gold electrode surface was presented. The experimental optimization was studied in detail. The immobilized Hb displayed an excellent electrocatalytic response to NO. The electrocatalytic currents were proportional to the NO concentration from 1.2 × 10[sup -8] to 5.0 × 10[sup -6] M and the detection limit was as low as 4.0 × 10[sup -9] M (S/N = 3) with good stability. Arginine, ascorbate, nitrite, uric acid, epinephrine and cystine didn't interfere with the determination of NO. The Michaelis-Menten constant (K[sub m]) was determined to be 0.19 mM. This resulting biosensor has been applied to the direct determination of trace NO in raw blood. [ABSTRACT FROM AUTHOR]