A Nitrite Biosensor Based on Coimmobilization of Nitrite Reductase and Viologen‐Modified Polysiloxane on Glassy Carbon Electrode

Abstract

AbstractCopper containing nitrite reductase (Cu‐NiR) and viologen‐modified sulfonated polyaminopropylsiloxane (PAPS‐SO3H‐V) were co‐immobilized on glassy carbon electrode (GCE) by hydrophilic polyurethane (HPU) drop‐coating, and the electrode was tested as a reagentless electrochemical biosensor for nitrite detection. The newly synthesized PAPS‐SO3H‐V as an electron transfer (ET) mediator between electrode and NiR was effective, and could be effectively immobilized in HPU membrane. The NiR and PAPS‐SO3H‐V co‐immobilized GCE used as a nitrite biosensor showed the following performance factors: sensitivity=12.0 nA μM−1, limit of detection (LOD)=60 nM (S/N=3), linear response range=0–18 μM (r2=0.996) and response time (t90%)=60 s, respectively. Lineweaver–Burk plot shows that apparent Michaelis–Menten constant (K$\rm{{_{M}^{app}})}$ is 101 μM. Storage stability of the sensor is 51 days (80% of initial activity) in condition of storing in ambient air at room temperature. The sensor showed a relative standard deviation (RSD) of 3.2% (n=5) even in condition of injection of 1 μM nitrite. Interference study showed that common anions in water sample such as chlorate, chloride, sulfate and sulfite do not interfere with the nitrite detection. However, nitrate interfered with a relative sensitivity of 80% due to inherent character of the enzyme used.