Copper, zinc superoxide dismutase and nitrate reductase coimmobilized bienzymatic biosensor for the simultaneous determination of nitrite and nitrate.
This work presents a novel bienzymatic biosensor for the simultaneous determination of nitrite (NO2(-)) and nitrate (NO3(-)) ions using copper, zinc superoxide dismutase (SOD1) and nitrate reductase (NaR) coimmobilized on carbon nanotubes (CNT)-polypyrrole (PPy) nanocomposite modified platinum electrode. Morphological changes of the PPy and CNT modified electrodes were investigated using scanning electron microscopy. The electrochemical behavior of the bienzymatic electrode (NaR-SOD1-CNT-PPy-Pt) was characterized by cyclic voltammetry exhibiting quasi-reversible redox peak at +0.06 V and reversible redox peaks at -0.76 and -0.62V vs. Ag/AgCl, for the immobilized SOD1 and NaR respectively. The electrocatalytic activity of SOD1 towards NO2(-) oxidation observed at +0.8 V was linear from 100 nM to 1mM with a detection limit of 50 nM and sensitivity of 98.5 ± 1.7 nA µM(-1)cm(-2). Similarly, the coimmobilized NaR showed its electrocatalytic activity towards NO3(-) reduction at -0.76 V exhibiting linear response from 500 nM to 10mM NO3(-) with a detection limit of 200 nM and sensitivity of 84.5 ± 1.56 nA µM(-1)cm(-2). Further, the present bienzymatic biosensor coated with cellulose acetate membrane for the removal of non-specific proteins was used for the sensitive and selective determinations of NO2(-) and NO3(-) present in human plasma, whole blood and saliva samples.
Biomedical Research Laboratory, Department of Chemistry, VHNSN College (Autonomous), Virudhunagar 626001, Tamil Nadu, India.
Thangamuthu
T
Madasamy
Manickam
M
Pandiaraj
Murugesan
M
Balamurugan
Kalpana
K
Bhargava
Niroj Kumar
NK
Sethy
Chandran
C
Karunakaran
D015374:Biosensing Techniques / Q000379:methods*; D004800:Enzymes, Immobilized / Q000737:chemistry; D006801:Humans; D050901:Nitrate Reductase / Q000737:chemistry; D009566:Nitrates / Q000097:blood / Q000302:isolation & purification*; D009573:Nitrites / Q000097:blood / Q000302:isolation & purification*; D013482:Superoxide Dismutase / Q000737:chemistry*
D004800:Enzymes, Immobilized; D009566:Nitrates; D009573:Nitrites; D013482:Superoxide Dismutase; D050901:Nitrate Reductase
Bienzymatic biosensor; Copper, zinc superoxide dismutase; Nitrate; Nitrate reductase; Nitrite; Simultaneous determination