Amperometric biosensor for direct blood lactate detection.
An amperometric sensor for lactate quantification is presented. The developed biosensor requires only 0.2 U of lactate oxidase, which is immobilized in a mucin/albumin hydrogel matrix. By protecting the platinum surface with a Nafion membrane, typical interference related to negatively charged species such as ascorbic acid has been minimized to practically undetectable levels. Electrochemical properties associated with the Nafion membrane are assessed as a function of Nafion concentration. In a phosphate buffer solution of pH 7.0, linear dependence of the catalytic current upon lactate bulk concentration was obtained between 2 and approximately 1000 microM. A detection limit of 0.8 microM can be calculated considering 3 times the standard deviation of the blank signal divided by the sensitivity of the sensor. The lactate biosensor presents remarkable operational stability and sensitivity (0.537 +/- 0.007) mA.M(-1), where the error is the standard deviation of the slope calculated from the linear regression of the calibration curve of a fresh biosensor. In this regard, the sensor keeps practically the same sensitivity for 5 months, while the linear range decreases until an upper value of 0.8 mM is reached. Assays performed with whole blood samples spiked with 100 microM lactate gave (89 +/- 6)% of recovery.
INFIQC, Departimento de Físico Química, Faculdad de Ciencias Químicas, UNC, Pab. Argentina, Ala 1, 2 degrees piso, Ciudad Universitaria, 5000 Córdoba, Argentina.
Marcelo Ricardo
MR
Romero
Facundo
F
Ahumada
Fernando
F
Garay
Ana M
AM
Baruzzi
D000418:Albumins / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods*; D055664:Electrochemical Techniques / Q000379:methods*; D004566:Electrodes; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism; D020100:Hydrogels / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000097:blood*; D006899:Mixed Function Oxygenases / Q000737:chemistry / Q000378:metabolism; D009077:Mucins / Q000737:chemistry; D010984:Platinum / Q000737:chemistry
D000418:Albumins; D004800:Enzymes, Immobilized; D020100:Hydrogels; D009077:Mucins; D019344:Lactic Acid; D010984:Platinum; D006899:Mixed Function Oxygenases; C021497:lactate 2-monooxygenase