Bienzymatic Biosensor for Malic Acid Based on Malate Dehydrogenase and Transaminase Immobilized onto a Glassy Carbon Powder/Carbon Nanotubes/Nad+ Composite Electrode
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- 作者：Rodolfo Mundaca-Uribe ; Daniela Valencia-Muñ ; oz ; Rosario Castillo Felices ; José ; Neira Hinojosa ; Mario Aranda Bustos and Carlos Peñ ; a-Farfal
- 刊名：Electroanalysis
- 出版年：2017
- 出版时间：January 2017
- 年：2017
- 卷：29
- 期：1
- 页码：238-243
- 全文大小：846K
- ISSN：1521-4109
文摘
A biosensor for malic acid detection in fruit juices, based on malate dehydrogenase (MDH) glutamate oxaloacetate transaminase (GOT) in a powder vitreous carbon, carbon nanotubes and mineral oil, composite matrix has been developed. By employing amperometry at a constant potential of 0.4 V (vs. Ag/AgCl), an enzymatic reaction promoted by these species in a support solution Mc Ilvaine buffer (phosphate/citrate pH 10.0) with glutamic acid was generated, causing the oxidation of electro active species, that was stoichiometrically equal to the amount of malic acid present in the sample. The response was linear over the range 2–50 mM, with an analytical sensitivity of 2.24×10−4 to 2,55×10−4 AM−1 and r2=0.9980 to 0.9983, a LOD of 4.02 μM and LOQ of 13.4 μM. Malic acid concentration detected was 0.23–1.07 g/L in fruit juice samples. Results were validated using an enzymatic spectrophotometric method as a reference. To the best of our knowledge, this is the first bienzymatic biosensor using both malate dehydrogenase and glutamate oxaloacetate transaminase enzymes.