Rapid and Sensitive Detection of Aspergillus niger Using a Single-Mediator System Combined with Redox Cycling
| Autor: | Eun-Min Cho, Sung Ik Yang, Jungwook Kwon, Ponnusamy Nandhakumar, Haesik Yang |
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| Rok vydání: | 2018 |
| Předmět: |
Tris
Microbiological Techniques Naphthols 010402 general chemistry Electrochemistry 01 natural sciences Sensitivity and Specificity Analytical Chemistry Electron transfer chemistry.chemical_compound Limit of Detection Humans Detection limit biology 010401 analytical chemistry Aspergillus niger Substrate (chemistry) NADPH Oxidases Reproducibility of Results Electrochemical Techniques biology.organism_classification Nitro Compounds Combinatorial chemistry 0104 chemical sciences Membrane chemistry NAD+ kinase Oxidation-Reduction |
| Zdroj: | Analytical chemistry. 90(22) |
| ISSN: | 1520-6882 |
| Popis: | Rapid and sensitive mold detection is becoming increasingly important, especially in indoor environments. Common mold detection methods based on double-mediated electron transfer between an electrode and molds are not highly sensitive and reproducible, although they are rapid and simple. Here, we report a sensitive and reproducible detection method specific to Aspergillus niger ( A. niger), based on a single-mediator system combined with electrochemical-chemical (EC) redox cycling. Intracellular NAD(P)H-oxidizing enzymes in molds can convert electro-inactive hydroxy-nitro(so)arenes into electro-active hydroxy-aminoarenes. Since the membrane and wall of A. niger is well permeable to both a substrate (4-nitro-1-naphthol) and a reduced product (4-amino-1-naphthol) in tris buffer (pH 7.5) solution, the electrochemical signal is increased in the presence of A. niger due to two reactions: (i) enzymatic reduction of the substrate to the reduced product and (ii) electrochemical oxidation of the reduced product to an oxidized product. When a reducing agent (NADH) is present in the solution, the oxidized product is reduced back to the reduced product and then electrochemically reoxidized. This EC redox cycling significantly amplifies the electrochemical signal. Moreover, the background level is low and highly reproducible because the substrate and the reducing agent are electro-inactive at an applied potential of 0.20 V. The calculated detection limit for A. niger in a common double-mediator system consisting of Fe(CN) |
| Databáze: | OpenAIRE |
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