Gold nanoparticle formation as an indicator of enzymatic methods: colorimetric l-phenylalanine determination

  An enzymatic-colorimetric method has been developed based on the reaction between l -phenylalanine ( l -Phe) and the l -amino acid oxidase (LAAO) in the presence of Au(III), which has led to the formation of gold nanoparticles. The intensity of the localized surface plasmon resonance (LSPR) band o...

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Bibliographic Details
Published in:Analytical and bioanalytical chemistry 2022-03, Vol.414 (8), p.2641-2649
Main Authors: Martín-Barreiro, Alba, de Marcos, Susana, Galbán, Javier
Format: Article
Language:English
Subjects:
Amino acid oxidase
Amino acids
Analysis
Analytical Chemistry
Biochemistry
Blood plasma
Characterization and Evaluation of Materials
Chemical synthesis
Chemistry
Chemistry and Materials Science
Colorimetric analysis
Colorimetry
Colorimetry - methods
Enzymes
Food Science
Gold
Gold - chemistry
Laboratory Medicine
Limit of Detection
Metal Nanoparticles - chemistry
Methods
Monitoring/Environmental Analysis
Nanoparticles
Optimization
Phenylalanine
Research Paper
Structure
Substrates
Surface plasmon resonance
Surface Plasmon Resonance - methods
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Summary:  An enzymatic-colorimetric method has been developed based on the reaction between l -phenylalanine ( l -Phe) and the l -amino acid oxidase (LAAO) in the presence of Au(III), which has led to the formation of gold nanoparticles. The intensity of the localized surface plasmon resonance (LSPR) band of the generated nanoparticles (550 nm) can be related to the concentration of l -Phe in the sample. The mechanism of the LAAO- l -Phe enzyme reaction in the presence of Au(III) has been studied through the evaluation and optimization of experimental conditions. These studies have reinforced the hypothesis that the catalytic center of the enzyme helps the Au(III) reduction and, thanks to the protein, the Au 0 form is stabilized as gold nanoparticles (AuNPs). In the calibration study, a sigmoidal relationship between the concentration of the substrate and the LSPR of the nanoparticles was observed. The linearization of the signal has allowed the determination of l -Phe in the range from 17 to 500 µM with an RSD% (150 μM) of 4.8% ( n  = 3). The method is free of other amino acid interference normally found in blood plasma. These highly competitive results open the possibility of further development of a rapid method for l -Phe determination based on colorimetry. Graphical abstract
ISSN:1618-2642
1618-2650
DOI:10.1007/s00216-022-03900-3