Highly Sensitive and Selective Detection of L-Tryptophan by ECL Using Boron-Doped Diamond Electrodes

• Published in: Sensors (Basel, Switzerland) Switzerland), 2024-06, Vol.24 (11), p.3627
• Main Authors: Scorsone, Emmanuel, Stewart, Samuel, Hamel, Matthieu
• Format: Article
• Language: English
• Subjects: Amino acids; Aqueous solutions; Biosensing Techniques - methods; Boron; Boron - chemistry; boron-doped diamond; Carbon; Chemical vapor deposition; Detectors; Diamond - chemistry; Electrochemical Techniques - methods; electrochemiluminescence; Electrodes; Electrons; High performance liquid chromatography; Humans; Hydrogen peroxide; Hydrogen Peroxide - analysis; Hydrogen Peroxide - chemistry; L-tryptophan; Limit of Detection; Luminescent Measurements - methods; Methods; Oxidation; Phosphates; Silicon wafers; Stereoisomers; Tryptophan; Tryptophan - analysis; Tryptophan - chemistry
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s24113627

L-tryptophan is an amino acid that is essential to the metabolism of humans. Therefore, there is a high interest for its detection in biological fluids including blood, urine, and saliva for medical studies, but also in food products. Towards this goal, we report on a new electrochemiluminescence (ECL) method for L-tryptophan detection involving the in situ production of hydrogen peroxide at the surface of boron-doped diamond (BDD) electrodes. We demonstrate that the ECL response efficiency is directly related to H O production at the electrode surface and propose a mechanism for the ECL emission of L-tryptophan. After optimizing the analytical conditions, we show that the ECL response to L-tryptophan is directly linear with concentration in the range of 0.005 to 1 µM. We achieved a limit of detection of 0.4 nM and limit of quantification of 1.4 nM in phosphate buffer saline (PBS, pH 7.4). Good selectivity against other indolic compounds (serotonin, 3-methylindole, tryptamine, indole) potentially found in biological fluids was observed, thus making this approach highly promising for quantifying L-tryptophan in a broad range of aqueous matrices of interest.