Quantificationof the Kynurenine Biomarker in SalivaUsing Smatphone-Based Fluorescence Digital Imaging

作者：José Gouveia da Silva Neto, Luis Vinicius Gonçalves de Melo, José Ailton Mota Nascimento, Helayne S. de Sousa, João Paulo Almeida, Severino Carlos Oliveira, Vagner Bezerra dos Santos · 发表于：Figshare · 年份：2026 · DOI：10.1021/acsomega.5c11977.s001 · 研究领域：Tryptophan and brain disorders、Biosensors and Analytical Detection、Carbon and Quantum Dots Applications

L-tryptophan (Trp) is an essential amino acid whose metabolism produces biologically relevant compounds such as serotonin, melatonin, kynurenine (Kyn), kynurenic acid (Kyna), and nicotinamide adenine dinucleotide (NAD+). Alterations in kynurenine pathway metabolism have been associated with several neurological and neurodegenerative disorders. Due to this importance, this study presents a fluorescence digital image-based (FDIB) analytical method for the quantification of kynurenine (Kyn) using a smartphone. The method is based on the derivatization reaction of Kyn with dansyl chloride (DNS-Cl), since the Kyn-DNS product exhibits high fluorescence when excited at 365 ± 50 nm. Thus, a UV-LED chamber was fabricated on a 3D printer, and it was used for excitation, as well as for capturing the fluorescence of Kyn-DNS using a smartphone, leading to the Kyn-DNS/3Dchamber/FDIB analytical method. The proposed method showed a linear range from 0.50 to 7.00 μmol L –1 , limit of detection (LOD) of 0.05 μmol L –1 and precision below 2.68%, making it suitable for quantifying Kyn in biological samples such as saliva and urine. The accuracy of the method was evaluated by recovery tests, and a recovery rate from 92.1% to 106% was achieved for synthetic saliva samples. A good agreement at a 95% confidence level with n = 3 was obtained when comparing the FDIB results with those supplied by spectrofluorometry and HPLC-UV methods, which certify the accuracy of the method. The Kyn-DNS/3Dchamber/F...