Recognition of Model Analyte Mixtures in the Presence of Blood Plasma Using a Mixture of Fluorophores (“Fluorescent Tongue”)

Abstract

The paper is devoted to the development of a version of the fingerprint method based on the effect of analytes on the shape of the fluorescence spectrum of a fluorophore mixture. The model analytes were medicinal substances (amikacin, sulfamethoxazole, pyracetam, and chloramphenicol) and binary to quaternary mixtures of these substances in equal concentrations. The mixtures were recognized using a fluorophore whose fluorescence was quenched to different extent by different model analytes (CdSe/CdS/ZnS quantum dots, Schiff base prepared from o-phthalic dialdehyde and polyethyleneimine, and also rhodamine B and fluorescein immobilized on silica nanoparticles to increase the degree of quenching – Rhod/SiO₂ and Fluor/SiO₂). The fluorophores were used as mixtures (“fluorescent reagents”) containing from one to four fluorophores. The classes of analytes were distinguished by calculating Mahalanobis distances on score plots of the principal component analysis method. It was found that it was more difficult to distinguish analyte mixtures in the presence of blood plasma than in a buffer solution and that the best fluorescent reagent was the mixture of all four fluorophores, which ensured the subdivision of 15 mixtures of 2–4 model analytes into seven classes. An alternative fingerprint method based on the use of UV absorption spectra allowed distinguishing of only five classes.