The Preparation of Fluorescence Dual-Modality Nanosensor for Discrimination and Determination of Biothiols in Real Sample and Its Practical Detection Kit

Abstract

Biothiols widely exist in living organisms and have a crucial function in the human body for maintaining redox balance. It is vital yet difficult to develop probes that can detect and distinguish biothiols at the same time. This study presented the use of a very sensitive dual-modality nanosensor, NBD-Nap@NCC, for the discrimination and determination of biothiols in the real sample and its practical application based on RGB analysis by smartphone. The sensitive nanosensor was successfully prepared by surface modification of nanocrystalline cellulose (NCC), combining NBD and naphthalene fluorophores. Due to the high electron-withdrawing behavior of the NBD group which led to the PET mechanism between fluorophores, the prepared NBD-Nap@NCC nanosensor has a very weak fluorescence response. After treatment with Hcy or Cys, NBD-Nap@NCC quickly provided remarkably and in different rates of fluorescence “turn-on” response in both the blue and green channels, which was attributable to naphthalene and NBD fluorophores as a result of inhibition of PET mechanism. However, after treatment with GSH, only a significant blue-channel emission that was attributed to naphthalene fluorophore was obtained, indicating the inhibition of the PET mechanism. Furthermore, the NCC platform improves sensitivity and selectivity by increasing surface area and the number of binding sites due to modification of the NBD group on the surface. The detection limit ranged between 0.910 to 1.150 mol.L-1 for biothiols with large dynamic response ranges. The quantity of the Hcy, Cys and GSH were successfully determined in real sample after the evaluation of accuracy by HPLC and spike/recovery analysis. Additionally, paper-based analysis kits were fabricated for the practical detection of biothiols by RGB changes which were determined via the smartphone application.