Dual-emission ratiometric fluorescent probe based on N-doped CQDs@UiO-66/PVA nanocomposite hydrogel for quantification of pethidine in human plasma.

A synchronous fluorescence spectroscopy (SFS) sensor for pethidine detection is described based on UiO-66 metal-organic frameworks (MOFs) modified with N-doped carbon quantum dots (N-CQDs) embedded in hydrogel nanocomposites. Benefitting from the inovative  design of the doping method in the carbonaceous structure, N-CQDs were successfully deposited in the pores of the UiO-66 network. Then, N-CQDs were employed as a sensitive segment toward the target molecules. UiO-66 was used for sensitive and selective sensing of the bonding interactions between N-CQDs and pethidine so that the electron transfer process from UiO-66 to the pethidine-N-CQD complex results in quenching the SFS intensity of UiO-66. To embed the stable and suitable sensing interface for pethidine assessment, the designed nanomaterial was inserted into the hydrogel network. This nanocomposite hydrogel showed two well-resolved emission peaks at 300 nm and 350 nm under ∆λ = 70, which corresponded to N-CQDs and UiO-66, respectively. The SFS sensing platform was employed for ratiometric detection of pethidine with a low limit of detection of 0.002 μg mL over a wide concentration range from 0.005 to 1.0 μg mL. The accurate monitoring of pethidine with a good recovery of 90.8-101.5% indicated their independency from matrix effects for pethidine detection in human plasma being a complicated biological matrix. Scheme 1. General procedure for synthesizing N-CQDs@UiO-66/PVA hydrogel-based nanoprobe and its application for pethidine determination.