Label-free fluorescence assay based on near-infrared B,N-doped carbon dots as a fluorescent probe for the detection of sialic acid

Abstract

Near-infrared fluorescent nanomaterials are highly promising materials for biomedical applications because of their avoidance of the auto-fluorescence of organisms. We herein report a facile one-pot synthesis of near-infrared B,N co-doped carbon dots (CDs) by using o-phenylenediamine (OPD) and 3-aminophenylboronic acid (ABPA) as precursors. The prepared near-infrared B,N-doped carbon dots with a fluorescence emission wavelength of 645 nm have abundant boric acid groups on the surface of the CDs that can combine with the ortho-dihydroxy group of sialic acid (SA) to form a five-membered ring, leading to the formation of a CD/SA complex, which can enhance the fluorescence intensity of the CDs. Thus a simple and sensitive fluorescence method for the detection of sialic acid was established. The fluorescence intensity change of the system (F/F₀) exhibited a good linear relationship with the concentration of sialic acid in the range of 20–1000 μM with a detection limit of 9.24 μM. This near-infrared fluorescent probe was successfully applied to the detection of sialic acid in simulating human saliva samples with satisfactory results.