Label-free fluorescence assay based on near-infrared B, N-doped carbon dots as a fluorescent probe for the detection of sialic acid
Near-infrared fluorescent nanomaterials are highly promising materials for biomedical applications because of their avoiding of 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 precursor. The prepared near-infrared B, N-doped carbon dots with fluorescence emission wavelength of 645 nm have abundant boric acid groups on the surface of CDs, that can combine with the ortho-dihydroxy group of sialic acid （SA）to form a five-membered ring, leading to the formation of CDs/SA complex, which can enhance the fluorescence intensity of 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.