Fluorescent detection of aspartate transaminase using N-doped carbon dots

Abstract

The evident spike in the mortality caused due to liver disorders such as liver cirrhosis raised an urgent need for rapid and accurate diagnosis of the disease. Recently, fluorescent carbon dots emerged as an excellent platform for rapid testing in biomedical research. In this work, carbon dots were synthesized by the facile one-step microwave-assisted process by using starch and 50X TAE buffer as the precursors. The synthesized novel nitrogen-doped carbon dots (NCD) exhibited bright blue color fluorescence under the UV lamp. The photoluminescence emission intensity peak was found to be maximum at 440 nm under an excitation wavelength of 350 nm (λex/λem ∼ 350/440 nm). The quantum yield of NCD was calculated as 53%. The microscopic analysis of NCD showed a uniformly spherical carbon dots with an average hydrodynamic diameter measured as 2.8 ± 0.8 nm. The synthesized NCD has been deployed for the detection of oxaloacetate as a biomarker for estimating the level of aspartate transaminase directly or indirectly in liver disorder. The PL emission response of NCD enhances as the concentration of oxaloacetate increases. The role of interfering agents such as Bilirubin (BR), Uric acid (UA), Ascorbic acid (AA), Glucose (Glu), and many more were tested against a similar concentration of oxaloacetate biomarker. The study revealed the higher selectivity of NCD towards oxaloacetate in the presence of several interfering molecules.