Nitrogen doped graphene quantum dots based on host guest interaction for selective dual readout of dopamine

摘要

Herein, yellow emissive nitrogen doped graphene quantum dots (N@GQDs) were prepared by a novel advanced thermal driven oxidation. The N@GQDs was functionalized with beta-cyclodextrin (beta-CD) to improve its catalytic performance towards dopamine (DA) detection. The beta-CD/N@GQDs exhibited strong fluorescence at lambda(em.) = 550 nm after excitation at 460 nm with a quantum yield of 38.6%. The beta-CD/N@GQDs showed good peroxidase like activity via catalyzing the oxidation of tetramethylbenzidine (TMB) in presence of H2O2 to form blue colored product at lambda(max) = 652 nm. In the colorimetric assay of DA, the detection based on the oxidation of TMB by H2O2 in presence of beta-CD/N@GQDs as a catalyst. Then, the color of the blue oxidized TMB (oxTMB) product was reduced by addition of DA. While the fluorometric detection of DA based on the ''inner filter effect" of the overlapped emission spectrum of beta-CD/N@GQDs with the absorption spectrum of oxTMB, where, addition of DA reduces oxTMB to TMB and restores the fluorescence intensity of beta-CD/N@GQDs. Under the optimized conditions, the colorimetric method achieved linearity range of 0.12-7.5 mu M and LOD (S/N = 3) of 0.04 mu M, while the fluorometric method achieved linearity range of 0.028-1.5 mu M and LOD (S/N = 3) of 0.009 mu M. The peroxidase like activity of beta-CD/N@GQDs was used to detect DA in human plasma and serum samples with good % recoveries. The colorimetric and fluorometric methods exhibited good sensitivity and selectivity toward DA detection. (C) 2021 Elsevier B.V. All rights reserved.