Nitrogen-Doped Graphene Quantum Dots@SiO₂ Nanoparticles as Electrochemiluminescence and Fluorescence Signal Indicators for Magnetically Controlled Aptasensor with Dual Detection Channels

Abstract

We proposed a facile method to prepare the nitrogen-doped graphene quantum dots (NGQDs) doped silica (NGQDs@SiO2) nanoparticles (NPs). The NGQDs@SiO2 NPs were further explored as a versatile signal indicator for ochratoxin A (OTA) aptasensing by combination with electrochemiluminescence (ECL) and fluorescence (FL) detection. In this strategy, the core-shell Fe3O4@Au magnetic beads (MBs) acted as a nanocarrier to immobilize the thiolated aptamer specific for OTA, and the amino modified capture DNA (cDNA) was efficiently tagged with NGQDs@SiO2 NPs. The multifunctional aptasensor was thus fabricated by assembly of the NGQDs@SiO2 NPs onto the surface of Fe3O4@Au MBs through the high specific DNA hybridization between aptamer and cDNA. Upon OTA incubation, the aptamer linked with Fe3O4@Au MBs preferred to form an aptamer-OTA complex, which resulted in the partial release of the preloaded NGQDs@SiO2 NPs. The more OTA molecules in the detection system, the more NGQDs@SiO2 NPs were released into the bulk solution and the less preloaded NGQDs@SiO2 NPs were accumulated on the magnetic electrode surface. This provided a dual channel for OTA detection by combination with the enriched solid-state ECL and homogeneous FL detection. The FL assay exhibits a wide dynamic range and is more reproducible due to the homogeneous detection while the ECL assay possesses a lower detection limit and is preferable by using a cheaper instrument. One can obtain a preliminary screen from FL assay and a more accurate result from ECL assay. Integrating the virtues of dual analytical modality, this aptasensing strategy well-balanced the rapidity, sensitivity, and dynamic range, making it promising to other targets with aptamer sequences.

A novel electrochemiluminescence sensor for the detection of nitroaniline based on the nitrogen-doped graphene quantum dots

“…S2A. Three peaks at 284.58, 400.75 and 531.34 eV can be attributed to C 1s, N 1s, and O 1s, respectively (Wang et al, 2015a(Wang et al, ,2015b. The C 1 s XPS can be deconvoluted into four peaks at 284.39, 285.11, 286.53, and 288.14 eV (Fig.…”

“…So, the highly sensitive and selective sensors for rapid and effective detection of NA is an extremely urgent issue concerning homeland security, environmental protection and humanitarian concerns. At present, various methods have been employed for the determination of NA, including capillary zone electrophoresis (Chen et al, 2012) and luminescent analytical methods Wang et al, 2015aWang et al, , 2015b. However, these methods reported previously suffered from limitations of complicated synthetic process, time-consuming and high operational cost.…”

“…Recently, luminescent methods have been combined with electrochemical techniques to expand GQDsbased sensing applications (Liu et al, 2014;Wu et al, 2015). And researchers have established kinds of N-GQDs-based ECL sensors which were successfully used to detect small molecules, organic compounds, protein, and so on (Zhang et al, 2015a(Zhang et al, , 2015bZhou et al, 2015;Du et al, 2015;Wang et al, 2015aWang et al, , 2015b.…”

Electrochemiluminescent functional nucleic acids‐based sensors for food analysis

“…Table lists the application of ECL aptasensor for common toxins in food. Ochratoxin A (OTA), one kind of ochratoxins, has been extensively studied because it is a potential carcinogen . Using N ‐(4‐aminobutyl)‐ N ‐ethyl‐isoluminol (ABEI) as the ECL probe, Wang et al reported a simple ECL aptasensor for OTA with a LOD of 0.007 ng/mL .…”

“…In these ECL aptasensors, ECL probes‐labeled DNAs or targets are obtained by complex cross‐linkers and purification processes, which were time‐consuming and of low yield. The development of label‐free ECL aptasensors could overcome these drawbacks . Wang et al used Ru(phen) 3 2+ as the probe to develop an aptasensor for adenosine and lysozyme, with the linear ranges of 0.5 × 10 −9 to 7 × 10 −9 mol/L and 0.5 to 9 ng/mL, respectively.…”