Abstract
The strongly fluorescent and highly catalytic N-doped carbon dots (CDN) were rapidly prepared by a microwave irradiation procedure and were characterized by electron microscopy (EM), laser scattering, infrared spectroscopy (IR), and by their fluorescence spectrum. It was found that the CDN had a strong catalytic effect on the fluorescence reaction of 3,3′,5,5′-tetramethylbenzidine hydroxide ((TMB)–H2O2) which produced the oxidation product of TMB (TMBOX) with strong fluorescence at 406 nm. The aptamer (Apt) was adsorbed on the CDN surfaces which weakened the fluorescence intensity due to the inhibition of catalytic activity. When the target molecule isocarbophos (IPS) was added, it reacted with the Apt to form a stable conjugate and free CDN which restored the catalytic activity to enhance the fluorescence. Using TMBOX as a fluorescent probe, a highly sensitive nanocatalytic method for determination of 0.025–1.5 μg/L IPS was established with a detection limit of 0.015 μg/L. Coupling the CDN fluorescent probe with the Apt–IPS reaction, a new CD fluorescence method was established for the simple and rapid determination of 0.25–1.5 μg/L IPS with a detection limit of 0.11 μg/L.
Highlights
Nucleic acid aptamers (Apt) can bind to target molecules and have been applied in genomics, food safety, medical diagnosis, biomedicine, and biological analysis [1]
A new Apt sensor based on fluorescence resonance energy transfer has been developed to detect 2–800 ng/mL 17β-estradiol (E2) by using Graphene nanoparticles (GN) as a fluorescent nanoquencher and shorter E2-specific Apt as a sensing probe with a detection limit of 1.02 ng/mL [8]
When a certain concentration of the Apt was present, it adsorbed on the surface of the carbon dot, resulting in the carbon dots (CDs) catalytic action weakening
Summary
Nucleic acid aptamers (Apt) can bind to target molecules and have been applied in genomics, food safety, medical diagnosis, biomedicine, and biological analysis [1]. As a new type of fluorescent nanomaterial, carbon dots (CDs) have received great attention due to their excellent optical properties, good chemical stability, low toxicity, excellent biocompatibility, and surface function adjustability. It has become the most popular carbon nanomaterial after fullerene, carbon nanotubes, and graphene, and has been used in bioimaging, fluorescence sensors, energy conversion, environmental monitoring, and nanomaterials [12,13,14]. Shi et al [30] used carbon dots as fluorescent labeling agents to modify complementary nucleic acids, and immobilized Apt on the surface of Fe3O4 nanoparticles to detect 0.25–50 ng/mL β-lactoglobulin with a detection limit of Nanomaterials 2019, 9, 223. On the basis of the Apt–IPS reaction, the CD fluorescence probe, and the TMBOX probe, two new, rapid, and sensitive methods for the detection of IPS were established
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