Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2019 Feb 7;9(2):223.
doi: 10.3390/nano9020223.

Using N-doped Carbon Dots Prepared Rapidly by Microwave Digestion as Nanoprobes and Nanocatalysts for Fluorescence Determination of Ultratrace Isocarbophos with Label-Free Aptamers

Xin Li  1   2 , Xin Jiang  3   4 , Qingye Liu  5   6 , Aihui Liang  7   8 , Zhiliang Jiang  9   10
Affiliations

Using N-doped Carbon Dots Prepared Rapidly by Microwave Digestion as Nanoprobes and Nanocatalysts for Fluorescence Determination of Ultratrace Isocarbophos with Label-Free Aptamers

Xin Li et al. Nanomaterials (Basel). .

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.

Keywords: TMB; aptamer; carbon dot catalysis; fluorescence; isocarbophos.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Principle of carbon dot (CD) and 3,3′,5,5′-tetramethylbenzidine hydroxide oxidation product (TMBOX) probes for isocarbophos (IPS) based on the aptamer (Apt) reaction.
Figure 2
Figure 2
Fluorescence (A) and excited (B) spectra of CDN. (a) 0 mg/L CDN; (b) 129.2 mg/L CDN; (c) 265.2 mg/L CDN; (d) 530.4 mg/L CDN; (e) 1060.8 mg/L CDN; (f) 2128.4 mg/L CDN; (g) 4250 mg/L CDN; (h) 8500 mg/L CDN; (i) 17,000 mg/L CDN.
Figure 3
Figure 3
Fluorescence (A) and excited (B) spectra of the Apt–IPS–CDN system. (a) 0.21 μmol/L Apt + 11.28 mg/L CDN + 0.027 mol/L NaH2PO4–Na2HPO4; (b) a + 0.25 μg/L IPS; (c) a + 0.5μg/L IPS; (d) a + 0.75μg/L IPS; (e) a + 1.0 μg/L IPS; (f) a + 1.25 μg/L IPS; (g) a + 1.5μg/L IPS.
Figure 4
Figure 4
Fluorescence of the CDN catalytic system (A) Fluorescence spectra of the Apt–IPS–CDN–H2O2–TMB catalytic analytical system, a: 31 nmol/L Apt + 0.45 mg/L CDN + 0.053 mmol/L H2O2 + 0.017 mmol/L TMB + 0.13 mmol/L pH 3.6 HAc–NaAc; b: a + 0.025 μg/L IPS; c: a + 0.1μg/L IPS; d: a + 0.3μg/L IPS; e: a + 0.5μg/L IPS; f: a + 0.7μg/L IPS; g: a + 0.9μg/L IPS; h: a + 1.2μg/L IPS. (B) Excited spectra of A. (C) Fluorescence spectra of the CDN–H2O2–TMB catalytic system, a: 0.13 mmol/L H2O2+33 μmol/L TMB + 0.13 mmol/L pH 3.6 HAc–NaAc; b: a + 0.028 mg/L CDN; c: a + 0.057 mg/L CDN; d: a + 0.113 mg/L CDN; e: a + 0.17 mg/L CDN; f: a + 0.34 mg/L CDN. (D) Fluorescence spectra of the Apt–CDN–H2O2–TMB system, a: 0.34 mg/L CDN + 0.053 mmol/L H2O2 + 0.017 mmol/L TMB + 0.13 mmol/L pH 3.6 HAc–NaAc; b: a + 5.17 nmol/L Apt; c: a + 7.23 nmol/L Apt; d: a + 10.33 nmol/L Apt; e: a + 15.5 nmol/L Apt IPS; f: a + 20.67 nmol/L Apt; g: a + 25.83 nmol/L Apt; h: a + 31 nmol/L Apt.
Figure 5
Figure 5
Mechanism of catalytic reaction of nitrogen-doped carbon dots.
Figure 6
Figure 6
(A) SEM, (B) TEM, (C) laser scattering, and (D) IR of CDN.
See this image and copyright information in PMC

References

    1. Huang R.R., Xi Z.J., He N.Y. Applications of aptamers for chemistry analysis, medicine and food security. Sci. Chi. Chem. 2015;58:1122–1130. doi: 10.1007/s11426-015-5344-7. - DOI
    1. Mahin S., Taghdisib S.M., Ansaric N., Langroodia F.A., Abnousd K., Ramezanie M. Aptamer based biosensors for detection of Staphylococcus aureus. Sens. Actuators B. 2017;241:619–635.
    1. Zhong D.L., Li Y.F., Jian L., Cheng Z.H. A Localized Surface Plasmon Resonance Light-Scattering Assay of Mercury (II) on the Basis of Hg2+−DNA Complex Induced Aggregation of Gold Nanoparticles. Environ. Sci. Technol. 2009;43:5022–5027. - PubMed
    1. Du G.S., Zhang D.W., Xia B., Xu L.R., Wu S.J., Zhan S.S., Ni X., Zhou X.T., Wang L.M. A label-free colorimetric progesterone aptasensor based on the aggregation of gold nanoparticles. Microchim. Acta. 2016;183:2251–2258. doi: 10.1007/s00604-016-1861-0. - DOI
    1. Ma L., Wen G.Q., Liu Q.Y., Liang A.H., Jiang Z.L. Resonance Rayleigh scattering determination of trace tobramycin using aptamer-modified nanogold as probe. Spectrosc. Spect. Anal. 2014;34:2481–2484. - PubMed