Journal of Fluorescence

, Volume 26, Issue 6, pp 2199–2212 | Cite as

Graphene Quantum Dots Functionalized with 4-Amino-2, 2, 6, 6-Tetramethylpiperidine-N-Oxide as Fluorescence “Turn-ON” Nanosensors

  • Ojodomo J. Achadu
  • Jonathan Britton
  • Tebello Nyokong


In this study, we report on the fabrication of simple and rapid graphene quantum dots (GQDs)-based fluorescence “turn-ON” nanoprobes for sensitive and selective detection of ascorbic acid (AA). Pristine GQDs and S and N co-doped-GQDs (SN-GQDs) were functionalized with 4-amino-2,2,6,6-tetramethylpiperidine-N-oxide (4-amino-TEMPO, a nitroxide free radical). The nitroxide free radicals efficiently quenched the fluorescence of the GQDs and upon interaction of the nanoconjugates with ascorbic acid, the quenched fluorescence was restored. The linear ranges recorded were 0.5–5.7 μM and 0.1–5.5 μM for GQDs-4-amino-TEMPO and SN-GQDs-4amino-TEMPO nanoprobes, respectively. Limits of detection were found to be 60 nM and 84 nM for SN-GQDS-4-amino-TEMPO and GQDs-4-amino-TEMPO for AA detection, respectively. This novel fluorescence “turn-ON” technique showed to be highly rapid and selective towards AA detection.


Graphene quantum dots 4-amino-2,2,6,6-tetramethylpiperidine-N-oxide Fluorescence “turn-ON” Ascorbic acid Nanoconjugates 



This work was supported by the Department of Science and Technology (DST) and National Research Foundation (NRF), South Africa through DST/NRF South African Research Chairs Initiative for Professor of Medicinal Chemistry and Nanotechnology (UID 62620) as well as Rhodes University/DST Centre for Nanotechnology Innovation, Rhodes University, South Africa.

Supplementary material

10895_2016_1916_MOESM1_ESM.doc (47 kb)
ESM 1 (DOC 46 kb)
10895_2016_1916_MOESM2_ESM.doc (25 kb)
ESM 2 (DOC 25 kb)
10895_2016_1916_MOESM3_ESM.doc (103 kb)
ESM 3 (DOC 102 kb)


  1. 1.
    Lin L, Rong M, Luo F, Chen D, Wang Y, Chen X (2014) Luminescent graphene quantum dots as new fluorescent materials for environmental and biological applications. Trends Anal Chem 54:83–102CrossRefGoogle Scholar
  2. 2.
    Ge J, Minhuan L, Zhou B, Liu W, Guo L, Wang H, Jia Q, Niu G, Huang X, Zhou H, Xiangmin M, Pengfei W, Chun-Sing L, Zhang W, Han X (2014) A graphene quantum dot photodynamic therapy agent with high singlet oxygen generation. Nat Commun 5:4596PubMedPubMedCentralGoogle Scholar
  3. 3.
    Zhu S, Zhang J, Liu X, Li B, Wang X, Tang S, Meng Q, Li Y, Shi C, Hu R, Yang B (2012) Graphene quantum dots with controllable surface oxidation, tunable fluorescence and up-conversion emission. RSC Adv 2:2717–2720CrossRefGoogle Scholar
  4. 4.
    Lin F, Pei D, He W, Huang Z, Huang Y, Guo X (2012) Electron transfer quenching by nitroxide radicals of the fluorescence of carbon dots. J Mater Chem 22:11801–11807CrossRefGoogle Scholar
  5. 5.
    Liu CP, TH W, Liu CY, Cheng HJ, Lin SY (2015) Interactions of nitroxide radicals with dendrimer-entrapped Au8-cluster: a fluorescent nanosensor for intracellular imaging of ascorbic acid. J Mater Chem B 3:191–197CrossRefGoogle Scholar
  6. 6.
    Maurel V, Laferrière M, Billone P, Godin R, Scaiano JC (2006) Free radical sensor based on CdSe quantum dots with added 4-amino-2,2,6,6-Tetramethylpiperidine oxide functionality. J Phys Chem B 110:16353–16358CrossRefPubMedGoogle Scholar
  7. 7.
    Ishii K, Kubo K, Sakurada T, Komori K, Sakai Y (2011) Phthalocyanine-based fluorescence probes for detecting ascorbic acid: phthalocyaninatosilicon covalently linked to TEMPO radicals. Chem Commun 47:4932–4934CrossRefGoogle Scholar
  8. 8.
    Adegoke O, Hosten E, McCleland C, Nyokong T (2012) CdTe quantum dots functionalized with 4-amino-2,2,6,6-tetramethylpiperidine-N-oxide as luminescent nanoprobe for the sensitive recognition of bromide ion. Anal Chim Acta 721:154–161CrossRefPubMedGoogle Scholar
  9. 9.
    Qu D, Zheng M, Du P, Zhou Y, Zhang L, Li D, Tan H, Zhao Z, Xied Z, Sun Z Highly luminescent S, N co-doped graphene quantum dots with broad visible absorption bands for visible light photocatalysts. Nanoscale 5:12272–12277Google Scholar
  10. 10.
    Connell PJ, Gormally C, Pravda M, Guilbault GG (2001) Development of an amperometric L-ascorbic acid (vitamin C) sensor based on electropolymerised aniline for pharmaceutical and food analysis. Anal Chim Acta 431:239–247CrossRefGoogle Scholar
  11. 11.
    Agater IB, Jewsbury RA (1995) Determination of plasma ascorbic acid by HPLC: method and stability studies. Eur J Pharm Sci 3:231–239CrossRefGoogle Scholar
  12. 12.
    Wu T, Guan Y, Ye J (2007) Determination of flavonoids and ascorbic acid in grapefruit peel and juice by capillary electrophoresis with electrochemical detection. Food Chem 100:1573–1579CrossRefGoogle Scholar
  13. 13.
    Zhang YF, Li BX, Xu CL (2010) Visual detection of ascorbic acid via alkyne-azide click reaction using gold nanoparticles as a colorimetric probe. Analyst 135:1579–1584CrossRefPubMedGoogle Scholar
  14. 14.
    GZ H, Guo Y, Xue QM, Shao SJ (2010) A highly selective amperometric sensor for ascorbic acid based on mesopore-rich active carbon-modified pyrolytic graphite electrode. Electrochim Acta 55:2799–2804CrossRefGoogle Scholar
  15. 15.
    Park HW, Alam SM, Lee SH, Karim MM, Wabaidur SM, Kang M, Choi JH (2009) Optical ascorbic acid sensor based on the fluorescence quenching of silver nanoparticles. Luminescence 24:367–371PubMedGoogle Scholar
  16. 16.
    Liu JJ, Chen ZT, Tang DS, Wang YB, Kang LT, Yao JN (2015) Graphene quantum dots-based fluorescent probe for turn-on sensing of ascorbic acid. Sensors Actuators B Chem 212:214–219CrossRefGoogle Scholar
  17. 17.
    Tshangana C, Nyokong T (2015) The photophysical properties of multi-functional quantum dots-magnetic nanoparticles – indium octacarboxy phthalocyanine nanocomposites. J Fluoresc 25:199–210CrossRefPubMedGoogle Scholar
  18. 18.
    Fashina A, Antunes E, Nyokong T (2013) Characterization and photophysical behaviour of phthalocyanines when grafted onto silica nanoparticles. Polyhedron 53:278–285CrossRefGoogle Scholar
  19. 19.
    Qu D, Zheng M, Zhang L, Zhao H, Xie Z, Jing X, Raid EH, Fan H, Sun Z (2014) Formation mechanism and optimization of highly luminescent N-doped graphene quantum dots. Sci Report 4:1–9Google Scholar
  20. 20.
    Fery-Forgues S, Lavabre D (1999) Are fluorescence quantum yields so tricky to measure? A demonstration using familiar stationery products. J Chem Ed 76:12660–11264CrossRefGoogle Scholar
  21. 21.
    Fischer S, Georges J (1996) Fluorescence quantum yields of Rhodamine 6G in ethanol as a function of concentration using lens spectrometry. Chem Phys Lett 260:115–118CrossRefGoogle Scholar
  22. 22.
    Idowu M, Nyokong T (2009) Interaction of water-soluble CdTe quantum dots with Octacarboxy metallophthalocyanines: a photophysical and photochemical study. J Lumin 129:356–362CrossRefGoogle Scholar
  23. 23.
    Yuan F, Ding L, Li Y, Li X, Fan L, Zhou S, Fang D, Yang S (2015) Multicolor fluorescent graphene quantum dots colorimetrically responsive to all-pH and a wide temperature range. Nanoscale 7:11727–11733CrossRefPubMedGoogle Scholar
  24. 24.
    Achadu OJ, Nyokong T (2016) Interaction of graphene quantum dots with 4-acetamido-2,2,6,6-tetramethylpiperidine-oxyl free radical: A spectroscopic and fluorimetric study. J Fluoresc 26:283–295CrossRefPubMedGoogle Scholar
  25. 25.
    Chua CK, Sofer Z, Šimek P, Jankovský O, KlÍmová K, Bakardjieva S, Kučková SH, Pumera M (2015) Synthesis of strongly fluorescent graphene quantum dots by cage-opening buckminsterfullerene. ACS Nano 9:2548–2555CrossRefPubMedGoogle Scholar
  26. 26.
    Nurunnabi M, Zehedina K, Nafiujjaman M, Dong L, Lee Y-k (2013) Surface Coating of Graphene Quantum Dots Using Mussel-Inspired Polydopamine for Biomedical Optical Imaging. ACS Appl Mater Interfaces 5:8246–8253CrossRefPubMedGoogle Scholar
  27. 27.
    Zheng XT, Ananthanarayanan KQ, Luo P, Chen P (2015) Glowing graphene quantum dots and carbon dots: properties, syntheses, and biological applications. Small 11:1620–1636CrossRefPubMedGoogle Scholar
  28. 28.
    Hu Y, Zhao G, Lu N, Chen Z, Zhang H, Li H, Shao L, Qu L (2013) Graphene quantum dots-carbon nanotubes hybrid arrays for supercapacitors. Nanotechnology 24:195401CrossRefPubMedGoogle Scholar
  29. 29.
    Chien C, Li S, Lai W, Yeh Y, Chen H, Chen I, Chen L, Nemoto IS (2012) Tunable photoluminescence from graphene oxide. Angew Chem Int Ed 51:6662–6666CrossRefGoogle Scholar
  30. 30.
    Dong Y, Lin J, Chen Y, Fu F, Chi Y, Chen G (2014) Graphene quantum dots and graphite nanocrystals in coal. Nanoscale 6:7410–7415CrossRefPubMedGoogle Scholar
  31. 31.
    Hoque MN, Basu A, Das G (2014) Fluorescence turn on sensor for sulfate ion in aqueous medium using Tripodal-Cu2+ ensemble. J Fluoresc 24:411–416CrossRefPubMedGoogle Scholar
  32. 32.
    Dɑnet AF, Badea M, Aboul-Enein HY (2000) Flow injection system with chemiluminometric detection for enzymatic determination of ascorbic acid. Luminescence 15:305–309CrossRefPubMedGoogle Scholar
  33. 33.
    WN H, Sun DM, Ma W (2010) Silver doped poly (L-valine) modified glassy carbon electrode for the simultaneous determination of uric acid, ascorbic acid and dopamine. Electroanalysis 22:584–589CrossRefGoogle Scholar
  34. 34.
    Chen YJ, Yan XP (2009) Chemical redox modulation of the surface chemistry of CdTe quantum dots for probing ascorbic acid in biological fluids. Small 5:2012–2018CrossRefPubMedGoogle Scholar
  35. 35.
    Wang XX, Wu P, Hou XD, Lv Y (2013) An ascorbic acid sensor based on protein modified Au nanoclusters. Analyst 138:229–233CrossRefPubMedGoogle Scholar
  36. 36.
    Sillen A, Engelborghs Y (1998) The correct use of “average” fluorescence parameters. Photochem Photobiol 67(5):475–486Google Scholar

Copyright information

© Springer Science+Business Media New York 2016

Authors and Affiliations

  • Ojodomo J. Achadu
    • 1
  • Jonathan Britton
    • 1
  • Tebello Nyokong
    • 1
  1. 1.Department of ChemistryRhodes UniversityGrahamstownSouth Africa

Personalised recommendations