Microchimica Acta

, 186:157 | Cite as

Multicolor emitting N/S-doped carbon dots as a fluorescent probe for imaging pathogenic bacteria and human buccal epithelial cells

  • Abhishek Pathak
  • Suneesh PV
  • John Stanley
  • T. G. Satheesh BabuEmail author
Original Paper


Carbon dots co-doped with nitrogen and sulfur (NSCDs) were obtained from thiourea and TAE (Tris-acetate-ethylenediamine) buffer using microwave assisted hydrothermal synthesis. The synergistic presence of nitrogen and sulfur as a dopant results in teasing fluorescence properties and a fluorescence quantum yield of 57%. An HR-TEM study showed the NSCDs to be mono-dispersed and seemingly spherical with an average hydrodynamic diameter of 3.6 ± 0.88 nm. The NSCDs are nontoxic as proven by an MTT assay for cytotoxicity. The optical characterization was done by using UV-Vis absorption and fluorescence spectroscopy which revealed excitation wavelength-dependent multicolor emissions. The characterization of surface topology was done by using X-ray diffraction, FTIR, and X-ray photoelectron spectroscopy. The NSCDs were used to image various pathogenic bacteria (E. coli, Klebsiella, Pseudomonas & Staphylococcus) and human buccal epithelial cells by applying multicolor fluorometry.

Graphical abstract

Schematic presentation of microwave-assisted hydrothermal synthesis of nitrogen and sulfur doped carbon dots (NSCD) based on Thiourea and 50X Tris-acetate-ethylenediamine (TAE) buffer having multicolor fluorescence, used for tagging and imaging pathogenic bacteria and Human buccal epithelial cells using fluorescence microscope.


Thiourea TAE buffer Doping Microwave-assisted hydrothermal synthesis Tagging Fluorescence microscopy Fluorescence quantum yield Multicolor fluorometry 



The authors gratefully acknowledge the Department of Biotechnology (DBT), Govt. of India for the financial support through the project no. 102SAN/2237/2016-2017 and project no. 102/IFD/SAN/1409/2018-2019. The authors would like to thank Sophisticated Analytical Instruments Facility (SAIF), Cochin University of Science and Technology (CUSAT) for their unsparing support in HR-TEM image acquisition. The authors would also like to thank Mr. Jayesh Vasudeva Adhikari (University of Southern California), Mr. Prateek Katare (Indian Institute of Science, Bangalore) and Ms. Divya Nair (Amrita School of Biotechnology, Kollam) for their generous help in providing the presentable schematics, MATLAB codes for particle size estimation and several other characterization techniques.

Compliance with ethical standards

The author(s) declare that they have no competing interests.

Supplementary material

604_2019_3270_MOESM1_ESM.docx (12.6 mb)
ESM 1 (DOCX 12935 kb)


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Copyright information

© Springer-Verlag GmbH Austria, part of Springer Nature 2019

Authors and Affiliations

  • Abhishek Pathak
    • 1
  • Suneesh PV
    • 1
    • 2
  • John Stanley
    • 1
    • 2
  • T. G. Satheesh Babu
    • 1
    • 2
    Email author
  1. 1.Amrita Biosensor Research Lab, Amrita School of EngineeringAmrita Vishwa VidyapeethamCoimbatoreIndia
  2. 2.Department of Sciences, Amrita School of EngineeringAmrita Vishwa VidyapeethamCoimbatoreIndia

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