Nano-carrier for gene delivery and bioimaging based on carbon dots with PEI-passivation enhanced fluorescence

Biomaterials. 2012 May;33(13):3604-13. doi: 10.1016/j.biomaterials.2012.01.052. Epub 2012 Feb 16.


Polyethylenimine (PEI) functionalized carbon dots (CD-PEI) were fabricated by one-step microwave assisted pyrolysis of glycerol and branched PEI25k mixture where the formation of carbon nanoparticles and the surface passivation were accomplished simultaneously. In this hybrid C-dot, PEI molecule played two key roles in the system - as a nitrogen-rich compound to passivate surface to enhance the fluorescence and as a polyelectrolyte to condense DNA. This CD-PEI was shown to be water soluble and emit stable bright multicolor fluorescence relying on excitation wavelength. The DNA condensation capability and cytotoxicity of CD-PEI could be regulated by pyrolysis time possibly due to the somewhat destruction of PEI during the formation of carbon dots. CD-PEI obtained at an appropriate pyrolysis time exhibited lower toxicity, higher or comparable gene expression of plasmid DNA in COS-7 cells and HepG2 cells relative to control PEI25k. Intriguingly, the CD-PEIs internalized into cells displayed tunable fluorescent emission under varying excitation wavelength, suggesting the potential application of CD-PEI in gene delivery and bioimaging.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • COS Cells
  • Carbon / chemistry*
  • Carbon / toxicity
  • Cell Death / drug effects
  • Chlorocebus aethiops
  • DNA / metabolism
  • Diagnostic Imaging / methods*
  • Drug Carriers / chemistry*
  • Electrophoresis, Agar Gel
  • Gene Transfer Techniques*
  • Hep G2 Cells
  • Humans
  • Microscopy, Confocal
  • Microscopy, Fluorescence
  • Nanoparticles / chemistry*
  • Nanoparticles / ultrastructure
  • Particle Size
  • Plasmids / metabolism
  • Polyethyleneimine / chemical synthesis
  • Polyethyleneimine / chemistry*
  • Polyethyleneimine / toxicity
  • Spectroscopy, Fourier Transform Infrared
  • Static Electricity
  • Transfection


  • Drug Carriers
  • Carbon
  • Polyethyleneimine
  • DNA