Dextran coated silver nanoparticles - Chemical sensor for selective cysteine detection

Colloids Surf B Biointerfaces. 2017 Dec 1;160:184-191. doi: 10.1016/j.colsurfb.2017.09.031. Epub 2017 Sep 12.


A simple, fast and non-costly method for selective cysteine (Cys) detection, based on optical changes of silver colloids, is developed. For that purpose, stable colloids consisting of silver nanoparticles (Ag NPs) coated with polysaccharide dextran (Dex), isolated from bacterium species Leuconostoc mesenteroides T3, were prepared. The synthesized samples were thoroughly characterized including absorption and FTIR spectroscopy, as well as transmission electron microscopy and X-ray diffraction analysis. The silver colloids display high sensitivity and selectivity towards Cys detection in aqueous solutions. The Ag NPs coated with Dex provide possibility to detect Cys among a dozen amino acids and its detection limit was found to be 12.0μM. The sensing mechanism - red shift of optical absorption - is discussed in terms of the agglomeration of Ag NPs due to formation of hydrogen bonds between Cys molecules attached to different Ag NPs.

Keywords: Ag nanoparticles; Cysteine detection; Dextran; Sensitivity and selectivity; Sensor.

MeSH terms

  • Colloids
  • Cysteine / analysis*
  • Glucosyltransferases / chemistry*
  • Glucosyltransferases / isolation & purification
  • Leuconostoc mesenteroides / chemistry
  • Limit of Detection
  • Metal Nanoparticles / chemistry*
  • Metal Nanoparticles / ultrastructure
  • Silver / chemistry*
  • Solutions
  • Spectroscopy, Fourier Transform Infrared


  • Colloids
  • Solutions
  • Silver
  • Glucosyltransferases
  • dextransucrase
  • Cysteine