Chemical etching of bovine serum albumin-protected Au25 nanoclusters for label-free and separation-free detection of cysteamine

Biosens Bioelectron. 2015 Apr 15;66:155-61. doi: 10.1016/j.bios.2014.10.073. Epub 2014 Nov 13.


This study describes a novel Au nanocluster-based fluorescent sensor for label-free, separation-free and selective detection of cysteamine (CSH). The sensing mechanism is based on CSH etching-induced fluorescence quenching of the bovine serum albumin-protected Au25 nanoclusters (BSAGNCs). A series of characterizations is carried out towards a better understanding of the CSH-induced fluorescence quenching of the BSAGNCs. It is found that CSH can etch the Au25 nanoclusters, exhibiting the potent etching activity. Other thiol-containing compounds such as glutathione and cysteine and other 19 natural amino acids do not interfere with such CSH-induced etching process. The decreases in fluorescence intensity of the BSAGNCs allow sensitive detection of free CSH in the range of 500-10,000nM. The detection limit for CSH is 150nM (S/N=3). The spiked human serum samples can be analyzed with satisfactory results.

Keywords: Cysteamine; Gold nanocluster; Nanocluster-based biosensor; Thiol etching; Thiol sensor.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids / chemistry
  • Biosensing Techniques / methods*
  • Cysteamine / isolation & purification*
  • Fluorescent Dyes / chemistry
  • Glutathione / chemistry
  • Gold / chemistry*
  • Humans
  • Metal Nanoparticles / chemistry*
  • Serum Albumin, Bovine / chemistry


  • Amino Acids
  • Fluorescent Dyes
  • Serum Albumin, Bovine
  • Cysteamine
  • Gold
  • Glutathione