The use of the ROS scavenger cysteine as a surface ligand of metal nanoclusters and its bactericidal elimination effect

Dyah Ika Krisnawati, Po Hsuan Hsu, Yu Hsiang Lin, Moh Alimansur, Didik Susetiyanto Atmojo, Elfi Quyumi Rahmawati, Dwi Rahayu, Muhamad Khafid, Ssu Chiao Lu, Tsung Rong Kuo

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


The bactericidal effects of fluorescent metal nanoclusters have impeded their bacterial bioimaging applications due to the reactive oxygen species (ROS) generation that is induced by the nanoclusters in bacteria to cause bacterial death. Herein, an ROS scavenger of cysteine was exploited as a surface ligand to prepare cysteine-conjugated gold nanoclusters (Cys-AuNCs) and cysteineconjugated silver nanoclusters (Cys-AgNCs) using a facile hydrothermal approach. The structural and optical characterizations demonstrated successful syntheses of Cys-AuNCs and Cys-AgNCs. With the same weight concentration, the bactericidal effect increased in the order of Cys-AuNCs, Cys-AgNCs, and silver nanoparticles (AgNPs), according to the results of the bacterial growth curves. Furthermore, based on the results of the standard colony-counting method, the Cys-AuNCs revealed the best biocompatibility compared to those of the Cys-AgNCs and AgNPs in Escherichia coli (E. coli). The superior biocompatibility of the Cys-AuNCs can be attributed to the use of the ligand of cysteine as an ROS scavenger to reduce ROS in E. coli. Electron paramagnetic resonance (EPR) analyses indicated that the use of the ROS scavenger cysteine as the surface ligand of the Cys-AuNCs eliminated the ROS production induced by the Cys-AuNCs in E. coli. The biocompatible Cys- AuNCs were also confirmed as a fluorescent probe using confocal microscopy. Highly biocompatible Cys-AuNCs could be a potential fluorescent probe in the application of bacterial bioimaging.

Original languageEnglish
Article number4095
JournalApplied Sciences (Switzerland)
Issue number9
Publication statusPublished - May 1 2021


  • Bactericidal effect
  • Cysteine
  • Nanoclusters
  • Reactive oxygen species
  • Scavenger

ASJC Scopus subject areas

  • General Materials Science
  • Instrumentation
  • General Engineering
  • Process Chemistry and Technology
  • Computer Science Applications
  • Fluid Flow and Transfer Processes


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