Diamond Relaxometry as a Tool to Investigate the Free Radical Dialogue between Macrophages and Bacteria

Kaiqi Wu, Linyan Nie, Anggrek C. Nusantara, Willem Woudstra, Thea Vedelaar, Alina Sigaeva, Romana Schirhagl*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

6 Citations (Scopus)
62 Downloads (Pure)


Although free radicals, which are generated by macrophages play a key role in antimicrobial activities, macrophages sometimes fail to kill Staphylococcus aureus (S. aureus) as bacteria have evolved mechanisms to withstand oxidative stress. In the past decades, several ROS-related staphylococcal proteins and enzymes were characterized to explain the microorganism's antioxidative defense system. Yet, time-resolved and site-specific free radical/ROS detection in bacterial infection were full of challenges. In this work, we utilize diamond-based quantum sensing for studying alterations of the free radical response near S. aureus in macrophages. To achieve this goal we used S. aureus-fluorescent nanodiamond conjugates and measured the spin-lattice relaxation (T1) of NV defects embedded in nanodiamonds. We observed an increase of intracellular free radical generation when macrophages were challenged with S. aureus. However, under a high intracellular oxidative stress environment elicited by lipopolysaccharides, a lower radical load was recorded on the bacteria surfaces. Moreover, by performing T1 measurements on the same particles at different times postinfection, we found that radicals were dominantly scavenged by S. aureus from 80 min postinfection under a high intracellular oxidative stress environment.

Original languageEnglish
Pages (from-to)1100-1111
Number of pages12
JournalAcs Nano
Publication statusAccepted/In press - 2022


  • bacterial infections
  • diamond magnetometry
  • fluorescent nanodiamonds
  • free radicals
  • microorganism antioxidative defense
  • S. aureus


Dive into the research topics of 'Diamond Relaxometry as a Tool to Investigate the Free Radical Dialogue between Macrophages and Bacteria'. Together they form a unique fingerprint.

Cite this