In situ measurement of magnetization relaxation of internalized nanoparticles in live cells

Dalibor Soukup, Sandhya Moise, Eva Céspedes, Jon Dobson, Neil D Telling

Research output: Contribution to journalArticlepeer-review

117 Citations (SciVal)


Magnetization relaxation mechanisms strongly influence how magnetic nanoparticles respond to high-frequency fields in applications such as magnetic hyperthermia. The dominant mechanism depends on the mobility of the particles, which will be affected in turn by their microenvironment. In this study AC susceptometry was used to follow the in situ magnetic response of model systems of blocked and superparamagnetic nanoparticles, following their cellular internalization and subsequent release by freeze-thaw lysis. The AC susceptibility signal from internalized particles in live cells showed only Néel relaxation, consistent with measurements of immobilized nanoparticle suspensions. However, Brownian relaxation was restored after cell lysis, indicating that the immobilization effect was reversible and that nanoparticle integrity was maintained in the cells. The results presented demonstrate that cellular internalization can disable Brownian relaxation, which has significant implications for designing suitable nanoparticles for intracellular hyperthermia applications. Further to this, the results highlight the possibility that particles could be released in reusable form from degrading cells following hyperthermia treatment, and subsequently reabsorbed by viable cells.

Original languageEnglish
Pages (from-to)231-240
Number of pages10
JournalACS Nano
Issue number1
Early online date9 Jan 2015
Publication statusPublished - 27 Jan 2015


  • Biological Transport
  • Cell Line, Tumor
  • Cell Survival
  • Freezing
  • Humans
  • Magnetic Phenomena
  • Magnetite Nanoparticles/chemistry
  • Models, Molecular
  • Molecular Conformation


Dive into the research topics of 'In situ measurement of magnetization relaxation of internalized nanoparticles in live cells'. Together they form a unique fingerprint.

Cite this