Detoxification of gold nanorods by treatment with polystyrenesulfonate

ACS Nano. 2008 Dec 23;2(12):2481-8. doi: 10.1021/nn800466c.


We address an outstanding issue associated with the biocompatibility of gold nanorods (GNRs), a promising agent for biomedical imaging and theragnostics. GNRs are typically prepared in the presence of cetyltrimethylammonium bromide (CTAB), a cationic surfactant whose rigorous removal is necessary due to its cytotoxicity and membrane-compromising properties. CTAB-stabilized GNRs can be partially purified by treatment with polystyrenesulfonate (PSS), an anionic polyelectrolyte often used as a surrogate peptizing agent, followed by chloroform extraction and ultrafiltration with minimal loss of dispersion stability. However, in vitro cytotoxicity assays of PSS-coated GNRs revealed IC(50) values in the low to submicromolar range, with subsequent studies indicating the source of toxicity to be associated with a persistent PSS-CTAB complex. Further exchange of CTAB-laden PSS with fresh polyelectrolyte greatly improves biocompatibility, to the extent that 85 microg/mL of "CTAB-free" GNRs (the highest level evaluated) has comparable toxicity to a standard phosphate buffer solution. Ironically, PSS is not effective by itself at stabilizing GNRs in CTAB-depleted suspensions: while useful as a detergent for GNR detoxification, it should be replaced by more robust coatings for long-term stability under physiological conditions.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Cell Line, Tumor
  • Cetrimonium
  • Cetrimonium Compounds / chemistry
  • Gold / chemistry*
  • Humans
  • Metal Nanoparticles / chemistry*
  • Nanotubes / chemistry*
  • Polystyrenes / chemistry


  • Cetrimonium Compounds
  • Polystyrenes
  • polystyrene sulfate
  • Gold
  • Cetrimonium