Identification and Localization of Gold Nanoparticles in Potassium Ion Pores: Implications for K(ir) Blockade

INTRODUCTION: In our previous study, we found that negatively charged gold nanoparticles with spermidine have the potential of blocking inwardly rectifying potassium channels (K(ir)), both at the cellular and the tissue level. METHODS: For the purpose of the present study, we purified the cytoplasmic domain of the K(ir) 3.1 receptor from Escherichia coli. Using single particles with surface coating by transmission electron microscopy, we identified the gold nanoparticles at the cytoplasmic side of the human K(ir) channel. RESULTS: Energy-dispersive X-ray spectroscopy showed the presence of the gold deposits in the cytoplasmic domain of the K(ir) receptor. CONCLUSION: In conclusion, we could identify undecagold in the ion pore of the K(ir)3.1 channel in order to clarify its direct blocking effect in the K(ir) ion pore by undecagold. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s40119-016-0060-8) contains supplementary material, which is available to authorized users.