Identification of intracellular cadmium transformation in HepG2 and MCF-7 cells

It is of significance to elucidate or understand the intracellular transformation & migration behaviors of heavy metals in specific cells. Herein, we report the fast and efficient separation of cadmium-metallothioneins (Cd-MTs) and Cd²⁺in cell lysate by a short column capillary electrophoresis (SC-CE), followed by coupling with inductively coupled plasma mass spectrometry (ICP-MS) to facilitate the speciation of intracellular cadmium species. The incorporation of sodium dodecyl sulfate (SDS) in running buffer significantly reduces the peak width of Cd²⁺from 170 s to 26 s in the electrophoretogram, causing a 5.3-fold improvement on the sensitivity. Linear ranges of 0.5-50 mg L^-1,0.056-5.6 mg L^-1 and 0.1-10 mg L^-1 are achieved for MTs, Cd-MTs (Cd) and Cd²⁺, respectively, along with detection limits of 0.013 mg L^-1 for Cd-MTs (Cd) and 0.020 mg L^-1 for Cd²⁺. The transformation of cadmium in HepG2 and MCF-7 cells is evaluated after their incubation with Cd²⁺ reinforced culture medium. Intracellular free Cd²⁺ cation and Cd-MTs are identified, along with Cd²⁺ transformation to Cd-glutathione (GSH) adduct/complex, as further demonstrated by ESI-MS.