Toxicity of CdSe Nanoparticles in Caco-2 Cell Cultures

Abstract

BackgroundPotential routes of nanomaterial exposure include inhalation, dermal contact, and ingestion. Toxicology of inhalation of ultra-fine particles has been extensively studied; however, risks of nanomaterial exposure via ingestion are currently almost unknown. Using enterocyte-like Caco-2 cells as a small intestine epithelial model, the possible toxicity of CdSe quantum dot (QD) exposure via ingestion was investigated. Effect of simulated gastric fluid treatment on CdSe QD cytotoxicity was also studied.ResultsCommercially available CdSe QDs, which have a ZnS shell and poly-ethylene glycol (PEG) coating, and in-house prepared surfactant coated CdSe QDs were dosed to Caco-2 cells. Cell viability and attachment were studied after 24 hours of incubation. It was found that cytotoxicity of CdSe QDs was modulated by surface coating, as PEG coated CdSe QDs had less of an effect on Caco-2 cell viability and attachment. Acid treatment increased the toxicity of PEG coated QDs, most likely due to damage or removal of the surface coating and exposure of CdSe core material. Incubation with un-dialyzed in-house prepared CdSe QD preparations, which contained an excess amount of free Cd2+, resulted in dramatically reduced cell viability.ConclusionExposure to CdSe QDs resulted in cultured intestinal cell detachment and death; cytotoxicity depended largely, however, on the QD coating and treatment (e.g. acid treatment, dialysis). Experimental results generally indicated that Caco-2 cell viability correlated with concentration of free Cd2+ ions present in cell culture medium. Exposure to low (gastric) pH affected cytotoxicity of CdSe QDs, indicating that route of exposure may be an important factor in QD cytotoxicity.

In vitro and in vivo toxicity assessment of nanoparticles

“…The exposure of CdSe quantum dot on enterocytelike Caco-2 cells as a model for intestine epithelium was investigated. Results suggested that acid treatment of PEGcoated quantum dots increased the toxicity [130]. Another study investigated the in vitro and in vivo toxicity of CdTe nanoparticles on human hepatoma HepG2 cells [131].…”

Oxidative stress response in neural stem cells exposed to different superparamagnetic iron oxide nanoparticles

“…11 Once the free iron enters the cytosol, it is able to interact with hydrogen peroxide physiologically formed by different types of enzyme-catalyzed reactions, generating free radicals. 12,13 In general, the cellular oxidative stress caused by the formation of ROS is considered to be a key mechanism of nanomaterial toxicity. 2,10,[14][15][16][17][18][19] Moreover, oxidative stress, together with its secondary consequences, is known to be involved in the pathogenesis of many diseases, such as cancer, diabetes, and respiratory problems, as well as in aging processes.…”

Voltammetric determination of size and particle concentration of Cd-based quantum dots

“…Typically, 10 mL of QDs in CHCl 3 were placed in an eppendorf tube and after total evaporation of CHCl 3 , 10 mL of HClO 4 1 M was dropped for the dissolution of the QDs. Previously, it has been reported in the literature that a concentrated acid is able to etch and dissolve Cd-based quantum dots [24,25]. Therefore, we could assume that the attack of CdSe QDs with concentrated acid is likely to follow a similar reaction to macroscopic CdSe (Eq.…”