Interference of engineered nanoparticles with in vitro toxicity assays

Area of Science:

• Nanotechnology
• Toxicology
• In vitro assays

Background:

• Engineered nanoparticles (ENPs) can interfere with standard cytotoxicity assays due to their properties.
• Accurate assessment of ENP toxicity requires understanding potential assay interferences.

Purpose of the Study:

• To evaluate the validity of four common in vitro assays (DCF, MTT, LDH, IL-8 ELISA) when used with 24 well-characterized ENPs.
• To analyze ENP interference with optical detection, substrate conversion, enzymatic activity, and cytokine binding.

Main Methods:

• Tested 24 ENPs across four in vitro assays: DCF, MTT, LDH, and IL-8 ELISA.
• Analyzed ENP interference with optical detection, substrate conversion, enzymatic activity, and cytokine binding.
• Investigated effects of varying particle concentrations and modified assay protocols.

Main Results:

• All tested ENPs interfered with optical measurements at concentrations ≥50 μg cm⁻² for DCF, MTT, and LDH assays.
• Particle interference was reduced by lowering concentrations to 10 μg cm⁻² for most ENPs, except Carbon Black.
• Specific ENPs showed unique interferences, such as Carbon Black oxidizing DCF and ZnO decreasing LDH activity, and TiO₂ affecting IL-8 levels.

Conclusions:

• Engineered nanoparticles interfere with in vitro cytotoxicity assays in a concentration-, particle-, and assay-specific manner.
• Each in vitro test system must be validated for each specific ENP type to ensure accurate toxicity evaluation.