Whole-cell based label-free capacitive biosensor for rapid nanosize-dependent toxicity detection

Area of Science:

• Nanotechnology
• Biosensing
• Toxicology

Background:

• Assessing nanoparticle (NM) toxicity is crucial, yet understanding size-related effects and cellular responses remains limited.
• Developing sensitive and rapid methods for NM toxicity evaluation is essential for safety assessments.

Purpose of the Study:

• To develop a whole-cell based capacitive biosensor (WCB) for determining nanoparticle (NP) toxicity.
• To investigate the size-dependent toxicity of iron oxide (Fe3O4) nanoparticles (NPs) using the WCB.

Main Methods:

• Fabricated a WCB chip with gold interdigitated microelectrodes immobilizing Escherichia coli cells.
• Measured cellular responses to varying sizes (5, 20, 100 nm) of Fe3O4 NPs via changes in capacitance.
• Validated WCB results with scanning electron microscopy (SEM) and cell viability assays.

Main Results:

• Smaller 5 nm Fe3O4 NPs induced maximum capacitance changes, indicating severe cellular deformation in E. coli.
• WCB demonstrated a size-dependent toxicity response, with 5 nm NPs showing effects at 2 µg/ml and larger NPs at 4 µg/ml.
• SEM confirmed significant cellular deformation caused by smaller NPs.

Conclusions:

• The developed WCB provides a real-time, label-free, and noninvasive method for detecting NP-induced cellular responses.
• This biosensor offers speed, simplicity, and sensitivity for toxicity screening of various NPs.
• The WCB technology advances the understanding of size-dependent NP toxicity and cellular interactions.