High sensitive mesoporous TiO2-coated love wave device for heavy metal detection

Area of Science:

• Materials Science
• Biosensor Technology
• Environmental Science

Background:

• Whole-cell biosensors offer sensitive detection of environmental contaminants.
• Polyelectrolyte multilayers (PEM) enhance biosensor performance.
• Silica (SiO2) guiding layers in acoustic sensors can degrade in saline environments.

Purpose of the Study:

• To design a highly sensitive whole-cell biosensor for heavy metal detection in liquid.
• To improve the stability and sensitivity of acoustic biosensors using mesoporous titanium dioxide (TiO2).
• To investigate the impact of TiO2 on bacteria immobilization and biosensor lifetime.

Main Methods:

• Fabrication of a Love wave biosensor with a quartz substrate, interdigitated transducers, and a SiO2 guiding layer.
• Coating the sensor with a mesoporous TiO2 layer via dip-coating.
• Immobilization of *Escherichia coli* bacteria as bioreceptors on the TiO2 surface.
• Real-time monitoring of frequency variations using an acoustic device.
• Characterization of biosurface morphology using Atomic Force Microscopy (AFM).

Main Results:

• The TiO2 layer significantly improved bacteria immobilization frequency shift (-20±1 kHz) compared to bare silica (-7±3 kHz).
• The mesoporous TiO2 layer enhanced mass effect sensitivity and provided a more stable platform for PEM deposition.
• Biosensor lifetime was extended when using the mesoporous TiO2 layer.
• The biosensor demonstrated heightened sensitivity towards cadmium detection.

Conclusions:

• Mesoporous TiO2 is a superior material for acoustic biosensor guiding layers, enhancing sensitivity and stability.
• The developed whole-cell biosensor provides a robust platform for sensitive heavy metal detection in liquid media.
• The findings contribute to the development of more durable and effective biosensing technologies for environmental monitoring.