Janus-micromotor-based on-off luminescence sensor for active TNT detection.

Area of Science:

• Nanotechnology
• Chemical Sensing
• Environmental Science

Background:

• 2,4,6-trinitrotoluene (TNT) is a hazardous explosive compound requiring sensitive detection methods.
• Upconverting nanoparticles (UCNPs) offer unique luminescent properties for sensing applications.
• Micromotor capsules provide a platform for active transport and enhanced reaction kinetics.

Purpose of the Study:

• To develop an active catalytic sensor for the sensitive detection of TNT.
• To utilize Janus upconverting nanoparticle (UCNP)-functionalized micromotor capsules for enhanced sensing performance.
• To achieve a low limit of detection for TNT in environmental samples.

Main Methods:

• Fabrication of Janus capsule motors via layer-by-layer assembly of UCNP-functionalized polyelectrolyte microcapsules.
• Sputtering a platinum layer onto half of the capsule to create asymmetry for propulsion.
• Utilizing catalytic decomposition of hydrogen peroxide to generate oxygen bubbles for micromotor propulsion.
• Implementing an "on-off" luminescence strategy for TNT detection.

Main Results:

• Janus UCNP capsule motors achieved rapid propulsion speeds up to 110 μm s^-1.
• The sensor demonstrated efficient "on-off" luminescent detection of TNT.
• A very low limit of detection of 2.4 ng mL^-1 for TNT was achieved within 1 minute.
• The unique motion of the Janus motors enhanced TNT molecule collision and reaction rates.

Conclusions:

• Bubble-propelled Janus UCNP capsule motors represent a promising active sensing platform.
• This technology offers a rapid and highly sensitive method for detecting TNT.
• The developed sensor has significant potential for the analysis of contaminated water.