Upconversion-based nanosystems for fluorescence sensing of pH and H₂O₂

Area of Science:

• Materials Science
• Analytical Chemistry
• Nanotechnology

Background:

• Hydrogen peroxide (H₂O₂) is a crucial reactive oxygen species with diverse roles in biological, industrial, and environmental contexts.
• Accurate and sensitive detection of H₂O₂ is vital for various applications.

Purpose of the Study:

• To design and evaluate novel upconversion nanosystems for the sensitive fluorescence sensing of H₂O₂.
• To compare a non-contact sensing approach with a conventional method using excitation energy attenuation (EEA) and fluorescence resonance energy transfer (FRET).

Main Methods:

• Development of two upconversion nanosystems: one non-contact utilizing EEA, and one conventional using EEA and FRET.
• Utilizing molybdenum trioxide-based nanosheets (MoO_3- NSs) as quenchers for upconversion luminescence (UCL).
• Investigating the H₂O₂-induced recovery of UCL for quantitative analysis.

Main Results:

• Both systems demonstrated H₂O₂ sensing capabilities, with the non-contact method achieving ultrahigh quenching efficiency (99.8%).
• The non-contact method achieved a low detection limit of 0.63 μM for H₂O₂, outperforming spectrophotometry and conventional upconversion methods.
• The strategy was successfully extended to pH sensing over a broad range (2.6–8.2).

Conclusions:

• The developed non-contact upconversion nanosystem offers a highly sensitive and efficient platform for H₂O₂ detection.
• This approach provides a versatile design strategy for fluorescence sensing of multiple analytes using a single quencher material.