Covalent organic framework-MnO₂ nanoparticle composites for shape-selective sensing of bithiols

Area of Science:

• Materials Science
• Analytical Chemistry
• Biotechnology

Background:

• Detecting biological macromolecules in aqueous or biological settings presents significant challenges.
• Covalent organic frameworks (COFs) offer potential for sensitive detection but require further development for complex environments.

Purpose of the Study:

• To develop a novel composite material for sensitive and specific detection of biothiols.
• To investigate the sensing mechanisms of the composite material for different biothiols.
• To demonstrate the practical application of the composite material in biological samples.

Main Methods:

• Synthesis of a fluorescent COF (IEP) and its combination with manganese dioxide (MnO2) nanocrystals to form the IEP-MnO2 composite.
• Utilizing fluorescence spectroscopy to monitor changes upon interaction with biothiols (glutathione, cysteine, homocysteine).
• Investigating sensing mechanisms including Förster resonance energy transfer (FRET) and photoelectron transfer (PET).

Main Results:

• The IEP-MnO2 composite exhibited distinct fluorescence responses ('turn-on' or 'turn-off') to different biothiols.
• Glutathione detection involved the elimination of FRET, while cysteine/homocysteine detection involved photoelectron transfer.
• The material demonstrated specificity in distinguishing between glutathione and cysteine/homocysteine.
• Successful detection of glutathione in whole blood (LOD 25.58 μM) and cysteine in human serum (LOD 4.43 μM).

Conclusions:

• The developed IEP-MnO2 composite material shows great promise for the sensitive and selective fluorescence detection of biothiols in complex biological matrices.
• This work expands the application scope of COFs in fluorescence sensing and provides a potential tool for disease-related biothiol monitoring.