Functional covalent organic framework H2S sensors for periodontitis monitoring and antibacterial treatment†

Periodontitis is a chronic disease that can lead to irreversible tooth loss and decreased quality of life, highlighting the importance of timely monitoring. Meanwhile, hydrogen sulfide (H₂S) in saliva, produced by periodontal pathogens, is a significant biomarker for monitoring periodontitis. However, the simple and portable operation required to achieve high sensitivity remains a technical challenge for directly sensing exhaled breath. In this study, by integrating the fluorescent indicator (sodium 1-pyrenebutyrate, PB) into a covalent organic framework (COF, EB-TFP), an indicator displacement assay (IDA)-based fluorescence enhanced gas sensor (EB-TFP@PB) was constructed. With the selective binding of H₂S to EB-TFP, the sensor substantiated excellent sensitivity, with a limit of detection (LOD) of 1.44 ppb for H₂S gas. In addition, EB-TFP@PB showed selective antibacterial activity against Staphylococcus aureus (S. aureus) under non-illuminated conditions. The antibacterial mechanism of EB-TFP@PB was further investigated using electron microscopy-related techniques. This work not only offers a reliable and sensitive design for noninvasive medical diagnosis of H₂S detection based on the IDA strategy but also provides a new idea for developing highly selective antibacterial COF composite materials.