High-Performance Odorant Receptor-Derived Peptide Sensor Based on Click Chemistry for Detecting o-Xylene Released from Paints

Ortho-xylene (o-xylene) is commonly present in living environments where paint has been used and represents the most toxic gas released from paint, necessitating convenient and sensitive detection methods. In this study, we developed a method based on click chemistry to efficiently conjugate an odorant receptor-derived peptide (ORP) with single-walled carbon nanotubes (SWCNTs) for fabricating high-performance sensors for detecting o-xylene. First, SWCNTs were alkynylated, while azide groups were incorporated into the ORP through sequence modification. Then, a click chemistry reaction of copper-catalyzed azide–alkyne cycloaddition was used to conjugate ORP with SWCNTs. Compared to previously reported thiol-gold ligation, this approach based on click chemistry immobilized 3.25 times more ORP onto the SWCNTs. Using this method, the fabricated ORP sensor achieved a limit of detection (LOD) as low as 10 ppb for gaseous o-xylene, which was 2 orders of magnitude lower than the previously reported minimum LOD. Additionally, the sensor’s performance in detecting o-xylene released from various commercial paints was tested, demonstrating excellent detection limits, selectivity, and stability. These results indicated that the ORP sensor fabricated via the proposed conjugation method was effective and held great potential for applications in environmental safety, home automation, and human health monitoring.