Construction of covalent organic framework nanozymes with photo-enhanced hydrolase activities for colorimetric sensing of organophosphorus nerve agents

• Published in: Analytica chimica acta 2023-10, Vol.1278, p.341706, Article 341706
• Main Authors: Xiao, Sai-Jin, Yuan, Ming-Yue, Shi, Ya-Di, Wang, Meng-Ping, Li, Hui-Han, Zhang, Li, Qiu, Jian-Ding
• Format: Article
• Language: English
• Subjects: Colorimetric detection; Covalent organic frameworks; Hydrolase; Nanozymes; Nerve agents
• ISSN: 0003-2670; 1873-4324; 1873-4324
• DOI: 10.1016/j.aca.2023.341706

Construction of covalent organic frameworks (COFs)-based nanozymes is of great importance for the extensive applications in catalysis and sensing fields. In this work, a two-dimensional COF (DAFB-DCTP COF) was fabricated via Knoevenagel condensation reaction. The integration of catalytically active sites of pyridine groups into the donor-acceptor (D-A) conjugated skeleton endows DAFB-DCTP COF with both hydrolytic and photosensitive properties. The DAFB-DCTP COF can be utilized as an artificial enzyme with selective and photo-enhanced catalytic efficiency, facilitating its application in photocatalytic degradation of hydrolase substrates (p-nitrophenyl acetate, pNPA) by nucleophilic reaction and further realizing colorimetric detection of the nanozyme inhibitor of organophosphorus nerve agent (diethyl cyanophosphonate, DCNP). The distinct color changes could be distinguished by naked eyes even at a low DCNP concentration, and the versatile smartphone analysis featured with reliability and simplicity. For the first time, the COFs' intrinsic hydrolase activity depending on their structural characteristics was investigated in synergy with the photosensitive performance originating from their photoelectric features. The present contribution provides a promising direction towards construction of colorimetric sensing platform based on the regulation of COFs’ non-oxidoreductase activity under visible light irradiation. A novel photosensitive and hydrolytically active covalent organic framework (DAFB-DCTP COF) is constructed, which can be utilized as an artificial enzyme for photocatalytic degradation of ester substrates via nucleophilic reaction, and thus colorimetric detection of the organophosphorus nerve agent can be realized due to its inhibition effect on the mimic hydrolase activity and the photosensitive property of DAFB-DCTP COF. [Display omitted] •A D-A conjugated COF with pyridine groups is successfully constructed.•The COF nanozyme involves selective and photo-enhanced hydrolase activities.•Organophosphorus nerve agents can inhibit the nanoenzymatic activity of the COF.•Nerve agents can be colorimetrically detected by naked eyes or versatile smartphones.