Electroactive and photoactive porphyrin-based covalent-organic framework for the construction of a bifunctional self-powered sensing platform toward real time analysis of nitride oxide from cancer cells

Sensitive and selective determination of nitrogen oxide (NO) from living cells is significant for early diagnosis of cancer. Herein, a novel bifunctional electrochemical (EC) and photoelectrochemical (PEC) sensing strategy for the in situ and sensitive analysis of NO released from cancer cells was constructed based on porphyrin-based covalent-organic framework (p-COF). Here, p-COF was synthesized using 4,4′,4′',4′''-(21H,23H-porphine-5,10,15,20-tetrayl) tetrakis-benzaldehyde (p-Por-CHO) and 2,2′-bipyridine-5,5′-diamine (bpy) as building blocks via the condensation polymerization method (denoted as p-bpy-COF). The p-bpy-COF nanospheres were assembled with multilayer nanosheets and possessed highly conjugated structure and abundant oxygen vacancy, affording remarkable visible-light adsorption, high electrochemical activity, and outstanding photoactivity property. The p-bpy-COF-based EC and self-powered PEC sensor showed low detection limits of 17.3 nM and 21.8 nM within 0.36–44.3 μM and 5–660 μM, respectively, outperforming to most of reported NO sensors. Moreover, the fabricated bifunctional sensor demonstrated high selectivity, excellent stability, good reproducibility, and accepted applicability for detecting NO from living cancer cells. This work can provide a new bifunctional sensing strategy for analysis of NO and broaden the application range of COF in biosensing fields.