TiCT MXene nanoribbons@MnO: A novel multifunctional probe for colorimetric and fluorescence dual-response sensing of trichlorfon.

Manganese dioxide nanosheets (MnO NSs) have garnered significant attention in analytical sensing, while the majority of the previous reports suffer from a complex preparation process involving reducing agents, template or high-temperature. In this work, a novel MnO NSs decorated TiCT MXene nanoribbons (TiCTNR@MnO) composite was firstly assemblied via a facile one-step strategy and applied as a bi-signal generator to enable colorimetric and fluorescence (FL) dual-response sensing. During the assembly process, TiCTNR innovatively acted as both reductant and carrier to prevent the aggregation of MnO NSs. Benefiting from the strong metal oxide-support interaction (SMOSI) between TiCTNR and MnO, the as-obtained multifunctional probe displayed enhanced oxidase-like activity and oxidation property. The oxidase-like activity and oxidation property of TiCTNR@MnO were evaluated using 3,3,5,5-tetramethylbenzidine (TMB) and thiamine (TH) as substrates, respectively. In the absence of trichlorfon (TCF), the MnO coating on TiCTNR surface exhibited specific recognition towards thiocholine (TCh), which originated from the hydrolysis of acetylthiocholine catalyzed by acetylcholinesterase (AChE). Consequently, TCh caused decomposition of MnO into Mn, resulting in diminished colorimetric and FL signals. However, in the presence of TCF, its inhibitory effect on AChE activity prevented the resolution of MnO into Mn by TCh, thereby restoring both colorimetric and FL signals. More importantly, the strong SMOSI effect and TCh-specific recognition unit of TiCTNR@MnO led to an enhanced detection sensitivity of the dual-mode sensor, which presented a low detection limit of 0.0856 and 0.798 ng mL using colorimetric and FL measurements, respectively. In summary, this approach presents a new inspiration to construct multifunctional probe for convenient and accurate detection in biosensing.