An innovative method for carbendazim (CBZ) detection was developed, consisting of an electrochemical-fluorescence dual-mode biosensor based on magneto-fluorescent composite M-CDs. M-CDs, as the fluorescent probe of this sensor, could combine the electrical signal-ferrocene to achieve the “signal switching” by specifically recognizing CBZ through aptamers, of which magnetic property was used to quickly separate from complex substrates without interference. The dual-mode sensor based on M-CDs demonstrated excellent linear responses in both electrochemical and fluorescence assays. It achieved detection ranges of 10 fg/mL − 300 ng/mL and 60 fg/mL – 100 ng/mL with detection limits (LODs) of 1.4 fg/mL and 2.3 fg/mL. The sensor exhibited exceptional detection performance, stability and anti-interference. In addition, the results of the sensor in actual samples were consistent with those of enzyme-linked immunosorbent assay (ELISA), which further demonstrated that the sensor could accurately trace detecting CBZ in real samples and had a certain application prospect.
Colorimetric biosensors are suitable for point-of-care assays due to the advantages of simple operation, fast analysis and direct visualization. Here a novel oxidase mimic of thioflavin T via light-activating was first discovered. Various chromogenic substrates can be efficiently oxidized via light-activated singlet oxygen ( 1 O 2 ). In particular, thioflavin T often binds to some unique conformations in bio-macromolecules (e.g., DNA G-quadruplex) with good specificity. This is valuable to develop versatile colorimetric biosensors with signal-switching functionality for direct visualizing of analytes. Using various recognition elements (molecular beacons, aptamers), we can realize the efficient assay of five different analytes, including mechlorethamine , DNA, K + , adenosine monophosphate, and amyloid fibril . Therefore light-activated oxidase mimic of thioflavin T can serve as a desirable tool to assay various analytes of pharmaceutical, food or environmental interest.
Bo Zhang,Jun Li,Lian-Zhi Li,Xiao-Chen Ren,Ming Pang,Ya-Nan Shao
By utilizing in situ-formed MCP ligands (HMCP+ = 1-methyl-4-(carboxyl)pyridinium) as decoration agents, two new iodoplumbate hybrids, namely, [Pb(MCP)2I]PbI3 (1) and Cs2[Pb(MCP)4]Pb3I10 (2), have been solvothermally prepared and structurally characterized. Compound 1 features the typical one-dimensional (1D) [PbI3]nn– anions, while compound 2 exhibits two-dimensional (2D) [Pb3I10]n4n– slabs perforated with large parallelogram-shaped windows. The intriguing structural characteristic of compounds 1 and 2 is that they contain unique chain-like cations of [Pb(MCP)2I]+ and [Pb(MCP)4]2+, respectively. Interestingly, upon alternate visible-light and full spectrum light irradiation, compounds 1 and 2 show stable and rapid photoelectric switching properties, whose photocurrent densities are comparable or larger than those of many metal halide hybrids. Additionally, their optical properties, Hirshfeld surface analyses, X-ray photoelectron spectra, as well as the theoretical band structures and density of states have also been studied.
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