The detection of drugs containing hydrochloric salt with conventional methods is time consuming and expensive. In this work, upon exposure to ciprofloxacin hydrochloride at different concentrations, the emission from CsPbBr3 NCs shifts to the blue from 513 nm to 442 nm. CsPbBr(3−x)Clx NCs are formed by the ion exchange and substitution of Br− and Cl− ions from surface to core of NCs. The first-principles calculations suggest that the substitution of Br− by Cl− ions plays a critical role in the tuning of the energy bandgap. The color of paper test strips changes immediately after exposure to different Ciproxan solutions. We propose that this rapid and portable method has a high potential application in other chloride salts for food safety.
Fluoride ion (F − ) is an essential micronutrient in the human body, however, an abnormal large intake of F − can result in adverse effects, such as skeletal fluorosis or DNA damage. Therefore, it is of great significance to develop convenient assays for the visual detection of F − with high sensitivity. We rationally developed the nanosized iron-based metal organic frameworks (Fe-MOFs) by using 3,5-dicarboxybenzeneboronic acid as organic linkers and Fe 3+ as metal ions through the solvothermal method, which can be applied for detecting F − with high sensitivity and selectivity owing to the specific recognition of boronic acid groups towards F − and the strong binding affinity between F − and Fe 3+ . The Fe-MOFs possess excellent peroxidase-like activity, which can be effectively inhibited by F − . Moreover, a portable test kit for the determination of F − was developed by embedding Fe-MOFs into hydrogel, and the visual measurement of F − was realized based on smartphone by identifying the color signal of the oxidation of 3,3',5,5'-tetramethylbenzidine dihydrochloride. The output signal (R/G) was linear with F − concentration in the range of 10.0–200.0 μM. The Fe-MOFs-based colorimetric strategy is easy-operation, low-cost and equipment-free, which has been further applied to detect F − in the real water samples.
Jing Xu,Yinbing Liu,Ke-Jing Huang,Renjie Wang,Xiaoxuan Sun
We report here for the first time a self-powered biosensing platform based on graphene/graphdiyne/graphene (GDY-Gr) heterostructure substrate material for ultrasensitive hepatocarcinoma marker (microRNA-21) detection in both electrochemical and colorimetric test modes. The dual-mode signal intuitively displayed on a smartphone fundamentally improves the detection accuracy. In electrochemical mode, the calibration curve is established in the linear range of 0.1–10000 fM, and the detection limit is as low as 0.333 fM (S/N = 3). Simultaneously, colorimetric analysis of the miRNA-21 is realized by using ABTS as an indicator. The detection limit is confirmed as 32 fM (S/N = 3), and miRNA-21 of concentration from 0.1 pM to 1 nM exhibit a linear relationship with R2 = 0.9968. Overall, the combination of GDY-Gr and multiple signal amplification strategy significantly improved the sensitivity by 310 times compared with traditional enzymatic biofuel cells (EBFCs) based detection platform, showing broad application prospects for on-site analysis and future mobile medical services.
危险品化学品经营许可证（带存储）