One-step synthesis of Mn-carbon dot nanoprobe for signal-on detection of arsenic and reversible temperature sensing

Manganese dioxide-carbon dot (MnO2CD) composite nanoparticles of size 45 nm have been synthesized in a single step from hydrothermal decomposition of KMnO4, polydopamine, and citric acid for multipurpose ap-plications. The mild emission of MnO2CD particles at 425 nm under excitation wavelength of 340 nm sub-stantially increases in the presence of arsenite, because of redox reaction between MnO2 and arsenite to give soluble Mn2+. This single probe sensor shows selective and sensitive response to arsenite in the linear range of 0-100 nM with a detection limit of 5.75 nM. This MnO2CD probe also shows satisfactory performance for detection of organoarsenic and organothioarsenic compounds such as dimethylarsenate (DMA), dimethyldi-thioarsinate (DMDTA), and dimethylmonothioarsinate (DMMTA). Interestingly, this sensor works well for monitoring arsenic in a plant root vascular system through fluorescence and confocal imaging which has been reported for the first time. Further, the fluorescence intensity of MnO2CD changes reversibly with temperature in the range of 25-75 ? This nanobionic sensor not only opens up a universal opportunity to detect As(III) in environment as well in agriculture but also sensing temperature in a microenvironment.