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

Manganese dioxide-carbon dot (MnO 2 CD) composite nanoparticles of size 45 nm have been synthesized in a single step from hydrothermal decomposition of KMnO 4 , polydopamine, and citric acid for multipurpose applications. The mild emission of MnO 2 CD particles at 425 nm under excitation wavelength of 340 nm substantially increases in the presence of arsenite, because of redox reaction between MnO 2 and arsenite to give soluble Mn 2+ . 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 MnO 2 CD probe also shows satisfactory performance for detection of organoarsenic and organothioarsenic compounds such as dimethylarsenate (DMA), dimethyldithioarsinate (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 MnO 2 CD changes reversibly with temperature in the range of 25–75 °C. 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.