Sensing ultra-trace dopamine by restoration of fluorescence on locally acidified gold nanoparticles.

An ultra-sensitive sensor was fabricated to measure dopamine through quenching and restoring FITC fluorescence by the competitive binding of dopamine and N-acetylneuraminic acid with mercaptophenylboronic acid anchored on the gold nanoparticles. Assessed by quantifying dopamine in human urine samples, it reached a limit of detection of as low as 50 pM dopamine over a linear range from 10-10 M to 10-7 M. It also features low technical barriers and operation cost, and the strategy proposed could be extendable to other analytes and not restricted to the gold nanoparticles.