ascorbic-acid and 4-carboxyfluorescein

The authors describe a fluorometric and resonance Rayleigh scattering dual-mode scheme for detection of the activity and inhibition of alkaline phosphatase (ALP). The method utilizes (a) CoOOH nanoflakes, which have high resonance Rayleigh scattering activity and can strongly adsorb ssDNA, and (b) Co(II)-dependent DNAzyme assisted signal amplification. ALP specifically catalyzes the hydrolysis of ascorbic acid-2-phosphate to produce ascorbic acid which reduces CoOOH nanoflakes to Co(II) ion. The Co(II)-dependent DNAzyme is then activated by Co(II) ion, and this results in the cleavage of a substrate labeled with both a fluorophore and a quencher. Following hydrolysis, fluorophore and quencher become separated and the fluorescence measured at excitation/emission wavelengths of 490/518 nm recovers, while the RRS signal at 405 nm decreases. The method works on the 0.2 to 2000 U L

Topics: Alkaline Phosphatase; Ascorbic Acid; Base Sequence; Biosensing Techniques; Cobalt; DNA, Catalytic; Enzyme Assays; Fluoresceins; Fluorescent Dyes; Humans; Limit of Detection; Metal Nanoparticles; Oxidation-Reduction; Oxides; Spectrometry, Fluorescence