Steady state and time-resolved fluorescence of 2-aminoacridone sugar derivatives

Abstract

The fluorescence properties of 2-aminoacridone (2-AMAC) and some polysaccharide derivatives have been studied in the steady state and with time-correlated single-photon counting. 2-AMAC in methanol has an absorption maximum at 425 nm and a fluorescence emission maximum at 530 nm. The absorption spectrum shows a sufficiently broad tail for satisfactory excitation by the light from an argon ion laser (488 nm). Lifetime decay analysis shows that the fluorescence lifetime of the aminoacridone moiety is not changed significantly by the addition of a sugar chain, or by the length or structure of that chain. 2-AMAC exhibits a fluorescence decay that may be fitted to a single exponential in both methanol (t ≈ 12 ns) and water (t ≈ 10 ns); in an equal mixture of the solvents the behaviour is best described by a sum of two exponential terms. We have also shown that the absorbance of a complex mixture of 2-AMAC tagged glycans is directly proportional to their fluorescence emission at 525 nm. These results have confirmed our previous studies that 2-AMAC is a useful and non-selective fluorescent tag in the analysis of polysaccharide chains.