Aspartic acid functionalized water-soluble perylene diimide as "Off-On" fluorescent sensor for selective detection Cu2+ and ATP

Aspartic functionalized water-soluble perylene diimide, N,N'-di(2-succinic acid)-perylene-3,4,9,10-tetracarboxylic diimide (PASP) has two absorbance maximums at 527 and 498 nm (epsilon approximate to 1.7 x 10(4) L cm(-1) mol(-1)) and two emission peaks at 547 and 587 nm respectively. Emission intensities decrease with the increase of PASP concentrations in 20-100 mu M ranges. Spectral titrations demonstrate that each PASP can coordinate to two Cu2+ ions in the absence of HEPES buffer. Its stability constant is estimated to be about 1.0 x 10(12) L-2 mol(-2) at pH 7.20 and its coordinate stoichiometry increased to 7.5 in the same pH in the presence of HEPES buffer. The emission of PASP will be completely quenched upon formation of Cu2+ complex. The lowest "turn-off" fluorescence detection limit was calculated to be 0.3 mu M Cu2+. PASP-Cu solution was used as a "turn-on" fluorescence biosensor to detect ATP. The sensitivity towards ATP is 0.3 mu M in 50 mM HEPES buffer at pH 7.20, which is one of the most sensitive fluorescence sensors. (C) 2013 Elsevier B.V. All rights reserved.