Synthesis, photophysical study and BSA association of water-insoluble squaraine dyes
摘要:
In this work, the synthesis, spectroscopic characterisation, photophysical study and bovine serum albumin association of water-insoluble squaraine dyes are described. The photophysical behaviour of the dyes was investigated using UV-vis and steady-state fluorescence in solution, as well as its association with bovine serum albumin in phosphate buffer solution. No squaraine aggregation was observed in organic solvents, but J-type aggregation could be observed in phosphate buffer solution. In the absence of protein, the J-aggregation promoted the fluorescence quenching; however, upon addition of protein, the fluorescence intensity increased by a factor of up to 80. Additionally, a linear relationship between the fluorescence intensity and the protein concentration could be observed for the squaraine dyes in a concentration range around 0.02-0.10 mu M. (C) 2012 Elsevier B.V. All rights reserved.
3-Butoxy-4-(1-butyl-3,3-dimethyl-3H-indol-2-ylidenemethyl)-3-cyclobut-1,2-dione exhibited the most intense florescence at fluorescence maxima 536 and 563 nm with fluorescence quantum yield 0.21 among any indolenine semi-squarylium dyes in the crystalline form due to the isolated dimer-type molecular packing and its suitable melting point. This compound showed aggregation-induced emission enhancement. (c) 2012 Elsevier Ltd. All rights reserved.