Synthesis Of Acridine Derivatives And Application As Forster-Resonance-Energy-Transfer Acceptor Of Tryptophan

Preliminary study of tryptophan as Forster-resonance-energy-transfer (FRET) donor, acridine derivatives as the receptors in ligand, to realize homogenous bioaffinity analysis is reported, for noncompetitive assay of protein, competitive assay of ligand affinities and ligand quantities.With diphenylamine, acetic acid through Bernthsen synthesis, a series of 9- methyl-acridine derivatives were synthesized, but the stability of these derivatives are very low. With o-chlorobenzoic acid, benzene by substitution, condensation reactions, acridine derivatives such as acridine, acridone, 9-chloro acridine were synthesized; such derivatives can be connected with other groups to obtain FRET probes, among which 9-aminoacridine fluorescent derivatives and acridine-9-carboxylic acid derivatives showed reasonable stability.An FRET probe composed of 9-aminoacridine and lauric acid caused a detectable quench of tryptophan fluorescence in human serum albumin. From acridine-9-carboxylic acid and biotinylethylenediamine, an FRET probe of streptavidin was designed and synthesized. It can effectively quench fluorescence of streptavidin. However, due to much lower quantum yield of acridines in nonhydrophophilic enviroments, no obvious enhancement of emission at the characteristic peak was detected upon the binding of the FRET probe to streptavidin. Utilizing the quench of streptavidin fluorescence by this FRET probe, the affinities of nonfluorescent biotin derivatives can be estimated via competitive binding. Alternatively, utilizing the sensitivity of acridine fluorescence to microenviroment upon binding of the FRET probe to streptavidin, the affinities of nonfluorescent biotin derivatives can be estimated via competitive binding.