The assembling of a coating of time-resolved fluorescent chelator BSPDA (abbreviated for 4,7-bis(sulfhydrylphenyl)-1,10-phenanthroline-2,9-dicarboxylic acid) onto a nano-gold layer was demonstrated. First, BSPDA was synthesized by simple procedures, and then an approach was developed to immobilize BSPDA onto the nano-gold layer deposited on a silane modified glass substrate, whereby europium ion (Ⅲ, Eu3+) was captured and released owing to the interactive process of complexation and dissociation between BSPDA functionalized coating and Eu3+ solution. The fluorescence spectra and related lifetimes were determined. Also, the BSPDA functionalized coating′s specific complexation with Eu3+ on the BSPDA assembly layer and the nonspecific adsorption of Eu3+ on the nano-gold layer were compared. These results allowed a selective complexation of Eu3+ by assembling a BSPDA chelating layer on the nano-gold layer; thus, a tunable time-resolved fluorescent layer was covalently attached. The results of the nanoparticle assembling and probing (or labeling) processes to specific bio-systems were very interesting and had significant implications to time-resolved-fluorescence-based detection on biosensor surfaces such as DNA chip and to arrayed light display devices.
