Effects of terbium chelate structure on dipicolinate ligation and the detection of Bacillus spores

The Role of Ligand Topology in the Decomplexation of Luminescent Lanthanide Complexes by Dipicolinic Acid

“…The presence of DPA as the main structural component of the protective outer layers of bacterial spores, for example, Bacillus Anthracis (approximately 5–15 % of the dry mass), has aroused the interest of many researchers in the development of fast and reliable sensor systems capable of detecting this endospore biomarker . In the past years, several analytical approaches have been adopted for the determination of dipicolinic acid mainly based on biochemical, electrochemical, or spectroscopic methods (photoluminescence, Raman, and surface enhanced Raman spectroscopy) . In this regard, luminescence‐based techniques have the edge over the others because, in general, they do not require laborious pretreatment of the sample such as extraction and/or concentration of dipicolinic acid.…”

“…The most common approach involves the formation of Ln(DPA) x (H 2 O) 9−3 x complexes (where x= 1, 2, or 3) starting from inorganic lanthanide salts, typically TbCl 3 . More recently, some authors have suggested that the use of preformed complexes of lanthanides, in which the number of coordination sites available for DPA binding is reduced, may overcome the analytical complications owing to the presence of complexes with different stoichiometry and luminescent properties …”

“…[9][10][11][12][13] In the past years, severalanalyticala pproaches have been adopted for the determinationo fd ipicolinic acid mainly based on biochemical, [14][15][16] electrochemical, [17][18] or spectroscopic methods (photoluminescence, Raman, and surface enhanced Ramans pectroscopy). [10][11][12][19][20][21][22][23][24][25] In this regard, luminescence-based techniques have the edge over the others because, in general, they do not require laboriousp retreatment of the sample such as extractiona nd/or concentration of dipicolinic acid. The most common approach involves the formation of Ln(DPA) x (H 2 O) 9À3x complexes (where x = 1, 2, or 3) startingf rom inorganic lanthanide salts, typically TbCl 3 .M ore recently,s ome authors have suggested that the use of preformed complexes of lanthanides,i nw hich the number of coordination sites available for In this study,w ep resent the aqueous solution behavior of two luminescent lanthanide antenna complexes (Eu 3 + &1,D y 3 + &9) with different ligand topologies in the presenceo fd ipicolinic acid (DPA, pyridine-2,6-dicarboxylic acid).…”

“…DPAb inding is reduced, mayo vercome the analytical complications owing to the presence of complexes with different stoichiometryand luminescent properties. [10][11][19][20][21][22][23][24][25][26][27][28] Thus, we decided to investigate the behavior of ap air of luminescent complexesw ith different ligand topologies ( Figure 1, Eu 3 + &1 probe and Dy 3 + &9 reference)i nt he presence of as trong coordinating ligand such as DPA, and to test its capabilityt ow ork as ar atiometric luminescence sensor. In both compounds, we adopted acetophenone as the light-harvesting unit as the favorable energy of the excited triplet state ( % 25 000 cm À1 ) [29][30] makes it suitable fort he sensitizationo f dysprosium ( 4 F 9/2 = 21 280 cm À1 )a nd europium ions ( 5 D 0 = 17 250 cm À1 ).…”

“…The ligand produces an egatively charged complex with europium and is expected to be flexible enough to allow the interaction of the Ln 3 + sites with polydentate anions. [19,35] The temporal stability of both luminescentc omplexes can be easily checked by recording their emission spectra at sequentialt ime intervals. This represents ap ractical and important qualityc ontrol for the sensor system, which would not be possible for sensing probes in which luminescence is activated by interaction of the lanthanide ions with the analytes.…”