Bacterial Endospore Detection Using Photoluminescence from Terbium Dipicolinate

Rosen, David L.

doi:10.1515/revac.1999.18.1-2.1

Cited by 33 publications

(9 citation statements)

References 31 publications

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“…Since the lowest triplet excited state of DPA is well matched energetically to the lowest emitting level of Tb 3+ , the dipicolinate complexes exhibit greatly enhanced (sensitized) luminescence (Figure 1). 38 In addition, these complexes have luminescent lifetimes in the micro- to millisecond range, 39,40 a property that makes it possible through time-gated techniques to reduce nanosecond fluorescence from interferents common in environmental samples. 6,40 …”

Section: Introductionmentioning

confidence: 99%

Enhancement of Anion Binding in Lanthanide Optical Sensors

Cable

Kirby²,

Gray

et al. 2013

Acc. Chem. Res.

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In the design of molecular sensors, researchers exploit binding interactions that are usually defined in terms of topology and charge complementarity. The formation of complementary arrays of highly cooperative, noncovalent bonding networks facilitates protein-ligand binding, leading to motifs such as the ‘lock-and-key.’ Synthetic molecular sensors often employ metal complexes as key design elements as a way to construct a binding site with the desired shape and charge to achieve target selectivity. In transition metal complexes, coordination number, structure and ligand dynamics are governed primarily by a combination of inner-sphere covalent and outer-sphere noncovalent interactions. These interactions provide a rich variable space that researchers can use to tune structure, stability and dynamics. In contrast, lanthanide(III)-ligand complex formation and ligand-exchange dynamics are dominated by reversible electrostatic and steric interactions, because the unfilled f shell is shielded by the larger, filled d shell. Luminescent lanthanides such as terbium, europium, dysprosium and samarium display many photophysical properties that make them excellent candidates for molecular sensor applications. Complexes of lanthanide ions act as receptors that exhibit a detectable change in metal-based luminescence upon binding of an anion. In our work on sensors for detection of dipicolinate, the unique biomarker of bacterial spores, we discovered that the incorporation of an ancillary ligand (AL) can enhance binding constants of target anions to lanthanide ions by as much as two orders of magnitude. In this Account, we show that selected ALs in lanthanide/anion systems greatly improve sensor performance for medical, planetary science and biodefense applications. We suggest that the observed anion binding enhancement could result from an AL-induced increase in positive charge at the lanthanide ion binding site. This effect depends on lanthanide polarizability, which can be established from the ionization energy of Ln3+ → Ln4+. These results account for the order Tb3+ > Dy3+ > Eu3+ ≈ Sm3+. As with many lanthanide properties, ranging from hydration enthalpy to vaporization energy, this AL-induced enhancement shows a large discrepancy between Tb3+ and Eu3+ despite their similarity in size, a phenomenon known as the ‘gadolinium break.’ This discrepancy, based on the unusual stabilities of the Eu2+ and Tb4+ oxidation states, results from the half-shell effect, as both of these ions have half-filled 4f-shells. The high polarizability of Tb3+ explains the extraordinarily large increase in the binding affinity of anions for terbium compared to other lanthanides. We recommend that researchers consider this AL-induced enhancement when designing lanthanide-macrocycle optical sensors. Ancillary ligands also can reduce the impact of interfering species such as phosphate) commonly found in environmental and physiological samples.

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Section: Introductionmentioning

confidence: 99%

Enhancement of Anion Binding in Lanthanide Optical Sensors

Cable

Kirby²,

Gray

et al. 2013

Acc. Chem. Res.

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“…The ASD employs a rapid chemical test for the detection of bacterial spores based on dipicolinic acid (DPA)-triggered terbium ion (Tb 3þ ) luminescence (Hindle and Hall, 1999;Pellegrino et al, 2002;Rosen, 1999Rosen, , 2006Sacks, 1990), which is closely related to a colorimetric assay first developed in 1958 (Janssen et al, 1958). DPA is present in high concentrations (up to 1 molar, $15% of dry weight) in the core of bacterial spores (Gould and Hurst, 1969).…”

Section: Introductionmentioning

confidence: 99%

“…Thermal lysis (i.e., rupture) of spores via dry heat or autoclaving efficiently releases DPA into the surrounding matrix (Janssen et al, 1958;Rotman and Fields, 1969), which enables DPA to bind to terbium ions with high affinity. Under UV excitation, the Tb-DPA complex formation triggers intense green luminescence (Hindle and Hall, 1999;Lester and Ponce, 2002;Pellegrino et al, 2002;Rosen, 1999;Sacks, 1990) (Fig. 1), signaling the presence of bacterial spores.…”

Section: Introductionmentioning

confidence: 99%

An automated front‐end monitor for anthrax surveillance systems based on the rapid detection of airborne endospores

Yung

Lester

Bearman

et al. 2007

Biotech & Bioengineering

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A fully automated anthrax smoke detector (ASD) has been developed and tested. The ASD is intended to serve as a cost effective front-end monitor for anthrax surveillance systems. The principle of operation is based on measuring airborne endospore concentrations, where a sharp concentration increase signals an anthrax attack. The ASD features an air sampler, a thermal lysis unit, a syringe pump, a time-gated spectrometer, and endospore detection chemistry comprised of dipicolinic acid (DPA)-triggered terbium ion (Tb(3+)) luminescence. Anthrax attacks were simulated using aerosolized Bacillus atrophaeus spores in fumed silica, and corresponding Tb-DPA intensities were monitored as a function of time and correlated to the number of airborne endospores collected. A concentration dependence of 10(2)-10(6) spores/mg of fumed silica yielded a dynamic range of 4 orders of magnitude and a limit of detection of 16 spores/L when 250 L of air were sampled. Simulated attacks were detected in less than 15 min.

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“…Several excellent reviews on ECL have appeared (1)(2)(3)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18). (21,22) and has also been used to suggest the presence of anthrax spores by fluorescence spectroscopy (23)(24)(25). However, techniques such as ECL that are suitable for on-line monitoring of samples (15,16,18), and that may result in lower detection limits and higher sensitivity, are also of interest.…”

Section: Introductionmentioning

confidence: 99%

Electrochemiluminescence of dipicolinic acid (DPA) and (bpy)₂Ru(DPA)⁺ (bpy = 2,2′‐bipyridine)

2005

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The spectroscopic and electrochemiluminescence (ECL) properties of dipicolinic acid (DPA), (bpy)(2)Ru(2+) (bpy = 2,2'-bipyridine) and the species formed when DPA and (bpy)(2)Ru(2+) [abbreviated to (bpy)(2)Ru(DPA)(+)] are allowed to react are reported. The UV-Vis absorption maxima for (bpy)(2)Ru(2+) and (bpy)(2)Ru(DPA)(+) are 493 and 475 nm, respectively, indicating the in situ formation of a complex between DPA and (bpy)(2)Ru(2+). DPA, (bpy)(2)Ru(2+) and (bpy)(2)Ru(DPA)(+) display ECL upon oxidation in the presence of the oxidative-reductive co-reactant tri-n-propylamine (TPrA). The ECL of (bpy)(2)Ru(DPA)(+) is at least two-fold higher than either of the parent species. An ECL spectrum of (bpy)(2)Ru(DPA)(+) displays a peak maximum 40 nm red-shifted from the photoluminescence peak maximum, suggesting that the excited state formed electrochemically is different from that formed spectroscopically.

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Bacterial Endospore Detection Using Photoluminescence from Terbium Dipicolinate

Cited by 33 publications

References 31 publications

Enhancement of Anion Binding in Lanthanide Optical Sensors

Enhancement of Anion Binding in Lanthanide Optical Sensors

An automated front‐end monitor for anthrax surveillance systems based on the rapid detection of airborne endospores

Electrochemiluminescence of dipicolinic acid (DPA) and (bpy)₂Ru(DPA)⁺ (bpy = 2,2′‐bipyridine)

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Bacterial Endospore Detection Using Photoluminescence from Terbium Dipicolinate

Cited by 33 publications

References 31 publications

Enhancement of Anion Binding in Lanthanide Optical Sensors

Enhancement of Anion Binding in Lanthanide Optical Sensors

An automated front‐end monitor for anthrax surveillance systems based on the rapid detection of airborne endospores

Electrochemiluminescence of dipicolinic acid (DPA) and (bpy)2Ru(DPA)+ (bpy = 2,2′‐bipyridine)

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Electrochemiluminescence of dipicolinic acid (DPA) and (bpy)₂Ru(DPA)⁺ (bpy = 2,2′‐bipyridine)