Detection Of Anthrax Biomarker Research Articles

A novel core–shell lanthanide coordination polymer ratiometric fluorescent probe for the ultrasensitive and visual detection of anthrax biomarker

A novel core–shell based lanthanide ratiometric fluorescent probe is designed for the rapid and sensitive detection of 2, 6-pyridine dicarboxylic acid (DPA), which is the biomarker of Bacillus anthracis. The fluorescent dye molecule 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) was encapsulated in silica nanoparticles as a reference signal and externally connected with guanine mononucleotide europium coordination polymers (Eu/GMP) as a response signal so as to construct a double-emission fluorescent sensor. The visual detection was enabled by the fluorescence color change from green to red under an UV lamp with the addition of DPA. In addition, the RGB auxiliary detection platform was built using color scanning software of smartphone. This work presents a novel and efficient method for detecting anthrax biomarkers.

Smartphone-assisted mobile fluorescence sensor for self-calibrated detection of anthrax biomarker, Cu2+, and cysteine in food analysis

Dipicolinic acid (DPA), as a biomarker for Bacillus anthracis, is highly toxic at trace levels. Rapid and on-site quantitative detection of DPA is essential for maintaining food safety and public health. This work develops a dual-channel self-calibrated fluorescence sensor constructed by the YVO4:Eu and Tb-β-diketone complex for rapid visual detection of DPA. This sensor exhibits high selectivity, fast response time, excellent detection sensitivity, and the detection limit is as low as 4.5 nM in the linear range of 0–16 μM. A smartphone APP and portable ultraviolet lamp can assemble a mobile fluorescence sensor for on-site analysis. Interestingly, adding Cu2+ ions can quench the fluorescence intensity of Tb3+. In contrast, the addition of cysteine can restore the fluorescence, allowing the accurate detection of Cu2+ ions and cysteine in environmental water and food samples. This work provides a portable sensor that facilitates real-time analysis of multiple targets in food and the environment.

Colorimetric fluorescence determination of anthrax biomarker using a bimetallic lanthanide metal–organic framework

Bacillus anthracis is toxic bacterial spore that cause human anthrax infections. Therefore, rapid and sensitive detection of Bacillus anthracis or its main biomarker 2, 6-pyridine dicarboxylic acid (DPA) is of great significance. Herein, a series of lanthanide–organic frameworks (Tb/Eu-MOF-1–6) were synthesized by the solvothermal reactions of 2,2′-bipyridine-6,6′-dicarboxylic acid (H2BPDC) with Eu3+ and Tb3+. Among these samples, Tb/Eu-MOF-6 exhibited selective detection of DPA with self-calibrating and colorimetric fluorescence determination. The sensitivity of Tb/Eu-MOF-6 revealed a linear response of ln (IN) = -10.896CDPA + 0.14366 with a limit of detection with 4.51 μM. The emission color of Tb/Eu-MOF-6 observed with the naked eye, turned yellow to red after introducing appropriate concentration of DPA.The energy-transfer behavior between BPDC2- Tb3+, and Eu3+ was systematically studied, which primarily controlled the sensitivity of detection. With the combined merits of self-calibrating, rapid and naked-eye recognition of DPA, Tb/Eu-MOF-6 can be counted as a promising contender for anthrax biomarker detection.

Smartphone-integrated ratiometric fluorescence sensing platform based on bimetallic metal-organic framework nanowires for anthrax biomarker detection.

Developing an intelligent, sensitive, and visual strategy for quickly identifying anthrax biomarkers is crucial for ensuring food safety and preventing disease outbreaks. Herein, a smartphone-integrated ratiometric fluorescent sensing platform based on bimetallic metal-organic framework (Eux/Tb1-x-MOF) nanowires was designed for specific recognition of pyridine-2,6-dicarboxylic acid (DPA, anthrax biomarker). The Eux/Tb1-x-MOF was prepared by coordinating Eu3+ and Tb3+ with BBDC ligands, which exhibited a uniform fibrous morphology and dual-emission fluorescence at 543 and 614nm. After the introduction of DPA, the red emission at 614nm displayed obvious fluorescence quenching, while the green emission at 543nm wasgradually enhanced. The ratiometric sensing offered a wide linear equation in the range of 0.06-15µg/mL and a low detection limit (LOD) of 20.69ng/mL. Furthermore, a portable smartphone installing the color recognition application can achieve sensitive, real-time, and visual detection of DPA. As a simple and effective smartphone-assisted sensing platform, this work holds admirable promise to broaden the applications in biomarker real-time determinations and other fields.

Eu(III)-based polymeric nanoparticles as dual-emission turn-off sensor for anthrax biomarker detection

Anthrax is an acute infectious disease with high mortality caused by bacillus anthracis, which can severely harm human healthy. 2,6-pyridinedicarboxylic acid (DPA) is the main component and a major biomarker of bacillus anthracis. Therefore, it is essential to develop a sensitive and selective sensor for DPA detection. In this study, luminescent lanthanide nanoparticles, poly(PTEu)-PAA, were successfully synthesized by introducing Europium(III)-based complex and N-(4-(1,2,2-triphenylvinyl)phenyl)acrylamide (TPENA) to a hydrophilic macro-chain transfer agent poly(PEGMA)-PAA. The obtained poly(PTEu)-PAA nanoparticles were spherical with good dispersity, water stability and average diameters of approximately 443 nm. Furthermore, poly(PTEu)-PAA nanoparticles can act as a dual emission ‘‘turn-off’’ probe for detecting DPA in water. Upon addition of DPA, the emission of Eu(TTA)2(AA)phen and TPENA centers in polymeric nanoparticles were quenched with the detection limits (LODs) of 0.30 μM (at 618 nm) and 6.1 μM (at 455 nm), respectively, which was considerably lower than an infectious dosage of bacillus anthracis spores (60 μM) for a human being. Additionally, it showed high recoveries (92.50 %–102.45 %) in tap water, bovine serum, human serum and human urine samples. This is the first example of DPA sensor based on a dual-emission "turn-off" mechanism for Eu(III)-based polymeric nanoparticles, which presents a new avenue for detecting DPA.

Self-calibrated HAp:Tb-EDTA paper-based probe with dual emission ratio fluorescence for binary visual and fluorescent detection of anthrax biomarker

Development of the portable device is significant for sensitive and rapid detection of an anthrax biomarker dipicolinic acid (DPA), existing in the B. anthracis. In this work, a novel HAp:Tb-EDTA paper-based ratiometric fluorescent sensor was obtained by a simple one-pot method for rapid and sensitive DPA detection. With the increased DPA concentration, the luminescence intensity of HAp (hydroxyapatite) remained constant, and thus applied as the stable reference signal, while the luminescence signal of Tb3+-EDTA was significantly enhanced due to the antenna effect. Therefore, the HAp:Tb-EDTA paper-based sensor was endowed with self-calibrated and ratiometric fluorescent detection performance for DPA. The proposed sensor showed excellent detection performance with a detection limit as low as 10.8 nM in the linear range of 0.5–30 μM. After combination with a smartphone, rapid visual and fluorescent detection of DPA was achieved. The proposed sensor was successfully applied to detect DPA from B. subtilis spore real samples, showing the application prospects of the paper-based sensors and opening a new horizon to develop novel paper-based point-of-care testing (POCT) devices.

A core–shell structure ratiometric fluorescent probe based on carbon dots and Tb3+ for the detection of anthrax biomarker

A novel core–shell structure ratiometric fluorescent probe was developed, which can selectively and sensitively detect 2,6-dipicolinic acid (DPA) as an anthrax biomarker. Carbon dots (CDs) was embedded into SiO2 nanoparticles, which was acted as an internal reference signal. Tb3+ with green emission was connected to the carboxyl functionalized SiO2, which was acted as a responsive signal. With the addition of DPA, the emission of CDs at 340 nm was unchanged, while the fluorescence of Tb3+ at 544 nm was enhanced by the antenna effect. In the concentration range of 0.1–2 μM, the fluorescence intensity ratio of I544/I340 showed a good linear relationship with the concentration of DPA, and the limit of detection (LOD) was 10.2 nM. In addition, the dual-emission probe showed an obvious fluorescence color change from colourless to green with increasing DPA under UV light, which enabled visual detection.

A Core-Shell Structure Ratiometric Fluorescent Probe Based on Carbon Dots and Tb3+ for the Detection of Anthrax Biomarker

A Core-Shell Structure Ratiometric Fluorescent Probe Based on Carbon Dots and Tb3+ for the Detection of Anthrax Biomarker

Contactless and robust dielectric microspheres-assisted surface-enhanced Raman scattering sensitivity improvement for anthrax biomarker detection.

This report presents a contactless and robust dielectric microspheres (DMs)-assisted surface enhanced Raman scattering (SERS) enhancement method to improve SERS detection sensitivity detection sensitivity. DMs that could focus and collect light were embedded within the polydimethylsiloxane (PDMS) film to avoid direct contact with the analytical solution and improve detection reliability. The as prepared DMs embedded PDMS DMs PD MS film was integrated with a microfluidic technique to enhance the SERS signal of a liquid substrate. Detection in microfluidic systems can reduce reagent consumption, shorten assay time, and avoid evaporation of the colloid substrate solution. The robustness and potential influencing factors of DMs PDMS film assisted SERS enhancement (DERS) were evaluated using 4-aminothiophenol (4-ATP) as the Raman probe. The sensing performance of the proposed method toward dipicolinic acid (DPA) was evaluated, and an evident signal intensification was obtained. Remarkably, the DMs PDMS film can also be implemented on solid substrates. A proof-of-concept experiment was performed by covering the DMs PDMS film directly over an AgNPs@Si solid substrate wherein a 5.7-fold sensitivity improvement was achieved.

Ion exchange fabrication of lanthanide functionalized layered double hydroxides microcapsules for rapid and visual detection of anthrax biomarker

Lanthanide ion probes have recently been considered as promising sensing materials due to their high sensitivity and good optical properties. Herein, the 3D hierarchical lanthanide functionalized layered double hydroxides microcapsules were synthesized via a facile ion exchange strategy and further developed as novel fluorescent probes for detecting trace amounts of the anthrax biomarker dipicolinicacid (DPA). Benefiting from the 3D porous superstructure and abundant unsaturated coordination sites of lanthanide ion, the ternary Ni-Fe-Ln-LDHs (Ln = Tb/Eu) not only possess a large reactive contact area to improve the sensitivity of DPA detection, but also demonstrate very fast reaction rate. The design of inexpensive fluorescent test strips can perform the on-site and real-time detection via a smartphone with a color recognition application. More prominently, the sensitivity of the system was evaluated by actual spore samples with the detection limit as low as 3.54 × 104 spores/mL. The 3D lanthanide functionalized LDHs nanoprobe constructed by ion exchange exhibits a new vision for the development of a sensing platform in other research areas.

Integrated ratiometric fluorescence probe-based acoustofluidic platform for visual detection of anthrax biomarker

The sensitive detection of dipicolinic acid (DPA) as an excellent biomarker of Bacillus anthracis, especially through visual point-of-care testing, is significant for accurate and rapid diagnosis of anthrax to timely prevent anthrax disease or biological terrorist attack. Herein, an acoustofluidics-based colorimetric platform with the integrated ratiometric fluorescence probe (INT-probe) was fabricated, which improved the sensitivity of visual detection for DPA and overcame the poor reproducibility of the existing acoustofluidics-assisted colorimetric analysis. For the design of INT-probe, Eu3+-EDTA complex as sensing moiety was grafted onto the surface of blue organosilane-functionalized carbon dots (SiCDs)-doped SiO2 nanoparticles (NPs). Upon exposure to DPA, Eu3+ was sensitized by DPA to emit red luminescence, while the SiCDs as reference inside the SiO2 NPs still kept the blue fluorescence unchanged. Attributed to the acoustic radiation force-driven enrichment of the INT-probe, slight color changes caused by low concentration of DPA could be amplified and distinguished by naked-eyes/smartphone. With the increase of DPA concentration, obvious color variations of INT-probe/DPA aggregates from blue to pink could be observed, and the color information of the fluorescent aggregates was converted to red, green and blue values for quantitative analysis, whose lowest detectable concentration reached 100 nM that is about 2–3 orders of magnitude lower than the infectious dosage of Bacillus anthracis spores (60 μM). Importantly, benefiting from the great color signal enhancement by acoustofluidic sensing platform, the usage of Eu3+ reduced to as low as 0.273 μmol per gram of SiO2 NPs, providing a meaningful way to utilize lanthanide resource efficiently.

Solvo-thermal synthesis of a unique cluster-based nano-porous zinc(II) luminescent metal-organic framework for highly sensitive detection of anthrax biomarker and dichromate

In this work a flexible multi-dentate 4,4′-(1H-1,2,4-triazole-1-yl) methylene-bis(benzonic acid) (H2L) ligand has been employed, a unique cluster-based nano-porous luminescent zinc(II) metal-organic framework {[Zn(μ6-L)]·(DMAC)2}n (1) (DMAC = Dimethylacetamide) has been isolated under solvo-thermal conditions. The H2L ligand adopts hexa-dentate coordination modes via one triazole nitrogen atom and four aromatic carboxylate oxygen atoms, which bridge the neighboring six-coordinated ZnII centers, leading to a three-dimensional (3D) nano-porous metal organic framework. A PLATON program analysis suggests the total potential solvent area volume is 2028.9 Å3, which occupy 62.5% percent of the unit cell volume (3248.4 Å3). PXRD Patterns of the as-synthesized samples 1 have been determined confirming the purity of the bulky samples. Photo-luminescent properties indicate strong fluorescent emissions of 1 at the room temperature. Further photo-luminescent measurements show that 1 can exhibit highly sensitive real-time luminescence sensing of anthrax biomarker dipicolinic acid (DPA) with high quenching efficiency (KSV = 1.48 × 105 M−1) and low detection limit (0.298 μM (S/N = 3)). Meanwhile 1 also exhibits highly selective and sensitive luminescence sensing for Cr2O72- ions in aqueous solutions with high quenching efficiency KSV = 1.22 × 104 L·mol−1 and low detection limit (0.023 μM (S/N = 3)). Therefore 1 can be used a unique multi-functional 3D cluster-based metal organic material in sensitive detection and effective detection of environment pollutants and biomarker molecules.

Comparison between terbium-doped carbon dots and terbium-functionalized carbon dots: Characterization, optical properties, and applications in anthrax biomarker detection

Rare earth-carbon dots (RE-CDs) nanomaterials combine the merits of both RE and CDs, which have been the promising candidates in the biochemical sensing field. Owing to the diversity of synthetic methods and precursors, the electronic structure, optical properties and sensing performances of RE-CDs vary greatly. Nevertheless, a comparing study focusing on the synthetic methods of RE-CDs using same precursors has not been reported to date. To facilitate the exploration of the interaction mechanisms for RE–CDs, same precursors (folic acid and terbium nitrate) were used to synthesize RE-CDs via two most common fabrication methodologies (doping and direct coordination) in this study. The morphologies, surface groups, and optical properties of the as-prepared terbium-doped CDs (Tb-CDs) and terbium functionalized CDs (Tb@CDs) were comprehensively compared and analyzed. The anthrax biomarker (dipicolinic acid, DPA) sensing performances of both RE-CDs were also evaluated. Taking the original CDs without terbium as control, the Tb-CDs had higher quantum yield (QY) and longer fluorescence lifetime, and the fluorescence emission peak was red-shifted, suggesting the effective passivation of surface defects. On the contrary, QY and fluorescence lifetime of Tb@CDs decreased, and the emission peak remained unchanged, indicating that interaction between free Tb3+ and CDs led to the less excited electrons, similar to the fluorescence quenching behavior of metal ions on CDs. Further characterization also helped in demonstrating the different interaction mechanisms. Moreover, for the superior performance in DPA detection, Tb-CDs was chosen as the probe for the follow-up application. The Tb-CDs exhibited a sensitive response to DPA in the concentration range of 0.05–8 μM with the detection limit of 44 nM. In addition, it was successfully applied to real samples of running water and lake water.

A time-resolved ratiometric luminescent anthrax biomarker nanosensor based on an Ir(III) complex-doped coordination polymer network.

Herein, an Ir(III) complex-doped coordination polymer network (Ir(III)@GMP-Eu3+) is fabricated for the first time for the ratiometric luminescent detection of the anthrax biomarker 2,6-dipicolinic acid (DPA) through the analysis of time-resolved emission spectra (TRES). The linear detection range is from 10 nM to 5 μM with a detection limit of 3.3 nM in aqueous solution. Attributed to the long lifetime of Ir(III)@GMP-Eu3+, the developed sensor exhibits an excellent DPA monitoring ability in a high-background solution through TRES.

Ion Exchange Fabrication of Lanthanide Functionalized Layered Double Hydroxides Microcapsules for Rapid and Visual Detection of Anthrax Biomarker

Ion Exchange Fabrication of Lanthanide Functionalized Layered Double Hydroxides Microcapsules for Rapid and Visual Detection of Anthrax Biomarker

Smart intercalation and coordination strategy to construct stable ratiometric fluorescence nanoprobes for the detection of anthrax biomarker

L@Mg-Al-Ln-LDHs (Ln = Tb, Eu) constructed by the intercalation coordination strategy exhibited a strong and stable fluorescence reference signal and achieved reliable ratiometric detection of DPA in complex environments and actual spores.

A water-stable europium-MOF sensor for the selective, sensitive ratiometric fluorescence detection of anthrax biomarker

Sensitive, efficient and rapid detection of 2, 6-pyridinedicarboxylic acid (DPA), commonly labeled as the main biology marker for bacillus anthracis, is of far-reaching consequence to eliminate potential threats. In this work, a 3D Eu-MOF ([Eu(DHBDC)1.5(DMF)2]·DMF) that has outstanding thermal and water stability was synthesized. The Eu-MOF showed characteristic fluorescence at 506 nm caused by ligand π-π* transition. The quantum calculation showed that there was a large energy difference between the 5D0 level of Eu3+ and the triplet energy level of 2,5-dihydroxy terephthalic acid ligand (DHBDC2-), which was why the coordination compound did not exhibit the characteristic fluorescence of Eu3+. Interestingly, it effectively restored the red fluorescence of Eu3+ (593, 618 and 699 nm) and showed a dual-emission fluorescence response at 506 and 593 nm when the DPA existed. Therefore, based on the high detection sensitivity of Eu-MOF (the detection limit is 1.3 μM) and outstanding anti-interference ability, it is expected to become a prospective ratiometric fluorescence sensor for the detection of DPA. In addition, combined with density functional theory (DFT) and a variety of other analytical methods, the detection mechanism of DPA by Eu-MOF was investigated in detail.

Ratiometric fluorescence detection of anthrax biomarker based on terbium (III) functionalized graphitic carbon nitride nanosheets

Detection of anthrax biomarker dipicolinic acid (DPA) is of great importance upon the crisis of bioterrorism. Development of fluorescent materials for DPA detection, particularly one that fully depends on single luminescent response, faces the challenge of being susceptible to interferences. The accompanying accuracy problems offer great opportunities for the establishment of more reliable ratiometric analysis method. Herein, a ratiometric fluorescent probe based on terbium functionalized graphitic carbon nitride nanosheets (Tb-g-C3N4NS) is attempted for quantitative detection of DPA to address the distinct function of g-C3N4NS as both carrier and reference fluorophore, which is a so-far unexplored option in fluorescent detection approaches. We achieve the incorporation of Tb3+ into framework of g-C3N4NS by using a simple synthetic strategy comprised of thermal pyrolysis and ultrasonic exfoliation. Combining the reference signal over g-C3N4NS at 440 nm (I440) with the response signal of Tb3+ at 546 nm (I546), concentration of DPA can be easily calculated via its linear correlation with the intensity ratio (I546/I440), giving a precise measurement towards DPA with a detection limit as low as 9.9 nM. Besides enabling an excellent self-calibrating detection of DPA, this work also inspires broader use of g-C3N4NS for relevant process.

AIE-based Tb3+ complex self-assembled nanoprobe for ratiometric fluorescence detection of anthrax spore biomarker in water solution and actual spore samples

Luminescent rare-earth (RE) complexes usually present outstanding advantages of long-lived emissions and high emission efficiency in aggregate and solid states. However, the combination of aggregation-induced emission (AIE)-based materials and RE complexes with excellent luminescent properties is rarely reported. Herein, AIE luminogens (AIEgens)-based Tb3+ complex (TPE-Tb) was designed and synthesized for the first time, which can self-assemble into novel TPE-Tb nanoparticles to be used as ratiometric fluorescent probe for sensitive and rapid detection of anthrax spore biomarker in aqueous solution or actual spores. The results indicated that the limit of detection (LOD) of this ratiometric fluorescent probe was as low as 0.187 nM and 1.64 × 104 spores/mL in water solution or actual spore samples, respectively. This work explored a new method for the combination of AIEgens-based materials and RE complexes by coordination mode and provided a versatile nanoprobe candidate for anthrax biomarker detection.

A design strategy of dual-ratiomentric optical probe based on europium-doped carbon dots for colorimetric and fluorescent visual detection of anthrax biomarker

In this work, a novel dual-ratiometric optical probe based on europium-doped carbon dots (Eu-CDs) was developed for colorimetric and fluorescent visual sensing dipicolinic acid (DPA), a anthrax biomarker. Eu-CDs with recessive signals were prepared via thermal pyrolysis method. And the magenta appears when Eu-CDs coordinates with Eriochrome Black T (EBT). Based on the ligand displacement strategy, DPA reduces magenta and makes blue appear, which develop ratiometric colorimetric visual detection methods of DPA. Under 270 nm excitation, DPA make the red fluorescence signal of Eu in EBT-CDs@Eu appear, based on the absorbance-energy transfer-emission effect, the ratiometric fluorescent visual detection assay of DPA has been developed. Based above, dual-ratiometric optical probe was designed successfully. The limit of detection (LOD) is 10.6 nM for ratio colorimetric assay. More prominently, naked-eye determination of DPA without instrument is as low as 1.0 μM. Furthermore, its practicability was verified by quantifying the DPA in Bacillus subtilis spores and human urine (with RSD≤2.35%). The sensor shows great superiority in on-site analysis of DPA, especially in limited instruments conditions.