Time-resolved Luminescent Research Articles

A terbium(III) complex-based time-resolved luminescent probe for selenocysteine as an inhibitor of selenoproteins.

A terbium(III) complex-based time-resolved luminescence probe for selenocysteine can inhibit selenoprotein activity via a selenolate-triggered cleavage reaction of sulfonamide bonds in living cells.

Self-calibrated magnetic aptamer sensor with dual Lanthanide-assisted Time-resolved luminescence for high-sensitive detection of melanoma exosomal PD-L1

Highly sensitive detection of melanoma-derived exosomal PD-L1 plays a key role in non-invasive diagnosis of melanoma. Here, we proposed a self-calibrated magnetic aptamer sensor (sCMAS) for sensitive detection of melanoma exosomal PD-L1, using the dual lanthanide-assisted luminescence as well as the ratiometric fluorescent probe strategy to overcome limitations caused by systematic or environmental factors, thereby providing a more stable and liable detection output. Generally, the sCMAS employs the Tb-based nanoparticles (TbNps), which were immobilized on magnetic Fe3O4 microparticles, for stable luminescent reference signal report and the BHHCT-Eu3+ complex for detection signal report of the specific exosomal PD-L1 recognition. Particularly, the dual time-resolved luminescent elements were bridged through the PD-L1-responsive aptamer and its complementary DNA hybridization chain. Recognition of exosomes with the aptamer expelled the detection signal (BHHCT-Eu3+) only, leading to an exosome concentration-dependent liner increase of reference signal/detection signal ratio value in a broad concentration range (1.05 × 105–1.05 × 1010 particles/mL), and an extremely low calculated detection limitation of 1.88 × 102 particles/mL. Further, sCMAS allowed a rapid and efficient differentiation of the health samples from melanoma samples, even those early metastatic melanoma cases. Promisingly, this sCMAS developed in this work would provide a vast opportunity for future evaluation of tumor markers (exosomes, cells, proteins, etc.), and will provide a powerful tool in liquid biopsies.

A simple synthesis method of microsphere immunochromatographic test strip for time-resolved luminescence detection of folic acid

Folic acid (FA) is an ingredient that must be added to infant milk powder to avoid potential defects. Rapid, sensitive and reliable detection methods are needed to determined FA addition levels. Thus, this study established a microsphere immunochromatographic test strip for time-resolved luminescence detection (TRLM-ICTS) based on carboxyl-functionalized time-resolved luminescent microspheres (Eu-TRLMs) prepared by a one-step method as fluorescent markers for the immediate quantitative detection of FA in milk powder. Eu-TRLMs prepared by the one-step method showed good dispersion, high stability and strong fluorescence intensity, which is improving the sensitivity of TRLM-ICTS. In the performance evaluation of TRLM-ICTS, the detection limit was 0.487 ng mL−1, the recovery rate was 97.3–105 %, and the actual sample detection results were in line with those of UPLC-MS/MS. TRLM-ICTS has the advantages of rapid, high sensitivity and strong specificity and could as a practical quantitative detection method for the detection of FA in milk powder.

Rapid and accurate detection of phosphate in complex biological fluids based on highly improved antenna sensitization of lanthanide luminescence

Rapid and accurate detection of phosphate (Pi) in complex biological fluid is of critical importance for timely warning of Pi accumulation and monitoring Pi related pathological process. Up to date, various luminescent probes have been developed for Pi determination in aqueous media. However, the huge obstacles of the current probes suffer from the inherent issues such as time-consuming, tedious preparation and unavoidable background interference during Pi detection. To circumvent this limitation, we proposed a universal and facile strategy to fabricate a novel sensitizer-Ln3+@surfactant micelle probe with time-resolved luminescent (TRL) superiority through the self-assembly of sensitizer, Ln3+ and surfactant. Through this design, the sensitizer-Ln3+ chelate can be encapsulated into the surfactant constructed micelle and Ln3+ luminescence can be substantially lighted up through the effective energy transfer from the coordinated sensitizer and the assistance of Triton X-100. Such high TRL signal can be sensitively and specifically quenched by Pi, which was attributed to the specific coordination competition between sensitizer and Pi towards Ln3+. Benefitting from the background-free interference and highly sensitive TRL response of the sensitizer-Ln3+@surfactant probe, we achieved the rapid, selective and sensitive detection of Pi in the range of 0.5–120 μM with a limit of detection (LOD) of 0.19 μM. Furthermore, the accuracy of the proposed method based on the Ln3+ involved micelle probes was further verified through the quantitation of Pi in real biological samples.

Human serum albumin-mediated recognition of soluble amyloid-β peptides using a time-resolved luminescent probe in plasma.

A terbium(iii) complex can recognize soluble Aβ in plasma through human serum albumin (HSA)-mediated co-assembly, which can not only circumvent the interference of HSA, but also benefit Aβ enrichment with amplified time-resolved luminescence enhancement.

Inorganic-Organic Hybrid Tongue-Mimic for Time-Resolved Luminescent Noninvasive Pattern and Chiral Recognition of Thiols in Biofluids toward Healthcare Monitoring.

In this work, manganese(II)-doped zinc/germanium oxide nanoparticles (Mn@ZGNPs) have been hydrothermally synthesized to equip with appealing time-resolved luminescence (TRL). Interestingly, we reveal that they can be readily quenched ("turn off") via a facile surface coating with bioinspired polydopamine (PDA) polymerized from dopamine (DA), resulting from PDA-triggered TRL resonance energy transfer (TRL-RET). Byintegrated with the thiol-induced inhibition of PDA formation, an ingenious inorganic-organic hybrid tongue-mimic sensor array is thus unveiled for noninvasive pattern recognition of thiols in biofluids in a TRL-RET-reversed "turn on" format toward healthcare monitoring. The sensing principle is based on the new finding that there are differential inhibitions from thiols against the polymerization of DA with various concentrations. Furthermore, density function theory (DFT) studies excellently prove our sensing principle and experimental results, reinforcing the power of the presented system. More importantly, chiral recognition of varied concentrations and mixtures of cysteine enantiomers using our platform are also been demonstrated, promising its practical usage. This is a novel concept of inorganic-organic hybrid-based pattern and chiral recognition platform for TRL background-free sensing and would sprout more novel relevant strategies toward broader applications.

The Chemistry of Europium(III) Encountering DNA: Sprouting Unique Sequence-Dependent Performances for Multifunctional Time-Resolved Luminescent Assays.

Screening functional DNA that can fruitfully interact with metal ions is a long-standing hot topic in the fields of biotechnology, medicine, and DNA-based sensors. In this paper, we focus on the chemistry of europium(III) (Eu)coupled with single-stranded DNA (ssDNA), and we innovatively unveil that cytosine- and thymine-rich ssDNA oligomers (e.g., C16 and T16) can be effective antenna ligands to sensitize the luminescence of Eu. Luminescence lifetime spectroscopy, circular dichroic (CD) spectroscopy, and isothermal titration calorimetry (ITC) have been used to systematically characterize the interaction involved between Eu and ssDNA. In light of the resultant sequence-dependent performances, the long luminescence lifetime Eu/ssDNA-based label-free and versatile probes are further devised as a pattern distinction system for time-resolved luminescent (TRL) sensing applications. The interactions of metal ions and ssDNA can distinctively shift the antenna effect of ssDNA toward Eu as accessible pattern signals. As a result, as few as two Eu/ssDNA label-free TRL probes can discriminate 17 metal ions via principal component analysis (PCA). In addition, thiols can readily capture metal ions to switch the luminescence of Eu/ssDNA probes initially altered by metal ions. Hence, four Eu/ssDNA-metal ion ensembles are demonstrated to be a powerful label-free TRL sensor array for pattern differentiation of eight thiols and even chiral recognition of cysteine enantiomers with different concentrations. Moreover, the sensitive TRL detection of thiols in biofluids can be successfully realized by using our method, promising its potential practical usage. This is the first report of a ssDNA-sensitized Eu-based TRL platform for label-free yet multifunctional background-free sensing and would open a door for sprouting of more novel lanthanide ion/DNA-relevant strategies toward widespread applications.

A Label-free Time-resolved Luminescent Platform for Sensitive Endonuclease V Detection Based on Exonuclease III Regulated DNA-Tb3+ Luminescence.

Endonuclease V (EndoV) plays the important role of nucleotide excision repair (NER) in the maintenance of genomic stability. Highly sensitive detection of EndoV was achieved through an oligonucleotides sensitizing Tb3+ luminescent technique. We found that although both guanine-rich (G-rich) single-stranded DNA and dGMP could enhance the time-resolved luminescence of Tb3+, their efficiencies of enhancement were considerably different. Employing such interesting phenomenon, a label-free and time-resolved luminescent strategy for the sensitive detection of EndoV activity was developed based on DNA-enhanced time-resolved luminescence (TRL) of Tb3+. The EndoV was used to cut off the deoxyinosine site (dI) and convert the 3'-protruding termini to a recessed end, and Exonuclease III (Exo III) was used to enhance the signal contrast via digestion of G-rich DNA to dNTP. Combining with the natural advantages of the TRL, the proposed method exhibited a good linear response to EndoV ranging from 0.005 to 0.4 U/mL, with a low limit of detection of 0.005 U/mL.

A time-resolved luminescent competitive assay to detect L-selectin using aptamers as recognition elements

L-selectin is a protein with potential importance for numerous diseases and clinical disorders. In this paper, we present a new aptamer-based luminescent assay developed to detect L-selectin. The sensing system working principle is based on Förster Resonance Energy Transfer (FRET) from a donor terbium complex (TbC) to an acceptor cyanine dye (Cy5). In the present approach, the biotinylated aptamer is combined with Cy5-labelled streptavidin (Cy5-Strep) to yield an aptamer-based acceptor construct (Apta-Cy5-Strep), while L-selectin is conjugated using luminescent TbC. Upon aptamer binding to the TbC-labelled L-selectin (L-selectin-TbC), permanent donor-acceptor proximity is established which allows for radiationless energy transfer to occur. However, when unlabelled L-selectin is added, it competes with the L-selectin-TbC and the FRET signal decreases as the L-selectin concentration increases. FRET from the TbC to Cy5 was observed with time-gated time-resolved luminescence spectroscopy. A significant change in the corrected luminescence signal was observed in the dynamic range of 10–500 ng/mL L-selectin, the concentration range relevant for accelerated cognitive decline of Alzheimer's disease, with a limit of detection (LOD) equal to 10 ng/mL. The aptasensor-based assay is homogeneous and can be realized within one hour. Therefore, this method has the potential to become an alternative to tedious heterogeneous analytical methods, e.g. based on enzyme-linked immunosorbent assay (ELISA).

A label-free and time-resolved luminescence strategy for the detection of proteins based on DNA-Tb(3+) luminescence quenched by graphene oxide.

A sensitive, label-free and time-resolved luminescent aptasensor to detect proteins was developed based on the DNA-enhanced time-resolved luminescence of Tb(3+) and graphene oxide (GO). We found that the DNA no matter with a G-quadruplex structure or not could greatly enhance the long-lived emission of Tb(3+), and the luminescence of DNA-Tb(3+) could be effectively quenched by GO after the DNA-Tb(3+) was adsorbed onto GO. The target protein combined with an aptamer to form a protein/DNA complex restrained the quenching of DNA-Tb(3+) emission by GO. Thrombin and a 29-mer anti-thrombin aptamer were employed as a model analyte and a recognition element. There is a good linear relationship between the aptamer-Tb(3+) complex luminescence with the thrombin concentrations of 1 to 100 nM with a low detection limit of 0.8 nM. Since the time-resolved luminescence can eliminate the unspecific background fluorescence, the proposed aptasensor has been successfully applied in complicated biological samples for thrombin detection. This novel strategy presents a potential universal method for detection of other molecules.

A terbium-based time-resolved luminescent probe for sulfide ions mediated by copper in aqueous solution

A novel Tb(III) complex-based time-resolved luminescent probe, BBPNA-(DO3A-Tb3+)2 (L), was designed and synthesized for the recognition of Cu2+ and sulfide ions in aqueous solutions. The luminescent probe L was efficiently quenched by Cu2+ and displayed “on–off” type luminescence change towards Cu2+. Once combined with Cu2+ to form the non-luminescent L–Cu complex, the L–Cu complex could serve as an “off–on” probe for sulfide ions due to the high affinity of sulfide ions towards Cu2+. In the presence of S2−, the L–Cu complex reacted with S2− to cause the release of the Cu2+ and turn on the luminescence of L again. The rebuilding of luminescence was highly selective to S2− over other common anions, which allowed L function as an “on–off–on” probe for Cu2+ and S2− alternately. Especially, the luminescence lifetime of the probe was about 1.91ms, much longer than most organic fluorophores. Due to the long luminescence lifetime of the probe L, the probe could be used for time-resolved luminescence measurements to eliminate the interferences from autofluorescence and scattering lights and significantly to improve the signal-to-noise for detection.

New Strategy for Label-Free and Time-Resolved Luminescent Assay of Protein: Conjugate Eu3+ Complex and Aptamer-Wrapped Carbon Nanotubes

We report here a carbon nanotube-based approach for label-free and time-resolved luminescent assay of lysozyme (LYS) by engineering an antilysozyme aptamer and luminescent europium(III) (Eu(3+)) complex. The sensing mechanism of the approach is based on the exceptional quenching capability of carbon nanotubes for the proximate luminescent Eu(3+) complex and different propensities of single-stranded DNA and the DNA/protein complex to adsorb on carbon nanotubes. The luminescence of a mixture of chlorosulfonylated tetradentate β-diketone-Eu(3+) and the antilysozyme aptamer was efficiently quenched by single-walled carbon nanotubes (SWNTs) unless the aptamer interacted with LYS. Due to the highly specific recognition ability of the aptamer for the target and the powerful quenching property of SWNTs for luminescence regents, this proposed approach has a good selectivity and high sensitivity for LYS. In the optimum conditions described, >700-fold signal enhancement was achieved for micromolar LYS, and a limit of detection as low as 0.9 nM was obtained, which is about 60-fold lower than those of commonly used fluorescent aptamer sensors. Moreover, due to the much longer lifetime of the Eu(3+) luminescence than those of the ubiquitous endogenous fluorescent components, the time-resolved luminescence technique could be conveniently used for application in complicated biological samples. LYS concentrations in human urine were thus detected using time-resolved luminescence measurement with satisfactory recoveries of 95-98%.

Development of a novel terbium chelate-based luminescent chemosensor for time-resolved luminescence detection of intracellular Zn 2+ ions

Time-resolved luminescence detection technique using lanthanide chelates as luminescent probes or sensors is a highly sensitive and widely used tool for the luminescence detections of various biological and bioactive molecules. The essential of this technique is the developments of various functional luminescent probes or sensors that can selectively recognize the biological targets. In this work, a dual-chelating ligand N,N,N 1,N 1-{2,6-bis(3′-aminomethyl-1′-pyrazolyl)-4-[N,N-bis(2-picolyl)amino-methylenepyridine]} tetrakis(acetic acid) (BBATA) has been designed and synthesized. The luminescence of its Tb 3+ chelate is very weak, but can be selectively and strongly enhanced upon reaction with Zn 2+ ions. Thus a Tb 3+ chelate-based luminescent chemosensor, BBATA-Tb 3+, for highly selective and sensitive time-resolved luminescence detection of Zn 2+ ions was developed. To confirm the utility of new chemosensor for the detection of intracellular Zn 2+ ions, the performance of BBATA-Tb 3+ as a chemosensor for time-resolved luminescent imaging detection of Zn 2+ ions in living cells was investigated. The results demonstrated the efficacy and advantage of the new luminescent chemosensor for time-resolved luminescence detection of intracellular Zn 2+ ions.

Time-resolved luminescent lateral flow assay technology

We here report a detection technology that integrates highly sensitive time-resolved luminescence technique into lateral flow assay platform to achieve excellent detection performance with low cost. We have developed very bright, surface-functionalized and mono-dispersed phosphorescent nanoparticles of long lifetime under ambient conditions. The phosphorescent nanoparticles have been used to conjugate with monoclonal antibody for C-reactive protein (CRP), an inflammatory biomarker. Lateral flow immunoassay devices have been developed using the conjugate for highly sensitive detection of CRP. The CRP assay can achieve a detection sensitivity of <0.2 ng mL −1 in serum with a linear response from 0.2 to 200 ng mL −1 CRP. We have also developed a low cost time-resolved luminescence reader for the lateral flow immunoassay (LFIA) devices. The reader does not use expensive band pass filter and still provide very low detection background and high detection sensitivity on solid substrates such as nitrocellulose membranes. The reader can detect less than 2.5 ng phosphorescent particles captured on a nitrocellulose membrane strip with more than three orders of magnitude linear detection dynamic range. The technology should find a number of applications, ranging from clinical diagnostics, detection of chemical and biological warfare agents, to food and environmental monitoring.

Time-resolved luminescence of radiation defects in GaPO 4 and AlPO 4 crystals at VUV-excitation

The study of structural defects in irradiated by fast electrons ( E = 10 MeV , fluence (1–2×10 17 electron/cm 2) AlPO 4 and GaPO 4 crystals are submitted. The measurements were executed using low-temperature ( T = 8 K ) vacuum ultraviolet time-resolved luminescent spectroscopy at selective excitation by synchrotron radiation. The four types of luminescence bands with characteristic individual excitation spectra and photoluminescence decay kinetics in nano- and microsecond ranges are revealed in spectral range 2–6 eV. Possible types of defects of the crystalline structure observable in PL irradiated crystals are discussed and analyzed.

Time-resolved luminescent spectra of J-aggregates with exciton traps

The possibility of coexistence of free and self-trapped excitons in one-dimensional molecular chains (J-aggregates) has been proved on the basis of experimental study of time-resolved low-temperature luminescence spectra.