Room-temperature Phosphorescence Detection Research Articles

Multi-mode luminescence anti-counterfeiting and visual iron(Ⅲ) ions RTP detection constructed by assembly of CDs&Eu3+ in porous RHO zeolite

Carbon dots (CDs)-based composites have shown impressive performance in fields of information encryption and sensing, however, a great challenge is to simultaneously implement multi-mode luminescence and room-temperature phosphorescence (RTP) detection in single system due to the formidable synthesis. Herein, a multifunctional composite of Eu&CDs@pRHO has been designed by co-assembly strategy and prepared via a facile calcination and impregnation treatment. Eu&CDs@pRHO exhibits intense fluorescence (FL) and RTP coming from two individual luminous centers, Eu3+ in the free pores and CDs in the interrupted structure of RHO zeolite. Unique four-mode color outputs including pink (Eu3+, ex.254 nm), light violet (CDs, ex.365 nm), blue (CDs, 254 nm off), and green (CDs, 365 nm off) could be realized, on the basis of it, a preliminary application of advanced information encoding has been demonstrated. Given the free pores of matrix and stable RTP in water of confined CDs, a visual RTP detection of Fe3+ ions is achieved with the detection limit as low as 9.8 μmol/L. This work has opened up a new perspective for the strategic amalgamation of luminous guests with porous zeolite to construct the advanced functional materials.

Dual-responsive carbon dots-based luminophore for ratiometric fluorescence and room-temperature phosphorescence detection of oxytetracycline

Dual-responsive probes emitting both fluorescence and phosphorescence signals are greatly advantageous to sensing. Here, we present a carbon dots-based luminophore (CDs@LP) with blue fluorescence and ultra-long yellow room-temperature phosphorescence (RTP) with lifetime of 1.33 s (that was visible to the naked eye for ∼ 13 s) for ratiometric detection of oxytetracycline (OTC). The CDs@LP was prepared by molten salt method through one-step treatment of 2, 6-diaminopyridine, KNO3, MgCl2, and KH2PO4. Upon the addition of OTC into CDs@LP aqueous solution, the fluorescence at 386 nm and RTP at 538 nm of CDs@LP were quenched as a result of the inner filter effect (IEF), while the fluorescence at 522 nm of OTC steadily enhanced due to the molecular restriction through the formation of OTC-Mg2+ complexes. Both fluorescence and RTP signals have excellent linear relationships with OTC concentration. The CDs@LP had a low detection limit of 3.2 nM (fluorescence) and 0.27 μM (phosphorescence), which also exhibited satisfactory selectivity and anti-interference performance towards other antibiotics. Moreover, the CDs@LP was successfully loaded on a filter paper and used for OTC sensing. Thus, it is a promising tool for OTC detection and can act as a foundation for producing dual-signal sensing tools.

Background-free room temperature phosphorescence and digital image colorimetry detection of melamine by carbon nitride quantum dots in cellulose matrix with smartphone-based portable device

Carbon nitride quantum dots (CNQDs) were embedded in the sodium carboxymethyl cellulose (CMC) matrix to form CNQDs-CMC film to explore the room temperature phosphorescence (RTP) of CNQDs, which suppress the non-radiative relaxation process due to the internal hydrogen bonding interactions between CMC and CNQDs. Then, a simple, inexpensive, background-free miniature device integrating with CNQDs-CMC film and smartphone was fabricated for rapid and quantitative detection of melamine (MEL). In the present of MEL, the yellow RTP color of the CNQDs-CMC film was quenched and photographed by the smartphone. The Color Recognizer APP in the smartphone recognized the red (R) value for quantitative detection of MEL. Thus, digital image colorimetry (DIC) determination of MEL was achieved due to the visible RTP color change of CNQDs-CMC film. The smartphone-based miniature device provided a promising platform for the on-site monitoring analytes in the complex matrix including food safety, environmental screening, health monitoring, and disease prevention.

In Situ Turn-On Room Temperature Phosphorescence and Vapor Ultra-sensitivity at Lifetime Mode

Organic room temperature phosphorescence (RTP) systems are rarely reported for vapor phase sensing due to the contradiction between vapor permeability and phosphorescence ability. Till now, almost all reported works are based on ″turn-off″ mode RTP detection by destroying the compact-packaging oxygen-free environment. ″Turn-on″ mode RTP detection owns additional anti-interference capability due to a lower initial RTP background signal, while its realization is even harder. In this research, in situ phosphorescence ″turn-on″ sensing was realized for methamphetamine (MPEA) vapor detection. Based on the formation of aromatic phenolic aldehyde-secondary amine ion pairs with air-stable RTP performance, the fluorescent tri-formyl phenol (TFP) film was converted into a stable RTP state after being exposed to the MPEA vapor, as supported by nuclear magnetic resonance (NMR) and mass spectrometry together with theoretical calculations. The red-shifted absorption and emission, enhanced emission intensity, and 49.7 μs phosphorescence lifetime allowed multiple mode MPEA vapor sensing from chromaticity to fluorescence to phosphorescence. The lifetime mode detection limit reached 0.4 ppt, 5 orders of magnitude lower than the intensity mode detection limit of 20.3 ppb.

Single-component color-tunable circularly polarized organic afterglow through chiral clusterization

Circularly polarized organic afterglow (CPOA) with both long-lived room-temperature phosphorescence (RTP) and circularly polarized luminescence (CPL) is currently attracting great interest, but the development of multicolor-tunable CPOA in a single-component material remains a formidable challenge. Here, we report an efficient strategy to achieve multicolor CPOA molecules through chiral clusterization by implanting chirality center into non-conjugated organic cluster. Owing to excitation-dependent emission of clusters, highly efficient and significantly tuned CPOA emissions from blue to yellowish-green with dissymmetry factor over 2.3 × 10−3 and lifetime up to 587 ms are observed under different excitation wavelengths. With the distinguished color-tunable CPOA, the multicolor CPL displays and visual RTP detection of ultraviolent light wavelength are successfully constructed. These results not only provide a new paradigm for realization of multicolor-tunable CPOA materials in single-component molecular systems, but also offer new opportunities for expanding the applicability of CPL and RTP materials for diversified applications.

Molecularly imprinted polymer coated Mn-doped ZnS quantum dots embedded in a metal–organic framework as a probe for selective room temperature phosphorescence detection of chlorpyrifos

As one of the most widely used organophosphorus pesticides, chlorpyrifos (CPF) is toxic to humans. However, the rapid, effective and sensitive detection of CPF is still a challenge. In this paper, a novel molecularly imprinted phosphorescent sensor with a core–shell structure (Mn:ZnS QDs@ZIF-8@MIP) using Mn:ZnS quantum dots (QDs) as phosphorescent emitters was prepared for the highly sensitive and selective detection of CPF, and a simple and rapid room-temperature phosphorescence (RTP) detection method for CPF was proposed. For the prepared Mn:ZnS QDs@ZIF-8@MIP, Mn:ZnS QDs had good phosphorescence emission characteristics, ZIF-8 as support materials was used to improve the dispersibility of Mn:ZnS QDs, and molecularly imprinted polymer (MIP) on the surface of ZIF-8 was used to improve the selectivity of Mn:ZnS QDs for CPF. Under the optimal response conditions, the RTP intensity of Mn:ZnS QDs@ZIF-8@MIP showed a rapid response to CPF (less than 5 min), the RTP intensity ratio of P0/P had a good linear relationship with the concentration of CPF in the range of 0–80 μM, and the detection limit of this method was 0.89 μM with the correlation coefficient of 0.99. Moreover, this simple and rapid method has been successfully used to detect CPF in real water samples with satisfactory results, and the recoveries ranged from 92% to 105% with a relative standard deviation of less than 1%. This method combines the advantages of phosphorescence emission and molecular imprinting, and greatly reduces the potential interferences of competitive substances, background fluorescence and scattered light, which opens up a broad prospect for the highly sensitive and selective detection of pollutants in water based on molecularly imprinted phosphorescent sensors.

Mercaptopropionic acid-capped Mn-doped ZnS quantum dots and Pb2+ as sensing system for rapid and sensitive room-temperature phosphorescence detection of sulfide in water

As a kind of serious concern environmental toxic pollutants, sulfide is widely used in various industrial processes, and generated from the process of biological metabolism. However, the sensitive, rapid and effective detection of sulfide still remains challenge. In this paper, a simple and rapid room-temperature phosphorescence (RTP) method for the detection of sulfide with a high selectivity and sensitivity was proposed by using mercaptopropionic acid (MPA)-capped Mn-doped ZnS quantum dots (QDs) and Pb2+ as a sensing system. Highly water-soluble MPA-capped Mn-doped ZnS QDs with phosphorescence emission property were successfully synthesized by microwave-assisted hydrothermal synthesis method. We discovered that the as-prepared QDs displayed effectively phosphorescence quenching to Pb2+ in pH 11.5 borax-NaOH buffer solution, then demonstrated remarkable phosphorescence recovery after the addition of sulfide to the QDs-Pb2+ system. Therefore, based on the phosphorescence "off-on" behavior of MPA-capped Mn-doped ZnS QDs, a simple, sensitive and selective phosphorescence method for rapid detection of sulfide was successfully developed. The quenching and recovery of the phosphorescence of MPA-capped Mn-doped ZnS QDs have been studied in detail. Under the optimized conditions, the recovered degree of RTP intensity had a very good linear relationship with sulfide concentration in the range of 2 × 10−7–80 × 10−7 mol L−1 with a correlation coefficient of 0.9982, and a lower detection limit of 6.89 × 10−8 mol L−1. The relative standard deviations for eleven times repeated detections of 5 × 10−6 and 8 × 10−6 mol L−1 sulfide were 3.24% and 4.50%, respectively. The proposed method could effectively avoid the interferences of common anions, fluorescence substances and scattering light. Furthermore, it was successfully applied to detect sulfide in real water samples with satisfactory results, and the recoveries were in the range from 94.2% to 107.1%. This work will provide the basis of method for the development of fast and on-line monitoring sensors of small molecule pollutions in water.

Facile detection of microRNA based on phosphorescence resonance energy transfer and duplex-specific nuclease-assisted signal amplification

MicroRNAs (miRNAs) play an important role in many biological processes, and its level in plasma and other biological fluids is closely related to many diseases. In this work, a selective room-temperature phosphorescence (RTP) detection method for miRNA was developed based on a duplex-specific nuclease (DSN) -assisted signal amplification strategy and phosphorescence resonance energy transfer (PRET) between poly-diallyldimethylammonium chloride-modified quantum dots (QDs@PDDA) and 6-carboxy-X-rhodamine-modified miRNA sequences complementary oligonucleotide (ROX-ssDNA). The positively charged QDs@PDDA could adsorb negatively charged ROX-ssDNA by electrostatic interaction, whereas the RTP signal of QDs@PDDA could be efficiently quenched by ROX-ssDNA via PRET. In the presence of microRNA-21 (miR-21) and DSN, miR-21 hybridized with ROX-ssDNA initially to form a DNA-RNA heteroduplex as the substrate of DSN, then ssDNA in DNA-RNA heteroduplex would be cleaved into small fragments by DSN and liberate miR-21 to hybridize with another ROX-ssDNA. Eventually, due to weak interaction between ROX-ssDNA fragments and QDs@PDDA, PRET efficiency continually decreased whereas the RTP signal was significantly amplified. By employing the strategy above, quantitative detection of miR-21 in the range of 0.25–40 nM with a detection limit of 0.16 nM was realized, showing excellent performance with simplicity, good selectivity and the ability to be a promising method for miRNA detection.

Mercaptopropionic acid-capped Mn-doped ZnS quantum dots as a probe for selective room-temperature phosphorescence detection of Pb2+ in water

A simple, sensitive and selective phosphorescence method for rapid detection of Pb2+ in water based on Mn-doped ZnS QDs.

Selective room temperature phosphorescence detection of heparin based on manganese-doped zinc sulfide quantum dots/polybrene self-assembled nanosensor

A selective system was developed to detect heparin in aqueous solutions by using MPA(3-Mercaptopropionic Acid)-capped Mn-doped ZnS quantum dots (QDs)/polybrene (hexadimethrine bromide) hybrids as a sensitive room temperature phosphorescence (RTP) nanosensor. In this system, the RTP intensity of QDs was remarkably enhanced via electrostatic self-assembly after the addition of polybrene. The addition of heparin into the system was competitively bound to polybrene and enable to deprive it from the surface of QDs, as a result, the RTP intensity of Mn-doped ZnS QDs/polybrene hybrids was reduced with the increased of heparin concentration. Based on this effect, a selective system was proposed to detect heparin. Under the optimal conditions, the change of RTP intensity was proportional to the heparin concentration from 0.05 to 1.4UmL−1 (about 0.38–10.76μgmL−1) and the limit of detection (LOD) was 0.021UmL−1 (about 0.16μgmL−1). This proposed nanosensor is simple and relatively free of interference from coexisting substances, which can be applied to detect heparin in heparin injection and human serum. In addition, a new pathway was also provided based on the assembly of QDs with other cationic homopolymers for further design of biosensors and detection of biomolecules.

Phosphorescent quantum dots/doxorubicin nanohybrids based on photoinduced electron transfer for detection of DNA

MPA-capped Mn-doped ZnS QDs/DXR nanohybrids (MPA: 3-mercaptopropionic acid; QDs: quantum dots; DXR: cetyltrimethyl ammonium bromide) were constructed via photoinduced electron transfer (PIET) and then used as a room-temperature phosphorescence (RTP) probe for detection of DNA. DXR as a quencher will quench the RTP of Mn-doped ZnS QDs via PIET, thereby forming Mn-doped ZnS QDs/DXR nanohybrids and storing RTP. With the addition of DNA, it will be inserted into DXR and thus DXR will be competitively desorbed from the surface of Mn-doped ZnS QDs, thereby releasing the RTP of Mn-doped ZnS QDs. Based on this, a new method for DNA detection was built. The sensor for DNA has a detection limit of 0.039mgL−1 and a linear range from 0.1 to 14mgL−1. The present QDs-based RTP method does not need deoxidants or other inducers as required by conventional RTP detection methods, and avoids interference from autofluorescence and the scattering light of the matrix that are encountered in spectrofluorometry. Therefore, this method can be used to detect the DNA content in body fluid.

Microwave-assisted aqueous synthesis of Mn-doped ZnS quantum dots and their room-temperature phosphorescence detection of indapamide

High-quality Mn-doped ZnS QDs were prepared using a green and rapid microwave-assisted synthetic approach in an aqueous solution, which were used for room-temperature phosphorescence (RTP) detection of indapamide.

Mn-Doped ZnS Quantum Dot Imbedded Two-Fragment Imprinting Silica for Enhanced Room Temperature Phosphorescence Probing of Domoic Acid

A novel strategy was presented to construct the enhanced molecularly imprinted polymer (MIP)-based room temperature phosphorescence (RTP) probe by combining the RTP of Mn-doped ZnS quantum dots (Mn-ZnS QDs) and two-fragment imprinting. Two fragments or structurally similar parts of the target analytes were used as the dummy templates. Polyethyleneimine capped Mn-ZnS (PEI-Mn-ZnS) QDs, offering the binding sites to interact with the carboxyl groups of templates, were imbedded into MIPs by the hydrolysis of tetraethoxysilane. The rebinding of the target analytes to their fragments' cavities (recognition sites) modulated the selective aggregation of Mn-ZnS QDs in QDs-MIPs and resulted in the RTP enhancement. This new method was suitable for the selective enhanced RTP detection of nonphosphorescent analytes without any derivatization and inducers. The proposed methodology was applied to construct the high selective enhanced MIP-based RTP probe for domoic acid (DA) detection. The RTP enhancement of two-fragment imprinting silica was about 2 times of one-fragment imprinting silica and 4 times of the nonimprinting silica. The two-fragment imprinting silica exhibited the linear RTP enhancement to DA in the range of 0.25-3.5 μM in buffer and 0.25-1.5 μM in shellfish sample. The precision for 11 replicate detections of 1.25 μM DA was 0.65% (RSD), and the limit of detection was 67 nM in buffer and 2.0 μg g(-1) wet weight (w/w) in shellfish sample.

Water-soluble Eu(iii)-doped ZnS quantum dots for the room-temperature phosphorescence detection of melamine in milk products

A new type of water-soluble Eu(III)-doped ZnS quantum dots (QDs) was synthesized and characterized. A novel, simple, sensitive and precise room-temperature phosphorescence (RTP) method was developed based upon measurement of the quenching of the phosphorescence intensity of the Eu(III)-doped ZnS QDs. Remarkable quenching of the phosphorescence intensity of Eu(III)-doped ZnS QDs by various concentrations of melamine was achieved at λex = 290 nm and pH 7.4 with a linear range of 5–500 ng mL−1 and a detection limit (3σ) of 1.22 ng mL−1. The relative standard deviation for five replicate measurements was 1.2%. The proposed method was satisfactorily applied in the detection of melamine in several milk products with recoveries of 96–103%.

Room Temperature Phosphorescence Sensor for Hg2+ Based on Mn-Doped ZnS Quantum Dots

Mercury pollution is one of the most serious concerns to human health and the environment. The development of highly sensitive and selective sensors to detect toxic mercury ions has been the focus of scientific research. In this study, L-cysteine-capped Mn-doped ZnS quantum dots (QDs) have been synthesized and used for the room temperature phosphorescence detection of Hg2+. The phosphorescence of the Mn-doped ZnS QDs could be selectively quenched in the presence of Hg2+. Under optimal conditions, good linear correlations were obtained over the concentration range from 2.0 x 10(-8) mol/L to 4.5 x 10(-6) mol/L with a detection limit of 3.8 x 10(-9) mol/L. Additionally, the long lifetime of the phosphorescence of the Mn-doped ZnS QDs can avoid the interference of the autofluorescence and scattering light of the background, which facilitates their application in real samples. The possible quenching mechanism was examined by UV-vis absorption spectra and Rayleigh scattering spectra.

Ultrasonic assisted synthesis of adenosine triphosphate capped manganese-doped ZnS quantum dots for selective room temperature phosphorescence detection of arginine and methylated arginine in urine based on supramolecular Mg2+–adenosine triphosphate–arginine ternary system

An ultrasonic assisted approach was developed for rapid synthesis of highly water soluble phosphorescent adenosine triphosphate (ATP)-capped Mn-doped ZnS QDs. The prepared ATP-capped Mn-doped ZnS QDs allow selective phosphorescent detection of arginine and methylated arginine based on the specific recognition nature of supramolecular Mg2+–ATP–arginine ternary system in combination with the phosphorescence property of Mn-doped ZnS QDs. The developed QD based probe gives excellent selectivity and reproducibility (1.7% relative standard deviation for 11 replicate detections of 10μM arginine) and low detection limit (3s, 0.23μM), and favors biological applications due to the effective elimination of interference from scattering light and autofluorescence.

Mn-doped ZnS quantum dots for the room-temperature phosphorescence detection of raceanisodamine hydrochloride and atropine sulfate in biological fluids

Now, the development of quantum dots (QDs)-based fluorescence sensors become very quickly, but as phosphorescence compared to fluorescent has many advantages, like longer shine time and emission wavelength. Therefore, the phosphorescence properties of QDs and their potential for phosphorescence detection have raised great concerns. In this paper, a novel room-temperature phosphorescence (RTP) quenching method was developed by Mn-doped ZnS quantum dots (QDs). The developed method is employed for detection of the raceanisodamine hydrochloride and atropine sulfate in biological fluids. The results showed a high selectivity of the Mn-doped ZnS QDs toward these medicines by phosphorescence quenching. Under the optimized experimental conditions, the detection limits (3s) for raceanisodamine hydrochloride and atropine sulfate were 0.11μM, 0.09μM, respectively. The relative standard deviations for eleven replicate detections of 2.0μM were 0.92–1.6%. The recovery of spiked solutions in human urine and serum samples ranged from 95% to 104%.

CTAB-capped Mn-doped ZnS quantum dots and label-free aptamer for room-temperature phosphorescence detection of mercury ions

A new room-temperature phosphorescence (RTP) mercury ions sensor has been developed based on cetyltrimethylammonium bromide-capped Mn-doped ZnS quantum dots (CTAB/Mn-ZnS QDs) and label-free thymine (T)-rich aptamer. The formed T-Hg(2+)-T dsDNA can linearly quench the RTP of Mn-ZnS QDs through electron transfer and aggregation effect, and give a detection limit of 1.5 nM.

Sensitized Enantioselective Laser-Induced Phosphorescence Detection in Chiral Capillary Electrophoresis

The sensitivity of enantioselective cyclodextrin-induced room-temperature phosphorescence detection of camphorquinone (CQ) is enhanced using sensitization via a donor with a high extinction coefficient. The enantiomeric distinction is based on the different phosphorescence lifetimes of (+)-CQ and (-)-CQ after their complexation with α-cyclodextrin (α-CD). The collisional Dexter energy transfer from the selected donor 2,6-naphthalenedisulfonic acid (2,6-NS) to the acceptor CQ is still very efficient despite the inclusion of the acceptor into CD. For coupling to the chiral separation of (±)-CQ in cyclodextrin-based electrokinetic chromatography, the donor was added to the deoxygenated background electrolyte that consisted of 20 mM α-CD, 10 mM carboxymethyl-β-CD, and 25 mM borate buffer at pH 9.0. Time-resolved batch studies on sensitized phosphorescence show a significant enantioselectivity for (+)- and (-)-CQ in the presence of both α-CD and CM-β-CD although the lifetime difference is somewhat reduced with respect to direct excitation. The enantiomers were distinguished after their separation using an online time-resolved detection system. Excitation was performed at 266 nm with a pulsed, small-sized, quadrupled Nd:YAG laser. With 1 × 10(-5) M 2,6-NS, limits of detection of 4.1 × 10(-8) M and 5.2 × 10(-8) M were found for (+)-CQ and (-)-CQ, respectively. The online measured lifetimes were 238 ± 8 μs for (+)-CQ and 126 ± 10 μs for (-)-CQ. The method was used to determine the concentration of (±)-CQ leaching from a cured dental resin into water. The extracts contained 4.7 ± 0.1 × 10(-7) M of both (+)-CQ and (-)-CQ.

Ascorbic Acid Induced Enhancement of Room Temperature Phosphorescence of Sodium Tripolyphosphate‐Capped Mn‐Doped ZnS Quantum Dots: Mechanism and Bioprobe Applications

Although quantum dot (QD)-based room temperature phosphorescence (RTP) probes are promising for practical applications in complex matrixes such as environmental, food and biological samples, current QD-based-RTP probes are not only quite limited but also exclusively based on the RTP quenching mechanism. Here we report an ascorbic acid (AA) induced phosphorescence enhancement of sodium tripolyphosphate-capped Mn-doped ZnS QDs, and its application for turn-on RTP detection. The chelating ability allows AA to extract the Mn and Zn from the surface of the QDs and to generate more holes which are subsequently trapped by Mn(2+), while the reducing property permits AA to reduce Mn(3+) to Mn(2+) in the excited state, thereby enhancing the excitation and orange emission of the QDs. The enhanced RTP intensity of the QDs increases linearly with the concentration of AA in the range of 0.05-0.8 μM. Thus, a QD-based RTP probe for AA is developed. The proposed QD-based turn-on RTP probe avoids tedious sample pretreatment, and offers good sensitivity and selectivity for AA in the presence of the main relevant metal ions and other molecules in biological fluids. The limit of detection (3s) of the developed method is 9 nM AA, and the relative standard deviation is 4.8 % for 11 replicate detections of 0.1 μM AA. The developed method is successfully applied to the analysis of real samples of human urine and plasma for AA with quantitative recoveries from 96 to 105 %.