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1.
Sensitive detection of doxorubicin (DOX) is critical for clinical theranostics. A novel ratiometric fluorescence strategy based on the inner filter effect (IFE) has been established for the sensitive detection of DOX by designing a ratiometric fluorescence probe. In the presence of DOX, the fluorescence intensity of copper nanoclusters (CuNCs) at 485 nm decreases, and the fluorescence intensity of carbon dots at 560 nm increases. Therefore, DOX can be quantitatively detected by measuring the ratio of the fluorescence intensities at 560 and 485 nm (F560/F485). The F560/F485 ratio exhibits a linear correlation with the DOX concentration in the range from 1.0 × 10−8 M to 1.0 × 10−4 M with the detection limit of 3.7 nM. Furthermore, this method was also successfully applied to the analysis of DOX in human plasma samples, affording an effective platform for drug safety management.  相似文献   

2.
We present a sensitive and quick way to determine benzene, toluene and dimethylbenzene (BTEX) in air, applying a cataluminescence (CTL) sensor based on a nano‐sized composite material, γ‐Al2O3/PtO2. The factors that affect the sensor's performance were studied, including the sensing material, temperature, rate of air carrier and wavelength. It was shown that when Pt accounted for 0.2% of the sensing material, the rate of the air carrier that carries target gas was 450 mL/min, the determination wavelength was 400 nm and temperature was 236°C, this sensor showed the best CTL intensity to BTEX. In addition, the CTL intensity had a high linear relation with the concentration of BTEX, with a linear range from 0.5 to 100 mL/m3, and a detection limit 0.22 mL/m3. This nano‐sized material had a quick response within 1.5 s, short recovery time within 1 min and a long lifetime, showing good potential for a variety of applications. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

3.
A new ‘naked-eye’ quinoline-based ‘reactive’ ratiometric fluorescent probe was prepared. The reactive stoichiometry of the probe with Hg2+ ion was 2:1. The probe exhibited high selectivity towards Hg2+ ion to other metal ions with a 410-fold increase in absorbance intensity ratio (A402/A340) in aqueous solution over a wide-range pH value (2–12), accompanied by a resonance color change from colorless to pale yellow visible to naked-eye.  相似文献   

4.
A series of Ce3+ ion single‐doped Ca2Al2SiO7 phosphors was synthesized by a combustion‐assisted method at an initiating temperature of 600 °C. The samples were annealed at 1100 °C for 3 h and their X‐ray diffraction patterns confirmed a tetragonal structure. The phase structure, particle size, surface morphology and elemental analysis were analyzed using X‐ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and energy dispersive X‐ray (EDX) spectroscopy techniques. Thermoluminescence (TL) intensity increased with increase in ultraviolet (UV) light exposure time up to 15 min. With further increase in the UV irradiation time the TL intensity decreases. The increase in TL intensity indicates that trap concentration increased with UV exposure time. A broad peak at 121 °C suggested the existence of a trapping level. The peak of mechanoluminescence (ML) intensity versus time curve increased linearly with increasing impact velocity of the moving piston. Mechanoluminescence intensity increased with increase in UV irradiation time up to 15 min. Under UV‐irradiation excitation, the TL and ML emission spectra of Ca2Al2SiO7:Ce3+ phosphor showed the characteristic emission of Ce3+ peaking at 400 nm (UV–violet) and originating from the Ce3+ transitions of 5d‐4f (2F5/2 and 2F7/2). The photoluminescence (PL) emission spectra for Ca2Al2SiO7:Ce3+ were similar to the ML/TL emission spectra. The mechanism of ML excitation and the suitability of the Ca2Al2SiO7:Ce3+phosphor for radiation dosimetry are discussed. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

5.
Coptisine (COP), one of the bioactive components in Rhizoma Coptidis, has many pharmacological effects. Meanwhile, the determination of COP is essential in pharmacological and clinical applications. Herein, we prepared carbon quantum dots (CQDs) by one-step oil-thermal method using paper mill sludge (PMS) as precursor, and developed a ratiometric fluorescence method for the determination of COP. The structural and optical properties of PMS-CQDs were evaluated through high-resolution transmission electron microscopy (HRTEM), Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), ultraviolet-visible (UV-vis), fluorescence, zeta potential and fluorescence lifetime experiments. Fluorescence intensity ratio at 550 nm and 425 nm (I550/I425) was recorded as an index for quantitative detection of COP. The detection concentration of COP ranges from 0.1 to 50 μM in good linear correlation (R2 = 0.9974) with a limit of detection of 0.028 μM (3σ/k). The quenching mechanism was deduced to be inner filter effect and static quenching. The ratiometric fluorescent probe showed impressive selectivity and sensitivity towards COP, and was successfully applied to the detection of COP in human urine with expected recoveries (95.22–111.00%) and relative standard deviations (0.46–2.95%), indicating that our developed method has a great application prospect in actual sample detection.  相似文献   

6.
Mathematical approaches made for both the charged dislocation model and piezoelectrically induced electron bombardment model of fracto‐mechanoluminescence (FML), the luminescence induced by fracture of solids, in ZnS:Mn phosphor indicate that the piezoelectrically induced electron bombardment model provides a dominating process for the FML of ZnS phosphors. The concentration of 3000 ppm Mn2+ is optimal for ML intensity of ZnS:Mn phosphor. The decay time of ML gives the relaxation time of the piston used to deform the sample and the time tm of maximum of ML is controlled by both the relaxation time of the piston and decay time of charges on the newly created surfaces of crystals. As the product of the velocity of dislocations and pinning time of dislocations gives the mean free path of a moving dislocation. Both factors play an important role in the ML excitation of impurity doped II–VI semiconductors. The linear increase of total ML intensity IT with the impact velocity indicates that the damage increases linearly with impact velocity of the load. Thus, the ML measurement can be used remotely to monitor the real‐time damage in the structures, and therefore, the ML of ZnS:Mn phosphor has also the potential for a structural health monitoring system. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

7.
An easy and effective strategy for synthesizing a ratiometric fluorescent nanosensor has been demonstrated in this work. Novel fluorescent BSA–AuNPs@Tb–AMP (BSA, bovine serum albumin; AMP, adenosine 5′‐monophosphate; AuNPs, Au nanoparticles) metal–organic framework (MOF) nanostructures were synthesized by encapsulating BSA–AuNPs into Tb–AMP MOFs for the detection of 2,6‐pyridinedicarboxylic acid (DPA) and Hg2+. DPA could strongly co‐ordinate with Tb3+ to replace water molecules from the Tb3+ center and accordingly enhanced the fluorescence of Tb–AMP MOFs. The fluorescence of BSA–AuNPs at 405 nm remained constant. While the fluorescence of BSA–AuNPs at 635 nm was quenched after Hg2+ was added, the fluorescence of Tb–AMP MOFs remained constant. Accordingly, a ratiometric fluorescence nanosensor was constructed for detection of DPA and Hg2+. The ratiometric nanosensor exhibited good selectivity to DPA over other substances. The F545/F405 linearly increased with increase of DPA concentration in the range of 50 nM to 10 μM with a detection limit as low as 17.4 nM. F635/F405 increased linearly with increase of Hg2+ concentration ranging from 50 nM to 1 μM with a detection limit as low as 20.9 nM. Additionally, the nanosensor could be successfully applied for the determination of DPA and Hg2+ in running water.  相似文献   

8.
Reactive oxygen species (ROS) are largely produced under pathological situations. To understand the etiology of disease, it is urgent to develop efficacious probes for detecting ROS. Herein, a novel nanoconjugate detection system constructed from gold clusters (AuNCs) and quantum dots (QDs) for fluorescence ratiometric‐sensing ROS was reported. Upon interacting with ROS, the red emission fluorescence (645 nm from QDs) in the detection system gradually decreased, while the green fluorescence (480 nm from AuNCs) changed little. The fluorescence ratio at the 2 wavelengths (I480 nm/I645 nm) was linearly correlated with the ROS, which could be used for the real‐time ratiometric detection of ROS. The developed nanoconjugates could be applied to monitor the ROS in inflammatory cells for its ability of generating abundant ROS and uptaking ability to nanoparticles. The stimulated ROS in inflammatory cells were monitored by AuNC‐QD and the results were consistent with the traditional 2′, 7′‐dichlorofluorescin diacetate method, confirming the reliability of the developed method. Featured with the merits of higher photostability, low background, high accuracy of ratiometric detection, the AuNC‐QD conjugate demonstrated its potential to be the probe for real‐time ROS detection in inflammatory cells.   相似文献   

9.
We show that a pH-sensitive derivative of the green fluorescent protein, designated ratiometric GFP, can be used to measure intracellular pH (pHi) in both gram-positive and gram-negative bacterial cells. In cells expressing ratiometric GFP, the excitation ratio (fluorescence intensity at 410 and 430 nm) is correlated to the pHi, allowing fast and noninvasive determination of pHi that is ideally suited for direct analysis of individual bacterial cells present in complex environments.  相似文献   

10.
Erbium(III) ion (Er3+) has abundant energy levels that can emit light covering a quite broad wavelength range in many hosts. Here we synthesized LaSrGaO4:Er3+ phosphors by a high-temperature solid-state method. Upon excitation at the ultraviolet (UV) band, LaSrGaO4:Er3+ phosphors could emit green, red and near-infrared emission simultaneously. The temperature dependent emission characteristics of the as-prepared samples was then studied and two kinds of luminescent ratiometric thermometry were constructed. The first one is on the basis of two green emission bands that stems from the 2H11/24I15/2 and 4S3/24I15/2 transitions of Er3+. The intensity ratio between these two emission bands was found to follow well with the Boltzmann distribution, and its maximum relative sensitivity was calculated to be 0.84% K−1 at 299 K. The other one depends on the 4F9/24I15/2 transition of Er3+ and self-luminescence of the host LaSrGaO4, considering that these two emission lines have different temperature response. The relative sensitivity of this type of luminescence intensity ratio (LIR) thermometry could reach 1.86% K−1 at 299 K, we have successfully developed materials with one of the largest relative sensitivities to date, which provides some basis for the subsequent development of a new type of non-contact temperature sensor.  相似文献   

11.
Ce3+‐doped calcium aluminosilicate phosphor was prepared by a combustion‐assisted method at an initiating temperature of 600°C. Structural characterization was carried out using X‐ray diffraction (XRD) and scanning electron microscopy (SEM). The absorption spectra of Ca2Al2SiO7:Ce3+ showed an absorption edge at 230 nm. The optical characterization of Ca2Al2SiO7:Ce3+ phosphor was investigated in a fracto‐mechanoluminescence (FML) and thermoluminescence (TL) study. The peak of ML intensity increased as the height of impact of the moving piston increased. The TL intensity of Ca2Al2SiO7:Ce3+ was recorded for different exposure times of UV and γ‐irradiation and it was observed that TL intensity was maximum for a UV irradiation time of 30 min and for a γ‐dose of 1180 Gy. The TL intensity had three peaks for UV irradiation at temperatures 82°C, 125°C and 203°C. Also the TL intensity had a single peak at 152°C for γ‐irradiation. The TL and ML emission spectra of Ca2Al2SiO7:Ce3+ phosphor showed maximum emission at 400 nm. The possible mechanisms involved in the TL and ML processes of the Ca2Al2SiO7:Ce3+ phosphor are also explained. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

12.
A europium (Eu)‐doped di‐calcium magnesium di‐silicate phosphor, Ca2MgSi2O7:Eu2+, was prepared using a solid‐state reaction method. The phase structure, particle size, surface morphology, elemental analysis, different stretching mode and luminescence properties were analyzed by X‐ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM) with energy dispersive X‐ray spectroscopy (EDX), Fourier transform infrared (FTIR) spectroscopy, photoluminescence (PL) and mechanoluminescence (ML). The phase structure of Ca2MgSi2O7:Eu2+ was an akermanite‐type structure, which belongs to the tetragonal crystallography with space group P4?21m; this structure is a member of the melilite group and forms a layered compound. The surface of the prepared phosphor was not found to be uniform and particle distribution was in the nanometer range. EDX and FTIR confirm the components of Eu2+‐doped Ca2MgSi2O7 phosphor. Under UV excitation, the main emission peak appeared at 530 nm, belonging to the broad emission ascribed to the 4f65d1→4f7 transition of Eu2+. The ML intensity of the prepared phosphor increased linearly with increasing impact velocity. A CIE color chromaticity diagram and ML spectrum confirmed that the prepared Ca2MgSi2O7:Eu2+ phosphor would emit green color and the ML spectrum was similar to that of PL, which indicated that ML is emitted from the same center of Eu2+ ions. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

13.
A blue CaMgSi2O6:Eu2+ phosphor was prepared by the solid‐state reaction method and the phosphor characterized in terms of crystal structure, particle size, photoluminescence (PL), thermoluminescence (TL) and mechanoluminescence (ML) properties using X‐ray diffraction (XRD), transmission electron microscopy (TEM), PL spectroscopy, TLD reader and ML impact technique. The XRD result shows that phosphor is formed in a single phase and has a monoclinic structure with the space group C2/c. Furthermore, the PL excitation spectra of Eu2+‐doped CaMgSi2O6 phosphor showed a strong band peak at 356 nm and the PL emission spectrum has a peak at 450 nm. The depths and frequency factors of trap centers were calculated using the TL glow curve by deconvolution method in which the trap depths were found to be 0.48 and 0.61 eV. The formation of CaMgSi2O6:Eu2+ phosphor was confirmed by Fourier transform infrared spectroscopy. The ML intensity increased linearly with the impact velocity of the piston used to deform the phosphor. It was shown that the local piezoelectricity‐induced electron bombardment model is responsible for the ML emission. Finally, the optical properties of CaMgSi2O6:Eu2+ phosphors are discussed. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

14.
Fluvial biofilms are subject to multistress situations in natural ecosystems, such as the co‐occurrence of light intensity changes and metal toxicity. However, studies simultaneously addressing both factors are rare. This study evaluated in microcosm conditions the relationship between short‐term light intensity changes and Zn toxicity on fluvial biofilms with long‐term photoacclimation to different light conditions. Biofilms that had long‐term photoacclimation to 25 μmol photons · m?2 · s?1 (low light [LL] biofilms), 100 μmol photons · m?2 · s?1 (medium light [ML] biofilms), and 500 μmol photons · m?2 · s?1 (high light [HL] biofilms) were characterized by different structural (Chlorophyll‐a [Chl‐a], total biomass‐AFDW, EPS, algal groups, and diatom taxonomy) and physiological attributes (ETR‐I curves and photosynthetic pigments). HL biofilms showed higher light saturation intensity and a higher production of xanthophylls than LL biofilms. In contrast, LL biofilms had many structural differences; a higher proportion of diatoms and lower AFDW and EPS contents than ML and HL biofilms. A clear effect of light intensity changes on Zn toxicity was also demonstrated. Zn toxicity was enhanced when a sudden increase in light intensity also occurred, mainly with LL biofilms, causing higher inhibition of both the Φ′PSII and the ΦPSII. A decoupling of NPQ from de‐epoxidation reaction (DR) processes was also observed, indicating substantial damage to photoprotective mechanisms functioning in biofilms (i.e., xanthophyll cycle of diatoms) due to Zn toxicity. This study highlights the need to take into account environmental stress (e.g., light intensity changes) to better assess the environmental risks of chemicals (e.g., metals).  相似文献   

15.
Di‐barium magnesium silicate phosphor doped with Eu2+ and Dy3+ was prepared using a solid‐state reaction technique under a reducing atmosphere. The sample underwent impulsive deformation by impact from a piston for mechanoluminescence (ML) investigations. The temporal ML characteristics of the phosphor were observed, which expressed a single sharp peak with a long decaying period. To investigate the luminescence centre responsible for the ML peak, the ML spectrum of the phosphor was also observed. The recorded ML spectrum was similar in shape and peak wavelength to the photoluminescence (PL) spectrum, which verifies the existence of a single emission centre due to the transition of Eu2+ ions, i.e. transitions from any of the sublevels of the 4f65d1 configuration to the 8S7/2 level of the 4f7 configuration. Decay rates for different impact velocities were also calculated using curve‐fitting techniques. The time of the ML peak and the rate of decay did not change significantly with respect to increasing impact velocity of the load and peak ML intensity varied linearly. The mechanism of the ML emission was also discussed. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

16.
Two wild strains of Zymomonas mobilis were isolated (named as ML1 and ML2) from sugar cane molasses obtained from different farms of Santander, Colombia. Initially, selection of the best ethanol-producer strains was carried out using ethanol production parameters obtained with a commercial strain Z. mobilis DSM 3580. Three isolated strains were cultivated in a culture medium containing yeast extract, peptone, glucose and salts, at pH 6 and 32°C with stirring rate of 65 rpm during 62 h. The best results of ethanol production were obtained with the native strain ML1, reaching a maximum ethanol concentration of 79.78 g l−1. ML1 and ML2 strains were identified as Z. mobilis, according to the morphology, biochemical tests and molecular characterization by PCR of specific DNA sequences from Z. mobilis. Subsequently, the effect of different nitrogen sources on production of ethanol was evaluated. The best results were obtained using urea at a 0.73 g/l. In this case, maximum concentration of ethanol was 83.81 g l−1, with kinetic parameters of yield of ethanol on biomass (YP/X) = 69.01(g g−1), maximum volumetric productivity of ethanol (Qpmax) = 2.28 (g l−1 h−1), specific productivity of ethanol (qP) = 3.54 (h−1) and specific growth rate (μ) = 0.12 h−1. Finally, we studied the effect of different culture conditions (pH, temperature, stirring, C/N ratio) with a Placket-Burman′s experimental design. This optimization indicated that the most significant variables were temperature and stirring. In the best culture conditions a significant increase in all variables of response was achieved, reaching a maximum ethanol concentration of 93.55 g l−1.  相似文献   

17.
In this paper, europium‐doped strontium aluminate (SrAl2O4:Eu2+) phosphors were synthesized using a combustion method with urea as a fuel at 600°C. The phase structure, particle size, surface morphology and elemental analysis were studied using X‐ray diffractometry (XRD), transmission electron microscopy (TEM), energy‐dispersive X‐ray spectroscopy (EDX) and Fourier transform infrared (FTIR) spectra. The EDX and FTIR spectra confirm the elements present in the SrAl2O4:Eu2+ phosphor. The optical properties of SrAl2O4:Eu2+ phosphors were investigated by photoluminescence (PL) and mechanoluminescence (ML). The excitation and emission spectra showed a broad band with peaks at 337 and 515 nm, respectively. The ML intensities of SrAl2O4:Eu2+ phosphor increased proportionally with the increase in the height of the mechanical load, which suggests that this phosphor could be used in stress sensors. The CIE colour chromaticity diagram and ML spectra confirm that the SrAl2O4:Eu2+ phosphor emitted green coloured light. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

18.
In the present work, Fe3O4–carbon nanotubes (CNTs) composite was explored as a sensing material candidate for ammonium sulfide. Intense chemiluminescence emission can be observed during the catalytic oxidation of ammonium sulfide on the surface of Fe3O4–CNTs composite. Based on this phenomenon, a selective and sensitive gas sensor for the determination of ammonium sulfide was demonstrated. Under the optimized conditions, the linear range of cataluminescence intensity vs concentration of ammonium sulfide gas was 1.4–115 µg mL?1 (R = 0.998) with a limit of detection (S/N = 3) of 0.05 µg mL?1. The relative standard deviation (n = 5) for 14.3 µg mL?1 ammonium sulfide was 1.9%. There was no response to common foreign substances, such as sulfur dioxide, toluene, aether, ethanol, acetone, hydrogen sulfide, carbon bisulfide, benzene and ammonia. The proposed sensor was successfully applied for the determination of ammonium sulfide in artificial air samples. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

19.
The present paper reports the impulsive excitation of mechanoluminescence (ML) in Sr0.97Al2O4:Eu0.01,Dy0.02 nanophosphors prepared using a combustion technique. The phosphors are characterized using X‐ray powder diffraction (XRD), high‐resolution transmission electron microscopy (HRTEM) and photoluminescence (PL). The XRD results show that the samples exhibit a monoclinic α‐phase in the crystal structure. The space group of SrAl2O4:Eu,Dy nanophosphors is monoclinic P21. The PL and ML spectra of SrAl2O4:Eu,Dy nanophosphors are excited using light with a wavelength of 365 nm and emission is found at 516 nm. The prepared nanophosphors exhibits an intense ML that can be seen in daylight with the naked eye. When a sample powder is deformed impulsively by the impact of a moving piston, the ML intensity initially increases linearly with time, attains a peak value, Im, at time tm, and then decreases with time. The peak ML intensity, Im, and total ML intensity, IT, increase linearly with applied pressure and impact velocity. The ML intensity decreases with successive impacts of load onto the phosphors, and the diminished ML intensity can be approximately recovered by UV irradiation. The activation energy using thermoluminescence is found to be 0.57 eV for SrAl2O4:Eu,Dy nanophosphors. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

20.
A fluorescent chemosensor, Py-His, based on histidine was easily synthesized in solid phase synthesis. Py-His displayed a highly sensitive ratiometric response to Zn(II) with potent binding affinity (Ka = 1.17 × 1013 M?2) in aqueous solutions. The detection limit of Py-His for Zn(II) was calculated as 80.8 nM. Moreover, Py-His distinguished Zn(II) and Hg(II) by different ratiometric response type; the chemosensor showed a more enhanced increase of excimer emission intensity to Zn(II) than Hg(II). Upon addition of Ag(I) and Cu(II), Py-His showed a turn-off response mainly due to the quenching effect of these metal ions. The binding stoichiometry (2:1 or 1:1) of Py-His to target metal ions played a critical role in the fluorescent response type (ratiometric and turn off response) to target metal ions. The role of imidazole group of Py-His for ratiometric detection of Zn(II) was proposed by pH titration experiments.  相似文献   

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