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Targeted imaging is playing an increasingly important role in the early detection and precise diagnosis of cancer. This need has motivated research into sensory nanomaterials that can be constructed into imaging agents to serve as biosensors. Graphene quantum dots (GQDs) as a valuable nanoprobe show great potential for use in two-photon biological imaging. However, most as-prepared GQDs exhibit a low two-photon absorption cross-section, narrow spectral coverage, and "one-to-one" signal conversion mode, which greatly hamper their wide application in sensitive early-stage cancer detection. Herein, a versatile strategy has been employed to fabricate an aptamer Sgc8c-functionalized hybrid as a proof-of-concept of the signal amplification strategy for targeted cancer imaging. In this study, GQDs with two-photon imaging performance, and silica nanoparticles (SiO2 NPs) as nanocarriers to provide amplified recognition events by high loading of GQD signal tags, were adopted to construct a two-photon hybrid-based signal amplification strategy. Thus, the obtained hybrid (denoted SiO2@GQDs) enabled extremely strong fluorescence with a quantum yield up to 0.49, excellent photostability and biocompatibility, and enhanced bright two-photon fluorescence up to 2.7 times that of bare GQDs (excitation at 760 nm; emission at 512 nm). Moreover, further modification with aptamer Sgc8c showed little disruption to the structure of the SiO2@GQDs-hybrid and the corresponding two-photon emission. Hence, SiO2@GQDs–Sgc8c showed specific responses to target cells. Moreover, it could be used as a signal-amplifying two-photon nanoprobe for targeted cancer imaging with high specificity and great efficiency, which exhibits a distinct green fluorescence compared to that of GQDs–Sgc8c or SiO2@GQDs. This signal amplification strategy holds great potential for the accurate early diagnosis of tumors and offers new tools for the detection a wide variety of analytes in clinical application. [ABSTRACT FROM AUTHOR]

With the development of solid-state lighting, full-spectrum lighting has gradually received extensive attention. Until now, Bi3+-doped narrow-band blue phosphors have been widely reported, but broadband green-yellow Bi3+-doped luminescent materials generated by metal-to-metal charge transfer have been rarely reported. In this study, a Bi3+ ion doped germanate luminescent material CsAlGe2O6:x%Bi3+ (1 ≤ x ≤ 11) is synthesized by a high-temperature sintering method. The phosphor can generate a broad green-yellow band peaking at 535 nm with a full width at half maximum of 165 nm under ultraviolet radiation. Through the analysis of the coordination environment, photoluminescence spectra and decay curves, the broadband emission spectra of Bi3+ ions are proved to be generated by the metal-to-metal charge transfer state and the 3P1 → 1S0 transition. By using theoretical research, luminescence kinetics, and Gaussian fitting, the luminescence mechanism of Bi3+ is examined. Meanwhile, the high quantum efficiency and superior thermal stability prove that the phosphor can be used as an efficient luminescent material in the field of full-spectrum LED devices. [ABSTRACT FROM AUTHOR]

Red phosphors often play a crucial role in enhancing the lighting quality of WLEDs. However, it remains difficult to develop a red phosphor that shows high efficiency, outstanding thermal stability, and high color purity. The struggle against "thermal stability" is always an inevitable task for photoluminescent materials. In this work, we propose a method inspired by nonlinear optical materials to synthesize a novel red-emitting pyrophosphate phosphor Cs2MgZn2(P2O7)2:Eu3+. The phase purity and morphology features are clearly investigated using X-ray diffraction and scanning electron microscopy. The emission spectra show that Cs2MgZn2(P2O7)2:20%Eu3+ can emit bright red light with a high color purity (84.68%) under ultraviolet light excitation. Rietveld refinement of the XRD pattern and luminescence kinetics as a function of the Eu3+ doping concentration were used to obtain information about the crystal structure and determine the Eu3+ site occupation preference. In particular, the sample exhibited excellent thermal stability (100%@170 °C) due to zero thermal quenching behavior, and the mechanism is described in detail. The present work provides a new possibility for the research and application of zero-thermal quenching phosphors. In addition, the fabricated WLED device was characterized via its satisfactory CIE coordinates (0.3508, 0.3233), outstanding correlated color temperature (CCT = 4608 K) and strong emission intensity, which demonstrates its potential for application in the field of WLED solid-state lighting. [ABSTRACT FROM AUTHOR]

The construction of the cyclopropyl quaternary carbon center can afford a series of 1,1-olefin bioisosteres. Here, we report tertiary cyclopropyl carbagermatranes, which can be easily obtained by the zinc-mediated decarboxylation of NHP esters. In addition, they exhibit efficient reactivity in the palladium-catalyzed cross-coupling reaction and orthogonal reactivity with boron reagents, therefore acting as robust nucleophiles for the synthesis of tertiary cyclopropane and efficient intermediates for the formation of quaternary centers. [ABSTRACT FROM AUTHOR]

Rare-earth doped phosphors have received growing interest in the luminescence field, and hold great potential for lighting and display backlight applications. Nonetheless, the practical implementation of white light-emitting diodes requires the development of a cost-effective and high-performance red phosphor, which is still a significant challenge. In this paper, Eu3+ doped Ba3Na0.32Nb6O12(Si2O7)2 red phosphors were prepared using a high-temperature solid-state method. The structure and phase purity of the samples were analyzed in detail by powder X-ray diffraction (XRD), structure refinement and energy dispersive spectroscopy analysis. Under 395 nm excitation, the phosphor exhibited an intense red emission due to the 5D0 → 7FJ (J = 1, 2, 3, 4) transitions. Through decay curve measurements, it is found that the decay time corresponding to the double-exponential equation decreased with the increase of activator concentration. Theoretical calculations showed that the quadrupole–quadrupole interaction played a dominant role in concentration quenching. The CIE chromaticity coordinates of the phosphor were (0.6436, 0.3556) and the color purity reached 92.07%, indicating that the sample has high color purity. In addition, the temperature-dependent intensity was investigated in detail. The results demonstrated that Ba3Na0.32Nb6O12(Si2O7)2:Eu3+ is a potential red-emitting phosphor for near-ultraviolet based white light-emitting diodes. [ABSTRACT FROM AUTHOR]

Fluorescent organic nanoparticles (FONs) with intriguing features have emerged as a kind of inspiring contrast reagent for various biomedical applications. However, the formation of preassembled nanoparticles requires stimuli (such as light, pH, heat, etc.), which hampers their application in all circumstances. The challenge lies in understanding and then exploring a simple and feasible method to prepare FONs without any external stimuli. Herein, we designed a novel in situ strategy to fabricate cobalt oxyhydroxide (CoOOH) nanoflake-loaded pyrene-based fluorescent organic nanoparticles (PyFONs), enabling sensitive monitoring and precision imaging of ascorbic acid (AA) in living cells. The pyrene-based FONs were constructed via a facile one-step co-precipitation method and used as the signal output. The π–π stacking-directed self-assembly process provides a brightness at 468 nm of the pyrene excimer emission accompanied by an almost disappeared monomer peak around 370–400 nm. The CoOOH nanoflakes were then in situ grown on the surface of PyFONs to serve as both an effective quencher and a recognition unit for AA. The as-synthesized PyFONs@CoOOH showed weak fluorescence signals via Förster resonance energy transfer (FRET). Subsequently, the turn-on fluorescence responses were triggered during CoOOH nanoflake reduction to Co2+ by AA, which resulted in the decomposition and collapse of the CoOOH nanoflakes. Owing to the specific oxidation–reduction reaction between the enediol group of AA and CoOOH on the surface of the PyFONs@CoOOH nanoprobe, excellent sensitivity and selectivity for AA detection was obtained with a wide linear relationship from 2.0 μM to 500 μM. The detection limit was calculated to be as low as 0.21 μM (S/N = 3). More importantly, the PyFONs@CoOOH nanoprobe also presented excellent sensitivity and selectivity for AA analysis in biological fluids, as well as for bioimaging of endogenous AA in living cells. Consequently, the proposed sensing systems can serve as a powerful tool to monitor and image AA and show broad potential applications in clinical diagnostics and drug screening. [ABSTRACT FROM AUTHOR]

In this work, a series of Eu3+ doped double perovskite phosphors Ba9La2W4O24:xEu3+ (0.2 ≤ x ≤ 1.0) were synthesized by a high temperature solid-state method. The phase purity and morphology features of phosphors were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Rietveld refinement was also executed and the results indicated that the cation site could provide a relative symmetrical environment, which will induce a large orange/red emission ratio. When excited by n-UV light, the phosphors could emit bright orange-red light with the strongest peak at 592 nm corresponding to the 5D0–7F1 transition. The optimal doping concentration of Eu3+ ions was x = 0.8 and the photoluminescence quantum yield could reach 82.9%. The concentration quenching effect was calculated to be dominated by the dipole–dipole interaction and transient spectrum results also gave direct evidence of the concentration quenching. At the operating temperature of the LED (145 °C), the photoluminescence emission intensity can still reach 97.16% at room temperature. The abnormal thermal quenching behavior was demonstrated to be compensated by electrons captured by traps. The satisfactory CIE coordinates, high color purity and strong emission intensity indicated that BLWO:0.8Eu3+ was a potential red phosphor for WLEDs with broad application prospects. [ABSTRACT FROM AUTHOR]

To realize early fire identification in cotton harvesting operations, a mid-infrared carbon monoxide (CO) sensor system was developed. To match the broadband light source with a 15° divergence angle, a multipass gas cell (MPGC) with an effective path length of 180 cm was designed to improve sensor sensitivity, leading to a limit of detection (LoD) of 0.83 parts-per-million by volume (ppmv). A damping module with springs at the bottom and front/back sides was fabricated, which can effectively reduce the vibration intensity by >80%. The sensor system can operate normally from −40 °C to 85 °C by stabilizing the temperature of the optical module through heating or cooling as well as using automotive electronic components. An adaptive early fire identification algorithm based on a dual-parameter threshold alarming method was proposed to avoid false and missing alarms. Field deployments on a harvester verified the good practicability of the sensor system. [ABSTRACT FROM AUTHOR]

One-dimensional nanotube heterostructures with IrO2-stabilized La2IrO6 is obtained by an electrospinning approach. The La2IrO6/IrO2 catalyst exhibits superior catalytic activity and strong stability for the oxygen evolution reaction. The synergistic cooperation between the two types of Ir as the active sites in La2IrO6/IrO2 is demonstrated by in situ Raman spectrum and DFT calculation. [ABSTRACT FROM AUTHOR]

Effective methods are required to quantify the organochlorine pesticide procymidone due to its potentially harmful effects toward human health and the environment. Here, hydrophilic hollow imprinted microspheres were prepared via a simple method as fluorescent sensors (@MIH-prm) for the sensitive and selective detection of PRM in ginseng. A new method of adsorption efficiency evaluation for @MIH-prm was subsequently introduced (EBS%), the effective binding site, which provided a comprehensive evaluation of the performance compared with conventional methods. The results showed that @MIH-prm could detect PRM in filtered and diluted ginseng juice with high sensitivity (LOD, 0.569 nM) and a rapid detection rate (quantitative detection of PRM within 18 min). Good selectivity was observed in the presence of combinations of different pesticides, and the adsorption of PRM could be described by the pseudo-second-order kinetic model. PRM concentrations exhibited good linearity over 1–40 nM, and the accuracy (recovery rates, 99.2 to 103.1%) and precision (RSD at 1.0 × 10−9 M, 3.14%) indicated that @MIH-prm could be used for the quantitative analysis of PRM in complex matrices. Hence, @MIH-prm has good application potential in pollution control monitoring and enforcement. [ABSTRACT FROM AUTHOR]

Tunable oxygen vacancies of LaNiO3 (LNO–Vo) are realized by theoretical prediction and the NaBH4-reduction approach. The LNO2.7 catalyst exhibits superior catalytic activity and long-term stability for water oxidation. Direct evidence of the active site center and the intermediates is observed from in situ Raman spectra and DFT calculations. [ABSTRACT FROM AUTHOR]