Fluorescence polymer nanoparticles (F-PNPs) were synthesized via one-pot strategy from hydroquinone and polyethyleneimine. The as-prepared F-PNPs display superior aqueous dispersibility, excellent ...photo-and chemical stability and excitation wavelength dependence. Its green luminescence could be responsive to SO32− and the quenching mechanism was discussed. Cu2+ could lead to the quenching effects at both 545 nm and 601 nm, thus providing a dual channel detection mode. To our knowledge, it will be the first example for the ratiometric sensing of SO32− and double sensing modes of Cu2+.
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•A novel fluorescence polymer nanoparticle was prepared.•Dual targets sensing has been evaluated.•Two routes to determine one analyte were reported.
Polymer dots possess superior emissive features, but most of them give rise to luminescence bands in the blue region. In addition, blue or green emissions have difficulty in penetrating tissue deeply. Therefore, long wavelength emissive signals are welcome for the development and application of polymeric dots towards sensing and bio-analysis. Herein, the color-tunable fluorescence polymer nanoparticles (F-PNPs) have been synthesized via one-step strategy based on the employment of hydroquinone and polyethyleneimine as precursors at low temperature. Moreover, its emission peak can be shifted from 523 nm to 612 nm by varying the excitation wavelength in the range of 380 nm to 480 nm. In view of sensing assessment, F-PNPs enable the quantitative determination of trace amount of SO32− and Cu2+. In the presence of SO32−, the polymer dots exhibit ratiometric fluorescence signals in deionized water and the color change from green to blue has been clearly observed by naked eyes (detection limit = 59 nM). In addition, two emission bands at 545 nm (green) and 601 nm (red) are observed to be responsive to the exposure of Cu2+. The entire dual sensing system for the detection of Cu2+ will be more accurate and reliable. The evaluation results reveal their optical signals are improved linearly due to the addition of Cu2+ at increasing concentrations and the detection limits are calculated to be 76 nM (green) and 41 nM (red), respectively. Such polymeric network will provide a new dynamic platform for sensing purposes in biomedicine study, environmental protection, and food safety.
In this article, a low-leakage-current and high-breakdown-voltage normally OFF p-GaN gate high-electron-mobility transistor (HEMT) on a Si substrate with low-damage NH3 plasma pretreatment was ...investigated. NH3 plasma pretreatment was performed in a plasma-enhanced chemical vapor deposition (PECVD) system before PECVD-SiNx deposition, which effectively removed surficial oxides and other impurities, suppressed the interface traps between those of SiNx and (Al)GaN, and reduced the overall drain leakage current of devices in the OFF-state. In comparison to the device without pretreatment, the normally OFF p-GaN gate HEMTs pretreated with NH3 plasma exhibited a high ON/OFF-current ratio of Formula Omitted, a low reverse gate leakage current of Formula Omitted mA/mm, a high gate breakdown voltage of 9.1 V, and a high breakdown voltage of 690 V at Formula Omitted/mm. Furthermore, NH3 plasma pretreatment effectively suppressed the threshold voltage shift induced by the charge/discharge effect in p-GaN. It was found that NH3 plasma pretreatment is effective in improving device performance, such as the leakage current, breakdown voltage, and threshold voltage stability.
In this article, a low-leakage-current and high-breakdown-voltage normally OFF p-GaN gate high-electron-mobility transistor (HEMT) on a Si substrate with low-damage NH<inline-formula> <tex-math ...notation="LaTeX">_{\text{3}}</tex-math> </inline-formula> plasma pretreatment was investigated. NH<inline-formula> <tex-math notation="LaTeX">_{\text{3}}</tex-math> </inline-formula> plasma pretreatment was performed in a plasma-enhanced chemical vapor deposition (PECVD) system before PECVD-SiN<inline-formula> <tex-math notation="LaTeX">_{\textit{x}}</tex-math> </inline-formula> deposition, which effectively removed surficial oxides and other impurities, suppressed the interface traps between those of SiN<inline-formula> <tex-math notation="LaTeX">_{\textit{x}}</tex-math> </inline-formula> and (Al)GaN, and reduced the overall drain leakage current of devices in the OFF-state. In comparison to the device without pretreatment, the normally OFF p-GaN gate HEMTs pretreated with NH<inline-formula> <tex-math notation="LaTeX">_{\text{3}}</tex-math> </inline-formula> plasma exhibited a high ON/OFF-current ratio of 10<inline-formula> <tex-math notation="LaTeX">^{\text{9}}</tex-math> </inline-formula>, a low reverse gate leakage current of 2.86 <inline-formula> <tex-math notation="LaTeX">\times</tex-math> </inline-formula> 10<inline-formula> <tex-math notation="LaTeX">^{-\text{8}}</tex-math> </inline-formula> mA/mm, a high gate breakdown voltage of 9.1 V, and a high breakdown voltage of 690 V at 1 <inline-formula> <tex-math notation="LaTeX">\mu </tex-math> </inline-formula>A/mm. Furthermore, NH<inline-formula> <tex-math notation="LaTeX">_{\text{3}}</tex-math> </inline-formula> plasma pretreatment effectively suppressed the threshold voltage shift induced by the charge/discharge effect in p-GaN. It was found that NH<inline-formula> <tex-math notation="LaTeX">_{\text{3}}</tex-math> </inline-formula> plasma pretreatment is effective in improving device performance, such as the leakage current, breakdown voltage, and threshold voltage stability.
Most of reported I-III-VI2 type chalcopyrites have been developed as indispensible materials for potential application in photovoltaic solar cells, magnetism or thermoeletrics. The exploration of its ...photoluminescence potentials has been very limited and the chemical sensing using fluorescence to signal a recognition event is realized by way of CuFeSe2 nanocrystals. A novel solution-based synthesis strategy has been developed for the preparation of CuFeSe2 quantum dots (QDs) via oleylamine and dodecanethiol as precursors. QDs possess an intense blue luminescence at 431 nm and excitation-dependent features are recorded. The nanocrystals exhibit transformation from ferromagnetism to paramagnetism state between 4 K and 298 K. Another distinct advantage of the quantum dots will be the signaling pathway in response to external analytes. It gives rise to a rapid and selective assay of Cr2O72- through an “on-off” switching process. A linear equation can be obtained in the range from 0 to 47.5 μM and the detection limit has been determined to be 0.46 μM. This cost-effective method will pave the way for the efficient synthesis of ternary chalcopyrites and provide suitable chemical routes for sensing purposes.
A novel solution-based synthesis strategy has been developed for the preparation of CuFeSe2 quantum dots (QDs) via oleylamine and dodecanethiol as precursors. QDs possess an intense blue luminescence at 431 nm and excitation-dependent features are recorded. It is observed the magnetic properties and the nanocrystals exhibit transformation from ferromagnetism to paramagnetism between 4 K and 298 K. It gives rise to a rapid and selective assay of Cr2O72- through an “on-off” switching process. Display omitted
•CuFeSe2 semiconductor nanocrystals have been assembled.•Magnetic property converted from paramagnetic to ferromagnetic.•Luminescence intensities could be controlled by Cr2O72-.
In this work, the electrical characteristics and bias stress reliability of GaN/AlN superlattices (SLs) metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) with Al2O3 ...dielectric are experimentally investigated. In comparison to the conventional AlGaN barrier MIS-HEMTs, the GaN/AlN SLs MIS-HEMTs exhibit a higher ON/OFF current ratio (<inline-formula> <tex-math notation="LaTeX">10^{{{10}}} </tex-math></inline-formula>), higher gate forward breakdown voltage (BV) (15.2 V) and OFF -state BV (495 V), lower ON-resistance (<inline-formula> <tex-math notation="LaTeX">9.5~\Omega </tex-math></inline-formula>/mm<inline-formula> <tex-math notation="LaTeX">^{{-{1}}} </tex-math></inline-formula>). Moreover, the threshold voltage (<inline-formula> <tex-math notation="LaTeX">V_{{\text {th}}} </tex-math></inline-formula>) shift and ON-resistance (R on) degradation under bias stress are further monitored. The GaN/AlN SLs MIS-HEMTs demonstrate excellent <inline-formula> <tex-math notation="LaTeX">V_{{\text {th}}} </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">R_{{\text {on}}} </tex-math></inline-formula> stability, attributed to the superior dielectric/barrier interface quality and effective 2-D electron gas confinement provided by the GaN/AlN superlattice structure. These results ensure the superior performance and stability of GaN/AlN SLs MIS-HEMTs for power/RF applications.
In this work, the electrical characteristics and bias stress reliability of GaN/AlN superlattices (SLs) metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) with Al2O3 ...dielectric are experimentally investigated. In comparison to the conventional AlGaN barrier MIS-HEMTs, the GaN/AlN SLs MIS-HEMTs exhibit a higher ON/OFF current ratio (Formula Omitted), higher gate forward breakdown voltage (BV) (15.2 V) and OFF -state BV (495 V), lower ON-resistance (Formula Omitted/mmFormula Omitted). Moreover, the threshold voltage (Formula Omitted) shift and ON-resistance (R on) degradation under bias stress are further monitored. The GaN/AlN SLs MIS-HEMTs demonstrate excellent Formula Omitted and Formula Omitted stability, attributed to the superior dielectric/barrier interface quality and effective 2-D electron gas confinement provided by the GaN/AlN superlattice structure. These results ensure the superior performance and stability of GaN/AlN SLs MIS-HEMTs for power/RF applications.
Fluorescent organic nanoparticles (FONs) play important roles in the monitoring and controls of biological systems. To fulfill such duties, we have to investigate how the nanoplatforms interact with ...living matters. Currently, very limited information concerning the potential risks and toxicity has been reported for FONs except the MTT assay. In this contribution, the amine-rich cationic precursor (polyethyleneimine) initiates one-pot copolymerization with methyldopa sesquihydrate and water-soluble fluorescent nanoparticles are afforded. The influence of reduction agent (sodium sulfite) on the luminescence, microstructure and crystallinity has been discussed and the corresponding stabilities are substantially improved. Further studies reveal that selective Cu2+ detection has been realized due to “on-off” change and the limit of detection is determined to be 52 nM. It has been discovered that glutathione (GSH) can recover its green luminescence in terms of strong affinity of GSH to copper ions. For the first time, three different cell viability experiments including MTS assay, Annexin V-APC/7-AAD kit and double stain technique have been performed to support the negligible cytotoxicity of FONs in living cells. Spectra imaging has been employed for the identification of Cu2+ and GSH in HeLa cells. In addition, the Cu2+-GSH pairs can generate an “AND” logic gate during recognition sequence operations. It will be the first example that the effectiveness of encryption and decryption has been verified via Cu2+ and GSH based on FONs.
S-PMDA NPs-based nanodots were prepared via one-pot strategy from polyethyleneimine and methyldopa sesquihydrate. Its green luminescence could be responsive to Cu2+ and the quenching mechanism was discussed. The incorporated GSH firmly trapped copper ions and the green fluorescence was recovered. Their logic gate operations and security ink potentials were also assessed. Three different cell viability experiments including MTS assay, Annexin V-APC/7-AAD kit and double stain technique have been performed and no obvious cytotoxicity was observed. Display omitted
•A novel type of FONs was developed.•Dual targets sensing has been assessed.•The intracellular detection of Cu2+-GSH pairs has been realized.•The potential for security ink was verified.
Since Cu
2+
and Fe
3+
ions have been considered as bioactive cations in oxygen transport and enzymatic reactions, the development of reliable ways for the monitoring of the two species will be highly ...desirable. But the optical stability of conventional organic chromophores needs to be improved. Therefore, the employment of quantum dots (quantum dots are abbreviated to be QDs) such as ternary CuFeS
2
QDs for the purpose of sensing has been reported in this study. CuFeS
2
QDs were synthesized by using oleylamine as the stabilizer at 180 °C and the particle size was around 2–3 nm. The monodispersed quantum dots with tetragonal chalcopyrite crystalline structure were identified. The corresponding excitation and emission wavelengths of the QDs were monitored at 372 and 458 nm. Magnetic properties were analyzed via applied magnetic field ranging between −6000 and 6000 Oe at 300 K and the ferromagnetic phase was verified. In this report, CuFeS
2
QDs has been used as an optical probe to detect the metal ions with high sensitivity, selectivity and fast responses. Two linear equations can be obtained in the range from 0 to 30 μM for Cu
2+
and from 0 to 45 μM for Fe
3+
(detection limits: Cu
2+
, 1.98 μM; Fe
3+
, 2.15 μM). These results may provide promising applications in cation sensing fields.
An efficient way to assemble Fe3O4@SiO2-NH2 nanocomposite has been developed by coupling (3-aminopropyl)trimethoxysilane onto surface of core-shell structure through facile impregnation of Fe3O4@SiO2 ...decorated with amino groups. The key step during the synthesis involves the incorporation of organic fluorophore and amines are treated with 1,8-naphthalic anhydride. The achieved hybrid inorganic-organic nanoparticle gives rise to blue emissions and shows enough stability. Furthermore, Cu2+ can be recognized by the organic building block via coordination reaction and the “on-off” quenching effect is observed. The nanosensor provides a response concentration range (1–6 μM) to Cu2+ with the detection limit of 0.65 μM. Owing to the magnetic properties, the hybrid nanoprobe can be easily retrieved from aqueous solution for repeated uses via magnetic separation (35 s). This approach will offer an alternative way for designing novel detection systems in biological related fields.
•Novel hybrid inorganic-organic network was assembled.•Cu2+ can be recognized by the organic building block.•The nanoprobe can be easily recovered via magnetic separation.
