ZrTe2 Compound Dirac Semimetal Contacts for High-Performance MoS2 Transistors.

Recent investigations reveal elemental semimetal (Bi and Sb) contacts fabricated with conventional deposition processes exhibit a remarkable capacity of approaching the quantum limit in two-dimensional (2D) semiconductor contacts, implying it might be an optimal option to solve the contact issue of 2D semiconductor electronics. Here, we demonstrate novel compound Dirac semimetal ZrTe2 contacts to MoS2 constructed by a nondestructive van der Waals (vdW) transfer process, exhibiting excellent ohmic contact characteristics with a negligible Schottky barrier. The band hybridization between ZrTe2 and MoS2 was verified. The bilayer MoS2 transistor with a 250 nm channel length on a 20 nm thick hexagonal boron nitride (h-BN) exhibits an ION/IOFF current ratio over 105 and an on-state current of 259 µA µm-1. The current results reveal that 2D compound semimetals with vdW contacts can offer a diverse selection of proper semimetals with adjustable work functions for the next-generation 2D-based beyond-silicon electronics.

Photoluminescent and multi-phonon resonance Raman scattering dual-mode immunoassays based on CdS nanoparticles for HIgG detection.

A dual-mode immunoassay strategy based on CdS nanoparticles as signal probes with both of photoluminescent (PL) and multi-phonon resonance Raman scattering (MRRS) properties was developed. Simplified structural design and preparation were achieved due to the intrinsic integration of PL and MRRS dual signals in the single-unit CdS nanoprobes. Human immunoglobulin G (HIgG) was sensitively and specifically detected using the proposed PL-MRRS dual-mode strategy. The linear relationship between the HIgG concentration and the intensity of 707 nm PL peaks/300 cm-1 MRRS peaks under the excitation of 488 nm laser was established. The limit of detection was 0.93 fg mL-1 for PL and 1.10 fg mL-1 for MRRS. In comparison with previous IgG detection methods, the proposed method exhibited prominent advantages in detection sensitivity and working range with good stability and repeatability. An internal self-calibration was realized which ensured the accuracy and reliability of detection results. Both results of specificity experiments and serum sample analysis further confirmed the feasibility of the designed immunoassay strategy in practical serological detection.

Upconversion luminescence-infrared absorption nanoprobes for the detection of prostate-specific antigen.

Aiming to the ongoing challenge of accurate and sensitive detection for cancer biomarkers, antibody-functionalized NaYF4:Yb3+, Er3+@SiO2 nanorods were developed as upconversion luminescence (UCL)-infrared absorption (IRA) nanoprobes. Benefiting from the shielding effect of the SiO2 shell, an enhanced UCL was achieved. Additionally, an IRA detection signal was introduced by the Si-O-Si bonds of SiO2. Its mutual verification with UCL signal was favorable for ensuring the accuracy of the assay. A UCL-IRA sandwich detection method was established for the detection of the prostate-specific antigen. The UCL intensity at 542 nm and IRA at 1095 cm-1 were chosen for quantitative assay. The method has high sensitivity (0.05 pg mL-1) and selectivity. The range of detection (200 fg mL-1-200 ng mL-1) was singnificantly broadened compared with that of single-readout UCL or IRA detection. The assay performance of human serum samples demonstrated the practicability of the method in clinical cancer diagnosis. Graphical abstract.

Colorimetric determination of copper(II) by using branched-polyethylenimine droplet evaporation on a superhydrophilic-superhydrophobic micropatterned surface.

A colorimetric method is described for the determination of Cu(II). It is based on branched polyethylenimine (BPEI) droplet evaporation on a superhydrophilic-superhydrophobic polystyrene micropatterned surface. Exposure to Cu(II) leads to a color change from colorless to light blue and dark blue. The micropatterned surface was fabricated via combining electrospinning with oxygen plasma and served as a detection substrate. Analysis requires only a single drop of blood. The method has a linear response in the 5.0 µM to 2.5 mM Cu(II) concentration range which is within the physiological range (15.7 ∼ 23.6 µM). Compared to an assay in solution, the detection limit is decreased from 386 nM to 89 nM. Excellent selectivity over other metal ions and anions was achieved. Graphical abstract A rapid and sensitive colorimetric detection platform for Cu(II) was fabricated by using branched-polyethylenimine droplet evaporation on a superhydrophilic-superhydrophobic micropatterned surface. Only a single drop of blood was needed for the analysis. The sensitivity was improved about 4.3 times.

Tri-signal CdS@SiO2 nanoprobes for accurate and sensitive detection of human immunoglobulin G with enhanced flexibility and internal validation.

Accurate and sensitive determination of human immunoglobulin G (HIgG) level is critical for diagnosis and treatment of various diseases, including rheumatoid arthritis, humoral immunodeficiencies, and infectious disease. In this study, versatile tri-signal probes were developed by preparing CdS@SiO2 nanorods that integrate photoluminescence (PL), multi-phonon resonant Raman scattering (MRRS) and infrared absorption (IRA) properties. Through the coating of multiple CdS nanoparticles as cores within SiO2 shells, the PL and MRRS properties of CdS were improved, resulting in a significantly lowered limit of detection (LOD), with the lowest LOD of 12.37 ag mL-1. Integration with the distinctive IRA property of SiO2 shells widened the detection range towards higher concentrations, establishing a final linear range of 50 ag mL-1 to 10 µg mL-1. The remarkable consistency among the three signals highlighted the robust internal verification capability for accurate detection. This approach enhances flexibility in selecting detection methodologies to suit diverse scenarios, facilitating HIgG detection. The tri-signal nanoprobes also exhibited excellent detection selectivity, specificity and repeatability. This study presents a fresh idea for developing high-performance detection strategies.

Deuteration-Induced Energy Level Structure Reconstruction of Carbon Dots for Enhancing Photoluminescence.

Constrained by a limited understanding of the structure and luminescence mechanisms of carbon dots (CDs), achieving precise enhancement of their photoluminescence (PL) performance without altering the emission wavelength and color remains a challenge. In this work, a deuterated CD is first achieved by simply replacing the reaction solvent from H2O to D2O. The substitution of D atoms for H atoms is not limited on the surface but also within the internal structure of CDs. Deuteration affects the formation of the π-conjugated network structure by altering the content of sp2 carbon and sp3 carbon, ultimately inducing a reconstruction for energy level structure of CDs. Both the intrinsic state and surface state emission, including quantum yield, emission intensity and lifetime, are significantly enhanced after deuteration. It benefits from the reduction in non-radiative transitions, since the lowered vibrational frequencies of D atoms and optimized local energy level distribution in CDs structure. The deuterated CDs are applied in the fabrication of white-light-emitting diodes to show their application potential. This work provides a highly versatile route for improving and controlling photoluminescence performance of CDs and has opportunities to guide the development of CDs for practical applications.

A dual-mode method for detection of miRNA based on the photoluminescence and resonance light scattering.

MicroRNAs (miRNAs) hold potential as useful biomarkers for early diagnosis and evaluation of diverse cancers, but their low abundance and short length make the detection of miRNAs face low sensitivity and accuracy. Herein, a photoluminescence (PL)-resonance light scattering (RLS) dual-mode method was developed for the sensitive and accurate detection of miRNA-141 using CdTe quantum dots (QDs) and Au nanoparticles. The presence of miRNA-141 induced PL quenching and RLS increasing. The limit of detection (LOD) was as low as 3.7 fM, and the miRNA-141 was detected linearly in a range from 10 fM to 10 nM. The dual signals generated no mutual interference and were detected using the same spectrophotometer, allowing for mutual validation to ensure the accuracy and reliability of the detection results. This study proposes valuable references for constructing dual-mode detection methods.

Solvent-induced luminescence behavior of NH2-MIL-53(Fe) in H2O and D2O: a potential approach for D2O detection.

An anomalous solvent-induced luminescence quenching of NH2-MIL-53(Fe) in D2O is reported. Contrary to conventional understanding, the quenching is originated from the inhibition of charge transfer by hydrogen bonding between NH2-MIL-53(Fe) and D2O, rather than protonation or high-frequency vibrations of solvent molecules. This enables accurate quantitative detection towards specific volume fractions of D2O in H2O.

Above-room-temperature strong intrinsic ferromagnetism in 2D van der Waals Fe3GaTe2 with large perpendicular magnetic anisotropy.

The absence of two-dimensional (2D) van der Waals (vdW) ferromagnetic crystals with both above-room-temperature strong intrinsic ferromagnetism and large perpendicular magnetic anisotropy (PMA) severely hinders practical applications of 2D vdW crystals in next-generation low-power magnetoelectronic and spintronic devices. Here, we report a vdW intrinsic ferromagnetic crystal Fe3GaTe2 that exhibits record-high above-room-temperature Curie temperature (Tc, ~350-380 K) for known 2D vdW intrinsic ferromagnets, high saturation magnetic moment (40.11 emu/g), large PMA energy density (~4.79 × 105 J/m3), and large anomalous Hall angle (3%) at room temperature. Such large room-temperature PMA is better than conventional widely-used ferromagnetic films like CoFeB, and one order of magnitude larger than known 2D vdW intrinsic ferromagnets. Room-temperature thickness and angle-dependent anomalous Hall devices and direct magnetic domains imaging based on Fe3GaTe2 nanosheet have been realized. This work provides an avenue for room-temperature 2D ferromagnetism, electrical control of 2D ferromagnetism and promote the practical applications of 2D-vdW-integrated spintronic devices.

A dual-mode immunosensing strategy for prostate specific antigen detection: Integration of resonance Raman scattering and photoluminescence properties of ZnS:Mn2+ nanoprobes.

Luminescence-based methods are widely used for the detection of prostate specific antigen (PSA), for example during the diagnosis of prostate cancer. However, the accuracy of these methods is sub-optimal. The aim of this study was to develop an accurate and sensitive dual-mode immunosensing technique using a combination of resonance Raman scattering (RRS) and photoluminescence (PL) signals for the detection of PSA. A ZnS:Mn2+ nanoprobe was used as the signal reporter, which exhibits both multi-phonon RRS and PL properties. The RRS signal intensity at 348 cm-1 and the PL signal intensity at 590 nm were used for the quantitative assay of PSA. The reproducibility, selectivity and specificity of this dual-mode immunosensing strategy demonstrated an improvement compared with commercial PSA ELISA kits in the analysis of serum samples. Therefore, the RRS-PL immunosensing technique developed in this study shows potential as a reliable technique to be used in the clinical diagnosis of prostate cancer.

Highly-Tunable Intrinsic Room-Temperature Ferromagnetism in 2D van der Waals Semiconductor Crx Ga1- x Te.

The combination of semiconductivity and tunable ferromagnetism is pivotal for electrical control of ferromagnetism and next-generation low-power spintronic devices. However, Curie temperatures (TC ) for most traditional intrinsic ferromagnetic semiconductors (≤200 K) and recently discovered two-dimensional (2D) ones (<70 K) are far below room temperature. 2D van der Waals (vdW) semiconductors with intrinsic room-temperature ferromagnetism remain elusive considering the unfavored 2D long-range ferromagnetic order indicated by Mermin-Wagner theorem. Here, vdW semiconductor Crx Ga1- x Te crystals exhibiting highly tunable above-room-temperature ferromagnetism with bandgap 1.62-1.66 eV are reported. The saturation magnetic moment (Msat ) of Crx Ga1- x Te crystals can be effectively regulated up to ≈5.4 times by tuning Cr content and ≈75.9 times by changing the thickness. vdW Crx Ga1- x Te ultrathin semiconductor crystals show robust room-temperature ferromagnetism with the 2D quantum confinement effect, enabling TC 314.9-329 K for nanosheets, record-high for intrinsic vdW 2D ferromagnetic semiconductors. This work opens an avenue to room-temperature 2D vdW ferromagnetic semiconductor for 2D electronic and spintronic devices.

Fluorescence-infrared absorption dual-mode nanoprobes based on carbon dots@SiO2 nanorods for ultrasensitive and reliable detection of carcinoembryonic antigen.

The level of carcinoembryonic antigen (CEA) in serum has the significant reference value for early diagnosis and treatment of various cancers. However, the CEA detection still suffers from the issue of limited sensitivity and reliability. Herein, a fluorescence (FL)-infrared absorption (IRA) dual-mode nanoprobe was fabricated based on carbon dots (CDs)@SiO2 nanorod for CEA detection. The FL and IRA signals display no mutual interference and can verify each other, ensuring the reliability of assay results. The highly sensitive FL signal originating from the CDs is enhanced by the surface passivation of SiO2 and improves the overall sensitivity of the detection. The detection range spans 9 orders of magnitude and the limit of detection reaches 794.6 ag mL-1, which are great superior to the commercial kits and most of the previous reports. Satisfactory recovery over the commercial kits was achieved in real serum samples. The ultrasensitive and reliable FL-IRA detection strategy sheds light on a new avenue toward promoting the practicability of the nanoprobes in clinical cancer diagnosis.

A self-floating electrospun nanofiber mat for continuously high-efficiency solar desalination.

Solar desalination is an environment-friendly and sustainable technology to address the shortage of freshwater resources. However, it still faces huge challenges to develop a salt-rejection solar desalination system with continuous high efficiency. Herein, an electrospun nanofiber mat was fabricated for continuously high-efficiency solar desalination with carbon nanotube as a photothermal material, polyvinylidene fluoride as a floating support material and polyvinylpyrrolidone as a pore-forming agent. The porous structure and superhydrophilic surface provide significant water transport channels and thus avoid salt deposition, even in the high-salinity brine (20 wt% NaCl). The integration of strong broadband absorption property, excellent photothermal performance, floatability, durability and stability endows the solar desalination system with continuously high evaporation efficiency. The evaporation rate and solar conversion efficiency reached up to 1.372 kg m-2 h-1 and 86.1%, respectively, in simulated seawater under one sun irradiation and lasted for 11 h with little fluctuation. This work opens a new avenue for the rational design and fabrication of solar desalination systems to promote practical application.

[Preparation and chiral recognition ability of chiral stationary phase based on immobilized polyacrylamide derivative].

High performance liquid chromatography (HPLC) has been widely considered as the most effective way for the separation and preparation of optically pure enantiomers. In the resolution by HPLC, the separation ability of a column strongly depends on the properties of a chiral stationary phase (CSP). Among many CSPs, the immobilized CSPs, which are becoming one of the most important kinds of CSPs, have the advantages of good solvent durability and enormous method flexibility. In this work, a novel optically active acrylamide derivative (S)-APACP was synthesized by two-step reactions, and its chemical structure was characterized by 1H NMR. The polyacrylamide derivatives were immobilized on silica gel by three-step reactions to prepare immobilized CSPs, and the immobilization amount of the polymers was tested by thermogravimetric analysis. The chiral recognition ability of the immobilized CSPs was evaluated by HPLC, and the effects of Lewis acid and mobile phase on the chiral recognition ability were investigated. The results showed that APACP polymer was successfully immobilized on silica gel to prepare immobilized-type CSP with better solvent durability, and the amount of immobilized polymer was 10. 2% to 11. 8%. The immobilized-type CSP showed good chiral recognition ability for several enantiomers.