化学最新文献

In photocatalysis, establishing an Ohmic junction could create an internal electric field between semiconductors and cocatalysts [1,2], effectively enhancing the transfer of photogenerated electrons. In this study, the 1T phase dominated oxygen atom doped MoS₂ cocatalyst (O-MoS₂), synthesized from KSCN molten salt with in-situ oxidation for the first time, is combined with CdS for boosting photocatalytic hydrogen production. In the hybrid photocatalyst, electrons could be efficiently extracted from CdS to O-MoS₂ due to the presence of Ohmic contact, thereby significantly enhancing the utilization of photogenerated electrons and the photocatalytic hydrogen evolution performance. The results demonstrate that an initial hydrogen evolution rate of 532.8 μmol^-1 could be achieved for CdS with the optimum loading amount of O-MoS₂ (CdS-5), 26.6 times higher than that of CdS alone. Additionally, CdS-5 exhibits an apparent quantum yield (AQY) of 80.4 % at 420 nm. The increased photocatalytic performance of CdS-5 is primarily attributed to the efficient electron transfer (ET) process between the CdS and O-MoS₂ in the presence of Ohmic junction, which accelerates the separation of the photogenerated carriers from CdS. It is strongly confirmed by the (photo)electrochemical experiments, steady-state/time-resolved photoluminescence (PL) spectra, Kelvin probe force microscope (KPFM), femtosecond transient absorption spectra (fs-TAS) and Density functional theory (DFT) calculation.

With the advancement of flexible electronics, the demand for low-cost, high-performance flexible humidity sensors for wearable devices has increased significantly. However, commercial humidity sensors require complex preparation methods and are expensive. Therefore, we report polyvinyl alcohol/chitosan/nano carbon powder (PVA/CS/NCP) humidity-sensitive composite materials, which were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and contact angle measurements. A resistive humidity sensor was fabricated using screen printing, and the device showed a good response at 33%RH-98%RH humidity, and at 98 % RH, the sensor achieved a response of 1.74. A fully printed field-effect transistor (FET) humidity sensor was prepared by integrating an ion gel transistor with a CS/PVA/NCP humidity-sensitive resistor to improve the response. The comparison reveals a significant improvement in the FET humidity sensor's response, reaching 6.27 at 98 % RH. In addition, both types of sensors exhibit less hysteresis and good repeatability. Lastly, we tested the constructed humidity sensors under non-contact and variable breathing conditions, laying the groundwork for future wearable applications.

Abnormal kinase expression affects phosphorylation in the human body, which is associated with numerous diseases, including cancer, diabetes mellitus, and Alzheimer's disease. In this study, we synthesized a highly stable, two-dimensional, luminescence-functionalized metal-organic framework with remarkable electrochemiluminescence (ECL) by immobilizing 9,10-Di(p-carboxyphenyl) anthracene (dca) on a zirconium cluster (dca-Zr₁₂) via a strong coordination bond between -COO⁻ and Zr⁴⁺. This novel and simple platform relies on the highly specific identification of phosphate molecules by the ultra-thin dca-Zr₁₂ nanoplate through carboxylate-Zr⁴⁺-phosphate chemistry. The ferrocene-labeled peptide substrate (Fc-S-Peptide) was phosphorylated in the presence of protein kinase A (PKA) and adenosine 5'-triphosphate (ATP), and the resulting phosphopeptide could subsequently be precisely captured by the zirconium sites of the dca-Zr₁₂-modified electrode and, eventually, quench the ECL and gain a signal-off state. This rapid and simple detection strategy was successfully employed to measure PKA activity, with a detection limit as low as 0.35 mU mL^-1. Based on the results, it exhibited high selectivity and can be applied for screening PKA inhibitors. The technique was subsequently applied to detect protein kinase activity in drug-stimulated MCF-7 cell lysates, demonstrating its potential for kinase-related investigations. Further, this platform could identify the activity of other kinase types with universal applicability.

Current methods for preparing single atom catalysts (SACs) often suffer from challenges such as high synthesis temperatures, complicated procedures, and expensive equipment. In this study, a facile and universal atomic diffusion strategy near Tamman temperature (AD-T_Tam) was proposed for the synthesis of semiconductor supported non-noble metal SACs, denoted as M/S, where M = Fe, Ni, Cu, Al and S = ZnO, C₃N₄, TiO₂(A), In₂O₃. Based on the empirical T_Tam (c.a. 1/2 of the melting point) phenomenon, this strategy utilized the higher atomic mobility in bulk metals near T_Tam to facilitate the migration of metal atoms to the support surface, thereby forming SACs at a relatively low temperature. A series of M/S SACs prepared using the AD-T_Tam strategy all exhibited enhanced photocatalytic H₂O₂ production activity. Notably, Cu/ZnO achieved an H₂O₂ production rate of 986.7 μmol g^-1h^-1 through the synergistic dual pathways of the water oxidation reaction and the oxygen reduction reaction, marking a 5.4-fold increase compared to pure ZnO. The introduction of Cu single atoms significantly improved the separation and migration of charge carriers in Cu/ZnO, thereby promoting the catalytic conversion of H₂O and O₂. Overall, this strategy is easily extensible at relatively low calcination temperatures and presents great potential for industrial applications.

Red tide events caused by Akashiwo sanguinea (A. sanguinea) pose a significant threat to ecosystems. However, studies that offer promising approaches for portable and onsite detection with precise identification of A. sanguinea remain insufficient. In this study, we developed an electrochemical biosensor (E-biosensor) for detecting A. sanguinea combined with cascade amplification strategies, termed TDW-E-biosensor. A predictive relationship was also established to predict algal cell density based on electrochemical signals. The experiment results showed that the TDW-E-biosensor was successfully applied for detecting A. sanguinea at the pre-outbreak stage and demonstrated excellent analytical performance, showing a low limit of detection (LOD) of 0.0676 fM and quantitation (LOQ) of 0.102 fM for the three-electrode system, and a low LOD of 6.873 fg μL^-1 and LOQ of 20.460 fg μL^-1 for the portable system. The accuracy of the TDW-E-biosensor was validated through comparison with droplet digital PCR (ddPCR) and Bland-Altman analysis, demonstrating a high level of agreement (a mean difference of 0.132 and a standard deviation of 0.184). The reliability of the predictive relationship was evidenced by controlled laboratory experiments and Bland-Altman analysis. The developed TDW-E-biosensor provides an innovative and promising tool for early warning efforts regarding harmful algae.

Clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 12a (CRISPR/Cas12a) detection system is now widely used for nucleic acid detection and disease diagnosis. However, there are still fewer detections for single nucleotide polymorphisms (SNPs) and limited diversified detection systems for pathogen and SNP sites detection, which greatly limits their applications. Obviously, the development of a more diversified and convenient suite of detection tools is essential to unlock the full potential of CRISPR/Cas12a technology and to expand its applications across a wider range of scenarios. We have successfully developed an integrated CRISPR/Cas12a assay system. This system introduces crRNA during protein expression, reducing the number of steps and reaction time by adding only a fluorescent reporter gene and target DNA during subsequent detection. It enables on-site visualization of the assay in combination with a Recombinase polymerase amplification (RPA) reaction. Combined with the RPA reaction, we are able to rapidly detect African swine fever virus (ASFV) pathogens with high specificity. The system also enables genotyping of the SNP site of the porcine prolificacy-associated estrogen receptor (ESR) gene and the sheep prolificacy-associated Fecundity booroola (FecB) gene. Visualization is possible up to a final concentration of 3 nM, and effective differentiation of low concentrations within the concentration range of the assay. The integrated CRISPR/Cas12a assay system we developed has a robust design that ensures high-fidelity genotyping and pathogen detection are no longer restricted to the lab, allowing for rapid field analysis, which is crucial for timely interventions in agricultural and clinical settings. In addition, it has the advantages of low cost, easy operation and visualization of results.

The indicator amino acid oxidation (IAAO) technique estimates the physiological requirements for amino acids and proteins in living organisms, including humans. It involves monitoring urinary amino acids and exhaled CO₂ after ingesting 1-¹³C-labeled (carboxy-labeled) amino acids. The most common IAAO indicator amino acid is 1-¹³C-labeled phenylalanine ([1-¹³C]Phe). Its urinary concentration in test subjects ranges from below the detection limit to several μM. A simple analytical method for distinguishing trace amounts of [1-¹³C]Phe in urine from high levels of naturally occurring Phe is crucial for making IAAO tests easier. This study presents a simple and reliable approach for the simultaneous quantification of [1-¹³C]Phe and Phe in human urine using conventional GC-EI-MS. In this method, urinary phenylalanine is reacted with pentafluorobenzyl bromide in a single-phase solvent system of acetone-borate buffer without dehydration or desalting to form disubstituted pentafluorobenzyl (PFB) derivatives, which are then analyzed by GC-EI-MS (SIM). The Phe and [1-¹³C]Phe PFB derivative peaks eluted at the same retention time on the gas chromatogram but could be differentiated on the basis of fragment ions (m/z 434, 435) derived from the loss of the phenyl group ([M - 91]⁺). Correcting the interference of the m+1 isotope peak of Phe in the [M - 91] fragment (m/z 435) of [1-¹³C]Phe using the m/z 434 peak intensity and natural isotope ratio, both Phe and [1-¹³C]Phe could be quantified in the concentration range found in urine. The method was successfully applied to examine the temporal enrichment of [1-¹³C]Phe in urine samples obtained from IAAO subjects following the ingestion of a test meal containing [1-¹³C]Phe.

A simple and efficient effervescence-assisted salting-out assisted liquid-liquid extraction (EA-SALLE) method was developed for the rapid extraction of pyrethroid insecticides in fruit juices and herbal extracts. By integrating effervescence extraction with SALLE, the extraction and phase separation processes were conducted simultaneously, significantly simplifying the experimental procedure and reducing the extraction time to just 3 min. Key factors influencing the method's efficiency were systematically optimized. Combined with gas chromatography with an electron capture detector, enabled the determination of nine pyrethroid insecticides, demonstrating excellent linearity (R² > 0.99), low limits of detection (0.03-0.17 ng/mL), satisfactory accuracy (recoveries ranging from 83.0 % to 107.9 %), and good precision (RSD < 9.1 %). The proposed EA-SALLE method offers a simple, efficient, and cost-effective sample preparation technique. It is characterized by ease of operation, short extraction time, and high sensitivity, providing an effective tool for the monitoring and assessment of pesticide residues in complex samples.

Hydrogen peroxide (H₂O₂) plays a key role in a diverse array of cellular signaling pathways, which is closely related to plant health and physiological status. The accurate and efficient monitoring of H₂O₂ in living plant cells has attracted enormous interest. Herein, we developed an electrochemical-colorimetric dual-mode sensor based on the peroxidase-like activity of a polyacrylamide (PAM) -modified copper electrode (Cu-PAM), allowing for the in situ detection of H₂O₂ released from tomato leaves. The co-electrodeposition of unique combination of Cu and polyacrylamide, as well as the active site structure of Cu-centered peroxidases, can enhance adsorption performance by the hydrogen bonds between PAM with H₂O₂, which exhibited excellent electrochemical performance with a low limit of detection (LOD) of 0.0167 mM and a detection range of 0.05-25.31 mM. Meanwhile, a colorimetric signal output of the sensor that can be quantified from 1 μM to 70 μM with a LOD value of 0.33 μM. This work demonstrates a huge potential application prospect of the polyacrylamide-modified copper in the field of biosensors.