Paraquat (PQ), a highly toxic and persistent herbicide, poses severe risks to environmental and public health. Herein, we developed a supramolecular indicator displacement assay (IDA) for PQ detection using a squaraine dye (J3-Ad) and cucurbit[7]uril (CB7). PQ displaces J3-Ad monomers from the J3-Ad&CB7 (J3&CB) complex, inducing J3-Ad self-assembly into H-aggregates. This process was characterized by Ultraviolet-visible (UV-vis) absorption and fluorescence spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy, and density functional theory (DFT) calculations. The assay achieved a detection limit of 1.86 μM with a linear range of 0-30 μM, and exhibited excellent anti-interference ability. It was successfully applied to visually detect PQ in soil and fruit samples, with recovery rates of 96.21-104.66%. This method provides a simple, rapid, and reliable approach for monitoring PQ residues in environmental and food safety applications.

Two-coordinate Cu(i) complexes featuring a carbene-Cu(i)-amine general structure have been developed as efficient thermally activated delayed fluorescence (TADF) materials for electroluminescent and photocatalytic applications. Revealing the underlying photophysical dynamics of this series of compounds allows proper tuning of deactivation pathways and excited state lifetimes. In this context, a complementary TADF mechanism involving vibronic coupling between triplets has been discussed. Both experimental and theoretical analyses provide insights to fully understand the spin-vibronic coupling in the spin-flip process between singlet and triplet excited states. By a rational design of the excited state energetic alignment, TADF decay lifetimes (tau TADF) can be tuned in a wide range from 1.9 to 67 mu s, enabling the propitious applications as luminescent dopants in organic light-emitting diodes (OLEDs) with short tau TADF and as photosensitizers in photocatalysis with long tau TADF.

Rational programming of immune receptor synergy is central to precise immune intervention. Inspired by natural immune synapses, we used DNA origami to physically construct a precisely assembled B cell receptor (BCR)-Toll-like receptor (TLR) signaling axis, enabling programmable artificial immune synapses in B cells. By varying the nanoscale spacing between BCR ligand and TLR9 agonist, we found that ∼20 nm maximized signaling synergy, leading to optimal B cell activation. This spacing enhanced BCR-TLR crosstalk, boosting Bruton’s tyrosine kinase (BTK) and p38 mitogen-activated protein kinase (MAPK) phosphorylation and upregulating activation genes. The same spatial rule applied to TLR7/8 agonists, revealing a universal scale for BCR-myeloid differentiation primary response protein 88 (MyD88)-dependent TLR synergy. Then, we designed a subunit vaccine with SARS-CoV-2 receptor-binding domain (RBD) and CpG ODN 1018 fixed ∼20 nm apart. This vaccine elicited higher neutralizing antibodies and memory B cell responses in mice than conventional aluminum-adjuvanted mixtures. Our work establishes a paradigm for physically programming immune receptor spatial synergy, enabling next-generation precision immunotherapies.

Detection of 3-hydroxy-2-butanone (acetoin), a characteristic volatile metabolite of Listeria monocytogenes (LM), represents a promising non-invasive strategy for monitoring contamination levels of foodborne pathogens in food. However, current sensing materials suffer from poor selectivity and insufficient sensitivity at trace concentrations. Herein, a series of Pd-loaded Cd2GeO4 (Pd/CGO) chemiresistive gas sensors that achieves highly selective and sensitive acetoin detection was reported. Among them, the 0.5wt% Pd/CGO-based sensor exhibits a high response, with an ultrafast response time and a detection limit as low as 10 ppb. The sensor also demonstrates excellent selectivity over common interfering gases, good reproducibility, and robust long-term stability. Mechanistic investigations combining O2-TPD, XPS, and DFT calculations reveal that Pd loading not only increases the proportion of chemisorbed oxygen species on the CGO surface, which enhances the overall sensing response, but also serves as new active sites. This work demonstrates that rational Pd modification combined with dual-site engineering offers a promising paradigm for designing high-performance metal oxide gas sensors for pathogen biomarker detection in food.

Polycyclic aromatic hydrocarbons (PAHs), especially pyrene, are hazardous pollutants with serious health risks. Effective detection methods for PAHs are essential for environmental monitoring. In this study, we construct a simple, efficient method to detect pyrene derivatives in water. A squaraine dye (J3-Ad) with dual host-guest sites was synthesized and paired with a β-cyclodextrin dimer (H2-CD) to regulate host-guest interactions. In the presence of pyrenes, J3-Ad monomers in the J3-Ad/H2-CD mixture (JH-AC) are displaced by pyrenes and self-assemble into H-aggregates, resulting in a ∼135 nm absorption spectral shift. The transformation was confirmed through Scanning Electron Microscope (SEM), Dynamic Light Scattering (DLS), and Density Functional Theory (DFT) analysis. The system showed high sensitivity, with detection limits of 1.76 nmol/L for pyrene and 60.02 nmol/L for 1-hydroxypyrene (1-OHP), along with strong anti-interference and reliable colorimetric recognition. A smartphone-based, real-time detection platform was developed for visual monitoring of pyrene in soil and vegetables. Pyrene in tap water and river water, as well as 1-OHP in urine, were successfully detected, with acceptable recovery rates and a relative standard deviation (RSD) of less than 10.14 %. This work provides a sensitive, rapid, and visual method for tracking PAH pollution, offering significant potential for practical, on-site environmental applications.

Singlet oxygen (1O2) plays a crucial role in cancer chemotherapy and ROS biology, driving the need for highly specific probes to monitor its dynamics in real time. Herein, we developed the ratiometric fluorescent probe NAP-t-PY, utilizing a 2-pyridone recognition unit. The probe's 1-methyl-3-benzyl-2-pyridone moiety reacts specifically with 1O2via [4 + 2] cycloaddition, forming the endoperoxide NAP-t-PY-EP. This reaction attenuates intramolecular charge transfer (ICT), inducing a significant blue shift from 562 nm to 446 nm, thereby enabling ratiometric detection with a large Stokes shift (138 nm). Demonstrates high sensitivity (LOD = 0.12 μM), excellent selectivity and rapid response (<15 min) towards 1O2. Its excellent photostability and low cytotoxicity facilitated biological application, successfully enabling real-time live-cell imaging of PDT-induced endogenous 1O2 in both A549 lung cancer cells and NCM460 normal colon cells.

The herbicide glyphosate, N-(phosphonomethyl)glycine, has been widely used in the past 40 years, and has had many adverse effects on human health. Here, we constructed a convenient "on-off-on" fluorescent platform for detection of glyphosate via Cu2+ modulated squaraine dye fluorescence quenching. The squaraine dye F-0 exhibited strong fluorescence, which could be quenched by the addition of Cu2+. However, the addition of glyphosate restored the fluorescence intensity of F-0 due to the formation of a Cu2+-glyphosate complex. F-0 was utilized as a fluorescent probe for the quantitative detection of glyphosate, with the lowest detection limit of 13.16 nmol L-1. Furthermore, this method demonstrated high selectivity and anti-interference capabilities. The successful monitoring of glyphosate in real samples was achieved using this detection strategy.

We synthesized a squaraine dye (F-0) to develop a method for detecting pyrophosphate (PPi) and alkaline phosphatase (ALP) by modulating the fluorescence of F-0. The fluorescence intensity of the F-0 system was quenched upon the addition of Cu2+ ions; however, it was restored when PPi was introduced due to the formation of a complex between PPi and Cu2+. Since ALP can hydrolyze PPi, the fluorescence of the system was quenched again upon the addition of ALP. Based on these principles, we established a fluorescent probe that exhibits an "off–on–off" fluorescence response. The detection limits of this method for PPi and ALP were 103 nmol dm−3 and 0.18 U dm−3, respectively. Moreover, this method demonstrates good selectivity and specificity and can be applied to the detection of PPi in actual samples.

An infrared squaraine dye was utilized to detect Cu2+ in solvents based on H-aggregates of squaraine dye. H-aggregates are a type of aggregation with enhanced photophysical properties compared to monomers. In the presence of a Ca2+ solution, F-Cl offers exceptional H-aggregators that can be transformed into monomers by adding Cu2+. Furthermore, this mode successfully demonstrated fluorescence changes in HeLa cells cultured in vitro after the addition of Ca2+ or Cu2+. A highly specific detection of Cu2+ was achieved using this transformation mode.

[Background]Volatile organic compounds(VOCs)in exhaled breath are closely associated with respiratory diseases and are linked to various metabolic reactions in the human body.A quanti-tative analytical method can provide technical support for studying VOCs related to various dis-eases. [Objective]To establish a thermal desorption-gas chromatography-mass spectrometry(TD-GC-MS)method for the determination of 27 VOCs in exhaled breath. [Methods]VOCs in exhaled breath were collected using a Bio-VOC sampler and enriched with Tenax TA thermal desorption tubes before TD-GC-MS analysis.Standards were collected using thermal desorption tubes and optimized for thermal desorption conditions as well as chromato-graphic and mass spectrometric conditions:The separation of the 27 VOCs was achieved by an optimized temperature program,the improvement of sensitivity by optimizing quantitative ions,and the increase of VOCs desorption efficiency by optimizing thermal desorption time and temperature.Limit of detection,limit of quan-tification,accuracy,precision,and stability of the proposed method were investigated by spiking with a blank gas bag,and exhaled breath samples from 20 healthy individuals were collected for an application study of the proposed method. [Results]The thermal desorption temperature was 280℃,and desorption time was 6 min.A VF-624ms chromatographic column was se-lected for the separation of target substances.The initial temperature of heating program was 35℃,maintained for 1 min,and then in-creased to 100℃at a heating rate of 3℃·min-1 for 1 min,followed by increasing to 210℃at a heating rate of 28℃·min-1 for 5 min.A quantitative analysis was conducted with a single ion monitoring(SIM)mode.Under these conditions,the 27 VOCs showed good linear relationships in their respective concentration ranges and the correlation coefficients were higher than 0.9990.The limits of detection of the method were in the range of 0.01-0.13 nmol·mol-1,the limits of quantification were in the range of 0.02-0.44 nmol·mol-1,and the spiked recoveries were in the range of 80.1%-120.5%,with intra-batch and inter-batch precision≤18.8%and 17.9%respectively.All sub-stances can be stored at room temperature(23-28 ℃)for 7 d and at 4 ℃ for 14 d.The proposed method was applied to exhaled breath samples from 20 subjects with detection rates≥80%(except for trans-2-pentene and decane)and a concentration range of 0.00-465.50 nmol·mol-1. [Conclusion]The established TD-GC-MS method for quantification of VOCs in exhaled breath is characterized by high sensitivity and good accuracy,and is suitable for quantitative determination of VOCs in exhaled breath,which can provide technical support for the study of exhaled breath VOCs.

Potassium ion (K+) plays an important role in the maintenance of cellular biological process for human health. Thus, the detection of K+ is very important. Here, based on the interaction between thiamonomethinecyanine dye and G-quadruplex formation sequence (PW17), K+ detection spectrum was characterized by UV-Vis spectrometry. The single-stranded sequence of PW17 can fold into G-quadruplex in the presence of K+. PW17 can induce a dimer-to-monomer transition of the absorption spectrum of cyanine dyes. This method shows high specificity against some other alkali cations, even at high concentrations of Na+. Further, this detection strategy can realize the detection of K+ in tap water.

A trimethine cyanine dye (MTC) was developed for Cu2+ detection. MTC can exhibit different aggregation modes, such as monomers, dimers, H- and J-aggregates. Here, G-quadruplex (G2) with modification of an alkyne at the 5′ end could regulate J-aggregates of MTC to monomers. Upon addition of Cu2+, sodium ascorbate, and another sequence (G1) with azide modification at the 3′ end, a new sequence was ligated by click chemistry of azide-alkyne cycloaddition, accompanied by MTC monomers assembling into J-aggregates again. The colors of the solution turned pink to blue. This strategy shows high specificity and selectivity and can realize monitoring Cu2+ in tap water. This simple method uses only a Uv-vis instrument to finish Cu2+ detection. A cyanine dye transformation between J-aggregates and monomers was applied to monitor the Cu2+ level via Cu+-promoted azide-alkyne cycloaddition of two rich guanine sequences.

Welding fume exposure is inevitable of welding workers and poses a severe hazard to their health since welding is a necessary industrial process. Thus, preclinical diagnostic symptoms of worker exposure are of great importance. The aim of this study was to screen serum differential metabolites of welding fume exposure based on UPLC–QTOF-MS/MS. In 2019, 49 participants were recruited at a machinery manufacturing factory. The non-target metabolomics technique was used to clarify serum metabolic signatures in people exposed to welding fume. Differential metabolites were screened by OPLS-DA analysis and Student's t-test. The receiver operating characteristic curve evaluated the discriminatory power of differential metabolites. And the correlations between differential metabolites and metal concentrations in urine and whole blood were analyzed utilizing Pearson correlation analysis. Thirty metabolites were increased significantly, and 5 metabolites were decreased. The differential metabolites are mainly enriched in the metabolism of arachidonic acid, glycero phospholipid, linoleic acid, and thiamine. These results observed that lysophosphatidylcholine (20:1/0:0) and phosphatidylglycerol(PGF1α/16:0) had a tremendous anticipating power with relatively increased AUC values (AUC > 0.9), and they also presented a significant correlation of Mo concentrations in whole blood and Cu concentrations in urine, respectively. The serum metabolism was changed significantly after exposure to welding fume. Lysophosphatidylcholine (20:1/0:0) and phosphatidylglycerol (PGF1α/16:0) may be a potential biological mediator and biomarker for laborers exposure to welding fume.

Herein, a highly selective and sensitive squaraine dye (F-0) for Cu2+ detection was developed. Upon addition of Cu2+, F-0 could greatly decrease absorption peak accompanying with fluorescent quenching about 170 folds. The detection limit can reach as low as 7.2 nmol/L. F-0 showed excellent water solubility and achieved naked eye detection of Cu2+. A paper strip pre-stained with F-0 solution was fabricated and showed color changed from blue to colorless upon addition of Cu2+. F-0 exhibited highly specific to Cu2+ over other metal ions. Furthermore, on the basic of low cell cytotoxicity, F-0 could be utilized to monitor Cu2+ in living cell and mice via fluorescence imaging. These results showed that F-0 has great potential for a more complex applications.

铅作为一种重金属离子在工业生产中被广泛应用,环境中不可避免的产生Pb2+污染,因而Pb2+的检测具有重要意义.菁染料聚集体具有可控性,聚集体之间转化伴随着明显光谱信号变化.本研究合成一种方酸菁染料(F-C1),其二聚体和单体可相互转化.以Pb2+敏感的富G碱基序列(T30695)为模板,当Pb2+存在时,富G序列形成G-四链体,诱导F-C1由二聚体转化成单体,使得紫外吸收信号改变,实现Pb2+的检测.该检测手段简单,仅需紫外光谱表征.同时该方法具有良好的特异性,线性区间为1～20 μmol/L,检测限为0.90μmol/L,响应时间快速.

研究设计合成一种新型噻菁染料Dyel,在PBS缓冲溶液中实现对人血清白蛋白(HSA)高选择性检测.向Dyel-PBS体系中加入HSA后,通过检测荧光,发现Dyel在444 nm处的荧光强度显著增加,说明此体系可应用于HSA检测.优化检测条件后,在HSA浓度为3-30 mg/L时,HSA与Dyel有良好的线性关系(R2 =0.988 6),检出限为1.8 mg/L,且反应迅速达到平衡,可以实现快速、高选择性检测HSA.

基于调控噻菁染料(Dye2)的超分子自组装性质及其与核酸适配体(T30695)特异性结合的能力,构建了Pb2+的特异性识别模块.结果表明,当体系中加入Pb2+时,T30695单链形成G-四链体,并将二聚体形式存在的噻菁染料诱导解聚为单体,引起422,445 nm处紫外吸收峰变化,仅需通过UV-vis光谱仪便可实现对Pb2+的高选择性、高灵敏度识别.该体系在Pb2+浓度为0.25～10.00 μmol/L时具有线性关系(R2 = 0.992 7),其检出限为0.115 μmol/L.

Small interfering RNA (siRNA) can effectively silence target genes through Argonate 2 (Ago2)-induced RNA interference (RNAi). It is very important to control siRNA activity in both spatial and temporal modes. Among different masking strategies, photocaging can be used to regulate gene expression through light irradiation with spatiotemporal and dose-dependent resolution. Many different caging strategies and caging groups have been reported for light-activated siRNA gene silencing. Herein, we describe a novel caging strategy that increases the blocking effect of RISC complex formation/process through host/guest (including ligand/receptor) interactions, thereby enhancing the inhibition of caged siRNA activity until light activation. This strategy can be used as a general approach to design caged siRNAs for the photomodulation of gene silencing of exogenous and endogenous genes.

The squaraine dye (F-Cl) was synthesized and developed as a probe to detect human serum albumin (HSA) based on disassembly of the dimeric aggregates to monomeric dye. A squaraine dye modified with two chlorine atoms could enhance more proportion of dimeric dye than that without modification in PBS buffer, and then these dimers could be disassembled to monomers by HSA. F-Cl showed a highly selective response to HSA over various amino acids, proteins and common ions. The detection limit was as low as 94 ?g/L. The results of mechanism showed that F-Cl might bind to HSA monomer mode of site II. It is a simple and low cost-efficiency method. The potential application of F-Cl for the detection of HSA in containing urine samples is described.

Small interfering RNAs (siRNAs) are widely studied for their highly specific gene silencing activity. However, obstacles remain to the clinical application of siRNAs. Attaching conjugates to siRNAs can improve their stability and broaden their application, and most functional conjugates of siRNAs locate at the 3′-terminus of the sense or antisense strand. In this work, we found that conjugating a group at the 5′-terminus of the antisense strand via phosphodiester was practicable, especially when the group was a flexible moiety such as an alkyl linker. When conjugating a bulky ligand, such as cRGD, the length of the 5′-phosphodiester linker between the ligand and the 5′-terminus of the antisense strand was the key in terms of RNA interference (RNAi). With a relative longer linker, the conjugates showed potency similar to siRNA. A highly efficient transfection system composed of a neutral cytidinyl lipid (DNCA) and a gemini-like cationic lipid (CLD) was employed to deliver siRNAs or their conjugates. The cRGD conjugates showed superior targeting delivery and antitumor efficacy in vivo and also selective cellular uptake in vitro. This unity of encapsulation and conjugation strategy may provide potential strategies for siRNA-based gene therapy.