Turn-on Effect Research Articles

Global analysis of endogenous protein disorder in cells.

Disorder and flexibility in protein structures are essential for biological function but can also contribute to diseases, such as neurodegenerative disorders. However, characterizing protein folding on a proteome-wide scale within biological matrices remains challenging. Here we present a method using a bifunctional chemical probe, named TME, to capture in situ, enrich and quantify endogenous protein disorder in cells. TME exhibits a fluorescence turn-on effect upon selective conjugation with proteins with free cysteines in surface-exposed and flexible environments-a distinctive signature of protein disorder. Using an affinity-based proteomic approach, we identify both basal disordered proteins and those whose folding status changes under stress, with coverage to proteins even of low abundance. In lymphoblastoid cells from individuals with Parkinson's disease and healthy controls, our TME-based strategy distinguishes the two groups more effectively than lysate profiling methods. High-throughput TME fluorescence and proteomics further reveal a universal cellular quality-control mechanism in which cells adapt to proteostatic stress by adopting aggregation-prone distributions and sequestering disordered proteins, as illustrated in Huntington's disease cell models.

Cadmium(II) and zinc(II) frameworks with a benzothiadiazole-based ligand as a turn-on fluorescence sensor for dopamine

Two new luminescent metal-organic frameworks (MOFs), [Cd3(AIBTD)4(HCOO)2(DMF)2] (Cd-MOF) and [Zn(AIBTD)(AA)] (Zn-MOF) (DMF = N,N-dimethylformamide, AA = acetate), were prepared by solvothermal reactions of 4-(7-(1H-imidazol-1-yl)benzo[c][1, 2, 5]thiadiazol-4-yl)benzoic acid (HAIBTD) possessing an emissive benzothiadiazole (BTD) moiety with cadmium nitrate and zinc nitrate, respectively. Single-crystal X-ray diffraction analyses show that Cd-MOF and Zn-MOF possess different two-dimensional (2D) networks and form three-dimensional (3D) frameworks with different stacking modes. Their fluorescence sensing ability for dopamine was studied and it was found that both Cd-MOF and Zn-MOF show fluorescence enhancement in DMF. The turn-on effect may be attributed to the absorbance-caused enhancement (ACE). The results indicate that Cd-MOF and Zn-MOF have potential as fluorescent sensors for dopamine.

Reaction Time Induced a Two-Step Dissolution and Recrystallization Structural Transformation with Three Eu Metal-Organic Frameworks: Crystal Structures and Multiresponsive Fluorescence Detection.

Under solvothermal conditions, three 3D lanthanide metal-organic frameworks (Ln-MOFs): [Eu(H2DHTA)1.5(DMF)2]·DMF (1), [Eu(H2DHTA)0.5(DHTA)0.5(DMF)(H2O)]·2H2O (2), and Eu(HCOO)3 (3) (H4DHTA = 2,5-dihydroxyterephthalic acid) have been synthesized by different reaction times. Interestingly, induced by reaction time, compounds 1-3 underwent a two-step dissolution and recrystallization structural transformation (DRST) reaction. Investigations on the DRST processes were carried out, and the transformation pathway was deduced, which was verified by XRD analyses. Notably, compound 2 demonstrates pronounced luminescence as well as high stability in water and other organic solvents. The fluorescent detection of furan antibiotics can serve as turn-off effects, and glutamic acid (Glu), aspartic acid (Asp), and riboflavin (VB2) can serve as the turn-on effect. To explain the enhancing and quenching mechanisms, XRD, UV-visible absorption spectroscopy, electrochemistry, IR spectra, theoretical calculation, fluorescence lifetimes, and XPS were discussed. Additionally, MOF-coated test strips were utilized to detect these analytes, exhibiting excellent agreement with fluorescence spectroscopy. This work provides an example for more effective designs to employ Ln-MOFs as multiresponsive fluorescent sensors for detection of environmental pollutants in aqueous solution.

Highly stable Tb(III) metal-organic framework derived from a new benzothiadiazole functionalized ligand for fluorescence recognition of ascorbic acid

Because ascorbic acid (AA) is one of the basic elements to maintain the normal physiological functions of human body, it is urgent to develop a material that can achieve efficient, rapid and in-situ detection for AA. A new fluorescence organic compound 4′,4′′′-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis([1,1′-biphenyl]-4-carboxylic acid) (H2BTBC) based on benzothiadiazole group has been synthesized, which can detect Fe3+ ions by fluorescence turn-off effect with a detection limit of 0.015 μM, as well as recognize linear amines by fluorescence turn-on effect. Moreover, a highly stable Tb(III) metal–organic framework has been solvothermally prepared with H2BTBC, namely {[(CH3)2NH2]2[Tb2(BTBC)4]∙solvents}n (JXUST-39), which can selectively detect AA among biological fluids by fluorescence enhancement effect with a detection limit of 0.077 μM. In addition, the mechanism for JXUST-39 detecting AA is possibly the cooperative effect of absorbance-caused enhancement and charge transfer between JXUST-39 and AA. Moreover, LED lamp beads, fluorescent films and fluorescent detection test paper based on JXUST-39 were prepared to achieve portable detection via fluorescence enhancement effect.

Antimicrobial profile and Turn-On sensing of cyanide and water traces using a dual chromophoric Dansyl-Acridine conjugate as multifunctional system

9-aminocridine derivatives bearing a dimethylmethanimidamide, L1, and the dyad conjugate dansyl-acridine, L2, were synthesized and their ability to be used as multifunctional materials using different polymer matrixes was investigated. L1 was found to modulate its emission in the presence of traces of water with a turn-on effect and to this end was used for the detection of water traces in organic solvents with a LOD and LOQ of 0.0028 and 0.0121 (V%) in acetonitrile, respectively. Due to the observed acidochromism for this compound and the different behaviour in acetonitrile and chloroform due to different stabilization of the excited state a turn-off and turn-on effect was observed for respective solvents. PMMA polymer doped films aided on the elucidation for this compound to be used as a sensor of strong acids. Furthermore, compound L2 was found fruitful for the detection of cyanide through an acid base anion sensing. Incorporation of these compounds in PVA:PVP polymer films and Irogran® microparticles were carried out to assess their antimicrobial profile.

Analyzing false turn-on events with varying gate drive parameters in high voltage GaN devices

In this paper, we address the problem of false turn-on effects in a half-bridge GaN power converter in terms of circuit and device parameters. The model shows that the inherent false turn-on problem is caused by slew rates dvdsdt and dvgsdtduring the switching transients occurring at the turn-on and off phases. A higher slew rate propagates the gate driver voltage to overshoot beyond the threshold voltage causing it to accidentally turn on This study shows that dvdsdt is dependent on the internal device parameters such as gfs (transconductance) and Coss(output capacitance). From the CV characteristics, it is pretty much evident that the internal capacitances Cossand Crss (reverse transfer capacitance) are reduced with higher drain voltage enabling higher slew rates which increases the probability of false turn-on problems. Experimental results at numerous operating points at 400 V with the variation in different gate drive parameters support the analysis.

Functional Three-Dimensional Ce-Based Coordination Polymer: Synthesis, Structure, and Selective Sensing of Lysine and Arginine Based on the Luminescence Turn-On Effect

Functional Three-Dimensional Ce-Based Coordination Polymer: Synthesis, Structure, and Selective Sensing of Lysine and Arginine Based on the Luminescence Turn-On Effect

A series of triphenylamine-derived fluorophores attached to a Cu-based MOF for gaseous CO optical sensing: synthesis, performance, and mechanism.

A series of triphenylamine-derived fluorescent dyes were attached to a Cu2+-containing MOF (metal-organic framework), denoted as Pm@CuMOF. The molecular structures of these dyes were discussed by the single crystal structures. Their major absorption bands peaked at 410-450 nm, showing emission bands ranging from 556 to 586 nm with emission quantum yields ranging from 8.0 to 15.1%. It was found that the [-N(C2H5)2] group generally improved sensing performance, and the -OH group in the dyes helped the Cu2+ quenching effect. Pm@CuMOF was observed by SEM as nanorods with a width of ~100 nm and a length of 300 nm. Their XRD patterns and N2 adsorption/desorption isotherms were recorded to confirm their porous structure. A low probe loading level of ~4% was determined by TGA result. The CO sensing mechanism was revealed as a Cu2+/Cu+-involved sensing mechanism based on the result of NMR titration, IR, XPS, and EPR. The fluorescence of these triphenylamine-derived dyes was firstly quenched by CuMOF. In contact with CO, Cu2+ was reduced to Cu+, accompanied by the release and fluorescence recovery of the fluorescent dyes, showing emission turn-on effect towards CO gas. Pm@CuMOF showed increased emission intensity at CO level of 0.005% (versus N2), with response times ranging from 123 s to 280 s (depending on various temperatures). Good selectivity was observed over competing alkane gases, with stable emission for at least 5 days, but no linear calibration plots were observed.

Experimental and theoretical study on the interaction of an ionic resorcin[4]arene and some pollutants in aqueous solution

The complexation process between an ionic resorcinarene, C-ethyl-tetraminomethylated-resorcin[4]arene hydrochloride, with resorcinol, phenol and potassium cyanide has been studied in aqueous solution using spectroscopic, calorimetric, and computational techniques. The results show the formation of resorcinarene-phenol and resorcinarene-resorcinol inclusion complexes stabilized by means of π-π interactions. On the other hand, the interaction between the macrocycle and the cyanide ions is principally mediated by ion pairing and electrostatic interactions. A turn-on effect on the fluorescence intensity is found when resorcinol or phenol is added to the macrocycle. The quantification and detection limits have been calculated and the obtained values are comparable to other sensors reported in the literature. These results extend the use of this type of macrocycles as chemosensors.

Two 3D Zn(II)/Co(II)-CPs as fluorescent sensors for turn-on and red-shift sensing of tryptophan and norfloxacin

Two three-dimensional (3D) coordination polymers (CPs), namely {[M(seb)(bbimb)]·3H2O}n (M = Zn for 1; Co for 2), were obtained via hydrothermal method using sebacic acid (H2seb) mixed with 1,4-bis(benzoimidazol-1-yl)butane (bbimb). The structures of 1 and 2 both display as 3D frameworks with a 5-fold interpenetrating dia topology. CPs 1 and 2 both exhibit excellent luminescent properties and good water stability. Fluorescence sensing experiments demonstrate that 1 and 2 both can selectively detect tryptophan (Trp) and norfloxacin (Nor) in aqueous solution through turn-on and red-shift effect with remarkable anti-interference ability and low detection limits. The limits of detection (LOD) toward Trp-and Nor are 0.07 μM, 0.08 μM for 1 and 0.41 μM, 0.11 μM for 2. In addition, theoretical calculations and different detection methods were utilized to thoroughly investigate the potential sensing mechanisms for Trp-and Nor. Importantly, 1 and 2 represent two rare examples for sensing both Trp-and Nor via turn-on and red-shift effects. The fluoresence test films of 1 and 2 were prepared which can detect Trp-and Nor quickly with naked eye.

Detection of Benzodiazepines Using Schiff Base as Optical Probe Based on Fluorescence Turn-On Effect for Forensic Investigation

Detection of Benzodiazepines Using Schiff Base as Optical Probe Based on Fluorescence Turn-On Effect for Forensic Investigation

APTES functionalization in SBA-15: the effect on SO2 capture and detection applications.

The development of adsorbents for air pollutant remediation and effective monitoring is of interest. Then, the effect of the APTES functionalization ratio on the impact of the adsorption and detection of SO2 molecules was evaluated. The higher APTES functionalization material (SBA-15_6.1APTES) shows a high uptake of 1.15 mmol g-1 at 0.001 bar and 298 K. Fluorescence, time-resolved photoluminescence, and quantum yield experiments revealed a turn-on effect specifically for SO2 molecules, indicating high selectivity, suggesting host-to-guest energy transfer. Attractively, XPS measurement provided an understanding of the mechanism, suggesting hydrogen bonding and dipole-dipole interactions as the main interactions between SO2 molecules and SBA-15_6.1APTES. DFT calculations were performed to confirm these interactions. Furthermore, this study highlights the application of SBA-15 materials with different amino modifications for SO2 treatment and provides insight into the interaction mechanism using experimental techniques.

Visualizing Dipeptidyl Peptidase-IV with an Advanced Non-π-Conjugated Fluorescent Probe for Early Thyroid Disease Diagnosis.

Early detection and effective treatment of thyroid cancer are vital due to the aggressiveness and high mortality rate of the cancer. Nevertheless, the exploration of dipeptidyl peptidase-IV (DPP-IV) as a biomarker for thyroid diseases has not been widely conducted. In this study, we developed a novel non-π-conjugated near-infrared fluorescent probe, MB-DPP4, specifically designed to visualize and detect endogenous DPP-IV. Traditional DPP-IV-specific fluorescent probes rely primarily on the intramolecular charge transfer mechanism. For this reason, these probes are often hampered by high background levels that can inhibit their ability to achieve a fluorescence turn-on effect. MB-DPP4 successfully surmounts several drawbacks of traditional DPP-IV probes, boasting unique features such as exceptional selectivity, ultrahigh sensitivity (0.29 ng/mL), innovative structure, low background, and long-wavelength fluorescence. MB-DPP4 is an "off-on" chemosensor that exhibits strong fluorescence at 715 nm and releases a methylene blue (MB) fluorophore upon interacting with DPP-IV, resulting in a visible color change from colorless to blue. Given these remarkable attributes, MB-DPP4 shows great promise as a versatile tool for advancing research on biological processes and for evaluating the physiological roles of DPP-IV in living systems. Finally, we conducted a comprehensive investigation of DPP-IV expression in human serum, urine, thyroid cells, and mouse thyroid tumor models. Our findings could potentially establish a foundation for the early diagnosis and treatment of thyroid diseases.

Gate Driver Design in 180 nm SOI CMOS Process for Heterogeneous Integration Inside SiC Power Module

This paper presents the design and test results of a non-isolated single-channel gate driver for heterogeneous integration inside a SiC power module. The driver is designed on a 180 nm silicon-on-insulator (SOI) CMOS process that can safely operate up to 175 degrees C, most likely even beyond this figure, to survive at the expected junction temperature. The gate driver consists of four pull–up (PMOS) slices and four pull-down (NMOS) slices placed in parallel as the current sourcing and sinking components. Each slice can be activated individually through a controller block, making the gate driver’s drive strength variable. To mitigate the parasitic turn-on effect due to the Miller capacitor, an active Miller clamping circuit is integrated with the driver without overly compromising the device’s switching performance. Under-voltage lockout (UVLO) is another key feature of this driver that ensures the system is protected against bias supply failure. A desaturation detection scheme is also integrated with the gate driver as a system protection feature to detect excessive current flowing through the power devices. The gate driver die area is approximately 5.4 mm x 3.3 mm with a pad area of 100 μm x 100 μm suitable for wire bonding inside the module.

Vitamin B6-based fluorescence chemosensor for selective detection of F- ions: design, synthesis, and characterization.

The present paper reports on the synthesis and characterization of a new chemosensor for fluoride ions, a hydrazone derived from pyridoxal 5'-phosphate and benzothiazole. The structure of the chemosensor was confirmed using 1H and 13C NMR, FT-IR and mass spectroscopy. The conformational diversity of the chemosensor influencing the sensor activity was studied by the quantum chemistry methods on the B3LYP/6-311++G(d, p) (H, C, N, O, P, S) level, and the optimal structure of the chemosensor was chosen. The selective capability of detecting F- in the aqueous solution, which also contains Cl-, Br-, I-, NCS-, ClO4-, HSO4-, and NO3- was demonstrated. The detection limit (LOD) for fluoride ions was 0.22µM as determined by the 3σ method. The turn-on effect in the presence of fluoride ions is based on the deprotonation of the chemosensor and its subsequent aggregation in DMSO. In addition, the chemosensor was used for the detection and estimation of F- in real samples using fluorescence spectroscopy.

A vapofluorochromic dimethylaniline naphthol Schiff base used for fabricating smart textiles for VOCs detection

This work presents the synthesis and photophysical properties of a vapoluminescent compound, (E)-1-(((4-(dimethylamino)phenyl)imino)methyl)naphthalen-2-ol (DPINO), and further studies its photophysical properties, mainly including twisted intramolecular charge transfer (TICT) and vapoluminescent behaviors. DPINO emits wreak fluorescence deposited on cellulose substrate, but exhibits a turn-on effect in response to various kinds of VOCs, showing fast response and high visual identification. Through spectral analysis, it is found that the physical interaction between DPINO and VOCs is influenced by multiple factors, including volatility, structural similarity and molecular size (steric hindrance), leading to varying degrees of fluorescence response toward different VOCs. Using RGB (red-green-blue) and CIE L*a*b* (CIELAB) color spaces, the output signals are well-quantified, deriving color shift (ΔE*) for sensitivity evaluation. And the limit of detection (LOD) is calculated to be 7.4 mg/m3 (2.22 ppm) and 2.4 mg/m3 (0.72 ppm), based on RGB and CIE L*a*b*, respectively. We further fabricated a bimolecular smart textile by dip-dyeing method, which includes the present DPINO as well as an inert luminogen MMA, i.e., fluorescent reference. The DPINO-MMA bimolecular smart textile can be freely designed in shape and size, and further made into smart clothes labels, e.g., chest card, arm band and wrist band. In scenario-based experiments, the smart textile shows notable turn-on fluorescence in response to VOCs, enabling high visual identification and real-time feedback.

Highly efficient and selective detection of sulfur ions and picric acid through salamo-Cd(II) coordination polymer chemosensor

A salamo-Cd(II) coordination polymer [Cd(HL)2(4,4ʹ-bipy)]n (CP-Cd(II)) was synthesized by introducing a auxiliary ligand 4,4ʹ-bipy to the host ligand H2L (4-chloro-4ʹ-bromo-6-bromo-6ʹ-tert-butyl-2,2ʹ-[ethylenedioxybis(nitrilomethylidyne)]di-phenol), and used as a fluorescent chemical sensor to detect sulfur ions (S2−) and picric acid (PA). Single crystal X-ray analysis demonstrated that the Cd(II) atom has a slightly distorted hexa-coordinate octahedron configuration and forms an infinite one-dimensional chain structure due to the intervention strategy of the auxiliary ligand. In fluorescence method, the sensor CP-Cd(II) exhibits good selectivity and sensitivity for S2− and PA with fluorescence turn-on and off effects sequentially. Additionally, the quenching efficiency of PA remains unchanged even after the sensor has been used for four cycles. At the same time, the sensor CP-Cd(II) can quickly detect S2− and PA within 10 s, which make them charming, recoverable and reliable luminescent coordination polymer sensor materials for detecting S2− and PA. The sensing mechanisms were attentively explored by mass spectrometry analysis, spectroscopic studies and density functional theory (DFT) calculations. Furthermore, the potential application of the sensor for further detection of S2− ions and PA in environmental systems was studied through actual water sample detection.

A thiazolothiazole based Zn(II) metal−organic framework with multi-responsive fluorescent sensing toward Al3+ and oxoacid anions in an aqueous solution

Luminescent metal−organic frameworks(LMOFs) have been utilized to identify dangerous and toxic contaminants, biomarkers, and biological species. However, the luminescent properties in MOFs have been limited by the organic connectors. In this study, we present a Zn-MOF based on thiazolothiazole ligand, which exhibits fluorescent sensing properties through a mixed bipyridine-dicarboxylate strategy. {[Zn2(NDC)2(4bppyttz)]·1.5DMF} (MOF 1) (4bppyttz=2,5-bis(4-(pyridin-4-yl)phenyl)thiazolo[5,4-d]thiazole, H2NDC=naphthalene-2,6-dicarboxylic acid) featured a three-fold interpenetrated pillared layer structure in the crystal structure. The fluorescent detection of Al3+ can be served as the turn-on effect and oxoacid anions such as CrO42−, Cr2O72−, and MnO4− can be served as turn-off effects. Furthermore, luminescence sensing studies demonstrated that MOF 1 showed high selectivity and multi-responsiveness primarily for Al3+, CrO42−, MnO4−, and Cr2O72− in an aqueous medium, with detection limits of 2.9, 3.4, 3.0, and 2.2 μM, respectively. To explain the quenching and enhancing mechanisms, XRD, absorption spectra, IR spectra, and theoretical calculations were discussed. Additionally, MOF-coated test strips were utilized to detect these ions, exhibiting excellent agreement with fluorescence spectroscopy. This work may offer a promising foundation for future thiazolothiazole-based MOFs applications in the detection of numerous contaminants.

A "Turn-on" Fluorescent Probe Based on Phenothiazine for Selectively Recognizing ClO- and its Practical Applications.

Hypochlorous acid (HClO), a highly reactiveoxygen species, has important effects on human health. High selectivity and sensitivity remain challenges of fluorescent probes for detection of ClO- with a large Stokes shift. This work designed and synthesized a novel phenothiazine-based fluorescent probe TF which can detect ClO- by colorimetric and fluorescent dual signals. TF displayed turn-on fluorescence effect toward ClO- with high selectivity (≥ 28-folds) and sensitivity (LOD = 0.472μM), fast response time (< 1min) and large Stokes shift (150nm) in PBS (pH = 7.4, 40% DMSO). Meanwhile, TF can visualize ClO- on the mung bean sprouts model and apply as testing strips for portable and rapid detecting ClO- by the naked eyes. A phenothiazine-based fluorescent probe with large Stokes shift was synthesized and its responding rapidly ability to detect ClO- was studied.

Activatable organic upconversion nanoprobe for bioimaging of monoamine oxidase B in Parkinson’s disease

Monoamine oxidase B (MAO-B) activity has been observed abnormally elevated in Parkinson’s disease patients and can be used as a potential biomarker. Herein, we report an activatable frequency upconversion luminescence (FUCL) MAO-B nano-probe (NIR-MNP) capable of highly specific and real-time MAO-B imaging in biological samples. The turn-on FUCL effect is beneficial to obtaining high-quality imaging and penetrating tissue to achieve in vivo imaging, making it stand out from the existing probes. Moreover, we used NIR-MNP to confirm the role of MAO-B inhibitor in delaying Parkinson’s disease (PD) progression in mouse PD models through bio-imaging technique in vivo. Finally, our study may offer a visual way help researchers to gain further insight into the involvement of MAO-B in PD onset and progression in animals.