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Modulating Protein-Protein Interactions with Visible-Light Responsive Peptide Backbone Photoswitches
摘要： Life relies on a myriad of carefully orchestrated processes, in which proteins and their direct interplay ultimately determine cellular function and disease. Modulation of these complex cross-talks has recently attracted attention, even as a novel therapeutic strategy. Here, we describe the synthesis and characterization of two visible-light responsive peptide backbone photoswitches based on azobenzene derivatives to exert optical control over protein-protein interactions (PPI). Our novel peptidomimetics undergo fast isomerization and reversibility with low photochemical fatigue under alternatively blue/green-light irradiation cycles. Both bind in the nanomolar rage to the protein of interest. Importantly, our best peptidomimetic displays a clear difference between isomers in its protein-binding capacity and, in turn, in its potential to inhibit enzymatic activity via PPI disruption. In addition, crystal structure determination, docking and MD calculations give a molecular interpretation and open new avenues in the design and synthesis of future photoswitchable PPI modulators.
关键词： protein-protein interactions,photopharmacology,visible-light irradiation,azobenzene,photoswitches
更新于2025-11-21 11:20:42
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TRACKING DOWN ALPHA-PARTICLES: THE DESIGN, CHARACTERISATION AND TESTING OF A SHALLOW-ANGLED ALPHA-PARTICLE IRRADIATOR
摘要： Human exposure to α-particles from radon and other radionuclides is associated with carcinogenesis, but if well controlled and targeted to cancer cells, α-particles may be used in radiotherapy. Thus, it is important to understand the biological effects of α-particles to predict cancer risk and optimise radiotherapy. To enable studies of α-particles in cells, we developed and characterised an α-particle automated irradiation rig that allows exposures at a shallow angle (70° to the normal) of cell monolayers in a 30 mm diameter dish to complement standard perpendicular irradiations. The measured incident energy of the α-particles was 3.3 ± 0.5 MeV (LET in water = 120 keV μm?1), with a maximum incident dose rate of 1.28 ± 0.02 Gy min?1, which for a 5 μm cell monolayer corresponds to a mean dose rate of 1.57 ± 0.02 Gy min?1 and a mean LET in water of 154 keV μm?1. The feasibility of resolving radiation-induced DNA double-strand breaks (DSB) foci along the track of α-particles was demonstrated using immuno?uorescent labelling with γH2AX and 53BP1 in normal MRC-5 human lung cells.
关键词： DNA double-strand breaks,irradiation rig,shallow angle,α-particles,immuno?uorescent labelling
更新于2025-11-21 11:08:12
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Effect of electron beam irradiation on structure, morphology, and optical properties of PVDF-HFP/PEO blend polymer electrolyte films
摘要： The effect of 8 MeV energy electron beam (EB) on poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/poly-ethylene oxide (PEO) (@ w/w 90:10, PHP10) polymer blend films have been prepared and studied. The change in structure, morphology, and optical properties at 40, 80, and 120 kGy EB doses were investigated. The effect of the radiation process may responsible to occurs the degradation (chain scission) and chain link (cross linking) which are confirmed by the FT-IR analysis. The band at 1401 cm?1 corresponding to the –CH2– bending or scission mode have shifted to 1397 cm?1 after 120 kGy EB dose is due to the intermolecular interaction and the changes of the macromolecular chain by breaking of bonds with increased EB dose was observed. The XRD pattern shows decreased in the crystallinity from 60.03 to 23.42% and increased amorphousity for 120 kGy EB dose the and the surface morphology was drastically changed by decreasing the size of spherulites upon increased EB dose. The increase in optical absorption and the shifting of wavelength toward a higher end (red shift) was observed after the irradiation. The energy band gaps (Eg), and Urbach energy were estimated and they are found to be decreased, but the number of carbon atoms in a cluster of was increased with increased EB dose. The obtained results notice that the physical properties of polymer blend electrolytes can be improved by EB irradiation to use in different potential applications.
关键词： Polymer electrolyte,FESEM,UV–visible spectroscopy,Structural analysis,Electron beam irradiation
更新于2025-11-21 11:01:37
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Photoluminescence enhancement <i>via</i> microwave irradiation of carbon quantum dots derived from solvothermal synthesis of <scp>l</scp> -arginine
摘要： Photoluminescence enhancement of carbon quantum dots was achieved via solvothermal synthesis followed by microwave irradiation. Nitrogen and phosphorous doped carbon quantum dots were prepared by solvothermal heating of L-arginine with phosphoric acid for 12 hours followed by microwave irradiation for 3 minutes. The photoluminescence enhancement was nearly two fold after microwave irradiation. The morphology, structure, and surface properties were the same for the solvothermal (CQDs-S) as well as after microwave (CQDs-M) irradiation. Thus, the enhancement is attributed to the decrease of surface defects within CQDs, which led to a decrease in the non-radiative transitions. The CQDs were quenched selectively by Fe3+ ions. The quenching led to the fabrication of the fluorescence probe for ferric ion determination. The CQDs-M had a low detection limit of 4.0 nM, while CQDs-S had a limit of 50 nM. This study gives a tool for enhancing photoluminescence quantum yields, which is highly desired for biosensing and bioimaging applications.
关键词： Photoluminescence enhancement,Fluorescence probe,Solvothermal synthesis,Ferric ion determination,Microwave irradiation,Carbon quantum dots
更新于2025-11-19 16:56:42
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Synergistic Effects of Photo-Irradiation and Curcumin-Chitosan/Alginate Nanoparticles on Tumor Necrosis Factor-Alpha-Induced Psoriasis-Like Proliferation of Keratinocytes
摘要： Psoriasis is a chronic inflammatory skin disease characterized by hyperproliferation of the epidermal cells and is clinically presented as thick, bright red to pink plaques with a silvery scale. Photodynamic therapy (PDT) using visible light has become of increasing interest in the treatment of inflammatory skin diseases. In this study, we demonstrate that a combination of curcumin-loaded chitosan/alginate nanoparticles (Cur-CS/Alg NPs) and blue light emitting diodes (LED) light irradiation effectively suppressed the hyperproliferation of tumor necrosis factor-alpha (TNF-α)-induced cultured human kerlatinocyte (HaCaT) cells. The Cur-CS/Alg NPs were fabricated by emulsification of curcumin in aqueous sodium alginate solution and ionotropic gelation with calcium chloride and chitosan using an optimized formulation derived from a Box-Behnken design. The fabricated Cur-CS/Alg NPs were characterized for their particle size, zeta potential, encapsulation efficiency, and loading capacity. The surrogate 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, to measure the relative number of viable cells, showed that the CS/Alg NPs were nontoxic to normal HaCaT cells, while 0.05 μg/mL and 0.1 μg/mL of free curcumin and Cur-CS/Alg NPs inhibited the hyperproliferation of HaCaT cells induced by TNF-α. However, the Cur-CS/Alg NPs demonstrated a stronger effect than the free curcumin, especially when combined with blue light irradiation (10 J/cm2) from an LED-based illumination device. Therefore, the Cur-CS/Alg NPs with blue LED light could be potentially developed into an effective PDT system for the treatment of psoriasis.
关键词： LED light,chitosan/alginate nanoparticles,curcumin,photo-irradiation,psoriasis
更新于2025-11-19 16:56:35
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Effect of conduction band potential on cocatalyst-free plasmonic H <sub/>2</sub> evolution over Au loaded on Sr <sup>2+</sup> -doped CeO <sub/>2</sub>
摘要： There is little information on the effect of the conduction band (CB) position on plasmonic hydrogen (H2) formation under visible light irradiation over gold (Au) nanoparticles supported on semiconductors because there were no appropriate materials for which the CB position gradually changes. In this study, we analyzed the flatband potential of strontium ion (Sr2+)-doped cerium(IV) oxide (CeO2:Sr) and found that the CB position gradually shifted negatively from +0.031 V to ?1.49 V vs. NHE with an increase in the Sr2+ mole fraction. Plasmonic photocatalysts consisting of Au nanoparticles, CeO2:Sr and a platinum (Pt) cocatalyst were prepared and characterized by using X-ray diffraction, UV-vis spectroscopy, and transmission electron spectroscopy. Photocatalytic reaction under visible light irradiation revealed that H2 was produced over Au nanoparticles supported on CeO2:Sr having the CB potential of ?0.61 V vs. NHE and that the negative limit of the CB position for electron injection from Au nanoparticles existed between ?0.61 V and ?1.49 V vs. NHE. We found that Au/CeO2:Sr plasmonic photocatalysts also produced H2 without the aid of a Pt cocatalyst due to the sufficiently negative potential of electrons injected into the CB of CeO2:Sr.
关键词： hydrogen evolution,visible light irradiation,gold nanoparticles,plasmonic photocatalysts,strontium-doped cerium oxide
更新于2025-11-19 16:51:07
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UV-activated porous Zn2SnO4 nanofibers for selective ethanol sensing at low temperatures
摘要： Porous ternary Zn2SnO4 nanofibers with a high surface-to-volume ratio were fabricated through an electrospinning technique. UV-activated ethanol sensing responses at low temperatures were revealed using these porous Zn2SnO4 nanofibers as a sensing active layer. The ethanol response was up to 32.5, and the calculated detection limit was as low as 1.6 ppm at a low temperature of 130 °C. The sensor exhibited good ethanol selectivity and stability under UV irradiation. The photoinduced electrons reacted with the absorbed oxygen molecules to form active O? species [O?(hν)], which contributed to the enhanced resistance modulation and low-temperature ethanol response of Zn2SnO4 nanofibers.
关键词： Zn2SnO4,Semiconductors,Electrospinning,UV irradiation,Sensors
更新于2025-11-14 17:04:02
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Effective Removal of Tetracycline by Using Biochar Supported Fe3O4 as a UV-Fenton Catalyst
摘要： Novel Fe3O4-decorate hierarchical porous carbon skeleton derived from maize straw(Fe3O4@MSC) was synthesized by a facile co-precipitation process and a calcination process, which was developed as a UV assisted heterogeneous Fenton-like catalyst. The as-synthesized catalysts were characterized via X-ray powder diffraction(XRD), scanning electron microscope(SEM), transmission electron microscope(TEM), Brunauer-Emmet-Teller(BET) and vibrating sample magnetometer(VSM) at room temperature. The morphology and structure analysis revealed that the as-prepared Fe3O4@MSC retained the original pore morphology of the maize straw material. The non-uniform polyhedral Fe3O4 grew on the whole surface of the MSC, which reduced the aggragation of Fe3O4 and provided more active sites to strengthen the UV-assisted Fenton-like reaction. As a result, the tetracycline(TC) degradation efficiency after 40 min reaction and total organic carbon(TOC) removal efficiency after 2 h reaction of Fe3O4@MSC catalyzing UV-Fenton system reached 99.2% and 72.1%, respectively, which were more substantial than those of Fe3O4@MSC/H2O2(31.5% and 2%), UV/H2O2 system(68% and 23.4%) and UV/Fe3O4/H2O2(80% and 37.5%). The electron spin resonance(ESR) results showed that the ?OH played an important role in the catalytic reaction. A possible degradation pathway of TC was proposed on the basis of the identified intermediates. Overall, the UV assisted heterogeneous Fenton-like process in Fe3O4@MSC improved the cycle of Fe3+/Fe2+ and activated the interfacial catalytic site, which eventually realized the enhancement of degradation and mineralization to tetracycline.
关键词： Degradation of tetracycline,Heterogeneous Fenton-like catalyst,Fe3O4,Carbon skeleton of maize straw,UV irradiation
更新于2025-11-14 17:04:02
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Latent tracks and novel infrared waveguide formation in lithium tantalate irradiated with swift heavy ions
摘要： In this work, the formation mechanisms of latent ion tracks and infrared-light waveguides in ion-irradiated LiTaO3 single crystals were comparatively studied using 200 MeV Kr17+ irradiation at a fluence of 1 × 1012 cm?2 and 247 MeV Ar12+ irradiation at fluences of 1 × 1012 cm?2 and 3 × 1012 cm?2. Because of the intense electronic energy loss, the produced lattice disorder and formed latent track were experimentally determined through complementary techniques, including the analysis of transmission electron microscopy patterns and Rutherford backscattering/channeling spectra. Corresponding to different ions with different irradiation energies and electronic energy losses, the related spatio-temporal evolutions of lattice temperatures in Kr17+- and Ar12+-irradiated LiTaO3 crystals were numerically calculated using the inelastic thermal spike model. The simulation results theoretically describe the experimentally observed lattice disorder and latent track behaviors. The lattice swelling in the latent-ion-track regions was demonstrated using high-resolution x-ray diffraction patterns; the lattice swelling resulted in a decrease in the refractive index, thereby providing a path to tailor the optical properties and fabricate the waveguide structure. Optical measurements and simulations indicated that the formed LiTaO3 waveguide could effectively support the guided modes and confine the light propagation, especially in the infrared region.
关键词： swift heavy ion irradiation,latent ion track,electronic energy loss,infrared waveguide
更新于2025-11-14 17:04:02
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Visible-light-triggered generation of persistent radical anions from perylenediimides: A substituent effect and potential application in photocatalytic reduction of Ag+
摘要： Three perylenediimide derivatives were reduced to their persistent radical anions in N-methyl-2-pyrrolidone (NMP) under ambient conditions by a visible light photoinduced electron transfer (PET). UV?vis and electron paramagnetic resonance (EPR) measurements were carried out to confirm the formation of radicals. The relationships between molecular structure, electrochemical property, phototransformation kinetics, and air stability of radical anions were investigated by the introduction of pyrimidine rings at the core position and fluoroalkylation substituents at the imide position. This study reveals that the electron-deficient pyrimidine rings and electron-withdrawing fluoroalkylation substituents can effectively enhance the phototransformation rate and the radical stability at ambient conditions. The effects of solvents and illuminance levels on the photoinduced reduction of perylenediimides were also studied. A photocatalytic reduction of Ag+ was successfully carried out using the perylenediimide with pyrimidine and fluoroalkylation substituents as catalyst upon irradiation with visible light.
关键词： Photocatalytic reduction,Perylene diimide derivative,Silver ion,Persistent radical anion,Visible light irradiation
更新于2025-11-14 17:03:37