A method for fast and highly sensitive detection of antibodies in serum would greatly facilitate the early diagnosis of disease and infection and dose optimization of therapeutic antibody. ...Bioluminescence detection with LUMABS (renamed mNeonG-LUMABS, where mNeonG is short for mNeonGreen) sensors based on bioluminescence resonance energy transfer (BRET) between blue-emitting luciferase Nluc and green fluorescent protein (FP) mNeonGreen has been demonstrated to enable fast detection of antibodies directly in serum with reasonable sensitivity. However, some mNeonG-LUMABS sensors exhibit low sensitivity, and thus, sensitivity improvement remains imperative. Here, we report a bright green FP, Clover4, obtained by structure-guided mutagenesis of green FP Clover. Despite similar brightness and fluorescence spectra of Clover and mNeonGreen, Clover4-LUMABS sensors exhibit a largely increased dynamic range (maximum 20-fold) and much lower limit of detection (LOD) (maximum 5.6-fold), most likely because Clover4 is positioned in a more parallel orientation to Nluc in LUMABS. Due to modular design, Clover4-LUMABS offers a general BRET system for fast and highly sensitive antibody detection in serum.
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IJS, KILJ, NUK, PNG, UL, UM
We report the design and synthesis of catalyst for electrochemical reduction of carbon dioxide, where the high geometric current of metal electrode and the excellent selectivity of molecular ...catalysts are combined. This was achieved by the construction of molecularly defined interface, here we term as MDI. Specifically, porous polymer networks (PPNs) based on tetrakis-5,10,15,20-(4-aminophenyl) porphyrin (H2TAPP) were directly synthesized by electrochemical oxidation deposition on electrode. The thickness of this polymer layer was precisely controlled from 20 to 120 nm by the number of voltammetry cycles. The formation of MDI, composed of the amine linked polymer and Au electrode, was evidenced by scanning electron microscopy (SEM), atomic force microscopy (AFM), and attenuated total reflectance infrared spectroscopy (ATR-IR). This interface was endowed with abundant amino groups and Au atoms, which provided excellent catalytic performance for electrochemical reduction of CO2 (CO2RR). Specifically, 95% of CO selectivity was achieved at the potential of −0.7 V (vs RHE), while the same gold surface only gave a 25% selectivity under the same condition. The thickness of PPN layer was found to be critical for the catalytic performance, and in this construct the ideal thickness was achieved at 60 nm.
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La doped BiGaO(3) (LxBGO) films were fabricated by the Sol-Gel method on the Pt/Ti/SiO(2)/Si substrates. X-ray diffraction analysis shows that the films are polycrystalline with an orthorhombic ...structure. The atomic force microscopy images of the LxBGO films suggest that the surface morphology is smooth. The optical properties of the samples were investigated by the spectroscopic ellipsometry in detail. The dielectric functions were extracted and in good agreement with the Adachi dispersion function. More one step, the optical band gap tends to increase with increasing La composition, which is consistent with the results of theoretical prediction. These results are helpful for the fabrication of Bi-based opto-electrical devices such as ultraviolet detectors.
The Bi(x)FeO(3) films (0.80 less than or equal to x less than or equal to 1.20) were prepared by sol-gel technique on Si substrates. Effects of x variation on microstructures and optical properties ...of the Bi(x)FeO(3) films are reported. It is shown that in the films with both insufficient and excess bismuth dosage, impurity phases such as Bi(2)Fe(4)O(9) and iron oxide appeared. Raman spectra of the films were presented in the spectral range of 50~800 cm(-1). The refractive index (n) of the films decreases with increasing x at wavelength lower than 600 nm, the extinction coefficients (k) of all films were comparable. The bandgaps of the films changed from 2.65 eV to 2.76 eV.
Facile and scalable approaches for preparing fluorescent microspheres are indispensable tools in material science due to their immense potential for reducing the tedious conditional trial-and-error ...experiments for every single material. In this study, we propose a microfluidic method based on oscillating electric field (OEF)-induced electrojetting to fabricate size-controllable fluorescent microspheres embedded with various fluorescent substances. Briefly, an oscillating electric field is used to manipulate the size and productivity of highly uniform droplets; the size of droplets can be adjusted by simply varying the intensity and frequency of the electric field over a range of near three orders of magnitude. Subsequently, ultraviolet (UV) irradiation is used to solidify the droplets to fabricate fluorescent microspheres. To demonstrate the universality of the proposed method in different types of fluorescent substances, we use fluorescein sodium (FS), green fluorescent protein (GFP), and CdTe quantum dots (QDs) to synthesize fluorescent microspheres. The prepared microspheres show narrow size distribution (average coefficient of variation below 2.1%) and intense fluorescence emission. Overall, the proposed method is a novel and facile approach for synthesizing fluorescent microspheres, showing great promise for the preparation of polymer, functionalized and other materials with potential applications in various fields of biomaterials and biochemical assays.
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•A facile and scalable method to fabricate size-controllable fluorescent microspheres is proposed.•A microfluidic emulsification system based on an OEFIE is firstly established.•The size of droplets can be adjusted within a range of near three orders of magnitude.•The prepared fluorescent microspheres exhibit an ultra-narrow size distribution.•The universality of the proposed method was demonstrated by applying it to various fluorescent substrates.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Genetically encoded voltage indicators (GEVIs) allow optical recording of neuronal activities with high spatial resolution. While most existing GEVIs emit in the green range, red-shifted GEVIs are ...highly sought after because they would enable simultaneous stimulation and recording of neuronal activities when paired with optogenetic actuators, or two-color imaging of signaling and neuronal activities when used along with GFP-based indicators. In this study, we present several improved red-shifted GEVIs based on the electrochromic Förster resonance energy transfer (eFRET) between orange/red fluorescent proteins/dyes and rhodopsin mutants. Through structure-guided mutagenesis and cell-based sensitivity screening, we identified a mutant rhodopsin with a single mutation that exhibited more than 2-fold improvement in voltage sensitivity. Notably, this mutation has been independently discovered by Pieribone et al. (Pieribone, V. A. et al. Nat Methods 2018, 15 (12), 1108−1116 ). In cultured rat hippocampal neurons, our sensors faithfully reported action potential waveforms and subthreshold activities. We also demonstrated that this mutation could enhance the sensitivity of hybrid indicators, thus providing insights for future development.
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IJS, KILJ, NUK, PNG, UL, UM, UPUK
Zn-Mn co-doped BaTiO(3) films were fabricated on Si (100) and LNO/Si (100) substrates by a sol-gel procedure. In order to study the effects of different doping levels on the microstructure and ...ferroelectric phase of BaTiO(3) thin films, -BTO films doped with Zn and Mn, respectively, were also investigated. Both the characterization of X-ray diffraction (XRD) and atomic force microscope (AFM) indicate uniform and dense films with average grain size under 30 nm. By comparisons of the optical constant refractive index and extinction coefficient of BaTiO(3) films in the wavelength from 400 nm to 700 nm, it was obtained that there is a change in the optical band gap due to the different amount of Zn and Mn added. Furthermore, a better defined P-E loop with a remnant polarization of 11.26 mu C/cm(2) shows that Zn and Mn dopanting play an essential role in ferroelectric improvement.
Genetically encoded voltage indicators (GEVIs) allow the direct visualization of cellular membrane potential at the millisecond time scale. Among these, red-emitting GEVIs have been reported to ...support multichannel recordings and manipulation of cellular activities with reduced autofluorescence background. However, the limited sensitivity and dimness of existing red GEVIs have restricted their applications in neuroscience. Here, we report a pair of red-shifted opsin-based GEVIs, Cepheid1b and Cepheid1s, with improved dynamic range, brightness, and photostability. The improved dynamic range is achieved by a rational design to raise the electrochromic Förster resonance energy transfer efficiency, and the higher brightness and photostability are approached with separately engineered red fluorescent proteins. With Cepheid1 indicators, we recorded complex firings and subthreshold activities of neurons on acute brain slices and observed heterogeneity in the voltage‑calcium coupling on pancreatic islets. Overall, Cepheid1 indicators provide a strong tool to investigate excitable cells in various sophisticated biological systems.
Genetically encoded red voltage indicators map neuronal and pancreatic action potentials in cultured cells and tissues.
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