Photoelectrochemical biosensing platform for the SARS-CoV-2 spike and nucleocapsid proteins

The COVID-19 pandemic is still a continuing worldwide challenge for public health systems. Early and ultrasensitive identification of the infection is essential for preventing the spread of COVID-19 by pre-symptomatic or asymptomatic individuals, particularly in the community and in-home settings. This work presents a versatile photoelectrochemical (PEC) immunosensor for SARS-CoV-2 detection based on a composite material formed by bismuth vanadate (BiVO₄) and strontium titanate (SrTiO₃). The PEC platform was denoted as BiVO₄/SrTiO₃/FTO, and it can be tuned for the detection of either Spike (S) or Nucleocapsid (N) protein by simply altering the antibody immobilized on the platform's surface. Chemical, morphological, and electrochemical characterizations were performed by X-Ray Diffraction, Scanning Electron microscopy, Energy-dispersive X-ray spectroscopy, Electrochemical Impedance Spectroscopy, and Amperometry. With a simple sensing architecture of the PEC platform, it was possible to achieve a linear response range of 0.1 pg mL⁻¹ to 1000 ng mL⁻¹ for S protein and 0.01 pg mL⁻¹ to 1000 ng mL⁻¹ for N protein. The PEC immunosensors presented recovery values for the two SARS-CoV-2 proteins in artificial saliva samples between 97 % and 107.20 % suggesting a good accuracy for the proposed immunosensors.     

Superprotonic solid solutions between CsHSO4 and CsH2PO4

Solid solutions of (CsHSO₄)_1 − x(CsH₂PO₄)_x (x = 0.25-0.75) were synthesized by mechanical milling method over a wide range of compositions. Superprotonic cubic phase was confirmed for all these samples between 293 and 420 K depending on its composition. These superprotonic phases have primitive cubic structure similar to that of CsH₂PO₄. The kinetic stability of the supercooled cubic phase depends both on the composition x and the humidity of surrounding atmosphere. The most stable composition of the cubic phase was found around x = 0.67 and could be maintained for several days even under ambient atmosphere. The ionic conductivities of these superprotonic phases reached 10^− 2–10^− 3 S∙cm^− 1 at 450 K. With increasing x the ionic conductivity at the superprotonic phase decreased continuously associated with the increase of the activation energy. These findings suggest that the average number of the hydrogen bonds between XO₄ (X = S, P) units plays an important role on the stability of the cubic phase and also on the conductivity.     

Ac vortex-dependent torsional oscillation response and onset temperature T0 in solid 4He

Detailed studies of ac velocity V_{ac} and T dependence of torsional oscillator responses of solid 4He are reported. A characteristic onset temperature T_{0} approximately 0.5 K is found, below which a significant V_{ac}-dependent change occurs in the energy dissipation for the samples at approximately 32 bar and for one at 49 bar. A V_{ac} dependence of the so-called "nonclassical rotational inertia" fraction also appears below approximately T_{0}. The log(V_{ac}) linear dependence, which suggests involvement of quantized vorticies, was examined in the nonclassical rotational inertia fraction. We find a common 1/T;{2} dependence for this linear slope change in all of the samples for 30相似文献   

Zone‐Drawn Poly(p‐phenylene) Films. Effects of Molecular Orientation on Electrical and Mechanical Properties

The electrochemically synthesized poly(p‐phenylene) film could be zone drawn by a factor of 1.57, where the orientation function (f) increased with the draw ratio (λ), regardless of the heater temperature (T_h) or applied tension (σ), and reached 0.428 for the resulting film. The electrical conductivity in the drawing direction rose with f but decreased as T_h became higher due to dedoping that occurred simultaneously with drawing. Young's modulus and tensile strength significantly increased to 4.5 GPa and 155 MPa by zone drawing from 1.1 GPa and 79 MPa of the as‐synthesized film.     

Visualization of molten pools and invisible laser beam profiles using an ultraviolet CCD camera

Experiments were conducted on the effects of a wall distance and velocity ratio of suction flow to injection flow on the flow and heat transfer characteristics of a circular impinging jet accompanying an annular suction flow. As a result, it is found that in the case of accompanying suction flow, a higher Nusselt number can be obtained compared with in the case without suction flow, under a condition of the wall distance within eight times of injection pipe diameter from the near pipe exit edge. In addition, when the effect of velocity ratio is examined at a fixed arbitrary wall distance, it is found that there exists an optimum velocity ratio where the Nusselt number becomes the maximum. It is shown that these heat transfer characteristics are closely associated with the fluctuating velocity and the mean velocity in the two-dimensional velocity field observed by Particle Image Velocimetry (PIV).     

Synthesis and Properties of Novel Cross‐Linked Fluoroalkyl End‐Capped Oligomeric Nanoparticles Containing Adamantane Units

Fluoroalkyl end‐capped cooligomers that contain both oxime‐blocked isocyanato and hydroxyadamantyl segments are prepared by the cooligomerization of fluoroalkanoyl peroxide with the corresponding monomers under mild conditions. This fluorinated cooligomer affords new cross‐linked fluoroalkyl end‐capped cooligomeric nanoparticles that contain adamantane segments by the deprotecting reaction of oxime‐blocked isocyanato segments in cooligomers in excellent to moderate isolated yield. A variety of cross‐linked fluoroalkyl end‐capped cooligomeric nanoparticles that contain adamantane segments are also prepared by similar deprotecting reactions with this fluorinated cooligomer in the presence of adamantane‐1,5‐diol. Furthermore, we have prepared cross‐linked fluoroalkyl end‐capped cooligomers that contain oxime‐blocked isocyanato segments by the use of 2‐hydroxyethyl acrylate and poly(ethylene glycol)‐containing methacrylate monomer as comonomers, respectively. However, the deprotecting reactions of the oxime‐blocked isocyanato segments in the cooligomers do not afford the expected nanoparticles, and these cross‐linked cooligomers are found to show a gelling characteristic. The thermal stability of these cross‐linked fluorinated cooligomeric nanoparticles that contain adamantane segments increases significantly compared to that of the parent fluorinated cooligomer. More interestingly, the thermal stability of these cross‐linked fluorinated nanoparticles is almost the same as that of the fluoroalkyl end‐capped acrylic acid oligomer/SiO₂ nanocomposites (content of SiO₂ in composites: 70%). In addition, these cross‐linked fluorinated nanoparticles have been applied to the surface modification of traditional organic polymers such as poly(methyl methacrylate) to exhibit a good oleophobicity imparted by fluorine on their surface.

     

Sum-frequency generation study of reacting species at surfaces

Received: 6 October 1998 / Revised version: 3 November 1998     

The Proton Cryptate of Hexaethylenetetramine

The next higher homologue of hexamethylenetetramine was synthesized as the proton cryptate H⁺@ 1 ⋅Br⁻ (shown schematically), and its X-ray structure determined. The proton trapped by the lone pairs accumulated at the center of the T-symmetric tetraaza cage could not be exchanged or removed, even after heating for three days in 3 M NaOD.     

Preparation and properties of macromolecular complexes consisting of chitosan derivatives,iron(III) hydroxide sulfate,and poly(potassium vinyl sulfate)

Glycol chitosan (GC) and methyl glycol chitosan (MGC) were separately reacted with poly(potassium vinyl sulfate) (PVSK) in the presence of iron(III) hydroxide sulfate (IHS) to form water-insoluble macromolecular complexes (MC's). The chemical compositions and properties of MC's obtained were compared with each other. The solubility of MC in the MGC-IHS-PVSK system was lower than that in the GC-IHS-PVSK system, and it was suggested that MGC contributes to the properties of MC.