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Phosphorylation of tau at Ser 396, 404 (p-tau

Coronavirus disease 2019 (COVID-19) is a newly emerged infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The number of COVID-19 cases is continuously increasing and no effective drugs or vaccines are currently available. Accurate and efficient diagnostic testing methods are desperately needed for the detection of SARS-CoV-2 and antiviral antibodies in infected individuals. Various assay techniques, including nucleic acid tests [eg, polymerase chain reaction (PCR), reverse transcription-PCR, real-time loop-mediated isothermal amplification, and CRISPR-Cas-based detection], serological tests [eg, immunoglobulin (Ig)A, IgM/G], imaging tests (eg, computed tomography and positron-emission tomography), and nanoparticle-based detections have been reported for COVID-19 diagnosis. This review aims to present the current diagnostic tools for SARS-CoV-2 and their performance characteristics to inform the appropriate selection of diagnostic and surveillance technologies at optimal testing times. We also describe the advantages of detection using combined nucleic acid and imaging tests, or serological testing and point-of-care diagnostics. Developing reliable protein biomarkers targeting the conserved proteins of SARS-CoV-2 rather than IgA, IgM, or IgG would be useful to manage SARS-CoV-2.

Due to the heterogeneity of amyloid β-42 (Aβ42) species, the potential correlation between plasma oligomeric Aβ42 (oAβ42) and cognitive impairments in cerebral small vessel disease (CSVD) remains unclear. Herein, a sandwich ELISA for the specific detection of Aβ42 oligomers (oAβ42) and total Aβ42 (tAβ42) was developed based on sequence- and conformation-specific antibody pairs for the evaluation of plasma samples from a Chinese CSVD community cohort. After age and gender matching, 3-Tesla magnetic resonance imaging and multidimensional cognitive assessment were conducted in 134 CSVD patients and equal controls. The results showed that plasma tAβ42 and oAβ42 levels were significantly elevated in CSVD patients. By regression analysis, these elevations were correlated with the presence of CSVD and its imaging markers (i.e., white matter hyperintensities). Plasma Aβ42 tests further strengthened the predictive power of vascular risk factors for the presence of CSVD. Relative to tAβ42, oAβ42 showed a closer correlation with memory domains evaluated by neuropsychological tests. In conclusion, this sensitive ELISA protocol facilitated the detection of plasma Aβ42; Aβ42, especially its oligomeric form, can serve as a biosensor for the presence of CSVD and associated cognitive impairments represented by memory domains.

Although amyloid-β42 (Aβ42) has been used as one of the core biomarkers for Alzheimer’s disease (AD) diagnosis, the dynamic changes of its different forms in the brain, blood, and even intestines and its correlation with the progression of AD disease remain obscure. Herein, we screened Aβ42-specific preferred antibody pairs 1F12/1F12 and 1F12/2C6 to accurately detect Aβ42 types using sandwich ELISA, including total Aβ42, Aβ42 oligomers (Aβ42Os), and Aβ42 monomers (Aβ42Ms). The levels of Aβ42 species in the brain, blood, and intestines of different aged APP/PS1 mice were quantified to study their correlation with AD progression. Total Aβ42 levels in the blood were not correlated with AD progression, but Aβ42Ms level in the blood of 9-month-old APP/PS1 mice was significantly reduced, and Aβ42Os level in the brain was significantly elevated compared to 3-month-old APP/PS1, demonstrating that the levels of Aβ42Ms and Aβ42Os in the blood and brain were correlated with AD progression. Interestingly, in 9-month-old APP/PS1 mice, the level of Aβ42 in the intestine was higher than that in 3-month-old APP/PS1 mice, indicating that the increased level of Aβ42 in the gastrointestinal organs may also be related to the progression of AD. Meanwhile, changes in the gut microbiota composition of APP/PS1 mice with age were also observed. Therefore, the increase in Aβ derived from intestinal tissues and changes in microbiome composition can be used as a potential early diagnosis tool for AD, and further used as an indicator of drug intervention to reduce brain amyloid.

Background: Shigella is among the most important human pathogenic microorganisms, infecting both humans and nonhuman and causing clinically severe diarrhea. Shigella must be enriched before detection, which is time-consuming. Objectives: To develop a sensitive, rapid, and specific method for Shigella detection. Materials and Methods: Shigella was used as an antigen to generate monoclonal antibodies (mAbs). mAbs were screened via indirect enzyme-linked immunosorbent assay (ELISA) and western blot, and two mAbs were selected. The mAb A3 showed high affinity and specificity and was used to develop immune magnetic beads (IMBs) for Shigella enrichment. An immunocapture (IC)-PCR primer was designed from the ipaH gene, and IC-PCR was developed based on the IMBs and PCR. Results: This system shortened the Shigella detection time to 70 min. The sensitivity of the IC-PCR was 9 colony-forming units.mL-1 in artificial milk. The accuracy of the IC-PCR was confirmed using 46 clinical samples collected from monkeys. The IC-PCR results were consistent with the serological and biochemical assays. Conclusion: The IC-PCR described herein accurately detected Shigella from milk samples, monkeys and can thus be used to complement classical detection methods.

Objective To prepare human anti-Mullerian hormone (AMH) immunomagnetic beads and HRP-labeled antibodies and establish a rapid double-antibody sandwich ELISA based on nanometer magnetic beads. Methods The expression vector of human AMH protein was constructed, and the recombinant AMH protein was expressed and purified. BALB/c mice were immunized with the recombinant protein to prepare the polyclonal antibody. Spleen cells were fused with myeloma Sp2/0 cells by PEG. Hybridoma cell lines which could stably secret monoclonal antibodies against AMH were screened out by ELISA. Monoclonal antibodies were produced from the ascites fluid of mice injected intraperitoneally with hybridoma cells and evaluated by Western blotting. Polyclonal antibodies purified from protein A were coupled to nano-magnetic' beads and used as capture antibodies, while HRP-labeled monoclonal antibody was prepared by sodium periodate method and used as probe antibody. A double antibody sandwich ELISA based on the nano-magnetic beads was established and optimized. Results A monoclonal antibody with good specificity for AMH was obtained,' and its subtype was IgG2b. The titers of purified polyclonal antibodies and monoclonal antibodies were up to 1:51 200. The capture antibody coupled with magnetic beads and the probe antibody labeled with HRP kept their good activity. The established method could detect AMH antigen within 1 hour and the detection limit was 50 ng/mL. Conclusion The prepared AMH immunomagnetic beads can be used for the fast and visualized detection of recombinant AMH.

Background: Zika Virus (ZIKV) is a new type of flaviviruses transmitted by mosquitoes to cause severe diseases including Guillain-Barre syndrome and congenital malformations during recent outbreaks. The early diagnosis of ZIKV infection and efficient vaccines would be effective in controlling epidemics and timely treatment. However, the native nonstructural protein 1 (NS1) mainly acquired from cells infected with ZIKV, which largely limits its application. Objectives: This study aimed to express and purify the recombinant NS1 protein and prepare its antibody that efficiently reacted with the native NS1 protein secreted in the supernatant of ZIKV infected host-cells. Methods: We constructed a prokaryotic expression vector containing the full length of the NS1 gene. Thus, the recombinant NS1 protein was efficiently expressed and purified. The purified NS1 protein was used to prepare an antibody. The Enzyme-linked Immunosorbent Assay (ELISA), Western blot, and Indirect Immunofluorescent Assay (IFA) were used to assess the reactivity and specificity of the antibody. Results: The recombinant NS1 protein from a prokaryotic expression vector had good immunogenicity and the prepared antibody could specifically react with the native NS1 produced in Vero, BHK-21 cells infected with ZIKV. Besides, the ELISA and Western blot showed that the native ZIKV-NS1 protein was secreted extracellularly and could play the role of an early diagnostic biomarker for ZIKV infection. Conclusions: The prepared antibody against the recombinant NS1 protein is a reliable biological tool that enables the rapid and sensitive detection of secreted NS1 from host cells infected with ZIKV. The recombinant NS1 protein and its antibody can contribute to developing vaccines and antibodies targeting the NS1 protein to prevent flavivirus disease progression.

We demonstrate here that theory-assisted near-edge X-ray absorption fine-structure (NEXAFS) spectroscopy enables the site-sensitive monitoring of on-surface chemical reactions, thus, providing information not accessible by other techniques. As a prototype example, we have used free-base 5,10,15-tris(pentafluorophenyl)corroles (3H-TpFPC) adsorbed on Ag(111) and present a detailed investigation of the angle-dependent NEXAFS of this molecular species as well as of their thermally induced derivatives. For this, we have recorded experimental C and N K-edge NEXAFS spectra and interpret them based on XAS cross-section calculations by using a continuous fraction approach and core-hole including multiprojector PAW pseudopotentials within DFT. We have characterized the as-deposited low temperature (200 K) phase and unraveled the subsequent changes induced by dehydrogenation (at 330 K) and ring-closure reactions (at 430 K). By exemplarily obtaining profound insight into the on-surface chemistry of free-base corrolic species adsorbed on a noble metal this work highlights how angle-dependent XAS combined with accurate theoretical modeling can serve for the investigation of on-surface reactions, whereby even highly similar molecular structures, such as tautomers and isomers, can be distinguished.

Surface-templated covalent coupling of organic precursors currently emerges as a promising route to the atom-precise fabrication of low-dimensional carbon materials. Here, we investigate the adsorption and the coupling reactions of 4,4''-diethynyl-1,1':4',1''-terphenyl on Au(110) under ultra-high vacuum conditions by using scanning tunneling microscopy combined with density functional theory and kinetic Monte Carlo calculations. Temperature treatment induces both 1,2,4-asymmetric cyclotrimerization and homocoupling, resulting in various reaction products, including a previously unreported, surface-templated H-shaped pentamer. Our analysis of the temperature-dependent relative product abundances unravels that 1,2,4-trimerization and homocoupling proceed via identical intermediate species with the final products depending on the competition of coupling to a third monomer versus dehydrogenation. Our study sheds light on the control of coupling reactions by corrugated surfaces and annealing protocols.

Background: Klebsiella pneumoniae is an important human pathogen that causes severe diseases including urinary tract infection, pneumonia, and bacteremia. However, a rapid and sensitive detection method remains to be developed. Objectives: This study aimed to develop a rapid, real-time, and visual detection method for K. pneumoniae. This is a primary screening method to improve the diagnosis of K. pneumoniae infection and save much precious time for clinical practice. Methods: Klebsiella pneumoniae was used as an antigen to produce a monoclonal antibodies (mAb). The mAb 1E6 recognizing outer membrane protein C on the surface of K. pneumoniae was screened by an indirect enzyme-linked immunosorbent assay (ELISA), Western Blot, and mass spectrometry assay, and then conjugated with the protein A/G coated magnetic beads to generate the immune magnetic beads (IMBs). Thereafter, the IMBs were used to capture K. pneumoniae, and the complex (beads-mAb-K. pneumoniae) was used for loop-mediated isothermal amplification (LAMP) assay. Results: We developed a rapid, real-time, and visual detection method employing an immunocapture loop-mediated isothermal amplification (IC-LAMP). The sensitivity of the IC-LAMP was 4 CFU mL-1. The process of K. pneumoniae detection lasted ~ 60 minutes and had no cross-reaction to other microbial strains. Besides, the accuracy of IC-LAMP was further verified by examining 39 clinical isolates. Conclusions: Without the need for enrichment of bacteria and extraction of its genome, the IC-LAMP developed here could be used as a primary screening method supplementary to traditional detection methods to improve the diagnosis of K. pneumoniae infection for clinical practice.

The controlled attachment of protecting groups combined with the ability to selectively abstract them is central to organic synthesis. The trimethylsilyl (TMS) functional group is a popular protecting group in solution. However, insights on its activation behavior under ultra-high vacuum (UHV) and surface-confined conditions are scarce. Here we investigate a series of TMS-protected alkyne precursors via scanning tunneling microscopy (STM) regarding their compatibility with organic molecular beam epitaxy (OMBE) and their potential deprotection on various coinage metal surfaces. After in-situ evaporation on the substrates held in UHV at room temperature, we find that all molecules arrived and adsorbed as intact units forming ordered supramolecular aggregates stabilized by non-covalent interactions. Thus, TMS-functionalized alkyne precursors with weights up to 1100 atomic mass units are stable against OMBE evaporation in UHV. Furthermore, the TMS activation through thermal annealing is investigated with STM and X-ray photoelectron spectroscopy (XPS). We observe that deprotection starts to occur between 400 K and 500 K on the copper and gold surfaces, respectively. In contrast, on silver surfaces, the TMS-alkyne bond remains stable up to temperatures where molecular desorption sets in (approximate to 600 K). Hence, TMS functional groups can be utilized as leaving groups on copper and gold surfaces while they serve as protecting groups on silver surfaces.

Surface-confined covalent coupling reactions of the linear compound 4-(but-3-en-1-ynyl)-4 `-ethynyl-1,1 `-biphenyl (1), which contains one alkyne and one enyne group on opposing ends, have been investigated using scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. The reactions show a surface-dependent chemoselectivity: on Au(111), compound 1 preferentially yields cyclotrimerization products, while on Cu(111), a selective coupling between the enyne and alkyne groups is observed. Linear, V-shaped string formations combined with Y-shaped bifurcation motifs result in a random reticulation on the entire surface. DFT calculations show that the C-H...pi(delta-) transition state of the reaction between the deprotonated alkyne group and a nearby H-donor of the alkene group plays a key role in the mechanism and high chemoselectivity. This study highlights a concept that opens new avenues to the surface-confined synthesis of covalent carbon-based sp-sp(2) polymers.

Background: The outbreak of Zika virus (ZIKV) in many countries caused alarming numbers of babies born with microcephalus and severe neurologic disorders, however, the methods for the detection of the ZIKV are limited at present. Objectives: The aim of this study was to produce polyclonal antibody against full length envelop protein of ZIKV (ZIKV-E protein) in prokaryotic system and to evaluate its efficacy to capture ZIKV virion. Methods: The recombinant full length ZIKV-E protein was purified and then used as an immunogen to vaccinate BALB/c mice to produce polyclonal antibody. Protein A/G coated magnetic beads were coated with the polyclonal antibody to capture the ZIKV virion in the culture medium of Vero cells infected with ZIKV. The products of immunoprecipitation were further used for Western Blot, Loop-mediated isothermal amplification (LAMP), and PCR assay. Results: Western Blot and indirect immunofluorescence analysis showed that the mouse polyclonal antibody could react specifically with the native E protein in Vero cells infected with ZIKV. The results of Western Blot, Immunocaptured-LAMP (IC-LAMP), and Immunocaptured-PCR (IC-PCR) showed that polyclonal antibody of ZIKV-E recombinant protein can capture ZIKV virion specifically, however, the polyclonal antibody against the ZIKV-NS1, Shigella, and Salmonella without such a function. Conclusions: These findings may provide the basis for the development of the rapid diagnostic kits such as, IC-PCR, IC-LAMP, and sandwich ELISA. The serum virion capture activity elicited by prokaryotic expressed recombinant ZIKV-E protein may also provide a basis for further preparation of neutralizing antibody and protein subunit vaccine candidate against ZIKV.

Shigella is an important human food-borne zoonosis bacterial pathogen, and can cause clinically severe diarrhea. There is an urgent need to develop a specific, sensitive, and rapid methodology for detection of this pathogen. In this study, loop-mediated isothermal amplification (LAMP) combined with magnetic immunocapture assay (IC-LAMP) was first developed for the detection of Shigella in pure culture, artificial milk, and clinical stool samples. This method exhibited a detection limit of 8.7 CFU/mL. Compared with polymerase chain reaction, IC-LAMP is sensitive, specific, and reliable for monitoring Shigella. Additionally, IC-LAMP is more convenient, efficient, and rapid than ordinary LAMP, as it is more efficiently enriches pathogen cells without extraction of genomic DNA. Under isothermal conditions, the amplification curves and the green fluorescence were detected within 30 min in the presence of genomic DNA template. The overall analysis time was approximately 1 h, including the enrichment and lysis of the bacterial cells, a significantly short detection time. Therefore, the IC-LAMP methodology described here is potentially useful for the efficient detection of Shigella in various samples.

International audience; Interfacial supramolecular self-assembly represents a powerful tool for constructing regular and quasicrystalline materials. In particular, complex two-dimensional molecular tessellations, such as semi-regular Archimedean tilings with regular polygons, promise unique properties related to their nontrivial structures. However, their formation is challenging, because current methods are largely limited to the direct assembly of precursors, that is, where structure formation relies on molecular interactions without using chemical transformations. Here, we have chosen ethynyl-iodophenanthrene (which features dissymmetry in both geometry and reactivity) as a single starting precursor to generate the rare semi-regular (3.4.6.4) Archimedean tiling with long-range order on an atomically flat substrate through a multi-step reaction. Intriguingly, the individual chemical transformations converge to form a symmetric alkynyl–Ag–alkynyl complex as the new tecton in high yields. Using a combination of microscopy and X-ray spectroscopy tools, as well as computational modelling, we show that in situ generated catalytic Ag complexes mediate the tecton conversion.

Shigella is an important human food-borne zoonosis bacterial pathogen, and can cause clinically severe diarrhea. There is an urgent need to develop a specific, sensitive, and rapid methodology for detection of this pathogen. In this study, loop-mediated isothermal amplification (LAMP) combined with magnetic immunocapture assay (IC-LAMP) was first developed for the detection of Shigella in pure culture, artificial milk, and clinical stool samples. This method exhibited a detection limit of 8.7 CFU/mL. Compared with polymerase chain reaction, IC-LAMP is sensitive, specific, and reliable for monitoring Shigella. Additionally, IC-LAMP is more convenient, efficient, and rapid than ordinary LAMP, as it is more efficiently enriches pathogen cells without extraction of genomic DNA. Under isothermal conditions, the amplification curves and the green fluorescence were detected within 30 min in the presence of genomic DNA template. The overall analysis time was approximately 1 h, including the enrichment and lysis of the bacterial cells, a significantly short detection time. Therefore, the IC-LAMP methodology described here is potentially useful for the efficient detection of Shigella in various samples.

Zika virus (ZIKV) is an emerging mosquito-transmitted flavivirus that can cause severe disease, including congenital birth defect and Guillain&minus, Barr&eacute, syndrome during pregnancy. Although, several molecular diagnostic methods have been developed to detect the ZIKV, these methods pose challenges as they cannot detect early viral infection. Furthermore, these methods require the extraction of RNA, which is easy to contaminate. Nonstructural protein 1 (NS1) is an important biomarker for early diagnosis of the virus, and the detection methods associated with the NS1 protein have recently been reported. The aim of this study was to develop a rapid and sensitive detection method for the detection of the ZIKV based on the NS1 protein. The sensitivity of this method is 120 ng mL&minus, 1 and it detected the ZIKV in the supernatant and lysates of Vero and BHK cells, as well as the sera of tree shrews infected with the ZIKV. Without the isolation of the virus and the extraction of the RNA, our method can be used as a primary screening test as opposed to other diagnosis methods that detect the ZIKV.

Organometallic nanostructures are promising candidates for applications in optoelectronics, magnetism and catalysis. Our bottom-up approach employs a cyano-functionalized terminal alkyne species (CN-DETP) on the Ag(110) surface to fabricate 2D domains of regularly stacked Ag-acetylide nanowires. We unravel their adsorption properties and give evidence to their organometallic character with the aid of complementary surface-sensitive techniques, i.e. scanning tunneling microscopy, X-ray photoelectron spectroscopy and near-edge X-ray absorption fine-structure spectroscopy. Guided by the anisotropic (110) surface, highly oriented nanowires form in two enantiomorphic domains of regularly stacked trans isomers, whereby the bifunctional design of CN-DETP gives rise to orthogonal bonding motifs. Based on STM imaging, we find high thermal stability of the Ag-bis-acetylide wires, without conversion into graphdiyne chains. Our approach based on orthogonal bifunctionalization and selective functional group recognition extends the toolbox of creating alkyne-based nanostructures at interfaces.