Ultrasensitive and Robust Point-of-Care Immunoassay for the Detection of Plasmodium falciparum Malaria.

Plasmodium falciparum malaria is widespread in the tropical and subtropical regions of the world. There is ongoing effort to eliminate malaria from endemic regions, and sensitive point-of-care (POC) diagnostic tests are required to support this effort. However, current POC tests are not sufficiently sensitive to detect P. falciparum in asymptomatic individuals. After extensive optimization, we have developed a highly sensitive and robust POC test for the detection of P. falciparum infection. The test is based on upconverting nanophosphor-based lateral flow (UCNP-LF) immunoassay. The developed UCNP-LF test was validated using whole blood reference panels containing samples at different parasite densities covering eight strains of P. falciparum from different geographical areas. The limit of detection was compared to a WHO-prequalified rapid diagnostic test (RDT). The UCNP-LF achieved a detection limit of 0.2-2 parasites/μL, depending on the strain, which is 50- to 250-fold improvement in analytical sensitivity over the conventional RDTs. The developed UCNP-LF is highly stable even at 40 °C for at least 5 months. The extensively optimized UCNP-LF assay is as simple as the conventional malaria RDTs and requires 5 μL of whole blood as sample. Results can be read after 20 min from sample addition, with a simple photoluminescence reader. In the absence of a reader device at the testing site, the strips after running the test can be transported and read at a central location with access to a reader. We have found that the test and control line signals are stable for at least 10 months after running the test. The UCNP-LF has potential for diagnostic testing of both symptomatic and asymptomatic individuals

Ultrasensitive and Robust Point-of-Care Immunoassay for the Detection of Plasmodium falciparum Malaria

Plasmodium falciparum malaria is widespread in the tropical and subtropical regions of the world. There is ongoing effort to eliminate malaria from endemic regions, and sensitive point-of-care (POC) diagnostic tests are required to support this effort. However, current POC tests are not sufficiently sensitive to detect P. falciparum in asymptomatic individuals. After extensive optimization, we have developed a highly sensitive and robust POC test for the detection of P. falciparum infection. The test is based on upconverting nanophosphor-based lateral flow (UCNP-LF) immunoassay. The developed UCNP-LF test was validated using whole blood reference panels containing samples at different parasite densities covering eight strains of P. falciparum from different geographical areas. The limit of detection was compared to a WHO-prequalified rapid diagnostic test (RDT). The UCNP-LF achieved a detection limit of 0.2-2 parasites/μL, depending on the strain, which is 50- to 250-fold improvement in analytical sensitivity over the conventional RDTs. The developed UCNP-LF is highly stable even at 40 °C for at least 5 months. The extensively optimized UCNP-LF assay is as simple as the conventional malaria RDTs and requires 5 μL of whole blood as sample. Results can be read after 20 min from sample addition, with a simple photoluminescence reader. In the absence of a reader device at the testing site, the strips after running the test can be transported and read at a central location with access to a reader. We have found that the test and control line signals are stable for at least 10 months after running the test. The UCNP-LF has potential for diagnostic testing of both symptomatic and asymptomatic individuals. </p

Bottom-up construction of a superstructure in a porous uranium-organic crystal

Bottom-up construction of highly intricate structures from simple building blocks remains one of the most difficult challenges in chemistry. We report a structurally complex, mesoporous uranium-based metal-organic framework (MOF) made from simple starting components. The structure comprises 10 uranium nodes and seven tricarboxylate ligands (both crystallographically nonequivalent), resulting in a 173.3-angstrom cubic unit cell enclosing 816 uranium nodes and 816 organic linkers—the largest unit cell found to date for any nonbiological material. The cuboctahedra organize into pentagonal and hexagonal prismatic secondary structures, which then form tetrahedral and diamond quaternary topologies with unprecedented complexity. This packing results in the formation of colossal icosidodecahedral and rectified hexakaidecahedral cavities with internal diameters of 5.0 nanometers and 6.2 nanometers, respectively—ultimately giving rise to the lowest-density MOF reported to date

Development of a Fast SARS-CoV-2 IgG ELISA, Based on Receptor-Binding Domain, and Its Comparative Evaluation Using Temporally Segregated Samples From RT-PCR Positive Individuals

SARS-CoV-2 antibody detection assays are crucial for gathering seroepidemiological information and monitoring the sustainability of antibody response against the virus. The SARS-CoV-2 Spike protein's receptor-binding domain (RBD) is a very specific target for anti-SARS-CoV-2 antibodies detection. Moreover, many neutralizing antibodies are mapped to this domain, linking antibody response to RBD with neutralizing potential. Detection of IgG antibodies, rather than IgM or total antibodies, against RBD is likely to play a larger role in understanding antibody-mediated protection and vaccine response. Here we describe a rapid and stable RBD-based IgG ELISA test obtained through extensive optimization of the assay components and conditions. The test showed a specificity of 99.79% (95% CI: 98.82-99.99%) in a panel of pre-pandemic samples (n = 470) from different groups, i.e., pregnancy, fever, HCV, HBV, and autoantibodies positive. Test sensitivity was evaluated using sera from SARS-CoV-2 RT-PCR positive individuals (n = 312) and found to be 53.33% (95% CI: 37.87-68.34%), 80.47% (95% CI: 72.53-86.94%), and 88.24% (95% CI: 82.05-92.88%) in panel 1 (days 0-13), panel 2 (days 14-20) and panel 3 (days 21-27), respectively. Higher sensitivity was achieved in symptomatic individuals and reached 92.14% (95% CI: 86.38-96.01%) for panel 3. Our test, with a shorter runtime, showed higher sensitivity than parallelly tested commercial ELISAs for SARS-CoV-2-IgG, i.e., Euroimmun and Zydus, even when equivocal results in the commercial ELISAs were considered positive. None of the tests, which are using different antigens, could detect anti-SARS-CoV-2 IgGs in 10.5% RT-PCR positive individuals by the fourth week, suggesting the lack of IgG response

Synthesis of Silver Nanoparticles from Malva parviflora Extract and Effect on Ecto-5'- Nucleotidase(5'-NT), ADA and AMPDA Enzymes in Sera of Patients with Arthrosclerosis

The present research included synthesis of silver nanoparticle from(1*10-3,1*10-4 and1*10-5) M aqueous AgNO3 solution through the extract of M.parviflora reducing agent. In the process of synthesizing silver nanoparticles we detected a rapid reduction of silver ions leading to the formation of stable crystalline silver nanoparticles in the solution. The characteristics of silver nanoparticles were studied by using UV-Visible absorption spectroscopy, and atomic force microscope (AFM) analysis. The AFM measurements showed that the average size of silver nanoparticles synthesized using (1*10-3,1*10-4 and1*10-5) M aqueous AgNO3 solution through the extract of M.parviflora were 102 to 114nm. UV-Vis spectra of the aqueous medium containing silver nanoparticles showed a surface peak at 220nm and 445nm for (1*10-3,1*10-4 and1*10-5) M aqueous AgNO3 solution through the extract of M.parviflora. The study of nanoparticles due to the possible application for the development of new technologies such as exhibited inhibitory effects on Ecto-5'- Nucleotidase (5'-NT), ADA and AMPDA enzymes in Sera of control and Patients with Arthrosclerosis. Further studies on other biological activities are required to exploit their full potentia

Low-Dose and In-Painting Methods for (Near) Atomic Resolution STEM Imaging of Metal Organic Frameworks (MOFs)

Metal-organic Frameworks (MOFs) are a group of crystalline and highly porous materials consisting of inorganic metal ions/clusters (nodes) that are coordinated by organic linkers. The ability to create a wide range of porous structures, where the pore size can be easily changed in size and shape offers the potential for many applications in gas storage/separation and catalysis. The presence of the organic linkers or “struts” in the sample creates challenges for high resolution microscopy as the sample itself is very sensitive to beam damage. A key challenge for understanding the structures of MOFs and how the applications can be modified by doping the nodes and changing the nature of the organic linkers, is therefore to be able to image the samples on the sub-nm length scale (the nodes are ~1 nm). The study of organics, where large single crystals with long-range order cannot be synthesized, is usually performed by either electron crystallography or direct imaging in the (scanning) transmission electron microscope (S/TEM). In the (S)TEM, large single crystals are not needed as the electron beam can be focused to a very small area (sub-nm if needed). The downside to this ability to see small areas is that because the electron beam has a strong interaction with the sample, it can cause significant levels of electron beam damage. However, the last 40 years of protein crystallography and more recently the use of in-situ liquid stages to study chemical reactions in the (S)TEM, have shown that this beam damage effect can in most cases be mitigated by the use of extremely low-dose imaging (a dose rate of less than 0.1 electrons/angstrom2/s and a cumulative dose of less than 10 electrons/angstrom2). In addition to simply lowering the dose through conventional means (changing the emission current and probe dwell time), more recent use of compressive sensing/in-painting methods for STEM has also been shown to lower the effective dose and dose rate

Trends of humoral immune responses to heterologous antigenic exposure due to vaccination & omicron SARS-CoV-2 infection: Implications for boosting

Background & objectives: Vaccination and natural infection can both augment the immune responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but how omicron infection has affected the vaccine-induced and hybrid immunity is not well studied in Indian population. The present study was aimed to assess the durability and change in responses of humoral immunity with age, prior natural infection, vaccine type and duration with a minimum gap of six months post-two doses with either ChAdOx1 nCov-19 or BBV152 prior- and post-emergence of the omicron variant. Methods: A total of 1300 participants were included in this observational study between November 2021 and May 2022. Participants had completed at least six months after vaccination (2 doses) with either ChAdOx1 nCoV-19 or an inactivated whole virus vaccine BBV152. They were grouped according to their age (≤ or ≥60 yr) and prior exposure of SARS-CoV-2 infection. Five hundred and sixteen of these participants were followed up after emergence of the Omicron variant. The main outcome was durability and augmentation of the humoral immune response as determined by anti-receptor-binding domain (RBD) immunoglobulin G (IgG) concentrations, anti-nucleocapsid antibodies and anti-omicron RBD antibodies. Live virus neutralization assay was conducted for neutralizing antibodies against four variants – ancestral, delta and omicron and omicron sublineage BA.5. Results: Before the omicron surge, serum anti-RBD IgG antibodies were detected in 87 per cent participants after a median gap of eight months from the second vaccine dose, with a median titre of 114 [interquartile range (IQR) 32, 302] BAU/ml. The levels increased to 594 (252, 1230) BAU/ml post-omicron surge (P<0.001) with 97 per cent participants having detectable antibodies, although only 40 had symptomatic infection during the omicron surge irrespective of vaccine type and previous history of infection. Those with prior natural infection and vaccination had higher anti-RBD IgG titre at baseline, which increased further [352 (IQR 131, 869) to 816 (IQR 383, 2001) BAU/ml] (P<0.001). The antibody levels remained elevated after a mean time gap of 10 months, although there was a decline of 41 per cent. The geometric mean titre was 452.54, 172.80, 83.1 and 76.99 against the ancestral, delta, omicron and omicron BA.5 variants in the live virus neutralization assay. Interpretation & conclusions: Anti-RBD IgG antibodies were detected in 85 per cent of participants after a median gap of eight months following the second vaccine dose. Omicron infection probably resulted in a substantial proportion of asymptomatic infection in the first four months in our study population and boosted the vaccine-induced humoral immune response, which declined but still remained durable over 10 months

Methane Oxidation to Methanol Catalyzed by Cu-Oxo Clusters Stabilized in NU-1000 Metal–Organic Framework

Copper oxide clusters synthesized via atomic layer deposition on the nodes of the metal–organic framework (MOF) NU-1000 are active for oxidation of methane to methanol under mild reaction conditions. Analysis of chemical reactivity, in situ X-ray absorption spectroscopy, and density functional theory calculations are used to determine structure/activity relations in the Cu-NU-1000 catalytic system. The Cu-loaded MOF contained Cu-oxo clusters of a few Cu atoms. The Cu was present under ambient conditions as a mixture of ∼15% Cu⁺ and ∼85% Cu²⁺. The oxidation of methane on Cu-NU-1000 was accompanied by the reduction of 9% of the Cu in the catalyst from Cu²⁺ to Cu⁺. The products, methanol, dimethyl ether, and CO₂, were desorbed with the passage of 10% water/He at 135 °C, giving a carbon selectivity for methane to methanol of 45–60%. Cu oxo clusters stabilized in NU-1000 provide an active, first generation MOF-based, selective methane oxidation catalyst