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#34562920   2021/09/10 To Up

Origami Paper-Based Electrochemical (Bio)Sensors: State of the Art and Perspective.

In the last 10 years, paper-based electrochemical biosensors have gathered attention from the scientific community for their unique advantages and sustainability vision. The use of papers in the design the electrochemical biosensors confers to these analytical tools several interesting features such as the management of the solution flow without external equipment, the fabrication of reagent-free devices exploiting the porosity of the paper to store the reagents, and the unprecedented capability to detect the target analyte in gas phase without any sampling system. Furthermore, cost-effective fabrication using printing technologies, including wax and screen-printing, combined with the use of this eco-friendly substrate and the possibility of reducing waste management after measuring by the incineration of the sensor, designate these type of sensors as eco-designed analytical tools. Additionally, the foldability feature of the paper has been recently exploited to design and fabricate 3D multifarious biosensors, which are able to detect different target analytes by using enzymes, antibodies, DNA, molecularly imprinted polymers, and cells as biocomponents. Interestingly, the 3D structure has recently boosted the self-powered paper-based biosensors, opening new frontiers in origami devices. This review aims to give an overview of the current state origami paper-based biosensors, pointing out how the foldability of the paper allows for the development of sensitive, selective, and easy-to-use smart and sustainable analytical devices.
Noemi Colozza, Veronica Caratelli, Danila Moscone, Fabiana Arduini

1273 related Products with: Origami Paper-Based Electrochemical (Bio)Sensors: State of the Art and Perspective.

1 g96TOne 96-Well Microplate Ki200ug 100ul1ml100ug Lyophilized50 mg100ug100ug Lyophilized25 mg

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#34562903   2021/09/03 To Up

Cocaine Detection by a Laser-Induced Immunofluorometric Biosensor.

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Martin Paul, Robert Tannenberg, Georg Tscheuschner, Marco Ponader, Michael G Weller

1642 related Products with: Cocaine Detection by a Laser-Induced Immunofluorometric Biosensor.

100tests 100ul100 assays100tests100 ul96 tests400 assays1 Kit100tests

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#34562851   2021/09/17 To Up

E484K mutation in SARS-CoV-2 RBD enhances binding affinity with hACE2 but reduces interactions with neutralizing antibodies and nanobodies: Binding free energy calculation studies.

The pandemic of the COVID-19 disease caused by SARS-CoV-2 has led to more than 200 million infections and over 4 million deaths worldwide. The progress in the developments of effective vaccines and neutralizing antibody therapeutics brings hopes to eliminate the threat of COVID-19. However, SARS-CoV-2 continues to mutate, and several new variants have been emerged. Among the various naturally-occurring mutations, the E484K mutation shared by many variants attracted serious concerns, which may potentially enhance the receptor binding affinity and reduce the immune response. In the present study, the molecular mechanism behind the impacts of E484K mutation on the binding affinity of the receptor-binding domain (RBD) with the receptor human angiotensin-converting enzyme 2 (hACE2) was investigated by using the molecular dynamics (MD) simulations combined with the molecular mechanics-generalized Born surface area (MMGBSA) method. Our results indicate that the E484K mutation results in more favorable electrostatic interactions compensating the burial of the charged and polar groups upon the binding of RBD with hACE2, which significantly improves the RBD-hACE2 binding affinity. Besides that, the E484K mutation also causes the conformational rearrangements of the loop region containing the mutant residue, which leads to tighter binding interface of RBD with hACE2 and formation of some new hydrogen bonds. The tighter binding interface and the new hydrogen bonds formation also contribute to the improved binding affinity of RBD to the receptor hACE2. In addition, six neutralizing antibodies and nanobodies complexed with RBD were selected to explore the effects of E484K mutation on the recognition of these antibodies to RBD. The simulation results show that the E484K mutation significantly reduces the binding affinities to RBD for most of the studied neutralizing antibodies/nanobodies, and the decrease in the binding affinities is mainly owing to the unfavorable electrostatic interactions caused by the mutation. Our studies revealed that the E484K mutation may improve the binding affinity between RBD and the receptor hACE2, implying more transmissibility of the E484K-containing variants, and weaken the binding affinities between RBD and the studied neutralizing antibodies/nanobodies, indicating reduced effectiveness of these antibodies/nanobodies. Our results provide valuable information for the effective vaccine development and antibody/nanobody drug design.
Wei Bu Wang, Yu Liang, Yu Qin Jin, Jing Zhang, Ji Guo Su, Qi Ming Li

1380 related Products with: E484K mutation in SARS-CoV-2 RBD enhances binding affinity with hACE2 but reduces interactions with neutralizing antibodies and nanobodies: Binding free energy calculation studies.

100.00 ug1000 TESTS/0.65ml100 ul100.00 ug100 ul100.00 ug100.00 ug100.00 ug100 μg100 ul10 Racks of 96 Tips/Unit0.2 mg

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#34562558   2021/09/22 To Up

Monitoring heterogeneity in therapeutic samples using Schlieren.

Antigen, antibodies and other therapeutic biomolecule solutions are likely to undergo physical and chemical processes during their development, manufacturing, transport and storage, which can induce internal stresses in the sample, resulting in aggregation, heterogeneities and an overall reduction in the sample quality, e.g., freeze-thawing of samples for storage. Monitoring mixing is thus crucial to ensure homogeneity and consistency while further optimizing downstream processes. We present a simple and portable all-lens Schlieren setup to detect and visualize heterogeneities in the protein/antigen or any other pharmaceutical solutions during and after thawing in real-time. We illustrate the capabilities of the proposed method by visualizing and quantifying heterogeneities during the thawing of BSA and IgG in four different formulation buffers. The local concentration gradients in a thawing sample lead to light intensity variations which are captured using the Schlieren technique. The sample heterogeneity can be quantified by relating these light intensity variations to concentration gradients. To this end, we first measure the refractive index, which varies linearly with the sample concentration. This linear relation is then used to extract the concentration gradient field from the light intensity data. Finally, we establish the validity of the proposed approach by demonstrating its accuracy in measuring the diffusion coefficients of sample solutions in a diffusion problem. The portability of the setup and its applicability to a wide range of samples make this Schlieren-based technique suitable for monitoring the mixing, heterogeneity and stability of pharmaceutical samples during freeze-thawing processes so that we can better control these processes.
Rishabh More, Andres Barrio-Zhang, Adib Ahmadzadegan, Sadegh Dabiri, Arezoo M Ardekani

2566 related Products with: Monitoring heterogeneity in therapeutic samples using Schlieren.

48 samples16 Arrays/Slide16 Arrays/Slide96 samples

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#34562491   2021/09/22 To Up

Intraspecific variability of the Central American rattlesnake (Crotalus simus) venom and its usefulness to obtain a representative standard venom.

Snake venoms are mixtures of proteins whose physicochemical features confer them toxicity and immunogenicity. Animals (e.g., horses or sheep) immunized with snake venoms produce antibodies towards the venom proteins. Since these antibodies can neutralize the venom toxicity, they have been used to formulate snake antivenoms. The efficacy of the antivenoms is widely accepted, and standard venoms are expected to be representative of the snake's population that inhabit in the region where the antivenom is intended to be used. The representativeness of a single venom collected from a Crotalus simus snake, and its usefulness as standard venom to produce an antivenom is evaluated. The use of an "average venom" might be as representative of the population intended to be used, as the standard venom composed by many venom samples. Variations in the relative abundance concentration of crotoxin in the C. simus leads to different clinical manifestations, as well as differences in the neutralization efficacy of the antivenoms. A monovalent anti-Cs antivenom was produced from a single venom C. simus specimen, and its efficacy in neutralizing the lethal activity of 30 C. simus snakes was tested. Despite the variations in the relative abundance content of crotoxin found in the proteomes, the monovalent anti-Cs antivenom was successful in neutralize the toxicity caused by the variations on the venom composition of three different snake population used. Interestingly, it seems that the sex is not a key factor in the lethality of the venoms tested. The concept of representative venom mixtures for immunization should be revised for the case of C. simus on the populations found in Costa Rica, since it might use as less as one representative individual whose venom covers the mainly toxic enzymes.
Aarón Gómez, Gabriela Solano, Arturo Chang-Castillo, Danilo Chacón, Greivin Corrales, Álvaro Segura, Ricardo Estrada, Guillermo León

2904 related Products with: Intraspecific variability of the Central American rattlesnake (Crotalus simus) venom and its usefulness to obtain a representative standard venom.

100ml1L500ml100ml1L500ml1 ml

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#34562431   2021/09/22 To Up

Seroprevalence and molecular characterization of Toxoplasma gondii infecting ruminants in the North-West of Egypt.

Toxoplasma gondii is a coccidian parasite known for its heavy toll on people and livestock. It can cause abortion and a variety of congenital diseases. The current study aimed to examine some seroprevalence and molecular attributes of T. gondii obtained from ruminants in the North-West of Egypt. Specimens were random selected from five different locations in Alexandria and Matrouh governorates. A total of 483 blood samples, collected from 96 mixed flocks, were screened for anti-T. gondii IgG antibodies using enzyme-linked immunosorbent assay (ELISA). The seropositive results were then confirmed using polymerase chain reaction (PCR) primers for the B1 and P30 genes. Specific PCR products were selected for sequencing and alignment against the GenBank, where phylogeny has been examined using the maximum likelihood, neighbor-joining, and maximum parsimony in MEGA6. ELISA confirmed the presence of T. gondii in 188 of the investigated samples (38.92%), indicating a higher prevalence in camels (64.51%) and sheep (43.75%) as compared to goats (27.93 %) and cattle (13.46%). PCR confirmed the presence of T. gondii-specific sequences in 159 seropositive specimens, with homology between 98.3 and 100%. The genetic distances between the investigated variants ranged from 0.1 to 0.9, and 7 single nucleotide polymorphisms (SNPs), were identified in the examined T. gondii specimens. The camel T. gondii parasite, isolated from Matrouh, showed a 100% homology with the most dangerous reference strains of T. gondii-RH in the GenBank. Our results showed that B1 and P30-specific PCR could detect T. gondii in blood samples more accurately than ELISA. In addition, the statistical analysis of our data indicated that species, age, sex, and animal location were all risk factors for toxoplasmosis. These findings are likely to boost disease control and help contain the spread of T. gondii infections.
Reham Abdel-Halim Khattab, Safaa Mohamed Barghash, Osama Mohammad Sayed Mostafa, Sahar Ali Allam, Hoda Abdel-Halim Taha, Ameen Abd El-Baqi Ashour

1035 related Products with: Seroprevalence and molecular characterization of Toxoplasma gondii infecting ruminants in the North-West of Egypt.

1 mg100 5 G100 µg100 1100

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#34562263   2021/09/25 To Up

Immunity after COVID-19 and vaccination: follow-up study over 1 year among medical personnel.

The long-term course of immunity among individuals with a history of COVID-19, in particular among those who received a booster vaccination, has not been well defined so far.
Vivian Glück, Sonja Grobecker, Josef Köstler, Leonid Tydykov, Manuela Bertok, Tanja Weidlich, Christine Gottwald, Bernd Salzberger, Ralf Wagner, Florian Zeman, Michael Koller, André Gessner, Barbara Schmidt, Thomas Glück, David Peterhoff

2134 related Products with: Immunity after COVID-19 and vaccination: follow-up study over 1 year among medical personnel.

25 mg1 mg1 mg100ug0.1 mg 5 G 1 G 1 G50 ug

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