scholarly journals Liquid Crystal Based Binding Assay for Detecting HIV-1 Surface Glycoprotein

2021 ◽  
Vol 9 ◽  
Author(s):  
Amna Didar Abbasi ◽  
Zakir Hussain ◽  
Usman Liaqat ◽  
Dooa Arif ◽  
Kun-Lin Yang
Keyword(s):  
Liquid Crystal ◽  
Early Stage ◽  
Low Cost ◽  
Surface Protein ◽  
High Specificity ◽  
Surface Glycoprotein ◽  
Optical Signals ◽  
Gp 120 ◽  
Binding Event ◽  
Hiv 1

Surface protein gp-120 of HIV-1 virus plays an important role in the infection of HIV-1, but detection of gp-120 during the early stage of infection is very difficult. Herein, we report a binding bioassay based on an RNA aptamer B40t77, which binds specifically to gp-120. The bioassay is built upon a hydrophobic glass slide with surface immobilized gp-120. When the glass surface is incubated in a solution containing B40t77, the aptamer is able to bind to gp-120 specifically and remove it from the surface after a short incubation time of 30 min. The result of the binding event can be amplified by using liquid crystal (LC) into optical signals in the final step. By using this bioassay, we are able to detect as low as 1 μg/ml of gp-120 with high specificity within 30 min. No response is obtained when gp-120 is replaced by other protein such as bovine serum albumin (BSA). This is the first qualitative bioassay which provides a simple way for the detection of gp-120 with the naked eye. The assay is robust, low-cost and does not require additional labeling. Thus, the bioassay is potentially useful for the early detection of HIV-1 in resources-limited regions.

scholarly journals Immobilized cellulose nanospheres in lateral flow immunoassay enable rapid nucleocapsid antigen-based diagnosis of SARS-CoV-2 from salivary samples

2021 ◽  
Author(s):  
Katariina Solin ◽  
Marco Beaumont ◽  
Maryam Borghei ◽  
Hannes Orelma ◽  
Pascal Mertens ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Low Cost ◽  
Surface Protein ◽  
Confocal Imaging ◽  
Diagnostic Systems ◽  
Viral Pathogens ◽  
Optical Signals ◽  
Antigen Tests ◽  
Antigen Testing ◽  
Oppositely Charged

Rapid and efficient diagnostic systems are essential in controlling the spread of viral pathogens and efficient patient management. The available technologies for low-cost viral antigen testing have several limitations, including lack of accuracy and sensitivity. Here, we develop sensitive antigen tests based on recently introduced, oppositely charged cellulose II nanoparticles (NPan and NPcat) that are effective in controlling surface protein interactions. Passivation against non-specific adsorption and augmented immobilization of sensing antibodies are achieved by adjusting the electrostatic charge of the nanoparticles. The interactions affecting the performance of the system are investigated by microgravimetry and confocal imaging. We further demonstrate SARS-CoV-2 nucleocapsid rapid sensing by saliva-wicking channels stencil-printed on flexible paper supports. Therein, NPcat inkjet printed on the channels elicit distinctive optical signals, visible after only a few minutes, allowing faster diagnosis compared to current microfluidic devices designed for saliva sampling.

scholarly journals Aptamer Laden Liquid Crystals Biosensing Platform for the Detection of HIV-1 Glycoprotein-120

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2893
Author(s):  
Amna Didar Abbasi ◽  
Zakir Hussain ◽  
Kun-Lin Yang
Keyword(s):  
Liquid Crystals ◽  
Hepatitis A Virus ◽  
Specific Interaction ◽  
High Specificity ◽  
Optical Microscope ◽  
Label Free ◽  
Gp 120 ◽  
Suitable Amount ◽  
Working Device ◽  
Hiv 1

We report a label-free and simple approach for the detection of glycoprotein-120 (gp-120) using an aptamer-based liquid crystals (LCs) biosensing platform. The LCs are supported on the surface of a modified glass slide with a suitable amount of B40t77 aptamer, allowing the LCs to be homeotropically aligned. A pronounced topological change was observed on the surface due to a specific interaction between B40t77 and gp-120, which led to the disruption of the homeotropic alignment of LCs. This results in a dark-to-bright transition observed under a polarized optical microscope. With the developed biosensing platform, it was possible to not only identify gp-120, but obtained results were analyzed quantitatively through image analysis. The detection limit of the proposed biosensing platform was investigated to be 0.2 µg/mL of gp-120. Regarding selectivity of the developed platform, no response could be detected when gp-120 was replaced by other proteins, such as bovine serum albumin (BSA), hepatitis A virus capsid protein 1 (Hep A VP1) and immunoglobulin G protein (IgG). Due to attributes such as label-free, high specificity and no need for instrumental read-out, the presented biosensing platform provides the potential to develop a working device for the quick detection of HIV-1 gp-120.

scholarly journals Evaluation of “Caterina assay”: An Alternative Tool to the Commercialized Kits Used for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Identification

Pathogens ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 325
Author(s):  
Germano Orrù ◽  
Alessandra Scano ◽  
Sara Fais ◽  
Miriam Loddo ◽  
Mauro Giovanni Carta ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Clinical Microbiology ◽  
Early Stage ◽  
Low Cost ◽  
High Specificity ◽  
N Gene ◽  
Molecular Test ◽  
Specificity And Sensitivity ◽  
Human Coronaviruses ◽  
Commercial Kits

Here we describe the first molecular test developed in the early stage of the pandemic to diagnose the first cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in Sardinian patients in February–March 2020, when diagnostic certified methodology had not yet been adopted by clinical microbiology laboratories. The “Caterina assay” is a SYBR®Green real-time reverse-transcription polymerase chain reaction (rRT-PCR), designed to detect the nucleocapsid phosphoprotein (N) gene that exhibits high discriminative variation RNA sequence among bat and human coronaviruses. The molecular method was applied to detect SARS-CoV-2 in nasal swabs collected from 2110 suspected cases. The study article describes the first molecular test developed in the early stage of the declared pandemic to identify the coronavirus disease 2019 (COVID-19) in Sardinian patients in February–March 2020, when a diagnostic certified methodology had not yet been adopted by clinical microbiology laboratories. The assay presented high specificity and sensitivity (with a detection limit ≥50 viral genomes/μL). No false-positives were detected, as confirmed by the comparison with two certified commercial kits. Although other validated molecular methods are currently in use, the Caterina assay still represents a valid and low-cost detection procedure that could be applied in countries with limited economic resources.

scholarly journals Automation of absolute protein-ligand binding free energy calculations for docking refinement and compound evaluation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Germano Heinzelmann ◽  
Michael K. Gilson
Keyword(s):  
Free Energy ◽  
Early Stage ◽  
Binding Free Energy ◽  
Low Cost ◽  
Free Energy Calculations ◽  
Free Energies ◽  
Energy Calculations ◽  
Drug Candidates ◽  
Binding Free Energy Calculations ◽  
Binding Free Energies

AbstractAbsolute binding free energy calculations with explicit solvent molecular simulations can provide estimates of protein-ligand affinities, and thus reduce the time and costs needed to find new drug candidates. However, these calculations can be complex to implement and perform. Here, we introduce the software BAT.py, a Python tool that invokes the AMBER simulation package to automate the calculation of binding free energies for a protein with a series of ligands. The software supports the attach-pull-release (APR) and double decoupling (DD) binding free energy methods, as well as the simultaneous decoupling-recoupling (SDR) method, a variant of double decoupling that avoids numerical artifacts associated with charged ligands. We report encouraging initial test applications of this software both to re-rank docked poses and to estimate overall binding free energies. We also show that it is practical to carry out these calculations cheaply by using graphical processing units in common machines that can be built for this purpose. The combination of automation and low cost positions this procedure to be applied in a relatively high-throughput mode and thus stands to enable new applications in early-stage drug discovery.

scholarly journals From Bend to Splay Dominated Elasticity in Nematics

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 831
Author(s):  
Davide Revignas ◽  
Alberta Ferrarini
Keyword(s):  
Liquid Crystal ◽  
Nematic Phase ◽  
Low Cost ◽  
Elastic Behavior ◽  
Computational Investigation ◽  
Apical Angle ◽  
Polar Order ◽  
The Past ◽  
Bend Angles ◽  
Analogous Effect

In the past decade, much evidence has been provided for an unusually low cost for bend deformations in the nematic phase of bent-core mesogens and bimesogens (liquid crystal dimers) having a bent shape on average. Recently, an analogous effect was observed for the splay mode of bent-core mesogens with an acute apical angle. Here, we present a systematic computational investigation of the Frank elastic constants of nematics made of V-shaped particles, with bend angles ranging from acute to obtuse. We show that by tuning this angle, the elastic behavior switches from bend dominated (K33>K11) to splay dominated (K11>K33), with anomalously low values of the splay and the bend constant, respectively. This is related to a change in the shape polarity of particles, which is associated with the emergence of polar order, longitudinal for splay and transversal for bend deformations. Crucial to this study is the use of a recently developed microscopic elastic theory, able to account for the interplay of mesogen morphology and director deformations.

Pedometer-Determined Step-Count Guidelines for Afterschool Programs

2012 ◽  
Vol 9 (1) ◽  
pp. 71-77 ◽  
Author(s):  
Michael W. Beets ◽  
Aaron Beighle ◽  
Matteo Bottai ◽  
Laura Rooney ◽  
Fallon Tilley
Keyword(s):  
Operating Characteristic ◽  
Low Cost ◽  
Vigorous Physical Activity ◽  
Area Under The Curve ◽  
High Specificity ◽  
Step Count ◽  
Afterschool Programs ◽  
Policy Goal ◽  
Community Based ◽  
Random Intercept

Background:Policies to require afterschool programs (ASPs, 3 PM to 6 PM) to provide children a minimum of 30 minutes of moderate-to-vigorous physical activity (MVPA) exist. With few low-cost, easy-to-use measures of MVPA available to the general public, ASP providers are limited in their ability to track progress toward achieving this policy-goal. Pedometers may fill this gap, yet there are no step-count guidelines for ASPs linked to 30 minutes of MVPA.Methods:Steps and accelerometer estimates of MVPA were collected concurrently over multiple days on 245 children (8.2 years, 48% boys, BMI-percentile 68.2) attending 3 community-based ASPs. Random intercept logit models and receiver operating characteristic (ROC) analyses were used to identify a threshold of steps that corresponded with attaining 30 minutes of MVPA.Results:Children accumulated an average of 2876 steps (standard error [SE] 79) and 16.1 minutes (SE0.5) of MVPA over 111 minutes (SE1.3) during the ASP. A threshold of 4600 steps provided high specificity (0.967) and adequate sensitivity (0.646) for discriminating children who achieved the 30 minutes of MVPA; 93% of the children were correctly classified. The total area under the curve was 0.919. Children accumulating 4600 steps were 25times more likely to accumulate 30 minutes of MVPA.Conclusions:This step threshold will provide ASP leaders with an objective, low-cost, easy-to-use tool to monitor progress toward policy-related goals.

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