scholarly journals Discrimination and isolation of the virus from free RNA fragments for the highly sensitive measurement of SARS-CoV-2 abundance on surfaces using a graphene oxide nano surface

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Hyun Jin Yoo ◽  
Yun Guang Li ◽  
Wen Ying Cui ◽  
Wonseok Chung ◽  
Yong-Beom Shin ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Detection Limit ◽  
Sample Preparation ◽  
Detection Method ◽  
Viral Rna ◽  
Detection Sensitivity ◽  
Environmental Surfaces ◽  
Highly Sensitive ◽  
Rna Fragments ◽  
Chemical Disinfection

AbstractIt is highly important to sensitively measure the abundance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on various surfaces. Here, we present a nucleic acid-based detection method consisting of a new sample preparation protocol that isolates only viruses, not the free RNA fragments already present on the surfaces of indoor human-inhabited environments, using a graphene oxide-coated microbead filter. Wet wipes (100 cm2), not cotton swabs, were used to collect viruses from environmental surfaces with large areas, and viruses were concentrated and separated with a graphene oxide-coated microbead filter. Viral RNA from virus was recovered 88.10 ± 8.03% from the surface and free RNA fragment was removed by 99.75 ± 0.19% from the final eluted solution. When we tested the developed method under laboratory conditions, a 10-fold higher viral detection sensitivity (Detection limit: 1 pfu/100 cm2) than the current commercial protocol was observed. Using our new sample preparation protocol, we also confirmed that the virus was effectively removed from surfaces after chemical disinfection; we were unable to measure the disinfection efficiency using the current commercial protocol because it cannot distinguish between viral RNA and free RNA fragments. Finally, we investigated the presence of SARS-CoV-2 and bacteria in 12 individual negative pressure wards in which patients with SARS-CoV-2 infection had been hospitalized. Bacteria (based on 16 S DNA) were found in all samples collected from patient rooms; however, SARS-CoV-2 was mainly detected in rooms shared by two patients.

scholarly journals A Label-Free Immunosensor Based on Graphene Oxide/Fe3O4/Prussian Blue Nanocomposites for the Electrochemical Determination of HBsAg

Biosensors ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 24 ◽  
Author(s):  
Shanshan Wei ◽  
Haolin Xiao ◽  
Liangli Cao ◽  
Zhencheng Chen
Keyword(s):  
Graphene Oxide ◽  
Hepatitis B ◽  
Prussian Blue ◽  
Hepatitis B Surface Antigen ◽  
Electrochemical Determination ◽  
Detection Sensitivity ◽  
Label Free ◽  
Serum Samples ◽  
Highly Sensitive

In this article, a highly sensitive label-free immunosensor based on a graphene oxide (GO)/Fe3O4/Prussian blue (PB) nanocomposite modified electrode was developed for the determination of human hepatitis B surface antigen (HBsAg). In this electrochemical immunoassay system, PB was used as a redox probe, while GO/Fe3O4/PB nanocomposites and AuNPs were prepared and coated on screen-printed electrodes to enhance the detection sensitivity and to immobilize the hepatitis B surface antibody (HBsAb). The immunosensor was fabricated based on the principle that the decrease in peak currents of PB is proportional to the concentration of HBsAg captured on the modified immunosensor. The experimental results revealed that the immunosensor exhibited a sensitive response to HBsAg in the range of 0.5 pg·mL−1 to 200 ng·mL−1, and with a low detection limit of 0.166 pg·mL−1 (S/N = 3). Furthermore, the proposed immunosensor was used to detect several clinical serum samples with acceptable results, and it also showed good reproducibility, selectivity and stability, which may have a promising potential application in clinical immunoassays.

Collision detection method for industrial robot based on envelope-like lines

2019 ◽  
Vol 46 (4) ◽  
pp. 510-517 ◽  
Author(s):  
Tie Zhang ◽  
JingDong Hong
Keyword(s):  
False Alarm ◽  
False Alarm Rate ◽  
External Force ◽  
Collision Detection ◽  
Detection Method ◽  
Industrial Robots ◽  
Detection Sensitivity ◽  
Content Type ◽  
Additional Equipment ◽  
Highly Sensitive

Purpose Successful sensorless collision detection by a robot depends on the accuracy with which the external force/torque can be estimated. Compared with collaborative robots, industrial robots often have larger parameter values of their dynamic models and larger errors in parameter identification. In addition, the friction inside a reducer affects the accuracy of external force estimation. The purpose of this paper is to propose a collision detection method for industrial robots. The proposed method does not require additional equipment, such as sensors, and enables highly sensitive collision detection while guaranteeing a zero false alarm rate. Design/methodology/approach The error on the calculated torque for a robot in stable motion is analyzed, and a typical torque error curve is presented. The variational characteristics of the joint torque error during a collision are analyzed, and collisions are classified into two types: hard and soft. A pair of envelope-like lines with an effect similar to that of the true envelope lines is designed. By using these envelope-like lines, some components of the torque calculation error can be eliminated, and the sensitivity of collision detection can be improved. Findings The proposed collision detection method based on envelope-like lines can detect hard and soft collisions during the motion of industrial robots. In repeated experiments without collisions, the false alarm rate was 0 per cent, and in repeated experiments with collisions, the rate of successful detection was 100 per cent. Compared with collision detection method based on symmetric thresholds, the proposed method has a smaller detection delay and the same detection sensitivity for different joint rotation directions. Originality/value A collision detection method for industrial robots based on envelope-like lines is proposed in this paper. The proposed method does not require additional equipment or complex algorithms, and highly sensitive collision detection can be achieved with zero false alarms. The proposed method is low in cost and highly practical and can be widely used in applications involving industrial robots.

An electrochemical sensor based on rhodamine B hydrazide-immobilized graphene oxide for highly sensitive and selective detection of Cu(ii)

2015 ◽  
Vol 39 (4) ◽  
pp. 3137-3144 ◽  
Author(s):  
Mengmeng Kang ◽  
Donglai Peng ◽  
Yuanchang Zhang ◽  
Yanqin Yang ◽  
Linghao He ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Detection Limit ◽  
Electrochemical Sensor ◽  
Rhodamine B ◽  
Selective Detection ◽  
Highly Sensitive ◽  
Rhodamine B Hydrazide

A novel Cu2+ sensor based on rhodamine B hydrazide (RBH)-immobilized graphene oxide (GO) was fabricated and estimated to be a detection limit of 0.061 nM for Cu2+ detection.

Alcohol Determination by HPLC with Postcolumn Derivatization Based on the Thiosulfate-catalyzed Reaction of Alcohols and Cerium(IV) and Fluorescence Detection of Cerium(III)

2020 ◽  
Vol 16 ◽  
Author(s):  
Ikko Mikami ◽  
Eri Shibayama ◽  
Kengo Takagi
Keyword(s):  
Detection Limit ◽  
Fluorescence Detection ◽  
Reaction Rate ◽  
Detection Method ◽  
Fluorescence Detector ◽  
Reaction Solution ◽  
Optimum Detection ◽  
Postcolumn Derivatization ◽  
Sensitive Method

Background: Determination of a reducing substance based on the reaction between Ce(IV) and a reducing substance and fluorescence detection of Ce(III) generated has been reported as a selective and sensitive method. However, this method could not be applied to the determination of alcohol due to the low reaction rate of alcohol and Ce(IV). Objective: We found that thiosulfate catalytically enhanced reaction of alcohols (such as, methanol, ethanol, and propanol) and Ce(IV). Utilizing this effect, we developed a new method for the determination of alcohols. Results: In the presence of thiosulfate, an increase in fluorescence intensity was detected by injecting alcohol at concentrations of several millimolar, whereas it was not observed even at the concentration of 10% v/v (2 M for ethanol) in the absence of thiosulfate. The optimum detection conditions were determined to be 4.0 mM Ce(IV) sulfate and 0.50 mM thiosulfate, and the detection limit (S/N = 3) of ethanol under these conditions was 1 mM. In the calibration curves, changes in the slope were observed when the alcohol concentrations were approximately 10–25 mM. Using a thiosulfate solution containing ethanol as the reaction solution, a calibration curve without any change in slope was obtained, although the concentration of ethanol at the detection limit increased. The alcohols in the liquor and fuel were successfully analyzed using the proposed detection method as a postcolumn reaction. Conclusion: This new alcohol detection method using a versatile fluorescence detector can be applied to the postcolumn reaction of HPLC omitting need of time-consuming pretreatment processes.

An ultra-highly sensitive and selective self-enhanced AIECL sensor for public security early warning in a nuclear emergency via a co-reactive group poisoning mechanism

2021 ◽  
Author(s):  
Ziyu Wang ◽  
Meiyun Xu ◽  
Nan Zhang ◽  
Jian-Bin Pan ◽  
Xinqi Wu ◽  
...  
Keyword(s):  
Detection Limit ◽  
Early Warning ◽  
High Selectivity ◽  
Public Security ◽  
Reactive Group ◽  
Low Detection Limit ◽  
Highly Sensitive ◽  
Vapor Sensors ◽  
Nuclear Emergency

A mechanism of co-reactive group poisoning (CGP) was discovered for designing efficient I2 vapor sensors for early warning of a nuclear emergency, which give an ultra-low detection limit of 0.13 ppt as well as high selectivity.

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