Raw municipal wastewater from five wastewater treatment plants representing the vast majority of the Qatar population was sampled between the third week of June 2020 and the end of August 2020, ...during the period of declining cases after the peak of the first wave of infection in May 2020. The N1 region of the SARS-CoV-2 genome was used to quantify the viral load in the wastewater using RT-qPCR. The trend in Ct values in the wastewater samples mirrored the number of new daily positive cases officially reported for the country, confirmed by RT-qPCR testing of naso-pharyngeal swabs. SARS-CoV-2 RNA was detected in 100% of the influent wastewater samples (7889 ± 1421 copy/L – 542,056 ± 25,775 copy/L, based on the N1 assay). A mathematical model for wastewater-based epidemiology was developed and used to estimate the number of people in the population infected with COVID-19 from the N1 Ct values in the wastewater samples. The estimated number of infected population on any given day using the wastewater-based epidemiology approach declined from 542,313 ± 51,159 to 31,181 ± 3081 over the course of the sampling period, which was significantly higher than the officially reported numbers. However, seroprevalence data from Qatar indicates that diagnosed infections represented only about 10% of actual cases. The model estimates were lower than the corrected numbers based on application of a static diagnosis ratio of 10% to the RT-qPCR identified cases, which is assumed to be due to the difficulty in quantifying RNA losses as a model term. However, these results indicate that the presented WBE modeling approach allows for a realistic assessment of incidence trend in a given population, with a more reliable estimation of the number of infected people at any given point in time than can be achieved using human biomonitoring alone.
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•First study that reports the detection of SARS-CoV-2 RNA fragments in wastewater in Qatar.•SARS-CoV-2 RNA was detected in all the influent wastewater samples (7,889 ± 1,421 copy/L – 542,056 ± 25,775) copy/L).•WBE modeling gives good estimation of infected population numbers supported by clinical seroprevalence data•WBE model shows that the number of infected people dropped from 542,313 ± 51,159 to 31,181± 3,081 over the sampling period
An electrochemical aptasensor was designed for the ultraselective and sensitive detection of Pb2+ by using lead‐specific binding DNA oligonucleotide as the molecular recognition element on Au ...nanoparticles/Nb4C3Tx MXene (Au@Nb4C3Tx) modified electrode. The Au@Nb4C3Tx is conjugated with thiol‐modified lead‐binding DNA through the Au−S bond. The DNA−Au@Nb4C3Tx modified glassy carbon electrode exhibited ultrahigh selectivity and enhanced response towards the detection of Pb2+ with a detection limit of 4 nM and linear range of 10 nM to 5 μM. This work has proved the possibility of using Nb4C3Tx as a robust immobilization platform for DNA oligonucleotides towards different environmental sensing and biomedical applications.
This paper evaluates the electrochemical performance of platinum nanoparticles/Ti3C2Tx nanocomposite (Pt@Ti3C2Tx) towards environmental sensing applications. The nanocomposite was prepared by ...self-reduction of Pt salt to Pt nanoparticles (PtNPs) on the surface of delaminated Ti3C2Tx nanosheets, in which Ti3C2Tx simultaneously acted as reducing agent as well as conductive matrix. The Pt@Ti3C2Tx nanocomposites with different Pt loading have been electrochemically characterized and it was found that 10%Pt@Ti3C2Tx has the highest electrochemical activity in the anodic potential window. Hence, 10%Pt@Ti3C2Tx has been used to develop an electrochemical sensor for the detection of Bisphenol A (BPA), which is one of the common environmental pollutants. At the optimal conditions, the oxidation peak of BPA was proportional to the analyte concentration from 50 nM to 5 μM with a detection limit of 32 nM. The practical application of the proposed sensor was successfully evaluated in drinking water and fresh milk samples.
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•Electrochemical performance of Pt@Ti3C2Tx (MXene) nanocomposites with different Pt loading is evaluated.•10%Pt@Ti3C2Tx (MXene) nanocomposite showed high electrochemical activity.•10%Pt@Ti3C2Tx can be used for the sensitive detection of bisphenol A.•The sensor achieved a detection limit of 32 nM with a linear range from 50 nM to 5 μM.
Rapid and real-time detection of l-cysteine (l-Cys) is important for early diagnostics of several diseases and biological disorders. We report here a stable and highly sensitive electrochemical ...sensor for the detection of l-Cys based on a Pd@Ti3C2Tx (MXene)-modified glassy carbon electrode (GCE). The Pd@Ti3C2Tx nanocomposite was prepared by in situ reduction of Pd(ii) salt on the surface of delaminated (DL) Ti3C2Tx nanosheets to form pseudo-spherical palladium nanoparticles (PdNPs) with 2–6 nm size distributions. The MXene acts as the conductive matrix and a reducing agent at the electrode surface, while PdNPs are there to improve the stability of Ti3C2Tx and to enhance the electrocatalytic activity towards l-Cys detection. The Pd@Ti3C2Tx/GCE sensor exhibited a detection limit of 0.14 μM and a linear electro-oxidative response to l-Cys within the concentration range from 0.5 to 10 μM. The sensor also demonstrated excellent selectivity over common interfering ions such as ascorbic acid, uric acid, dopamine and glucose.
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•The electrochemical performance of Nb2CTx and Nb4C3Tx MXenes in aqueous media was evaluated.•Both Nb2CTx and Nb4C3Tx are electrochemically stable up to an anodic potential of ...0.5 V.•It was found that Nb4C3Tx is more electrochemically active than Nb2CTx.•Nb4C3Tx can be used as an immobilization platform for the sensitive detection of dopamine with a detection limit of 23 nM.
In this work, we study the electrochemical performance of Nb2CTx and Nb4C3Tx MXenes in the aqueous media and their application as a sensing platform for small biomolecules. Both Nb2CTx and Nb4C3Tx are electrochemically stable up to an anodic potential of 0.5 V. It was found that Nb4C3Tx is more electrochemically active than Nb2CTx. Based on this, Nb4C3Tx was evaluated for the electrochemical detection of aqueous media solutions containing ascorbic acid, uric acid and dopamine. This work opens the door for the wider application of Nb-based MXenes in aqueous electrochemical sensing applications.
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•Interlinked chitosan-ZnO (CZNC-10) nanocomposite inhibited the biocorrosion of SRB on carbon steel.•CZNC-10 co-formed protective film on carbon steel to prevent bacterial attack ...during initial days of incubation.•CZNC-10 inhibitor caused damage to SRB cells and significant reduction of corrosion products.•Charge transfer resistance (Rct) increased 3.2 times than the control after 21 days of incubation in presence of CZNC-10.
In this report, interlinked chitosan-ZnO nanocomposite at 10% ZnO (CZNC-10) is successfully used as green biocide for biofilm control and reduction of biocorrosion on carbon steel material. It was found that 250 μg/mL CZNC-10 can be used efficiently for the inhibition of sulfate reducing bacteria (SRB) biofilm on carbon steel. The Rct values after 21 and 28 days of incubation in presence of CZNC-10 are almost 3.2 and 2.8 times higher than the control respectively, indicating a strong corrosion inhibition with 74% as maximum inhibition efficiency.
In this work, uniform cross-linked chitosan/lignosulfonate (CS/LS) nanospheres with an average diameter of 150–200 nm have been successfully used as a novel, environmentally friendly biocide for the ...inhibition of mixed sulfate-reducing bacteria (SRB) culture, thereby controlling microbiologically influenced corrosion (MIC) on carbon steel. It was found that 500 µg·mL−1 of the CS/LS nanospheres can be used efficiently for the inhibition of SRB-induced corrosion up to a maximum of 85% indicated by a two fold increase of charge transfer resistance (Rct) on the carbon steel coupons. The hydrophilic surface of CS/LS can readily bind to the negatively charged bacterial surfaces and thereby leads to the inactivation or damage of bacterial cells. In addition, the film formation ability of chitosan on the coupon surface may have formed a protective layer to prevent the biofilm formation by hindering the initial bacterial attachment, thus leading to the reduction of corrosion.
The control of microbiologically influenced corrosion (MIC) is of great significance in many industrial applications. Attention has been devoted to emerging nanomaterials as ‘green’ biocides for ...their remarkable antimicrobial function and relatively low environmental risk. Understanding the antimicrobial inhibition mechanisms is the key to increase the efficiency of nanoparticles and enhance the feasibility of their application against various MIC microorganisms under different environmental conditions. This study gives an overview of the recent advancements of different nanomaterials and nanocomposites used as biocides for the inhibition of MIC. The potential and associated challenges in developing NPs as effective biocides are highlighted.
Abstract
An electrochemical aptasensor was designed for the ultraselective and sensitive detection of Pb
2+
by using lead‐specific binding DNA oligonucleotide as the molecular recognition element on ...Au nanoparticles/Nb
4
C
3
T
x
MXene (Au@Nb
4
C
3
T
x
) modified electrode. The Au@Nb
4
C
3
T
x
is conjugated with thiol‐modified lead‐binding DNA through the Au−S bond. The DNA−Au@Nb
4
C
3
T
x
modified glassy carbon electrode exhibited ultrahigh selectivity and enhanced response towards the detection of Pb
2+
with a detection limit of 4 nM and linear range of 10 nM to 5 μM. This work has proved the possibility of using Nb
4
C
3
T
x
as a robust immobilization platform for DNA oligonucleotides towards different environmental sensing and biomedical applications.
Rapid and real-time detection of l -cysteine ( l -Cys) is important for early diagnostics of several diseases and biological disorders. We report here a stable and highly sensitive electrochemical ...sensor for the detection of l -Cys based on a Pd@Ti 3 C 2 T x (MXene)-modified glassy carbon electrode (GCE). The Pd@Ti 3 C 2 T x nanocomposite was prepared by in situ reduction of Pd( ii ) salt on the surface of delaminated (DL) Ti 3 C 2 T x nanosheets to form pseudo-spherical palladium nanoparticles (PdNPs) with 2–6 nm size distributions. The MXene acts as the conductive matrix and a reducing agent at the electrode surface, while PdNPs are there to improve the stability of Ti 3 C 2 T x and to enhance the electrocatalytic activity towards l -Cys detection. The Pd@Ti 3 C 2 T x /GCE sensor exhibited a detection limit of 0.14 μM and a linear electro-oxidative response to l -Cys within the concentration range from 0.5 to 10 μM. The sensor also demonstrated excellent selectivity over common interfering ions such as ascorbic acid, uric acid, dopamine and glucose.