Memristive approach for estimation of bacterial pathogen E. coli concentration using ZnS quantum dots

2021 ◽  
Vol 43 ◽  
pp. 3891-3895
Author(s):  
Himadri Duwarah ◽  
Neelotpal Sharma ◽  
Jutika Devi ◽  
Kandarpa Kumar Saikia ◽  
Pranayee Datta
Keyword(s):  
Quantum Dots ◽  
Bacterial Pathogen ◽  
E Coli

scholarly journals Conjugation of Carboxylated Graphene Quantum Dots with Cecropin P1 for Bacterial Biosensing Applications

2020 ◽  
Author(s):  
Jonathan Bruce ◽  
Jude Clapper
Keyword(s):  
Quantum Dots ◽  
Structural Modification ◽  
Light Emission ◽  
Limit Of Detection ◽  
Graphene Quantum Dots ◽  
Strong Light ◽  
E Coli ◽  
Cecropin P1 ◽  
Compact Field ◽  
Test Kit

<p>Quantum dots have proven to be strong candidates for biosensing applications in recent years, due to their strong light emission properties and their ability to be modified with a variety of functional groups for the detection of different analytes. Here, we investigate the use of conjugated carboxylated graphene quantum dots (CGQDs) for the detection of <i>E. coli</i>, using a biosensing procedure that focuses on measuring changes in fluorescence quenching. We have also further developed this biosensing assay into a compact, field-deployable test kit focused on rapidly measuring changes in absorbance to determine bacterial concentration. Our CGQDs were conjugated with cecropin P1, a naturally-produced antibacterial peptide that facilitates the attachment of CGQDs to <i>E. coli</i> cells. We also confirm the structural modification of these conjugated CGQDs in addition to analyzing their optical characteristics. Our findings have the potential to be used in situations where rapid, reliable detection of bacteria in liquids, such as drinking water, is required, especially given our biosensor’s relatively low observed limit of detection (LOD).</p><br>

scholarly journals Bactericides Properties of Chitosan Metal Quantum Dots Microbial Pathogenicity Against E. coli, S. aureus, and S. Typhi

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Galo Cárdenas-Triviño ◽  
María J. Saludes-Betanzo ◽  
Luis Vergara-González
Keyword(s):  
Quantum Dots ◽  
Antibacterial Properties ◽  
Inhibition Zone ◽  
Bactericidal Effect ◽  
Salmonella Typhi ◽  
Disk Diffusion ◽  
Initial Inoculum ◽  
E Coli ◽  
Growth Inhibition Zone ◽  
Average Size

The nanotechnology is considered as a tool to overcome antibiotic-resistant infections. The aim of this study was to investigate the antibacterial properties of quantum dots (QDs) of Au, Ag, and Cu supported in chitosan against Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 29213), and Salmonella Typhi (ATCC 9993) strains. The QDs were synthesized by the method (Chemical Liquid Deposition, CLD) using 2-ethoxyethanol as solvent (1×10−3 M approximate dispersion concentration). Then, NPs supported in chitosan were synthesized by solvated metal atom dispersion (SMAD) in two concentrations, labelled [A] and [B] (0.05 and 0.1 g/L) for each metal with chitosan resulting in an average size of Au 10±2.0, Ag 6±1.3, and Cu 10±2.4 nm, respectively. Several other techniques were performed such as TEM, SEM/EDX, TGA, DSC, and FT-IR for characterizing QDs. The antibacterial assay was performed with 8 agents on cultures of E. coli, S. aureus, and S. Typhi by disk diffusion, broth macrodilution, and determining death curve to the most sensitive pathogen. The antibacterial effect of the nanoparticles was compared using the diameter of growth inhibition zone by agar disk diffusion and through the minimal inhibitory concentration (MIC) and minimal bactericide concentration (MBC) obtained by macrodilution in batch culture with an initial inoculum of 5×105 CFU/mL. The highest bactericidal effect was obtained with nanoparticles of Au, Ag, and Cu (0.1 g/L) with MIC and MBC of 200 and 400 mg/mL, respectively. The greatest bactericidal effect considering the three pathogens turned out to be Ag QDs (0.05 and 0.1 g/L). A bactericidal effect of metal nanoparticles is affected mainly by the electronegativity, the concentration of nanoparticles, and the bacterial age culture.

scholarly journals Utilization of Mn-Doped ZnSe/ZnS Core/Shell Quantum Dots for Rapid Detection of Escherichia coli O157:H7 and Methicillin-Resistant Staphylococcus aureus

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Thi-Diem Bui ◽  
Quang-Liem Nguyen ◽  
Thi-Bich Luong ◽  
Van Thuan Le ◽  
Van-Dat Doan
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Quantum Dots ◽  
Fluorescent Labeling ◽  
Core Shell ◽  
Bacterial Cells ◽  
Bacterial Strains ◽  
Methicillin Resistant ◽  
E Coli ◽  
Mn Doped

In this study, Mn-doped ZnSe/ZnS core/shell quantum dots (CSQDs) were synthesized in aqueous solution using polyethylene glycol as a surface stabilizer and successfully applied in the detection of Escherichia coli O157:H7 and methicillin-resistant Staphylococcus aureus (MRSA) for the first time. The CSQDs were conjugated with anti-E. coli antibody and anti-MRSA antibody via protein A supported by 1-ethyl-3-(-3-dimethylaminopropyl)carbodiimide hydrochloride for fluorescent labeling of the intact bacterial cells. The detection was performed for the bacterial strains cultivated in Luria-Bertani liquid medium. The obtained results indicate that E. coli O157:H7 and MRSA can be detected within 30 min at a high sensitivity of 101 CFU/mL. This labeling method based on the highly fluorescent CSQDs may have great potential for use in the food industry to check and prevent outbreaks of foodborne illness.

scholarly journals Synthesis of Carbon Doped TiO2 Quantum Dots for Photocatalytic Sterilization under the Visible Light Irradiation and the Mechanisms

2019 ◽  
Vol 118 ◽  
pp. 01013 ◽  
Author(s):  
Wei Xiong ◽  
Altair T.F. Cheung ◽  
Michael K.H. Leung
Keyword(s):  
Quantum Dots ◽  
Visible Light ◽  
Visible Light Irradiation ◽  
Superoxide Radical ◽  
Light Irradiation ◽  
Doping Amount ◽  
E Coli ◽  
Carbon Doped ◽  
Chemical States ◽  
Self Protection

In this article, the carbon doped TiO2 (C-TiO2) quantum dots (QDs) were prepared through the hydrothermal method and calcination. The size of the C-TiO2 QDs is about 5.7 nm. The doping amount of carbon can be tuned by adjusting the volumes of the carbon source, ethylene glycol added. The carbon atoms are proved to be doped into the interstitial sites of TiO2 lattice and induce the change of chemical states of Ti 2p and C 1s. The doping of carbon leads to the increasing photocatalytic sterilization of E. coli under the visible light irradiation. The survival rate of E. coli cells over C-TiO2 is only 1.5 % after 6 h. The reactive oxygen species (ROS), such as hydroxyl radical and superoxide radical, are considered as the primary factors for the photocatalytic sterilization. Due to oxidative stress of the attack by ROS, the enzyme activity per cells increases for self-protection during the photocatalytic sterilization.

scholarly journals Cloning and Characterization of SmeDEF, a Novel Multidrug Efflux Pump from Stenotrophomonas maltophilia

2000 ◽  
Vol 44 (11) ◽  
pp. 3079-3086 ◽  
Author(s):  
Ana Alonso ◽  
José L. Martínez
Keyword(s):  
Stenotrophomonas Maltophilia ◽  
Efflux Pump ◽  
Bacterial Pathogen ◽  
Drug Susceptibility ◽  
Multidrug Resistant ◽  
Transcriptional Unit ◽  
Chromosomal Dna ◽  
Multidrug Efflux Pump ◽  
E Coli ◽  
Wide Range

ABSTRACT Stenotrophomonas maltophilia is a nosocomial bacterial pathogen intrinsically resistant to several antibiotics. The mechanisms involved in this intrinsic multiresistance phenotype are poorly understood. A library of chromosomal DNA from a spontaneous multidrug-resistant S. maltophilia D457R mutant (A. Alonso and J. L. Martinez, Antimicrob. Agents Chemother. 41:1140–1142, 1997) was screened for complementation of erythromycin susceptibility on an antibiotic-hypersusceptible Escherichia coli ΔacrABstrain. Cloning and further analysis revealed that a 6-kbp region constituting a transcriptional unit was capable of complementing the antibiotic-susceptible phenotype of an E. coli ΔacrABstrain. We identified three open reading frames, smeD,smeE and smeF, which code for members of the membrane fusion protein, resistance nodulation division, and outer membrane factor families, respectively. Drug susceptibility assays indicated that the SmeDEF system cloned in E. coli mediates resistance to a wide range of antibiotics. Ethidium bromide and norfloxacin accumulation experiments in the presence and in the absence of carbonyl cyanide m-chlorophenylhydrazone showed that this system constitutes a drug efflux pump dependent on the membrane proton motive force. The presence of high levels of smeDEFmRNA in the multiresistant D457R mutant was consistent with the high levels of SmeF (formerly Omp54) observed in the same strain. In contrast, transcription levels of smeDEF in the D457 strain were tiny, which correlates with the low levels of SmeF observed for this strain. Also, for both the D457 and D457R strains, we observed growth phase-dependent regulation in which the highest level of transcription corresponded to early exponential phase, with transcription decreasing throughout the growth curve to undetectable levels at 24 h.

Size-Dependent Antibacterial Behavior of Graphene Quantum Dots

2013 ◽  
Author(s):  
Siheng Su ◽  
Carla B. Shelton ◽  
Jingjing Qiu
Keyword(s):  
Quantum Dots ◽  
Surface Chemistry ◽  
Graphene Quantum Dots ◽  
Gel Filtration ◽  
Filtration Method ◽  
E Coli ◽  
Size Dependent ◽  
Mtt Method ◽  
Diphenyltetrazolium Bromide ◽  
Standard Plate

In this study, the antibacterial behavior of differing sized graphene quantum dots (GQDs) was studied. The gram negative bacteria, Escherichia coli (E. coli), were used as the bacteria mode. Different sized GQDs with tunable fluorescent colors were acquired by a gel-filtration method. The size, surface chemistry, and photoluminescence properties of GQDs were characterized, respectively. The viability of GQDs treated bacteria was determined by the standard plate counting method. Moreover, the reactive oxidative species (ROS) level was detected by the 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) method. The integrality of the bacteria membrane was observed under the scanning electron microscopy (SEM). The experimental results indicated that GQDs demonstrated size-dependent and surface chemistry-dependent antibacterial behaviors. This research provided insightful guidelines in the selection of suitable GQDs for their potential bioapplications.

scholarly journals P-Doped Carbon Quantum Dots with Antibacterial Activity

Micromachines ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1116
Author(s):  
Shuiqin Chai ◽  
Lijia Zhou ◽  
Shuchen Pei ◽  
Zhiyuan Zhu ◽  
Bin Chen
Keyword(s):  
Quantum Dots ◽  
Antibacterial Activity ◽  
Bacterial Infections ◽  
Fluorescence Emission ◽  
Carbon Quantum Dots ◽  
Microbial Pathogens ◽  
Electronic Interaction ◽  
Minimal Inhibitory Concentrations ◽  
E Coli ◽  
Zeta Potential Analysis

It is a major challenge to effectively inhibit microbial pathogens in the treatment of infectious diseases. Research on the application of nanomaterials as antibacterial agents has evidenced their great potential for the remedy of infectious disease. Among these nanomaterials, carbon quantum dots (CQDs) have attracted much attention owing to their unique optical properties and high biosafety. In this work, P-doped CQDs were prepared by simple hydrothermal treatment of m-aminophenol and phosphoric acid with fluorescence emission at 501 nm when excited at 429 nm. The P-doped CQDs showed effective antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The minimal inhibitory concentrations (MICs) of P-doped CQD were 1.23 mg/mL for E. coli and 1.44 mg/mL for S. aureus. Furthermore, the morphologies of E. coli cells were damaged and S. aureus became irregular when treated with the P-doped CQDs. The results of zeta potential analysis demonstrated that the P-doped CQDs inhibit antibacterial activity and destroy the structure of bacteria by electronic interaction. In combination, the results of this study indicate that the as-prepared P-doped CQDs can be a promising candidate for the treatment of bacterial infections.

scholarly journals Optimised Heterologous Expression and Functional Analysis of the Yersinia pestis F1-Capsular Antigen Regulator Caf1R

2021 ◽  
Vol 22 (18) ◽  
pp. 9805
Author(s):  
Dharmender K. Gahlot ◽  
Gyles Ifill ◽  
Sheila MacIntyre
Keyword(s):  
Yersinia Pestis ◽  
Vaccine Development ◽  
Recombinant Expression ◽  
Bacterial Pathogen ◽  
Clinical Value ◽  
Mobility Shift ◽  
E Coli ◽  
Capsular Antigen ◽  
Mobility Shift Assay

The bacterial pathogen, Yersinia pestis, has caused three historic pandemics and continues to cause small outbreaks worldwide. During infection, Y. pestis assembles a capsule-like protective coat of thin fibres of Caf1 subunits. This F1 capsular antigen has attracted much attention due to its clinical value in plague diagnostics and anti-plague vaccine development. Expression of F1 is tightly regulated by a transcriptional activator, Caf1R, of the AraC/XylS family, proteins notoriously prone to aggregation. Here, we have optimised the recombinant expression of soluble Caf1R. Expression from the native and synthetic codon-optimised caf1R cloned in three different expression plasmids was examined in a library of E. coli host strains. The functionality of His-tagged Caf1R was demonstrated in vivo, but insolubility was a problem with overproduction. High levels of soluble MBP-Caf1R were produced from codon optimised caf1R. Transcriptional-lacZ reporter fusions defined the PM promoter and Caf1R binding site responsible for transcription of the cafMA1 operon. Use of the identified Caf1R binding caf DNA sequence in an electrophoretic mobility shift assay (EMSA) confirmed correct folding and functionality of the Caf1R DNA-binding domain in recombinant MBP-Caf1R. Availability of functional recombinant Caf1R will be a valuable tool to elucidate control of expression of F1 and Caf1R-regulated pathophysiology of Y. pestis.

scholarly journals Complete Bypass of Restriction Systems for Major Staphylococcus aureus Lineages

mBio ◽  
2015 ◽  
Vol 6 (3) ◽  
Author(s):  
Ian R. Monk ◽  
Jai J. Tree ◽  
Benjamin P. Howden ◽  
Timothy P. Stinear ◽  
Timothy J. Foster
Keyword(s):  
Staphylococcus Aureus ◽  
Plasmid Dna ◽  
High Efficiency ◽  
Recombinant Dna ◽  
Genetic Manipulation ◽  
Bacterial Pathogen ◽  
Type I ◽  
Content Type ◽  
E Coli ◽  
Adenine Methylation

ABSTRACTStaphylococcus aureusis a prominent global nosocomial and community-acquired bacterial pathogen. A strong restriction barrier presents a major hurdle for the introduction of recombinant DNA into clinical isolates ofS. aureus. Here, we describe the construction and characterization of the IMXXB series ofEscherichia colistrains that mimic the type I adenine methylation profiles ofS. aureusclonal complexes 1, 8, 30, and ST93. The IMXXB strains enable direct, high-efficiency transformation and streamlined genetic manipulation of majorS. aureuslineages.IMPORTANCEThe genetic manipulation of clinicalS. aureusisolates has been hampered due to the presence of restriction modification barriers that detect and subsequently degrade inappropriately methylated DNA. Current methods allow the introduction of plasmid DNA into a limited subset ofS. aureusstrains at high efficiency after passage of plasmid DNA through the restriction-negative, modification-proficient strain RN4220. Here, we have constructed and validated a suite ofE. colistrains that mimic the adenine methylation profiles of different clonal complexes and show high-efficiency plasmid DNA transfer. The ability to bypass RN4220 will reduce the cost and time involved for plasmid transfer intoS. aureus. The IMXXB series ofE. colistrains should expedite the process of mutant construction in diverse genetic backgrounds and allow the application of new techniques to the genetic manipulation ofS. aureus.

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