The Experts below are selected from a list of 38208 Experts worldwide ranked by ideXlab platform
Zhifeng Ding - One of the best experts on this subject based on the ideXlab platform.
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probing cd2 stressed live Cell Membrane Permeability with various redox mediators in scanning electrochemical microscopy
Journal of Physical Chemistry C, 2016Co-Authors: Fraser P. Filice, Jeffrey D. Henderson, Zhifeng DingAbstract:Heavy metal cytotoxicity has become a mainstay in scientific research due to the vast range of detrimental effects on living organisms. Cd2+ in particular can activate a wide range of physiological pathways that can cause significant increases in oxidative stress, cancer formation, or Cellular death. This is partly due to its ability to bioaccumulate in the body with a long half-life for excretion. Here, we used hydrophilic redox mediators, ferrocenecarboxylate, 1′1-ferrocene dicarboxylate and hexaamineruthenium, as molecular probes in scanning electrochemical microscopy (SECM) to determine the Membrane Permeability in single live human bladder cancer (T24) Cells affected by Cd2+. Hydrophilic and charged sensing agents should be impermeable to the Cells. However, when T24 Cells were treated with 25 μM Cd2+ (t ≤ 6 h), the Membrane Permeability to these sensing agents can be induced to approximately 7.0 × 10–5 m/s. For acute mM Cd2+ exposure, the Membrane Permeability can be induced to 2.0 × 10–4 m/s within...
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Probing Cd2+-Stressed Live Cell Membrane Permeability with Various Redox Mediators in Scanning Electrochemical Microscopy
2016Co-Authors: Fraser P. Filice, Jeffrey D. Henderson, Zhifeng DingAbstract:Heavy metal cytotoxicity has become a mainstay in scientific research due to the vast range of detrimental effects on living organisms. Cd2+ in particular can activate a wide range of physiological pathways that can cause significant increases in oxidative stress, cancer formation, or Cellular death. This is partly due to its ability to bioaccumulate in the body with a long half-life for excretion. Here, we used hydrophilic redox mediators, ferrocenecarboxylate, 1′1-ferrocene dicarboxylate and hexaamineruthenium, as molecular probes in scanning electrochemical microscopy (SECM) to determine the Membrane Permeability in single live human bladder cancer (T24) Cells affected by Cd2+. Hydrophilic and charged sensing agents should be impermeable to the Cells. However, when T24 Cells were treated with 25 μM Cd2+ (t ≤ 6 h), the Membrane Permeability to these sensing agents can be induced to approximately 7.0 × 10–5 m/s. For acute mM Cd2+ exposure, the Membrane Permeability can be induced to 2.0 × 10–4 m/s within an hour. This increase in Membrane Permeability is indicative of the loss in Membrane integrity, where species can now enter the Cell through nonspecific diffusion channels, pore formation, or structural collapse of the Membrane. Using the MTT proliferation assay, we were able to confirm that the low dosage Cd2+ treatment had very minor effect on Cellular viability, while the acute treatments decreased viability to 68%. Our SECM results coupled with the MTT assays show the sufficient permeation of these sensors and compromised Cell viability. These findings by means of SECM demonstrate that hydrophilic redox mediators are ideal in sensing the effects of toxins, which may induce Permeability through detrimental effects on the Membrane integrity of the Cells
Fraser P. Filice - One of the best experts on this subject based on the ideXlab platform.
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probing cd2 stressed live Cell Membrane Permeability with various redox mediators in scanning electrochemical microscopy
Journal of Physical Chemistry C, 2016Co-Authors: Fraser P. Filice, Jeffrey D. Henderson, Zhifeng DingAbstract:Heavy metal cytotoxicity has become a mainstay in scientific research due to the vast range of detrimental effects on living organisms. Cd2+ in particular can activate a wide range of physiological pathways that can cause significant increases in oxidative stress, cancer formation, or Cellular death. This is partly due to its ability to bioaccumulate in the body with a long half-life for excretion. Here, we used hydrophilic redox mediators, ferrocenecarboxylate, 1′1-ferrocene dicarboxylate and hexaamineruthenium, as molecular probes in scanning electrochemical microscopy (SECM) to determine the Membrane Permeability in single live human bladder cancer (T24) Cells affected by Cd2+. Hydrophilic and charged sensing agents should be impermeable to the Cells. However, when T24 Cells were treated with 25 μM Cd2+ (t ≤ 6 h), the Membrane Permeability to these sensing agents can be induced to approximately 7.0 × 10–5 m/s. For acute mM Cd2+ exposure, the Membrane Permeability can be induced to 2.0 × 10–4 m/s within...
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Probing Cd2+-Stressed Live Cell Membrane Permeability with Various Redox Mediators in Scanning Electrochemical Microscopy
2016Co-Authors: Fraser P. Filice, Jeffrey D. Henderson, Zhifeng DingAbstract:Heavy metal cytotoxicity has become a mainstay in scientific research due to the vast range of detrimental effects on living organisms. Cd2+ in particular can activate a wide range of physiological pathways that can cause significant increases in oxidative stress, cancer formation, or Cellular death. This is partly due to its ability to bioaccumulate in the body with a long half-life for excretion. Here, we used hydrophilic redox mediators, ferrocenecarboxylate, 1′1-ferrocene dicarboxylate and hexaamineruthenium, as molecular probes in scanning electrochemical microscopy (SECM) to determine the Membrane Permeability in single live human bladder cancer (T24) Cells affected by Cd2+. Hydrophilic and charged sensing agents should be impermeable to the Cells. However, when T24 Cells were treated with 25 μM Cd2+ (t ≤ 6 h), the Membrane Permeability to these sensing agents can be induced to approximately 7.0 × 10–5 m/s. For acute mM Cd2+ exposure, the Membrane Permeability can be induced to 2.0 × 10–4 m/s within an hour. This increase in Membrane Permeability is indicative of the loss in Membrane integrity, where species can now enter the Cell through nonspecific diffusion channels, pore formation, or structural collapse of the Membrane. Using the MTT proliferation assay, we were able to confirm that the low dosage Cd2+ treatment had very minor effect on Cellular viability, while the acute treatments decreased viability to 68%. Our SECM results coupled with the MTT assays show the sufficient permeation of these sensors and compromised Cell viability. These findings by means of SECM demonstrate that hydrophilic redox mediators are ideal in sensing the effects of toxins, which may induce Permeability through detrimental effects on the Membrane integrity of the Cells
Pete N Urns - One of the best experts on this subject based on the ideXlab platform.
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sonoporation by ultrasound activated microbubble contrast agents effect of acoustic exposure parameters on Cell Membrane Permeability and Cell viability
Ultrasound in Medicine and Biology, 2009Co-Authors: Raffi Karshafia, Ross Williams, Sanya Samac, Pete D Eva, Pete N UrnsAbstract:Abtract This work investigates the effect of ultrasound exposure parameters on the sonoporation of KHT-C Cells in suspension by perflutren microbubbles. Variations in insonating acoustic pressure (0.05 to 3.5 MPa), pulse frequency (0.5 to 5.0 MHz), pulse repetition frequency (10 to 3000 Hz), pulse duration (4 to 32 μs) and insonation time (0.1 to 900 s) were studied. The number of Cells permeabilised to a fluorescent tracer molecule (70 kDa FITC-dextran) and the number of viable Cells were measured using flow cytometry. The effect of exposure on the microbubble population was measured using a Coulter counter. Cell viability and Membrane Permeability were found to depend strongly on the acoustic exposure conditions. Cell Permeability increased and viability decreased with increasing peak negative pressure, pulse repetition frequency, pulse duration and insonation time and with decreasing pulse centre frequency. The highest therapeutic ratio (defined as the ratio of permeabilised to nonviable Cells) achieved was 8.8 with 32 ± 4% permeabilisation and 96 ± 1% viability at 570 kPa peak negative pressure, 8 μs pulse duration, 3 kHz pulse repetition frequency, 500 kHz centre frequency and 12 s insonation time with microbubbles at 3.3% volume concentration. These settings correspond to an acoustic energy density (E SPPA ) of 3.12 J/cm 2 . Cell Permeability and viability did not correlate with bubble disruption. The results indicate that ultrasound exposure parameters can be optimized for therapeutic sonoporation and that bubble disruption is a necessary but insufficient indicator of ultrasound-induced permeabilisation. (E-mail: raffik@sri.utoronto.ca )
Mark D P Willcox - One of the best experts on this subject based on the ideXlab platform.
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mode of action of the antimicrobial peptide mel4 is independent of staphylococcus aureus Cell Membrane Permeability
PLOS ONE, 2019Co-Authors: Muhammad Yasir, Debarun Dutta, Mark D P WillcoxAbstract:Mel4 is a novel cationic peptide with potent activity against Gram-positive bacteria. The current study examined the anti-staphylococcal mechanism of action of Mel4 and its precursor peptide melimine. The interaction of peptides with lipoteichoic acid (LTA) and with the cytoplasmic Membrane using DiSC(3)-5, Sytox green, Syto-9 and PI dyes were studied. Release of ATP and DNA/RNA from Cells exposed to the peptides were determined. Bacteriolysis and autolysin-activated Cell death were determined by measuring decreases in OD620nm and killing of Micrococcus lysodeikticus Cells by Cell-free media. Both peptides bound to LTA and rapidly dissipated the Membrane potential (within 30 seconds) without affecting bacterial viability. Disturbance of the Membrane potential was followed by the release of ATP (50% of total Cellular ATP) by melimine and by Mel4 (20%) after 2 minutes exposure (p<0.001). Mel4 resulted in staphylococcal Cells taking up PI with 3.9% Cells predominantly stained after 150 min exposure, whereas melimine showed 34% staining. Unlike melimine, Mel4 did not release DNA/RNA. Cell-free media from Mel4 treated Cells hydrolysed peptidoglycan and produced greater zones of inhibition against M. lysodeikticus lawn than melimine treated samples. These findings suggest that pore formation is unlikely to be involved in Mel4-mediated Membrane destabilization for staphylococci, since there was no significant Mel4-induced PI staining and DNA/RNA leakage. It is likely that the S. aureus killing mechanism of Mel4 involves the release of autolysins followed by Cell death. Whereas, Membrane interaction is the primary bactericidal activity of melimine, which includes Membrane depolarization, pore formation, release of Cellular contents leading to Cell death.
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smode of action of the antimicrobial peptide mel4 is independent of staphylococcus aureus Cell Membrane Permeability
bioRxiv, 2019Co-Authors: Muhammad Yasir, Debarun Dutta, Mark D P WillcoxAbstract:Mel4 is a novel cationic peptide with potent activity against Gram-positive bacteria. The current study examined the anti-staphylococcal mechanism of action of Mel4 and its precursor peptide melimine. The interaction of peptides with lipoteichoic acid (LTA) and with the cytoplasmic Membrane using DiSC(3)-5, Sytox green, Syto-9 and PI dyes were studied. Release of ATP and DNA/RNA from Cells exposed to the peptides were determined. Bacteriolysis and autolysin-activated Cell death were determined by measuring decreases in OD620nm and killing of Micrococcus luteus Cells by Cell-free media. Both peptides bound to LTA and rapidly dissipated the Membrane potential (within 30 seconds) without affecting bacterial viability. Disturbance of the Membrane potential was followed by the release of ATP (50% of total Cellular ATP) by melimine and by Mel4 (20%) after 2 minutes exposure (p<0.001). Mel4 resulted in staphylococcal Cells taking up PI with 3.9% Cells predominantly stained after 150 min exposure, whereas melimine showed 34% staining. Unlike melimine, Mel4 did not release DNA/RNA. Cell-free media from Mel4 treated Cells hydrolysed peptidoglycan and produced greater zones of inhibition against M. luteus lawn than melimine treated samples. These findings suggest that pore formation is unlikely to be involved in Mel4-mediated Membrane destabilization for Staphylococcci, since there was no significant Mel4-induced PI staining and DNA/RNA leakage. It is likely that the S. aureus killing mechanism of Mel4 involves the release of autolysins followed by Cell death. Whereas, Membrane interaction is the primary bactericidal activity of melimine, which includes Membrane depolarisation, pore formation, release of Cellular contents leading to Cell death.
Zhenhui Kang - One of the best experts on this subject based on the ideXlab platform.
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size dependent and real time effect of sio2 nanoparticles on a single living hela Cell s Membrane Permeability
Journal of Materials Chemistry B, 2015Co-Authors: Weiqian Kong, Juan Liu, Hui Huang, Yang Liu, Yuzhi Han, Zhenhui KangAbstract:In this study, we provide the quantitative data on the Membrane Permeability of a HeLa Cell in the presence of different sizes of SiO2 nanoparticles (NPs, 50, 100 and 200 nm). SiO2 NPs have low cytotoxicity, but 50 and 100 nm SiO2 NPs can increase the Cell Membrane Permeability (a reversible effect) by 12.5% (0.02 mg mL-1, 4 min) and 9% (0.02 mg mL-1, 6 min), respectively. However, the 200 nm SiO2 NPs cannot affect the Cell Membrane Permeability.
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quantitative and real time effects of carbon quantum dots on single living hela Cell Membrane Permeability
Nanoscale, 2014Co-Authors: Weiqian Kong, Juan Liu, Hui Huang, Yang Liu, Ruihua Liu, Jian Liu, Shuittong Lee, Zhenhui KangAbstract:The interaction between carbon quantum dots (CQDs) and a single living Cell was explored in real time. Here, we provide the quantitative data on the Permeability of the HeLa Cell Membrane in the presence of CQDs with different surface functional groups (CQDs terminated with –OH/–COOH (CQD–OH), –PEG (CQD–PEG), and –NH2 (CQD–NH2)). Although these CQDs have very low toxicity towards HeLa Cells, they still increase the Cell Membrane Permeability by 8%, 13%, and 19% for CQD–PEG, CQD–OH, and CQD–NH2, respectively, and this kind of Permeability was irreversible. These observations are valuable for promoting the bio-applications of carbon nanostructures in living systems.