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Cellular binding of nanoparticles disrupts the membrane potential.

ABSTRACT: All cells generate an electrical potential across their plasma membrane driven by a concentration gradient of charged ions. A typical resting membrane potential ranges from -40 to -70 mV, with a net negative charge on the cytosolic side of the membrane. Maintenance of the resting membrane potential depends on the presence of two-pore-domain potassium "leak" channels, which allow for outward diffusion of potassium ions along their concentration gradient. Disruption of the ion gradient causes the membrane potential to become more positive or more negative relative to the resting state, referred to as "depolarization" or "hyperpolarization," respectively. Changes in membrane potential have proven to be pivotal, not only in normal cell cycle progression but also in malignant transformation and tissue regeneration. Using polystyrene nanoparticles as a model system, we use flow cytometry and fluorescence microscopy to measure changes in membrane potential in response to nanoparticle binding to the plasma membrane. We find that nanoparticles with amine-modified surfaces lead to significant depolarization of both CHO and HeLa cells. In comparison, carboxylate-modified nanoparticles do not cause depolarization. Mechanistic studies suggest that this nanoparticle-induced depolarization is the result of a physical blockage of the ion channels. These experiments show that nanoparticles can alter the biological system of interest in subtle, yet important, ways.

SUBMITTER: Warren EA

PROVIDER: S-EPMC4326017 | biostudies-literature | 2015 Jan

REPOSITORIES: biostudies-literature

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Cellular binding of nanoparticles disrupts the membrane potential.

Warren Emilie A K EA Payne Christine K CK

RSC advances 20150101 18

All cells generate an electrical potential across their plasma membrane driven by a concentration gradient of charged ions. A typical resting membrane potential ranges from -40 to -70 mV, with a net negative charge on the cytosolic side of the membrane. Maintenance of the resting membrane potential depends on the presence of two-pore-domain potassium "leak" channels, which allow for outward diffusion of potassium ions along their concentration gradient. Disruption of the ion gradient causes the ...[more]

PMID: 25685328

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Project description:IntroductionThe use of flavors in electronic cigarettes appeals to adults and never-smoking youth. Consumption has rapidly increased over the last decade, and in the U.S. market alone, there are over 8000 unique flavors. The U.S. Food and Drug Administration (FDA) has begun to regulate e-liquids, but many have not been tested, and their impact, both at the cellular level, and on human health remains unclear.MethodsWe tested e-liquids on the human cell line HEK293T and measured toxicity, mitochondrial membrane potential (ΔΨ m), reactive oxygen species production (ROS), and cellular membrane potential (Vm) using high-throughput screening (HTS) approaches. Our HTS efforts included single-dose and 16-point dose-response curves, which allowed testing of ≥90 commercially available e-liquids in parallel to provide a rapid assessment of cellular effects as a proof of concept for a fast, preliminary toxicity method. We also investigated the chemical composition of the flavors via gas chromatography-mass spectrometry.ResultsWe found that e-liquids caused a decrease in ΔΨ m and Vm and an increase in ROS production and toxicity in a dose-dependent fashion. In addition, the presence of five specific chemical components: vanillin, benzyl alcohol, acetoin, cinnamaldehyde, and methyl-cyclopentenolone, but not nicotine, were linked with the changes observed in the cellular traits studied.ConclusionOur data suggest that ΔΨ m, ROS, Vm, and toxicity may be indicative of the extent of cell death upon e-liquid exposure. Further research on the effect of flavors should be prioritized to help policy makers such as the FDA to regulate e-liquid composition.ImplicationsE-liquid cellular toxicity can be predicted using parameters amenable to HTS. Our data suggest that ΔΨ m, ROS, Vm, and toxicity may be indicative of the extent of cell death upon e-liquid exposure, and this toxicity is linked to the chemical composition, that is, flavoring components. Further research on the effect of flavors should be prioritized to help policy makers such as the FDA to regulate e-liquid composition.

Project description:Interaction of nanomaterials with the mammalian cells remains to be poorly understood at the molecular level. Here we report the first synthesis of hybrid nanomaterial termed phage mimetic nanorods (PMN’s) inspired from filamentous bacteriophage present in nature. We emulate filamentous bacteriophage structure by combining two separate nanoscale entities, one functionalized gold nanorods and the other is coat proteins isolated from filamentous bacteriophage obtained through landscape phage screening. Utilizing biochemical interactions between a phage-derived protein and functionalized gold nanorods, we synthesized novel phage mimetic nanorods. The resulting nanovectors showed excellent multi functional properties including target specificity, imaging and photo destruction ability in a model SKBR-3 breast cancer cells. In addition, to gain insight into the molecular interactions involved during internalization of PMNs by SKBR-3 cells, we performed gene expression profiling of cells exposed to PMNs as compared with naive cells. We identified 70 upregulated and 26 downregulated genes responding to PMNs. Heparin binding internalization was identified as most plausible mechanisms of PMNs entry. Members of Major Histocompatibility complex I (MHC class I) were activated by PMNs, leading to enhanced lysosome and proteasome activity. Seven members of poorly annotated G antigen family (GAGE) of genes were upregulated, and may represent novel mechanism of PMNs entry recognition by cells. In summary, we present a versatile technique of PMNs production as any protein isolated from phage libraries selected against any in vitro and in vivo cells can be used as a source to synthesize PMN’s. This study also opens new avenues to understand the role of nanomaterials at the molecular level. Investigate the effect of phage mimetic nanorods onto SKBT-3 cells Two groups were compared, three biological replicates each. One group was control cells and the other was test.

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Cellular binding of nanoparticles disrupts the membrane potential.

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Cellular binding of nanoparticles disrupts the membrane potential.

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