Adsorption and transport of charged vs. neutral hydrophobic molecules at the membrane of murine erythroleukemia (MEL) cells

The selection of solvent for preparing a working electrode (and to act as the electrolyte) is known to influence the efficiency of dye‐sensitized solar cells. In this topical review, results taken from a systematic study are presented from the authors’ own lab examining how protic and aprotic solvents, as well as solvent polarity, affect adsorption of carboxylic dyes on the titanium dioxide nanoparticle surface and electron injection from the dye to the semiconductor. Adsorption of dye molecules on nanoparticle surfaces is measured through second harmonic light scattering and electron injection through ultrafast transient mid‐infrared absorption. It is revealed that protic solvents do not allow direct adsorption of the dye onto the semiconductor surface, due to hydrogen bonding with the dye and competitive binding to the semiconductor surface. Aprotic solvents, on the other hand, support solvation of the dye molecules but also facilitate dye adsorption on the semiconductor nanoparticle. Among aprotic solvents, it is found that solvents with higher polarity result in larger adsorption free energy for the dye and faster electron injection. Overall, these studies reveal that aprotic solvents with high solvent polarity (such as acetonitrile) yield more efficient solar cell devices.

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“…Incorporating the two equilibria, the molecular surface coverage in protic solvents can be expressed as [104] 1 1 4…”

Section: Aprotic Versus Protic Solventsmentioning

confidence: 99%

Influence of Solvent on Dye‐Sensitized Solar Cell Efficiency: What is so Special About Acetonitrile?

Fang

Wilhelm

et al. 2021

Part & Part Syst Charact

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“…In addition to bacterial cells, we have also studied membrane‐specific adsorption and transport in eukaryotic cells, in particular, cancerous mouse blood cells. Specifically, when these murine erythroleukemia (MEL) cells are incubated in polar organic solvents, they continue to differentiate in a manner similar to healthy normal blood cells .…”

Section: Molecule—membrane Interactions Monitored With Second Harmonimentioning

confidence: 99%

“…For verifying the SHS results, we have also developed time‐resolved bright‐field transmission microscopy (BTM) as a complementary method which is sensitive to changes in the intracellular molecular concentration. The remainder of the review will focus on specific studies, reported from our own lab, using time‐resolved SHS to investigate: molecular transport across the dual membranes in a Gram‐negative bacteria, the effects of molecular charge and structure on adsorption and transport across a plasma membrane, the effect of membrane structure on molecular transport, the mechanism of the well‐known staining protocol for differentiating Gram‐positive and Gram‐negative bacteria, chemically‐induced changes to membrane permeability, and the mechanism‐of‐action of an antimicrobial compound . We have also developed a method, based on competition induced perturbations in the SHS signal, to monitor transport of SHG inactive compounds .…”

Section: Introductionmentioning

confidence: 99%

Molecule‐Membrane Interactions in Biological Cells Studied with Second Harmonic Light Scattering

Wilhelm

Dai

2019

Chemistry An Asian Journal

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The nonlinearo ptical phenomenon second harmonic light scattering (SHS) can be used for detecting molecules at the membrane surfaces of living biological cells. Over the last decade, SHS has been developed for quantitatively monitoring the adsorption and transport of smalla nd medium size molecules (both neutral and ionic) across membranes in living cells. SHS can be operated with both time and spatial resolution and is even capableo fisolating molecule-membrane interactions at specific membrane surfaces in multi-membrane cells, such as bacteria. In this review,w e discuss select examples from our lab employingt ime-resolved SHS to study real-time molecular interactions at the plasma membranes of biological cells. We first demonstrate the utility of this method for determining the transport rates at each membrane/interfacei naGram-negative bacterial cell. Next, we show how SHS can be used to characterize the molecular mechanism of the centuryo ld Gram stain protocol for classifyingb acteria. Additionally,w ee xamine how membrane structures and molecular charge and polarity affect adsorption and transport, as well as how antimicrobial compounds alter bacteria membrane permeability.F inally, we discuss adaptation of SHS as an imaging modality to quantify molecular adsorption and transport in sub-cellular regionso fi ndividual livingcells.[a] Prof.

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“…This characteristic mechanism has previously been employed to monitor molecular adsorption and transport across phospholipid membranes in biomimetic model liposomes (12)(13)(14)(15)(16)(17)(18)(19) and living cells. (20)(21)(22)(23)(24)(25)(26)(27)(28) When SHG-active molecules adsorb onto the exterior surface of the membrane, they align with one another due to the similarity of the interaction driving the adsorption process. This oriented ensemble of SHG-active molecules gives rise to a coherent SHS response, the intensity of which scales as the square of the molecular surface density.…”

Section: Introductionmentioning

confidence: 99%

Determination of Bacterial Surface Charge Density Via Saturation of Adsorbed Ions

Wilhelm

Gh.

Chang

et al. 2020

Preprint

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Bacterial surface charge is a critical characteristic of the cell's interfacial physiology that influences how the cell interacts with the local environment. A direct, sensitive, and accurate experimental technique capable of quantifying bacterial surface charge is needed to better understand molecular adaptations in interfacial physiology in response to environmental changes. We introduce here the method of second harmonic light scattering (SHS) which is capable of detecting the number of molecular ions adsorbed as counter charges on the exterior bacterial surface, thereby providing a measure of the surface charge. In this first demonstration, we detect the small molecular cation, malachite green, electrostatically adsorbed on the surface of representative strains of Gram-positive and Gram-negative bacteria. Surprisingly, the SHS deduced molecular transport rates through the different cellular ultra-structures are revealed to be nearly identical. However, the adsorption saturation densities on the exterior surfaces of the two bacteria were shown to be characteristically distinct. The negative charge density of the lipopolysaccharide coated outer surface of Gram-negative E. coli (8.7±1.7 nm-2) was deduced to be seven times larger than that of the protein surface layer of Gram-positive L. rhamnosus (1.2±0.2 nm-2). The feasibility of SHS deduced bacterial surface charge density for Gram-type differentiation is presented.

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Adsorption and transport of charged vs. neutral hydrophobic molecules at the membrane of murine erythroleukemia (MEL) cells

Cited by 45 publications

References 52 publications

Influence of Solvent on Dye‐Sensitized Solar Cell Efficiency: What is so Special About Acetonitrile?

Influence of Solvent on Dye‐Sensitized Solar Cell Efficiency: What is so Special About Acetonitrile?

Molecule‐Membrane Interactions in Biological Cells Studied with Second Harmonic Light Scattering

Determination of Bacterial Surface Charge Density Via Saturation of Adsorbed Ions

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