Interfacial electrostatics of poly(vinylamine hydrochloride), poly(diallyldimethylammonium chloride), poly-<scp>l</scp>-lysine, and poly-<scp>l</scp>-arginine interacting with lipid bilayers

McGeachy, Alicia C.; Dalchand, Naomi; Caudill, Emily R.; Li, Tianzhe; Doğangün, Merve; Olenick, Laura L.; Chang, Hak; Pedersen, Joel A.; Geiger, Franz M.

doi:10.1039/c7cp07353d

Cited by 23 publications

(28 citation statements)

References 68 publications

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“…The SHG intensity from an initially negatively charged surface decreases upon cation adsorption, as the surface potential is rendered less negative, according to: E SHG ∝ A + BΦ 0 where, A and B contain the second- and third-order macroscopic susceptibility of the interface, respectively, and the applied oscillating electromagnetic field from the incident laser, all of which are assumed to remain constant throughout, and Φ 0 is . The SHG adsorption isotherms were generated and analyzed largely as described previously, 39 , 72 but employed the Hill model as discussed in the ESI. †…”

Section: Experimental Methodsmentioning

confidence: 99%

Counting charges on membrane-bound peptides

et al. 2018

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Quantifying the number of charges on peptides bound to interfaces requires reliable estimates of (i) surface coverage and (ii) surface charge, both of which are notoriously difficult parameters to obtain, especially at solid/water interfaces. Here, we report the thermodynamics and electrostatics governing the interactions of l-lysine and l-arginine octamers (Lys8 and Arg8) with supported lipid bilayers prepared.

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Section: Experimental Methodsmentioning

confidence: 99%

Counting charges on membrane-bound peptides

et al. 2018

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“…Figure 8 shows that when accounting for the positive charge present (the concentration of each respective polycation multiplied by the respective amount of repeat units), the experimental binding curves, and thus the binding constants, for all polycations surveyed were comparable, regardless of molecular weight or structure. 63 Reversibility studies were carried out by SHG spectroscopy in order to assess the extent of binding reversibility of the respective polycations ( Figure 9). All polycations aside from PDADMAC exhibit partial to full reversibility to the bilayers surveyed.…”

Section: Polycations Bind To Bilayers With Comparable ∆Gadsmentioning

confidence: 99%

Electrostatics, Hydrogen Bonding, and Molecular Structure at Polycation and Peptide:Lipid Membrane Interfaces

Dalchand

Cui

Geiger

2019

ACS Appl. Mater. Interfaces

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Polycation and peptide modified surfaces represent opportunities for developing potentially novel biocidal materials in a growing effort to combat bacterial resistance to traditional bactericides. It is well known that the positive charge of these compounds is crucial to their function in biofouling prevention and as antimicrobials, however, methods for quantifying the number of positive charges on surface-bound polycations and peptides are necessary in order to predict, control, and optimize the design and therefore, the utility of these compounds. This Spotlight on Applications reports on such an approach that combines second harmonic generation (SHG) spectroscopy, quartz crystal microbalance with dissipation monitoring (QCM-D), and atomistic simulations to obtain mechanistic insight into polycation-membrane interactions using supported lipid bilayers (SLBs) as our model system. We find that at high surface coverage, the large polycations we surveyed feature a considerably smaller percentage of ionization when compared to the smaller polycations and peptides. At these high charge densities, we suspect a pKa shift of the charged groups to lower charge-charge repulsion as well as the formation of a loop-like conformation such that less monomeric units form contact-ion pairs with the bilayer. Our sum frequency generation (SFG) spectroscopy results complement our understanding of the

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“…Interactions between polycations and anionic lipid membranes have been extensively investigated using experimental methods 8 , 9 as well as computer simulations. 10 , 11 In experiments, liposomes and supported lipid bilayers with lipid compositions mimicking those of biomembranes are commonly used as model membranes.…”

Section: Introductionmentioning

confidence: 99%

Polycation–Anionic Lipid Membrane Interactions

et al. 2020

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Natural or synthetic polycations are used as biocides or as drug/gene carriers. Understanding the interactions between these macromolecules and cell membranes at the molecular level is therefore of great importance for the design of effective polymer biocides or biocompatible polycation-based delivery systems. Until now, details of the processes at the interface between polycations and biological systems have not been fully recognized. In this study, we consider the effect of strong polycations with quaternary ammonium groups on the properties of anionic lipid membranes that we use as a model system for protein-free cell membranes. For this purpose, we employed experimental measurements and atomic-scale molecular dynamics (MD) simulations. MD simulations reveal that the polycations are strongly hydrated in the aqueous phase and do not lose the water shell after adsorption at the bilayer surface. As a result of strong hydration, the polymer chains reside at the phospholipid headgroup and do not penetrate to the acyl chain region. The polycation adsorption involves the formation of anionic lipid-rich domains, and the density of anionic lipids in these domains depends on the length of the polycation chain. We observed the accumulation of anionic lipids only in the leaflet interacting with the polymer, which leads to the formation of compositionally asymmetric domains. Asymmetric adsorption of the polycation on only one leaflet of the anionic membrane strongly affects the membrane properties in the polycation–membrane contact areas: (i) anionic lipid accumulates in the region near the adsorbed polymer, (ii) acyl chain ordering and lipid packing are reduced, which results in a decrease in the thickness of the bilayer, and (iii) polycation–anionic membrane interactions are strongly influenced by the presence and concentration of salt. Our results provide an atomic-scale description of the interactions of polycations with anionic lipid bilayers and are fully supported by the experimental data. The outcomes are important for understanding the correlation of the structure of polycations with their activity on biomembranes.

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Interfacial electrostatics of poly(vinylamine hydrochloride), poly(diallyldimethylammonium chloride), poly-l-lysine, and poly-l-arginine interacting with lipid bilayers

Cited by 23 publications

References 68 publications

Counting charges on membrane-bound peptides

Counting charges on membrane-bound peptides

Electrostatics, Hydrogen Bonding, and Molecular Structure at Polycation and Peptide:Lipid Membrane Interfaces

Polycation–Anionic Lipid Membrane Interactions

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