We use diamond nanoparticles (DNPs) wrapped in the cationic polyelectrolyte poly(allylamine) hydrochloride (PAH) and bilayers composed of either pure DOPC or a mixture of DOPC/DOPG to investigate the influence of membrane phospholipid composition and net surface charge on nanoparticle-membrane interactions and the extent of nanoparticle adhesion to supported phospholipid bilayers. Our results show that in all cases electrostatic attractions between the negatively charged bilayer and cationic PAH-DNP were responsible for the initial attachment of particles, and the lateral electrostatic repulsion between adsorbed particles on the bilayer surface determined the final extent of PAH-DNP attachment. Upon attachment, NPs attract lipids by the contact ion pairing between the ammonium groups on PAH and phosphate and glycerol groups on the lipids and acquire a lipid corona. Lipid corona formation on the PAH-DNP reduces the effective charge density of the particle and is in fact a key factor determining the final extent of NP attachment to the bilayer. Incorporation of DOPG to the bilayer leads to a decrease in efficiency and final extent of attachment compared to DOPC alone. The reduction in PAH-DNP attachment in the presence of DOPG is attributed to the adsorption of free PAH in equilibrium with bound PAH in the nanoparticle solution, thus reducing electrostatic attraction between PAH-DNPs and SLBs. This leads to an increase in hydrogen bonding interactions between lipid headgroups that limits extraction of phospholipids from the bilayer by PAH-DNP, lessening the reduction in interparticle repulsion achieved by acquisition of a lipid corona. Our results indicate that the inclusion of charged phospholipids in SLBs changes bilayer rigidity and stability and hinders the attachment of PAH-DNPs by preventing lipid extraction from the bilayer.
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Lipid bilayer disruption induced by amphiphilic Janus nanoparticles: the non-monotonic effect of charged lipids
In this study, we report the complex effects of charged lipids on the interaction between amphiphilic Janus nanoparticles and lipid bilayers. Janus nanoparticles are cationic on one hemisphere and hydrophobic on the other. We show that the nanoparticles, beyond threshold concentrations, induce holes in both cationic and anionic lipid bilayers mainly driven by hydrophobic interactions. However, the formation of these defects is non-monotonically dependent on ionic lipid composition. The electrostatic attraction between the particles and anionic lipid bilayers enhances particle adsorption and lowers the particle concentration threshold for defect initiation, but leads to more localized membrane disruption. Electrostatic repulsion leads to reduced particle adsorption on cationic bilayers and extensive defect formation that peaks at intermediate contents of cationic lipids. This study elucidates the significant role lipid composition plays in influencing how amphiphilic Janus nanoparticles interact with and perturb lipid membranes.
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- Award ID(s):
- 1705384
- NSF-PAR ID:
- 10104863
- Date Published:
- Journal Name:
- Soft Matter
- Volume:
- 15
- Issue:
- 11
- ISSN:
- 1744-683X
- Page Range / eLocation ID:
- 2373 to 2380
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Graphical Abstract
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/c8sm02525h
