Gaston, J. | Search bioRxiv

bioRxiv2025

The effect of PEGylation on surface tethering of liposomes via DNA nanotechnology.

Polyethylene glycol (PEG) is widely used in liposome formulation due to its blocking properties and ability to prolong circulation in vivo, to create biomimetic liposomes and drug delivery devices. Similarly, membrane-embedded DNA nanotechnology is increasingly used to modulate cellular behaviour and communication. However, there is a gap in knowledge in how PEG-lipid formulations can be optimised for both liposome properties and control of selective DNA hybridisation. To address this, we systematically investigated the effect of liposome PEG content on DNA mediated tethering of liposomes to glass surfaces. We formulated liposomes of two different lipid compositions (DOPE/DOPC or DPhPC), with varying amounts of PEGylated lipid (0-50%). We measured the effect of increased PEG content on liposome size and polydispersity through dynamic light scattering (DLS). Small amounts of PEG (0-20%) introduced repulsive forces that reduced size, while large amounts of PEG (30-50%) increased polydispersity. PEG-liposomes were then decorated with cholesterol-DNA strands and labelled with either intercalating lipid dyes or fluorescently labelled lipids. Binding to surfaces via complementary DNA strands was quantified using total internal reflection fluorescence (TIRF) microscopy. We found that PEGylation of DNA-liposomes could either block or enhance surface binding, depending on the amount of PEG. DNA-liposomes with reduced surface binding included DPhPC/DiD with 10% or 20% PEG-lipid. In contrast, DNA-liposome surface binding increased for DOPE/DOPC/DiD with increasing PEG%. This study highlights that while PEG can act to stabilise liposome formulations, its ability to block specific DNA binding interactions on membranes is variable and dependent on membrane composition. Table of contents figure O_FIG O_LINKSMALLFIG WIDTH=197 HEIGHT=200 SRC="FIGDIR/small/663613v1_ufig1.gif" ALT="Figure 1"> View larger version (55K): org.highwire.dtl.DTLVardef@183b215org.highwire.dtl.DTLVardef@1208fd6org.highwire.dtl.DTLVardef@c343ccorg.highwire.dtl.DTLVardef@1982f80_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗

bioRxiv2020

Evolution and adaptation of Pseudomonas aeruginosa in the paranasal sinuses of people with cystic fibrosis

People with the genetic disorder cystic fibrosis (CF) harbor lifelong respiratory infections, with morbidity and mortality frequently linked to chronic lung infections dominated by the opportunistically pathogenic bacterium Pseudomonas aeruginosa. During chronic CF lung infections, a single clone of P. aeruginosa can persist for decades and dominate end-stage CF lung disease due to its propensity to adaptively evolve to the respiratory environment, a process termed "pathoadaptation". Chronic rhinosinusitis (CRS), chronic inflammation and infection of the sinonasal space, is highly prevalent in CF and the sinuses may serve as the first site in the respiratory tract to become colonized by bacteria that then proceed to seed lung infections. We identified three evolutionary genetic routes by which P. aeruginosa evolves in the sinuses of people with CF, including through the evolution of mutator lineages and proliferative insertion sequences and culminating in early genomic signatures of host-restriction. Our findings raise the question of whether a significant portion of the pathoadaptive phenotypes previously thought to have evolved in response to selective pressures in the CF lungs may have first arisen in the sinuses and underscore the link between sinonasal and lung disease in CF. Graphical abstract and highlightsO_LIPseudomonas aeruginosa undergoes adaptive evolution in the sinuses of people with CF C_LIO_LIOver time, pathoadapted strains display early signatures of genome degradation consistent with recent host restriction C_LIO_LIMutations previously thought to occur in CF lungs may have first evolved in sinuses C_LI O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/359844v1_ufig1.gif" ALT="Figure 1"> View larger version (50K): org.highwire.dtl.DTLVardef@13b36aborg.highwire.dtl.DTLVardef@8230e1org.highwire.dtl.DTLVardef@1570c3eorg.highwire.dtl.DTLVardef@1e4e530_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗