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Structural changes in lipid mesophases due to intercalation of dendritic polymer nanoparticles: Swollen lamellae, suppressed curvature, and augmented structural disorder

DOI: 10.1016/j.actbio.2019.12.036 DOI Help

Authors: Laura J. Fox (University of Bristol) , Lauren Matthews (University of Bristol) , Holly Stockdale (University of Bristol) , Supakit Pichai (University of Bristol) , Tim Snow (Diamond Light Source) , Robert M. Richardson (University of Bristol) , Wuge H. Briscoe (University of Bristol)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acta Biomaterialia

State: Published (Approved)
Published: January 2020
Diamond Proposal Number(s): 20365

Abstract: Understanding interactions between nanoparticles and model membranes is relevant to functional nano-composites and the fundamentals of nanotoxicity. In this study, the effect of polyamidoamine (PAMAM) dendrimers as model nanoparticles (NP) on the mesophase behaviour of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) has been investigated using high-pressure small-angle X-ray scattering (HP-SAXS). The pressure-temperature ( p−T ) diagrams for POPE mesophases in excess water were obtained in the absence and presence of G2 and G4 polyamidoamine (PAMAM) dendrimers (29 Å and 45 Å in diameter, respectively) at varying NP-lipid number ratio (ν = 0.0002-0.02) over the pressure range p = 1-3000 bar and temperature range T = 20–80°C. The p−T phase diagram of POPE exhibited the Lβ, Lα and HII phases. Complete analysis of the phase diagrams, including the relative area pervaded by different phases, phase transition temperatures (Tt) and pressures (pt), the lattice parameters (d-spacing), the pressure-dependence of d-spacing (Δd/Δp), and the structural ordering in the mesophase as gauged by the Scherrer coherence length (L) permitted insights into the size- and concentration-dependent interactions between the dendrimers and the model membrane system. The addition of dendrimers changed the phase transition pressure and temperature and resulted in the emergence of highly swollen lamellar phases, dubbed Lβ-den and Lα-den. G4 PAMAM dendrimers at the highest concentration ν = 0.02 suppressed the formation of the HII phase within the temperature range studied, whereas the addition of G2 PAMAM dendrimers at the same concentration promoted an extended mixed lamellar region in which Lα and Lβ phases coexisted.

Journal Keywords: Lipid Mesophases; PAMAM dendrimers; Nanoparticles; High-Pressure Small Angle X-ray Scattering; Nanotoxicity; Membrane Models; Cellular Uptake; Endocytosis; Synchrotron Scattering

Subject Areas: Biology and Bio-materials

Instruments: I22-Small angle scattering & Diffraction

Added On: 08/01/2020 09:29

Discipline Tags:

Biomaterials Materials Science Nanoscience/Nanotechnology Life Sciences & Biotech

Technical Tags:

Scattering Small Angle X-ray Scattering (SAXS)