Distribution of Fullerene Nanoparticles between Water and Solid Supported Lipid Membranes: Thermodynamics and Effects of Membrane Composition on Distribution

Abstract

The distribution coefficient (Klipw) of fullerene between solid supported lipid membranes (SSLMs) and water was examined using different lipid membrane compositions. Klipw of fullerene was significantly higher with a cationic lipid membrane compared to that with a zwitterionic or anionic lipid membrane, potentially due to the strong interactions between negative fullerene dispersions and positive lipid head groups. The higher Klipw for fullerene distribution to ternary lipid mixture membranes was attributed to an increase in the interfacial surface area of the lipid membrane resulting from phase separation. These results imply that lipid composition can be a critical factor that affects bioconcentration of fullerene. Distribution of fullerene into zwitterionic unsaturated lipid membranes was dominated by the entropy contribution (ΔS) and the process was endothermic (ΔH > 0). This result contrasts the partitioning thermodynamics of highly and moderately hydrophobic chemicals indicating that the lipid-water distribution mechanism of fullerene may be different from that of molecular level chemicals. Potential mechanisms for the distribution of fullerene that may explain these differences include adsorption on the lipid membrane surfaces and partitioning into the center of lipid membranes (i.e., absorption).

Dependence of fullerene aggregation on lipid saturation due to a balance between entropy and enthalpy

“…Fullerenes (C60) are nanoparticles that are soluble in various organic solvents 24–26 and their strong hydrophobicity can be used to assist hydrophilic drugs in translocation across lipid membranes 14,27–29 . On the other hand, in polar solvents such as water, fullerenes form aggregates with the average diameter typically ranging from tens to few hundreds of nanometers 27,30–32 . We have previously shown how fullerenes aggregate in water and how such clusters can passively translocate into lipid membranes 14 .…”

Effects of fullerene on lipid bilayers displaying different liquid ordering: a coarse-grained molecular dynamics study

“…Simple and reproducible systems, such as model lipid membranes, are appropriate to elucidate the physical principles governing these complex interactions. A few experimental studies have been performed on the distribution of fullerene between aqueous solutions and simple solid supported lipid membranes [18,19].…”

“…Global descriptors such as the water/lipid partition coefficient clearly evidence the ability of fullerene to be preferentially placed in the lipid phase [18,19], thus confirming its potential bioaccumulation in biological cell membranes. The use of small lipid vesicles as biocompatible platforms for the dispersion of fullerene particles has been also attempted [20,21].…”

Quantification of C60-induced membrane disruption using a quartz crystal microbalance

“…They penetrate into the interior of membranes and then remain encased in the hydrophobic lipid tails revealed by both molecular dynamic simulations and experimental conrmation. 13,14,66,67 C 60 forms stable aggregates in water. Transferring one C 60 from the aggregate into bulk water is highly unfavorable, but removing one C 60 from a large aggregate and placing it into the lipid bilayer interior is favorable.…”