Adsorption of Nanoceria by Phosphocholine Liposomes

Abstract

Nanoceria (CeO2 nanoparticle) possesses a number of enzyme-like activities. In particular, it scavenges reactive oxygen species (ROS) leading in vitro and in vivo anti-oxidation studies. An important aspect of fundamental physical understanding is its interaction with lipid membranes, the man component of the cell membrane. In this work, adsorption of nanoceria onto phosphocholine (PC) liposomes was performed. PC lipids are the main constituent of the cell outer membrane. Using fluorescence quenching assay, nanoceria adsorption isotherm was determined at various pH's and ionic strengths. A non-Langmuir isotherm occurred at pH 4.0 due to lateral electrostatic repulsion among adsorbed cationic nanoceria. The phosphate group in the PC lipid is mainly responsible for the interaction, and adsorbed nanoceria can be displaced by free inorganic phosphate. The tendency of the system to form large aggregates is a function of pH and the concentration of nanoceria, attributable to nanoceria being positively charged at pH 4 and neural at physiological pH. Calcein leakage test indicates that nanoceria induces liposome leakage due to transient lipid phase transition, and cryo-TEM indicates that the overall shape of the liposome is retained although deformation is still observed. This study provides fundamental biointerfacial information at a molecular level regarding the interaction of nanoceria and model cell membranes.3

Green synthesis of nano-liposomes containing Bunium persicum and Trachyspermum ammi essential oils against Trichomonas vaginalis

“…A similar uptake pattern has been reported for calcein-loaded liposomes [44], as well as for hyaluronic acid-magnetic-loaded liposomes [45]. It has been reported that liposome can interact with cells by four mechanisms, including endocytosis, adsorption to the cell surface, transfer of liposomal lipids to the cell membrane and lipid-mediated fusion with the intracellular membranes, the main pathways for liposomal internalization [46,47,48]. Moreover, factors such as size due to aggregation, surface charge and surface a nity seem to have a major impact on nanoparticle binding to the cell membrane and subsequent cell uptake [49].…”

Analytical High-resolution Electron Microscopy Reveals Organ-specific Nanoceria Bioprocessing

“…Furthermore, we show that available phosphate seems to limit the location where nanoneedles are formed (Figure 4) by inducing metal precipitation as Ce phosphate. Nanoceria may adsorb to the phosphate group of phosphocholine, a precursor to phosphatidylcholine, a major component of eukaryotic cell membranes (Liu and Liu 2016), which could contribute to the observed distribution of nanoceria around membrane-bound intracellular structures. Nanoceria has phosphatase mimetic activity, the ability to release terminal phosphate from nucleotides and related compounds (Janoš et al 2017), which may provide some of the phosphate groups seen in the Ce-phosphate nanoneedles.…”

Preparation, Characterization, and Preliminary In Vitro Testing of Nanoceria-Loaded Liposomes

“…A study of interaction between liposomes and nanoceria has been approached by Liu et al, who exploited phosphocoline-based liposomes as a model of the cell membrane, but focusing their investigations only on the interaction between nanoceria and biological membranes [ 38 ].…”