Surface Coating Structure and Its Interaction with Cytochrome in EG-Coated Nanoparticles Varies with Surface Curvature.

The composition, orientation, and conformation of proteins in biomolecular coronas acquired by nanoparticles in biological media contribute to how they are identified by a cell. While numerous studies have investigated protein composition in biomolecular coronas, relatively little detail is known about how the nanoparticle surface influences the orientation and conformation of the proteins associated with them. We previously showed that the peripheral membrane protein cytochrome adopts preferred poses relative to negatively charged 3-mercaptopropionic acid (MPA)-gold nanoparticles (AuNPs).

Quantitative Mapping of Oxidative Stress Response to Lithium Cobalt Oxide Nanoparticles in Single Cells Using Multiplexed in Situ Gene Expression Analysis.

Engineered nanoparticles (NPs) can negatively impact biological systems through induced generation of reactive oxygen species (ROS). Overproduced ROS cause biochemical damage and hence need to be effectively buffered by a sophisticated cellular oxidative stress response system. How this complex cellular system, which consists of multiple enzymes, responds to NP-induced ROS is largely unknown.

Impact of lithiated cobalt oxide and phosphate nanoparticles on rainbow trout gill epithelial cells.

Metal oxide and phosphate nanoparticles (NPs) are ubiquitous in emerging applications, ranging from energy storage to catalysis. Cobalt-containing NPs are particularly important, where their widespread use raises questions about the relationship between composition, structure, and potential for environmental impacts. To address this gap, we investigated the effects of lithiated metal oxide and phosphate NPs on rainbow trout gill epithelial cells, a model for environmental exposure.

Peripheral Membrane Proteins Facilitate Nanoparticle Binding at Lipid Bilayer Interfaces.

Molecular understanding of the impact of nanomaterials on cell membranes is critical for the prediction of effects that span environmental exposures to nanoenabled therapies. Experimental and computational studies employing phospholipid bilayers as model systems for membranes have yielded important insights but lack the biomolecular complexity of actual membranes. Here, we increase model membrane complexity by incorporating the peripheral membrane protein cytochrome c and studying the interactions of the resulting membrane systems with two types of anionic nanoparticles.

Cascading Effects of Nanoparticle Coatings: Surface Functionalization Dictates the Assemblage of Complexed Proteins and Subsequent Interaction with Model Cell Membranes.

Interactions of functionalized nanomaterials with biological membranes are expected to be governed by not only nanoparticle physiochemical properties but also coatings or "coronas" of biomacromolecules acquired after immersion in biological fluids. Here we prepared a library of 4-5 nm gold nanoparticles (AuNPs) coated with either ω-functionalized thiols or polyelectrolyte wrappings to examine the influence of surface functional groups on the assemblage of proteins complexing the nanoparticles and its subsequent impact on attachment to model biological membranes. We find that the initial nanoparticle surface coating has a cascading effect on interactions with model cell membranes by determining the assemblage of complexing proteins, which in turn influences subsequent interaction with model biological membranes.

Resonantly Enhanced Nonlinear Optical Probes of Oxidized Multiwalled Carbon Nanotubes at Supported Lipid Bilayers.

With production of carbon nanotubes surpassing billions of tons per annum, concern about their potential interactions with biological systems is growing. Herein, we utilize second harmonic generation spectroscopy, sum frequency generation spectroscopy, and quartz crystal microbalance with dissipation monitoring to probe the interactions between oxidized multiwalled carbon nanotubes (O-MWCNTs) and supported lipid bilayers composed of phospholipids with phosphatidylcholine head groups as the dominant component. We quantify O-MWCNT attachment to supported lipid bilayers under biogeochemically relevant conditions and discern that the interactions occur without disrupting the structural integrity of the lipid bilayers for the systems probed.

Cells Respond to Distinct Nanoparticle Properties with Multiple Strategies As Revealed by Single-Cell RNA-Seq.

The impact of distinct nanoparticle (NP) properties on cellular response and ultimately human health is unclear. This gap is partially due to experimental difficulties in achieving uniform NP loads in the studied cells, creating heterogeneous populations with some cells "overloaded" while other cells are loaded with few or no NPs. Yet gene expression studies have been conducted in the population as a whole, identifying generic responses, while missing unique responses due to signal averaging across many cells, each carrying different loads.

Alteration of Membrane Compositional Asymmetry by LiCoO2 Nanosheets.

Given the projected massive presence of redox-active nanomaterials in the next generation of consumer electronics and electric vehicle batteries, they are likely to eventually come in contact with cell membranes, with biological consequences that are currently not known. Here, we present nonlinear optical studies showing that lithium nickel manganese cobalt oxide nanosheets carrying a negative ζ-potential have no discernible consequences for lipid alignment and interleaflet composition in supported lipid bilayers formed from zwitterionic and negatively charged lipids. In contrast, lithiated and delithiated LiCoO2 nanosheets having positive and neutral ζ-potentials, respectively, alter the compositional asymmetry of the two membrane leaflets, and bilayer asymmetry remains disturbed even after rinsing.

Lipopolysaccharide Density and Structure Govern the Extent and Distance of Nanoparticle Interaction with Actual and Model Bacterial Outer Membranes.

Design of nanomedicines and nanoparticle-based antimicrobial and antifouling formulations and assessment of the potential implications of nanoparticle release into the environment requires understanding nanoparticle interaction with bacterial surfaces. Here we demonstrate the electrostatically driven association of functionalized nanoparticles with lipopolysaccharides of Gram-negative bacterial outer membranes and find that lipopolysaccharide structure influences the extent and location of binding relative to the outer leaflet-solution interface. By manipulating the lipopolysaccharide content in Shewanella oneidensis outer membranes, we observed the electrostatically driven interaction of cationic gold nanoparticles with the lipopolysaccharide-containing leaflet.

Synthesis and detection of oxygen-18 labeled phosphate.

Phosphorus (P) has only one stable isotope and therefore tracking P dynamics in ecosystems and inferring sources of P loading to water bodies have been difficult. Researchers have recently employed the natural abundance of the ratio of (18)O/(16)O of phosphate to elucidate P dynamics. In addition, phosphate highly enriched in oxygen-18 also has potential to be an effective tool for tracking specific sources of P in the environment, but has so far been used sparingly, possibly due to unavailability of oxygen-18 labeled phosphate (OLP) and uncertainty in synthesis and detection.

Entry of protein toxins in polarized epithelial cells.

The action of a number of toxins used in the formation of immunotoxins was studied in polarized cells. Diphtheria toxin inhibited protein synthesis most efficiently when added to the basolateral side of the kidney cells, MDCK-I, MDBK and Pt K2, and the colon carcinoma cell Caco-2. Similar findings were made with Pseudomonas aeruginosa exotoxin A in MDCK-I, Pt K2, and Caco-2 cells, and with modeccin and volkensin in MDCK-I cells.

Effect of monensin on ricin and fluid phase transport in polarized MDCK cells.

The effect of monensin on endocytosis, transcytosis, recycling and transport to the Golgi apparatus in filter-grown Madin-Darby canine kidney (MDCK) cells was investigated using 125I-labeled ricin as a marker for membrane transport, and horseradish peroxidase (HRP) as a marker for fluid phase transport. Monensin (10 microM) stimulated transcytosis of both markers about 3-fold in the basolateral to apical direction. Transcytosis of HRP in the opposite direction, apical to basolateral, was reduced to approximately 50% of the control by monensin, whereas that of ricin was slightly increased.

Endocytosis, intracellular transport and transcytosis of the toxic protein ricin by a polarized epithelium.

The toxic plant protein ricin binds to both the apical and basolateral surface domains of MDCK (strain I) cells grown on polycarbonate filters. Endocytosis of 125I-labeled ricin was not only higher from the basolateral than from the apical surface--an observation which can be explained by the higher surface area of the basolateral surface--but it also appeared to be more efficient when measured as a percentage of total cell-associated ricin. Monovalent ricin-horseradish peroxidase (Ri-HRP), which is known to behave like native ricin with respect to intracellular transport, also binds to, and is taken up from, both the apical and the basolateral surfaces.

Rabbit cardiomyopathy associated with a virus antigenically related to human coronavirus strain 229E.

A new disease of rabbits is described. Following an acute febrile course, animals die or recover by the 11th day postinoculation. The characteristic pathologic finding is multifocal myocardial degeneration and necrosis.