Interaction particle-cell

No more than one particle may occupy a cell, and only nearest-neighbour cells that are both occupied mteract with energy -c. Otherwise the energy of interactions between cells is zero. The total energy for a given set of occupation numbers ] = (n, of the cells is then... 

PEG is hydrophilic and is widely used in biological research because it protects surfaces from interacting with cells or proteins. Thus, coated particles may result in increased blood circulation time. For their preparation, 10-mg magnetite particles were dispersed in 1.0 mU of deoxygenated water by sonication for 30 min. The aqueous dispersion of MNPs was dissolved in the aqueous cores of reverse micelles... 

In many cases the target protein is bound to membranes or particles or is aggregated as a consequence of its hydrophobic characteristics. In these cases, detergents and chaotropic agents can be used to weaken these interactions during cell disruption and extraction steps. The detergent performance is highly dependent on pH and temperature. 

The rate of deposition of particles onto a surface, in the presence of London, double-layer, and gravitational forces, is calculated in terms of the energy of interaction between cell and surface by assuming that Brownian motion over a potential energy barrier is the rate-determining step of the... 

The use of nanosilica particles as drug carriers raises questions concerning the nature of forces controlling the adsorption interaction of cells with Si02 nanoparticles.15 The average diameter of human erythrocytes is 7500 nm16 while typical dimensions of silica nanoparticles with specific area of 200 to 300 m2/g commonly used for water dispersions are from 20 to 10 nm, with dissipation of 4 to 17 nm (within a 90 per cent interval).2,8... 

The BBB intimately interacts with cells and their secretions that are in both the CNS and periphery. Some neuroimmune substances, exemplified by cytokines, can cross the BBB directly and also have direct effects on the BBB. The BBB is itself a source of neuroimmune substances and can receive signals from one side, for example the brain side, and release substances in response to that signal from its other side. The passage of immune cells across the BBB is a highly regulated event as is the passage of viruses and viral particles. Overall, the BBB is an important component of the neuroimmune axis and the only component, v hich is simultaneously physically in both the peripheral and central compartments of the neuroimmune system. 

The concept of direct attack mechanisms as direct contact phenomena requiring intimate physical contact between the mineral surface and the organism requires some precise definition. Vanselow (1976) has thrown some light on the possible physical interactions between cells and minerals in studies on the effects of dilution on the rates of oxygen uptake by T. ferrooxidans strains in the presence of synthetic covellite. The dilution of a slurry will lower the rate of copper sulfide oxidation per unit volume, and the relationship between the dilution factor, and the factor by which the oxidation rate is lowered, will depend upon the nature of the physical interaction between the cells and the mineral particles. Three principal situations were postulated, namely, that in which the oxidation was carried out by cells... 

A possible explanation was that the proton sponge effect, as discussed later, may be more efficient with larger complexes. Larger particles may also sediment to interact with cells more readily under in vitro culture conditions... 

Blank F, Rothen-Rutishauser BM, Schurch S, Gehr P (2006) An optimized in vitro model of the respiratory tract wall to study particle cell interactions. J Aerosol Med 19(3) 392 405... 

When talking about the NM dose, one has to make a distinction between three dose metrics (1) the administered dose (particle mass, number, or surface area administered per volume media at the onset of an experiment), (2) the delivered dose (particle mass, number, or surface area to reach the cell monolayer via diffusion and sedimentation over the duration of an experiment), and (3) the cellular dose (particle mass, number, or surface area internalized by the cells during the experiment). The determination of the cellular and delivered dose of NMs is essential for accurate interpretation of results derived from in vitro particle-cell interaction studies (e.g., particle uptake, cytotoxicity, biokinetic studies) [36], Using two different cell culture configurations, upright and inverted, Cho et al. [37] have recendy shown that the uptake of NPs is gready sensitive to the position in which cells are cultured and strongly... 

The process of PEGylation involves covalent attachment of PEG chains to the hydrophobic surface of the particles. PEGylation clearly changes the nature of the surface, turning often a very hydrophobic nanoparticle surface into a hydrophilic one, forming a protective layer, which is a barrier to flocculation and perhaps interaction with cell surfaces. This effect of PEG depends on its chain length (118). PEG 5000 has a greater effect than PEG 2000 or PEG 750 as predicted by calculations of enthalpic and... 

This multipole expansion is only valid if the separation between the interacting particles (be they atoms, molecules or cells) is larger than the sum of the radii of convergence of the multipoles. In the cell multipole method, the multipole expansion is used for interactions that are more than one cell distance away. For interactions that are within one cell distance the usual atomic pairwise interaction method is employed. 

The labeling of nanoparticles with fluorescent dyes allows one to use them as markers in biomedical appUcations. One possibility is to immobilize the fluorescent dyes physically or chemically on the particle s surface (e.g. FITC-dextran [29]). However, either desorption can occur, or the surface is changed that much that the biological response (cell uptake, toxicity) is significantly modified or even totally hindered. Therefore, an incorporation of hydrophobic dyes into the polymeric nanoparticles leads to marker systems where only the polymer and the highly variable surface functionaUty are the relevant factors for particle-cell interactions. 

The construction of LbL multilayer films of biomaterials on colloid particles is of particular interest in applications where a microscopic contact is essential, such as protein interaction and cell communication, and where high surface area is desirable, such as in catalysis. For example, enzyme LbLs on particle surfaces are useful for biorelated catalysis since microscopic objects of higher surface area can potentially yield higher enzymatic reaction efficiencies than their planar film counterparts. If the LbL assembly is conducted on microparticles with certain functions, we can... 

Chemical modifications by derivitizing the surfaces of mineral fiber silicates have revealed alterations in reactivity in in vitro cell toxicity studies, suggesting a multifactorial character of particle/cell interactions [171]. In addition, the adsorption of bovine serum albumin onto asbestos fibers has been shown by infrared spectroscopy and NMR to be mediated by O—H—N hydrogen bonds [172]. In view of the various hypotheses put forward in the bulk biochemical studies and the apparent surface-oriented origins of these reactions, it is important to examine the features of the silicate/cell interfaces and surfaces. Herein we present a typical case of the interaction between a related alumino-silicate (i.e., cummingtonite) and bioorganic cell interaction. 

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