774 research outputs found
On the adhesion of particles to a cell layer under flow
The non-specific adhesion of spherical particles to a cell substrate is
analyzed in a parallel plate flow chamber, addressing the effect of the
particle size. Differently from other experiments, the total volume of the
injected particles has been fixed, rather than the total number of particles,
as the diameter d of the particles is changed from 500 nm up to 10 m. From
the analysis of the experimental data, simple and instructive scaling adhesion
laws have been derived showing that (i) the number of particles adherent to the
cell layer per unit surface decreases with the size of the particle as d^(-1.7)
; and consequently (ii) the volume of the particles adherent per unit surface
increases with the size of the particles as d^(+1.3). These results are of
importance in the "rational design" of nanoparticles for drug delivery and
biomedical imaging.Comment: Submitted on behalf of TIMA Editions
(http://irevues.inist.fr/tima-editions
Particle compositions with a pre-selected cell internalization mode
A method of formulating a particle composition having a pre-selected cell internalization mode involves selecting a target cell having surface receptors and obtaining particles that have i) surface moieties, that have an affinity for or are capable of binding to the surface receptors of the cell and ii) a preselected shape, where a surface distribution of the surface moieties on the particles and the shape of the particles are effective for the pre-selected cell internalization mode
The transport of nanoparticles in blood vessels: the effect of vessel permeability and blood rheology
The longitudinal transport of nanoparticles in blood vessels has been analyzed with blood described as a Casson fluid. Starting from the celebrated Taylor and Aris theory, an explicit expression has been derived for the effective longitudinal diffusion (Deff) depending non-linearly on the rheological parameter xi(c), the ratio between the plug and the vessel radii; and on the permeability parameters pi and omega, related to the hydraulic conductivity and pressure drop across the vessel wall, respectively. An increase of xi(c) or pi has the effect of reducing Deff, and thus both the rheology of blood and the permeability of the vessels may constitute a physiological barrier to the intravascular delivery of nanoparticles
Unraveling the vascular fate of deformable circulating tumor cells via a hierarchical computational model
Distant spreading of primary lesions is modulated by the vascular dynamics of
circulating tumor cells (CTCs) and their ability to establish metastatic
niches. While the mechanisms regulating CTC homing in specific tissues are yet
to be elucidated, it is well documented that CTCs possess different size,
biological properties and deformability. A computational model is presented to
predict the vascular transport and adhesion of CTCs in whole blood. A
Lattice-Boltzmann method, which is employed to solve the Navier-Stokes equation
for the plasma flow, is coupled with an Immersed Boundary Method. The vascular
dynamics of a CTC is assessed in large and small microcapillaries. The CTC
shear modulus k ctc is varied returning CTCs that are stiffer, softer and
equally deformable as compared to RBCs. In large microcapillaries, soft CTCs
behave similarly to RBCs and move away from the vessel walls; whereas rigid
CTCs are pushed laterally by the fast moving RBCs and interact with the vessel
walls. Three adhesion behaviors are observed, firm adhesion, rolling and
crawling over the vessel walls, depending on the CTC stiffness. On the
contrary, in small microcapillaries, rigid CTCs are pushed downstream by a
compact train of RBCs and cannot establish any firm interaction with the vessel
walls; whereas soft CTCs are squeezed between the vessel wall and the RBC train
and rapidly establish firm adhesion. These findings document the relevance of
cell deformability in CTC vascular adhesion and provide insights on the
mechanisms regulating metastasis formation in different vascular districts
Unraveling the Vascular Fate of Deformable Circulating Tumor Cells Via a Hierarchical Computational Model
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