The margination propensity of spherical particles for vascular targeting in the microcirculation.

The propensity of circulating particles to drift laterally towards the vessel walls (margination) in the microcirculation has been experimentally studied using a parallel plate flow chamber. Fluorescent polystyrene particles, with a relative density to water of just 50 g/cm3comparable with that of liposomal or polymeric nanoparticles used in drug delivery and bio-imaging, have been used with a diameter spanning over three order of magnitudes from 50 nm up to 10 mum. The number n approximately s MathType@MTEF@5@5@+=feaagaart1ev2aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacPC6xNi=xH8viVGI8Gi=hEeeu0xXdbba9frFj0xb9qqpG0dXdb9aspeI8k8fiI+fsY=rqGqVepae9pg0db9vqaiVgFr0xfr=xfr=xc9adbaqaaeGaciGaaiaabeqaaeqabiWaaaGcbaGafmOvayLbaGaadaWgaaWcbaGaem4Camhabeaaaaa@2EB4@ of particles marginating per unit surface have been measured through confocal fluorescent microscopy for a horizontal chamber, and the corresponding total volume V approximately s MathType@MTEF@5@5@+=feaagaart1ev2aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacPC6xNi=xH8viVGI8Gi=hEeeu0xXdbba9frFj0xb9qqpG0dXdb9aspeI8k8fiI+fsY=rqGqVepae9pg0db9vqaiVgFr0xfr=xfr=xc9adbaqaaeGaciGaaiaabeqaaeqabiWaaaGcbaGafmOvayLbaGaadaWgaaWcbaGaem4Camhabeaaaaa@2EB4@ of particles has been calculated.

The effect of shape on the margination dynamics of non-neutrally buoyant particles in two-dimensional shear flows.

The margination dynamics of microparticles with different shapes has been analyzed within a laminar flow mimicking the hydrodynamic conditions in the microcirculation. Silica spherical particles, quasi-hemispherical and discoidal silicon particles have been perfused in a parallel plate flow chamber. The effect of the shape and density on their margination propensity has been investigated at different physiologically relevant shear rates S.

Flow chamber analysis of size effects in the adhesion of spherical particles.

The non-specific adhesion of spherical micro- and nano-particles to a cell substrate is investigated in a parallel plate flow chamber. Differently from prior in-vitro analyses, the total volume of the particles injected into the flow chamber is kept fixed whilst the particle diameter is changed in the range 0.5-10 microm.

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.