Abstract
Drug delivery by micro- and nano-carriers enables controlled transport of pharmaceuticals to targeted sites. Even though carrier fabrication has made much progress recently, the delivery including controlled particle distribution and adhesion within the body remains a great challenge. The adhesion of carriers is strongly affected by their margination properties (migration toward walls) in the microvasculature. To investigate margination characteristics of carriers of different shapes and sizes and to elucidate the relevant physical mechanisms, we employ mesoscopic hydrodynamic simulations of blood flow. Particle margination is studied for a wide range of hematocrit values, vessel sizes, and flow rates, using two- and three-dimensional models. The simulations show that the margination properties of particles improve with increasing carrier size. Spherical particles yield slightly better margination than ellipsoidal carriers; however, ellipsoidal particles exhibit a slower rotational dynamics near a wall favoring their adhesion. In conclusion, micron-sized ellipsoidal particles are favorable for drug delivery in comparison with sub-micron spherical particles.
Highlights
Theoretical Soft Matter and Biophysics, Institute of Complex Systems and Institute for Advanced Simulation, Forschungszentrum Julich, 52425 Julich, Germany
Particle margination is mediated by red blood cells (RBCs), which migrate to the vessel center[19] due to hydrodynamic interactions with the walls[20,21] leading to a RBC-free layer near the walls
Blood is modeled as a suspension of RBCs and micro- or nanoparticles, while blood flow is studied in idealized microvessels using simulations in 2D and 3D, see Fig. 1 and Methods section for details
Summary
To investigate margination characteristics of carriers of different shapes and sizes and to elucidate the relevant physical mechanisms, we employ mesoscopic hydrodynamic simulations of blood flow. The development of efficient strategies for the delivery of carriers, including their distribution in the organism following systemic administration[8] and their transport through biological barriers[8,9,10] (e.g., microvascular walls, interstitial space, and cell membranes), requires a much more detailed understanding of the relevant physical and biological mechanisms[2,8,11,12]. The cross-sectional distribution of microand nano-particles depends on several relevant parameters, which concern blood flow properties (such as flow rate, red blood cell deformability, and hematocrit – the volume fraction of red blood cells), vessel size, and particle characteristics (such as size, shape, and deformability). To better understand the adhesion potential of micro- and nano-particles, a quantitative description of particle margination under realistic blood flow conditions is required
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