Rheological examination of erythrocyte aggregation in the presence of lipid-based fine particles

Abstract

The development of lipid-based fine particles as potential drug carriers requires a detailed investigation of the possible effects of these carriers on the rheological properties of blood. In this study, we investigated the influence of dynamic conditions on aggregate formation and stability in dispersions of lipid-based fine particles in whole blood under in vitro conditions. The rheological parameters of two concentrations of liposome dispersion and two concentrations of lipid emulsion in blood were examined. A micro-rheological model of aggregating dispersions is proposed in which the apparent viscosity is estimated as the sum of the hydrodynamic and structural parts which are correlated with system structural ordering in the flow. The dynamics of structural ordering of the aggregating system an considered by examining the evolution of the state of the system in phase space depending on the shear rate. The addition of lipid-based particles induced aggregate formation in the blood, which was more pronounced at higher concentrations of lipid-based fine particles. Furthermore, larger and more stable aggregates are formed in liposome dispersions as compared to lipid emulsions in blood.

Razvoj lipidnih čestica za primenu kao nosači lekova zahteva dodatno ispitivanje efekata koje ovi nosači imaju na reološke osobine krvi. U ovoj studiji je ispitivan uticaj dinamičkih uslova na formiranje agregata l njihovu stabilnost u disperzijama lipidnih čestica u krvi, u uslovima in vitro. Određivani su reološki parametri za dve koncentracije lipozoma i lipidne emulzije u krvi. U radu je predložen mikro-reološki model za agregirajuće disperzije kod koga se prividna viskoznost izražava kao suma hidrodinamičkog i strukturnog dela koji se povezuju sa strukturnim uređivanjem u toku. Razmatrana je dinamika strukturnog uređivanja agregišućeg sistema ispitivanjem evolucije sistema u faznom prostoru u zavisnosti od brzine smicanja. Dodavanje lipidnih čestica krvi izazivaju formiranje agregata, što je više izraženo pri većim koncentracijama lipidnih čestica. Veći i znatno stabilniji agregati se formiraju u disperzijama lipozoma nego u disperzijama lipidnih emulzija.