Alternative sample preparation prior to two-dimensional electrophoresis protein analysis on solid lipid nanoparticles

The proteins adsorbing onto the surface of intravenously injected drug carriers are regarded as a key factor determining the organ distribution. Depending on the particle surface properties, certain proteins will be preferentially adsorbed, leading to the adherence of the particle to cells with the appropriate receptor. Therefore, the knowledge of the protein adsorption pattern and the correlation to in vivo behavior opens the perspective for the development of intravenous colloidal carriers for drug targeting. After incubation in plasma, the adsorbed proteins were analyzed using two-dimensional polyacrylamide gel electrophoresesis (2-D PAGE, 2-DE). The purpose of the present study was to develop an alternative separation method to separate solid lipid nanoparticles (SLN) carriers from plasma by gel filtration prior to 2-D PAGE. Via the specific absorption coefficients and a two-equation system, elution fractions were identified being practically plasma-free. This allows protein analysis on SLN which are typically in density too close to the density value of water to be separated by the standard centrifugation method. The SLN used for establishing the gel filtration were prepared in a way that they had a sufficiently low density to be additionally separated by centrifugation. The adsorption patterns obtained after separation with both methods were qualitatively and quantitatively identical, showing the suitability of the gel filtration.