Polysorbate-stabilized solid lipid nanoparticles as colloidal carriers for intravenous targeting of drugs to the brain: comparison of plasma protein adsorption patterns.

Plasma proteins enriched on the surface of drug-delivery-purpose nanoparticles are regarded as key factors for determination of in vivo organ distribution after intravenous injection. Polysorbate 80-coated polybutylcyanoacrylate (PBCA) nanoparticles, preferentially adsorbing apolipoprotein E (apoE) on their surface, have previously been considered to deliver various drugs to the brain. In the present study, in vivo well tolerable solid lipid nanoparticles (SLN) using different types of polysorbates as stabilizers were produced. The influence of the different surfactants on in vitro adsorption of human plasma proteins was investigated using two-dimensional polyacrylamide gel electrophoresis (2-DE). Possible correlations of different amounts of adsorbed apoE to the hydrophilic-lipophilic balance (HLB) of the polysorbates are shown and discussed. Apolipoprotein C-II, albumin and immunoglobulin G, which are also decisive plasma proteins with regard to site-specific drug delivery of intravenously injected carriers to the brain, are compared with regard to adsorption. Moreover, certain similarities to the plasma protein adsorption patterns of previously analysed brain-specific PBCA nanoparticles could be detected. Despite some differences in adsorption behavior of proteins on the surface of polysorbate-stabilized SLN and PBCA nanoparticles, we conclude that in both cases polysorbate 80 might have the highest potential to deliver drugs to the brain.

Protein adsorption patterns on poloxamer- and poloxamine-stabilized solid lipid nanoparticles (SLN).

Solid lipid nanoparticles (SLN) were produced using a full range of poloxamer polymers and poloxamine 908 for stabilization. The protein adsorption pattern acquired on the surface of these particles after intravenous injection is the key factor determining the organ distribution. Two-dimensional polyacrylamide gel electrophoresis (2-DE) was employed for determination of particle interactions with human plasma proteins. The objective of this study was to investigate changes in the plasma protein adsorption patterns in the course of variation of the polymers stabilizing the SLN. Considerable differences in the protein adsorption with regard to preferential adsorbed proteins were detected for the different stabilizers. Possible correlations between the polyethylene oxide (PEO) chain length and the adsorption of various proteins (first of all apolipoproteins) are shown and discussed. Besides the study of protein adsorption patterns, the total protein mass adsorbed to the SLN was also evaluated using the bicinchoninic acid (BCA)-protein assay. The knowledge concerning the interactions of proteins and nanoparticles can be used for a rational development of particulate drug carriers. Based on the findings presented in this paper, we anticipate that the in vivo well-tolerable SLN are a promising site-specific drug delivery system for intravenous injection.

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.

Plasma protein adsorption of Tween 80- and poloxamer 188-stabilized solid lipid nanoparticles.

The plasma proteins adsorbing onto intravenously injected carriers are considered to be crucial factors determining the organ distribution. Plasma protein adsorption patterns were analyzed on solid lipid nanoparticles (SLN) stabilized with Tween 80 or stabilized with poloxamer 188. The binding patterns were determined by applying two different sample preparation methods, i.e. removal of the SLN from the plasma by (a) centrifugation and (b) gel filtration to assess, if the separation method has an effect on the patterns obtained. The Tween 80-modified SLN adsorbed the major plasma proteins known from particles with blood-brain barrier specificity. Poloxamer 188-surface modified SLN adsorbed the proteins known from model particles that exhibit prolonged circulation time in the blood. It is concluded that the biodegradable SLN stabilized with Tween 80 can potentially be used as drug carriers to the blood-brain barrier having a relatively long residence time in the blood stream. For the poloxamer 188-stabilized SLN a relatively long resistance time in the blood is predicted leading to potential accumulation in the bone marrow when looking at the distinct CII/CIII adsorption.