Characterization of cross-linked gelatin nanoparticles by electrophoretic techniques in the liquid and the gas phase.

Biodegradable nanoparticles (NPs) and hence e.g. NPs prepared from glutaraldehyde crosslinked gelatin (gelatin NPs) are lately receiving increased attention in various fields like pharmaceutical technology and nutraceutics as biocompatible carriers for hardly water soluble drugs, molecules intended for sustained release or targeted transport. However, in vivo application of such materials requires a thoroughly characterization of corresponding particles. In a previous manuscript we demonstrated the applicability of chip electrophoresis for the separation of gelatin NPs from NP building blocks. Following our previous results we intensified our efforts in the characterization of gelatin NPs by electrophoresis in the liquid (capillary and chip format) and the gas phase (gas phase electrophoretic mobility molecular analysis, GEMMA). In doing so, we demonstrated differences between nominally comparable (from the concentration of initially employed material for crosslinking) gelatin NP preparation batches concerning (i) the amount of obtained NPs, (ii) the degree of NP crosslinking, (iii) the amount of NP building blocks present within samples and (iv) the electrophoretic mobility diameter of NPs. Differences were even more pronounced when NP preparations from batches with different content of initially employed gelatin were compared. Additionally, we compared three setups for the removal of low molecular weight components from samples after fluorescence labeling of NPs. In overall, the combination of the three employed analytical methods for gelatin NP characterization - CE in the capillary and the chip format as well as GEMMA - allows a more thoroughly characterization of NP containing samples.