Blood components, electrostatic interaction

Fig. 7 Schematic model for the proposed drug delivery system consists of two components, a PLLA-h-PEG micelle conjugated to TAT and a pH-sensitive diblock polymer PSD-i-PEG. (a) At normal blood pH, the sulfonamide is negatively charged, and when mixed with the TAT micelle, it shields the TAT by electrostatic interaction. Only PEG is exposed to the outside, which could make the carrier long circulating (b) when the system experiences a decrease in pH (near tumor), sulfonamide loses charge and detaches, thus exposing TAT for interaction with tumor cells (adapted from Ref [199] with permission)...

Among cationic polymers, cationic polysaccharides secured an important position in this research area. Cationic polysaccharides most widely used for this purpose are chitosan, dextran, cyclodextrin (CD), pullulan and schizophyllan. These pol3aners act through the formation of an electrostatic complex, but they also create some problems like undesired interaction with blood components, low transfection efficiency and failure from endosomal escape, etc. Various modifications have been proposed to solve all these issues. 

In order to reduce the interaction of dextran with blood components, the negatively charged dextran sulfate (DS) was used to prepare polyelectrolyte complexes (PECs) together with cationic natural or synthetic polymers, such as chitosan or PEI. PECs can be synthesized by direct interaction of oppositely charged polyelectrolytes in solution. In PECs, the outer coat of dextran sulfate minimizes electrostatic interactions, while the inner posi-... 

The multicomponent biofluid blood consists, among other components, of proteins and cells and still represents a challenge for interaction studies with PEC particles. A comprehensive study on the interaction of complexes of PDMAEMA and either a crosslinked CHT or poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPSNa) with human blood from healthy volunteers was reported by Yancheva et al. [176]. Thereby, PDMAEMA complexed with CHT no longer caused inherent cytotoxicity compared with the uncomplexed state, but haemostatic activity was still present. However, PEC of PDMAEMA/PAMPSNa featured both low cytotoxicity and low haemostatic activity. The degree of PDMAEMA quatemization had an additional influence on both blood compatibility parameters. In particular, the authors claimed a higher interaction of samples containing higher quatemized PDMAEMA with the cell walls of blood cells (both red and white) because of electrostatic attraction to the anionic compounds of their cell membranes. 

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