Affiliations: Department of Physics and Biophysics, Medical Faculty, Medical University Sofia, Sofia, Bulgaria | Institute of Medical Physics and Biophysics, University Leipzig, Leipzig, Germany
Note: [] Corresponding author: Svetoslav Jovtchev, Dept. Physics and Biophysics, Medical Faculty, Medical University Sofia, Street Zdrave 2, 1431 Sofia, Bulgaria. Tel.: +359 2 9172 696; E-mail: jovchev@medfac.acad.bg.
Abstract: Covalent binding of poly(ethylene glycol), abbreviated as PEG, to red blood cells (RBC) surface leads to masking of the RBC blood group determinants and the PEG layer on the cell surface sterically hinders RBC–RBC and RBC–plasma protein interactions. We cross-linked linear mPEG-SPA of various molecular mass (2000, 5000, 20000) to washed human RBC under varying incubation ratios polymer to RBC. The electrophoretic mobility (EM) of the modified RBC decreases with increasing of chain length and concentration of PEG up to 50%. It may reflect the alteration in the surface layer thickness and friction. The aggregation behaviour of the pegylated RBC was studied with the Zeta sedimentation technique modifying the cell–cell interactions pressing them toward each other under centrifugal forces of various magnitudes. As a rule at low centrifugation forces the increase in chain length and concentration of PEG linked to RBC surface reduces the dextran-induced aggregation probably via elevation of the steric repulsion, which counteracts the depletion force generated by the free polymer. This effect was reversed to some extent by elevation of free dextran concentration and centrifugation forces. If cell–cell polymer bridging starts playing a role under these conditions requires further experimental and theoretical investigations.
Keywords: Pegylated red blood cells, aggregation, dextran, Zeta sedimentation ratio
