title: Studies on the aggregation behaviour of pegylated human red blood cells with the Zeta sedimentation technique.
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.
authors.affiliation: Department of Physics and Biophysics, Medical Faculty, Medical University Sofia, Sofia, Bulgaria. jovchev@medfac.acad.b
authors.forename: S
authors.initials: S
authors.lastname: Jovtchev
authors.forename: S
authors.initials: S
authors.lastname: Stoeff
authors.forename: K
authors.initials: K
authors.lastname: Arnold
authors.forename: O
authors.initials: O
authors.lastname: Zschörnig
mesh_terms: D001799:Blood Sedimentation; D002449:Cell Aggregation; D003470:Culture Media; D003584:Cytological Techniques; D004903:Erythrocyte Aggregation; D004912:Erythrocytes / Q000166:cytology*; D018056:Hemorheology / Q000379:methods; D006801:Humans; D008970:Molecular Weight; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D012212:Rheology / Q000379:methods
chemical_list: D003470:Culture Media; D011108:Polymers; D011092:Polyethylene Glycols