PS-b-PAA nanovesicles coated by modified PEIs bearing hydrophobic and hydrophilic groups

Abstract The PS- b -PAA copolymer was studied to form vesicles that were subsequently coated by modified PEIs in order to improve its biocompatibility. Due to its high charge density, unmodified PEI can interact strongly with cell membrane disturbing its integrity then causing irreversible cell damage. The PEI is a polyelectrolyte, bearing positive charges arising from the amino groups, and was chemically modified to render hydrophobic (n-alkyl) and/or hydrophilic (lactose) as grafted groups. Using established procedures both linear and branched PEI gave 10% of n-alkyl groups while three different substitution degrees (10, 25 and 50%) were obtained using lactose. The possibility of controlling PEI charge density by modifying its structure is expected to help in biocompatibility. The PS- b -PAA vesicles were prepared using the co-solvent method (dioxane/water) resulting in nanovesicles with less than 150 nm of diameter (PDI at 173° = 0.113) measured by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The decoration process of these vesicles was made by mixing such colloidal suspensions with modified PEI at specific [PEI-x]/[PS- b -PAA] ratios and measuring the change in size and surface charge (through DLS and zeta potential). At a stage where the coverage process is complete (surface positive charges) the vesicles were slightly bigger ( b -PAA] ratio.