Evaluation of nanomechanical properties of hyperbranched polyglycerols as prospective cell membrane engineering block

Owing to the excellent biocompatibility, hyperbranched polyglycerols (hbPGs) are one of the most promising polymers and widely employed in drug delivery. Presented as an excellent bioinert coating material, hbPGs can significantly improve the biosafety of biomedical nanomaterials. However, it is still unclear what specific properties of hbPGs are the key effectors to bioinertness. Here, atomic force microscopy was employed to test the Young's modulus and adhesion of hbPGs, spin-coated onto mica substrate. High Young's modulus indicated that the hbPGs cannot be further compressed and low adhesion implied that it is not easy to form hbPGs aggregators. This could owe to the intramolecular hydrogen bond. Morphology characterization of hbPGs self-assembled monolayer onto Si(100) substrate, confirmed the lower adhesion among different hbPGs and indicated their biofouling properties. Further confocal laser microscopy of cell membrane modified with alkyl chain (C18)-modified hbPGs and hbPGs-NH₂, confirmed that the antifouling properties of hbPGs are determined by terminal glycerol units. Our findings demonstrated that only hbPGs with entire terminal surface can be used as perspective cell membrane modification skeleton.