Dendronized oligoethylene glycols (dendron OEGs) with two phosphonate groups (phosphonate tweezers) have been drawing significant attention as a new class of coating materials for superparamagnetic iron oxide surfaces. However, despite dendron OEGs showing outstanding stability in physiological fluids in previous studies, little is understood about their structure and mechanical properties. Herein we report the surface and internal structures and mechanical properties of dendron OEGs, and quantitatively determine their ability to avoid non-specific adhesion of blood platelets. To gain insight into the interfacial force interactions, we measured the coarse-scale surface force acting on cell-sized particles and mapped the nanoscopic pinning centers by fast force mapping.