Protein Adsorption Hysteresis and Transient States of Fibrinogen and BMP-2 as Model Mechanisms for Proteome-Binding to Implants

Abstract

Protein adsorption studies returned to the focus of medical therapeutics, when it was found that up to 2500 non-plasma proteins adsorbed to hip implants during arthroplastic surgery, challenging peri-implant healing models. Questions have re-emerged as to the implications of uncontrolled protein unfolding after adsorption. In past studies on the cooperativity of protein binding we discovered protein adsorption hysteresis, a thermodynamically irreversible process. The present precursory study comprises real-time kinetic (TIRF-Rheometry) and equilibrium (125I-tracer ) studies on the hysteretic binding of fibrinogen and rhBMP-2 to titanium and glass surfaces via transient states. Thermodynamic constants (GOn), as well as kinetically derived (K'A ) and hysteresis derived (K'HA ) association constants in the range of 106 to 1012 M-1lead to a consistent picture.

Keywords

• adsorption and desorption isotherms
• total internal reflection fluorescence (tirf)
• tirf-rheometry
• binding constants
• hill constants
• on-rate (k+1)
• off-rate (k-1)