Real-time monitoring of the immobilization of thiol-terminated proteins on a gold surface. The signal shows that the monolayer formation takes place in three distinct phases: a short period of compressive stress is observed when the molecules come into contact with the cantilever (1). This is followed by a period of tensile stress (2), until the flow of molecules finishes and a longer phase of relaxation and signal inversion begins (3).
Valuable information about dynamic processes involved in surface layer formation can be extracted from such data.
Formation of polyelectrolyte multilayers are monitored in real time in static and dynamic cantilever sensor operation mode. The static deflection of cantilevers (blue) provides information about generation and release of surface stress during the layer formation process. The dynamic resonance frequency shift (orange) gives complementary information related to the addition of mass in each step.