Biomaterial surface modification represents an important tool allowing to control the interface between an implant substrate and its host environment. As such, biomolecule-based coatings are widely applied in the field of biomaterial surface engineering in order to encompass biological activity onto an otherwise inert surface. Moreover, protein adsorption is considered as a primary event taking place at the biomaterial surface upon implantation. Yet, for an in-depth understanding the interaction between the biomaterial and the biological environment advanced surface characterization techniques are key. Characterization of biomolecule films, such as protein films either purposely applied or spontaneously adsorbed after implantation, is quite challenging due to the limited thickness of the proteinaceous layer and the instrumental limitation of analytical tools. X-ray photoelectron spectroscopy (XPS) and Time-of-Flight Secondary Ions Mass Spectrometry (ToF-SIMS) are two advanced surface characterization techniques that are often used to study protein-based layers on biomaterial surfaces due to their low surface penetration and high sensitivity¹. Moreover, ToF-SIMS supported by multivariate principal component analysis (PCA) enables a statistical comparison between various specimens². Addition to that, a difference in disulfide signals (S2^-; values related to the peptide bond CNO^-) is compared by using distinct negative ToF-SIMS signals¹. It is elucidated that the tertiary protein structure is not influenced by the method of deposition, thus, the activity of the protein is not compromised. In this study, alternating current electrophoretic deposition (AC-EPD) was used as a tool to immobilize deoxyribonuclease I (DNase I) on polydopamine treated titanium (Ti) substrates. It could be shown that AC-EPD does not introduce structural changes in the coated proteins by revealing the high peak fraction of the peptide bond content via XPS, amino acid related fragments and no sign of structural changes via ToF-SIMS. To investigate the protein adsorption kinetics, several techniques such as atomic force microscopy (AFM) or XPS have been suggested, however, these measure protein adsorption not in real-time. Alternatively, streaming potential or streaming current measurements can be applied as a tool to study protein adsorption, since it allows to analyze changes at the solid/liquid interface. In this study, we applied the model protein bovine serum albumin (BSA) as an adsorbate. To this end, AC-EPD chitosan-based coatings are brought in contact with a phosphate buffered saline (PBS) electrolyte supplemented with BSA and the streaming current was measured as a function of time. The resulting surface zeta potentials show two different phenomena. An absolute streaming current value is reduced for bare Ti substrate, however, it is increased for CS-coated Ti substrate upon contact with proteins. These prove that the surface modification of Ti substrates elevates protein adsorption. An overview of different surface characterization methods is shown in Figure 1. These methods are specifically adapted to probe the thin and heat-sensitive protein layer in terms of surface chemistry evaluation and protein adsorption kinetics and are allowed to understand the complex interaction between the implant surface and the host environment.