Tailoring surfaces using protein-polyelectrolyte complexes and cluster ion beams

The biofunctionalization of surfaces, i.e. immobilization of proteins at interfaces, is a cornerstone technology in diverse fields of application. Deposition from aqueous protein solutions has proven efficient for some utilizations. However, such methods suffer from several drawbacks, reducing the range of achievable functions. Among those disadvantages, the inherent drying step often causes problems such as the loss of 3D conformation of immobilized proteins, a lack of control on the spatial distribution of the engineered layer, etc. Therefore, recent research aims at the development of new methods outpacing the drawbacks of current ones. This master thesis investigates the elaboration of a new protein immobilization technique that uses large argon clusters produced by a Time-of-Flight Secondary-Ion Mass Spectrometer (ToF-SIMS) in order to transfer proteins from one surface rich in proteins to another one clean. The idea is to take advantage of the low energy per atom of such clusters to induce the sputtering of intact proteins under ultra-high vacuum. For the purpose of granting proteins with an extra protection, those were complexed with oppositely-charged polyelectrolytes (PE) resulting in protein-PE complexes (PPCs). Three different PPCs containing protein of different sizes were considered during this thesis. First, the synthesis of the different PPCs was investigated with the aim of optimizing the different parameters of the complexation. Moreover, the efficiency of the PPCs production method and the activity of complexed proteins were assessed. Using optimized parameters, more than 80% of the proteins were found to be complexed with their corresponding PE. The complexed proteins tend to lose part of their activity, but it was shown that this one is retrievable. Second, PPCs were transferred with a 10keV Ar_5000^+ cluster ion beam inside the ToF-SIMS chamber. Finally, the collecting surface was characterized by ToF-SIMS and multivariate analysis. It appeared that protein material was successfully transferred with a semi-circular deposition pattern. Other characterization methods that aim to determine whether proteins were transferred intact and to quantify their amount and biological activity are presented.