Deposition of Biomolecular Layers via Gas Cluster Ion Beams: Instrument Conception and Applications
(2025)
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- Abstract
- Gas Cluster Ion Beams (GCIB) were utilized in this work for the gentle sputtering and transfer of molecules from one surface to another. The impact of large clusters composed of a few thousands of atoms is sufficiently soft to transfer large molecules such as proteins intact. Indeed, the internal energy of the desorbed molecules is low enough to result in a reduced amount of fragmentation. At the beginning of this doctoral work, a commercial GCIB source was used to answer fundamental questions and make progress toward practical applications. Deposition rate and fragmentation were assessed under Ar_n^+ bombardment for different cluster sizes (n = 1500 - 7000) and energies (5 - 10 keV). A first application was the construction of dry multilayers and molecular architectures that cannot be achieved using solvent-based methods. Glucose oxidase (GOx, ≈ 80 kDa) and horseradish peroxidase (HRP, ≈ 40 kDa)—two enzymes involved in the same catalytic cascade—were successively deposited onto β-D-glucose. This resulted in the formation of an on-demand release material, where the enzymes and substrate were combined into a dry trilayer structure. The enzymatic reaction was triggered only upon rehydration, enabling precise control over the activation of the system. The second application demonstrated the soft transfer of a large quantity of neutral molecules from a tissue sample to another surface. This method, called microvolume expansion, aimed to enhance sensitivity in secondary ion mass spectrometry (SIMS) analysis—an aspect that often presents a limitation for this technique. In parallel with these results, a molecular transfer and soft-landing instrument named CLASH (Cluster-Assisted Soft-Landing Hub) was developed from scratch. The system, described in this work, comprises two vacuum chambers: one for supersonic jet generation and cluster formation, and another for sample impact and deposition. Mass selected large Ar_n^+ and (CO2)_n^+ clusters were obtained and analyzed using time-of-flight spectrometry. This highly adaptable setup enables new deposition experiments through its advanced cluster generation via a home-built pulsed valve.
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Tomasetti, B. (2025). Deposition of Biomolecular Layers via Gas Cluster Ion Beams: Instrument Conception and Applications. https://hdl.handle.net/2078.5/270895