student profile: Mr Miguel Correia Dos Santos


Thesis work


Supervisors: Steven WISE, Marcela BILEK

Thesis abstract:

Plasma processing technologies have been extensively used as surface modification platforms in many biomedical applications. Particularly, plasma polymerization (PP) is a versatile deposition technology which has the potential to deliver biocompatible interfaces for a myriad of medical devices. To successfully translate new materials for specific clinical applications, the plasma process needs to be scalable and incorporate appropriate control feedback strategies. Comprehensive process parameterization is an essential first step towards identifying optimal deposition windows, which will vary depending on the required interface specifications. However, the plasma medium in PP is exceptionally complex and identifying the main physical quantities that allow a suitable formulation and description of the interface growth mechanisms is challenging.�br /� �br /� The first part of the thesis reports the design and optimization of a single step ion assisted PP process to create plasma-activated coatings (PAC) that meet the extreme mechanical demands for cardiovascular implants and in particular, stents. An ideal working window in the parameter space is identified, and found suitable for the synthesis of PAC interfaces that are mechanically robust, haemocompatible and allow covalent protein binding. This window is identified by combining plasma optical emission spectroscopy (OES) with a comprehensive macroscopic process description that isolate key coating growth mechanisms. To further narrow the working conditions best suited for stent applications the best surfaces were screened for covalent protein binding and compatibility with platelet rich plasma and whole human blood. During process scalability, OES diagnostics revealed the formation of plasma polymer nanoparticles (nanoP3), usually known as plasma dust, in parallel with the deposition of PAC coatings. Plasma dust is usually regarded as a contaminant in plasma-based manufacturing industries. However, as both PAC coatings and nanoP3 are synthesized in parallel inside the plasma reactor, it is first hypothesized that both are constituted from the same material, and therefore share similar physical-chemical properties.�br /� �br /� The second part of the thesis reports the pioneering demonstration of carbonaceous plasma nanoparticles for nanomedicine applications. By controlling nanoparticle formation and collection, nanoP3 were engineered with unique immobilization capabilities facilitating multifunctional nanocarriers. The unique surface chemistry of nanoP3, allowing a robust immobilization with the cargo without the need for intermediate functionalization strategies, has great potential to overcome major limitations of currently proposed platforms. Since unpaired electrons and surface functionalities are preserved and crosslinked on the nanoP3 during their formation, PP provides a cost and time effective synthetic route for multifunctional nanocarriers with a long shelf-life. The universal binding surface of nanoP3 paves the way for the design of personalized nanocarriers, allowing the final user to obtain theranostic agents in a one-step incubation and according to immediate needs. As many of the favourable characteristics of nanoP3 are inherent to the fabrication process, this work proposes PP as a nanoparticle synthetic route with valuable potential for broad clinical and commercial applications.

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