Treatment of bacterial infections is a major challenge due to the overuse of antimicrobial agents, which in turn leads to resistance. One of the common mechanisms of bacterial resistance is biofilm formation. Bacteria clump together on surfaces to form organized three-dimensional structures that protect them from harmful environmental agents. Bacteria protected by biofilms can be up to a thousand times more resistant to external influences than planktonic bacteria; approximately 80% of chronic infections are attributed to biofilms.
This Master’s thesis’ content is linked to an ARRS project named: “Bactericidal nanoblades: a proof-of-concept approach for bimodal chemo-mechanical eradication of persistent biofilms”. One of the goals of this project is preparation of nanoparticles shaped as blades that respond to magnetic field, and coating of their surface with lipophilic compounds with positive charge that are supposedly biocidal. Besides that, we want to monitor these nanoparticles with a fluorescent microscope; for this purpose, we would like to mark them with fluorophores which would allow us to more easily observe their reaction with bacterial biofilms. In this work we prepared fluorophores that are suitable for binding to silica-based surfaces of nanoparticles; we observed said fluorophores’ binding to silica nanoparticles. For this purpose, we synthesized lanthanide complexes and among all prepared compounds we found that the most suitable for binding to silica nanoparticles is an europium complex (compound 4).
For the preparation of compounds with biocidal effect, we synthesized positively charged quaternary ammonium compounds with azide or alkyne groups that we intended to further bind to a complementary silyl reagent using click chemistry. For the synthesis of silyl reagents, we tried different approaches for the introduction of alkyne groups to these reagents and we discovered that silyl ethers are resistant to higher temperatures. Unfortunately, we did not perform their binding to nanoparticles because at the time we did not have the appropriate nanomaterial for the preparation of biocidal surfaces.
In this work, we have succeeded in preparing a stable suspension of silica nanoparticles labeled with europium complex and suitable for observation with fluorescent microscope. In the future, we also hope to bind positively charged silyl reagents to the surface of nanoparticles.
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