Research Profile Dr. Christoph Rehbock
Group LeaderDr. Christoph Rehbock
Faculty of Chemistry, Technical Chemistry I
University of Duisburg-Essen
Universitätsstraße 7
45117 Essen
Room: S07 S01 C35
Phone: +49 201 183 3040
Email: Christoph.Rehbock@uni-due.de
Publications:
Research focus of the Rehbock Group
Nanoparticles, lasers and beyond – discover our possibilities
Laser-based nanoparticle synthesis and processing
The group uses advanced laser ablation, laser fragmentation, and laser melting techniques in liquids to produce high-purity, ligand-free metal, alloy, and ceramic nanoparticles of precisely controlled size and composition. We are particularly interested in how the target material (e.g., FeAu, AgAu, or PtAu), solvent (aqueous and organic), and additives allow for precise adjustment of the optical properties. One current focus in this field is fluorescent metal nanoclusters with diameters < 3 nm.
Nano-bio functional systems and coatings
Laser-synthesized NPs serve as a platform for biomolecule conjugation and medical technology applications. Thiol chemistry is used to simultaneously anchor nucleotides, peptides, or proteins to the particle surfaces, creating multimodal nano-bioconjugates for targeted drug delivery and imaging. Such functionalized colloids are being researched, for example, as photoactivatable carrier systems in therapies or as potential nanomedicines for neurodegenerative diseases (e.g., Alzheimer's). Another focus is integration into biomaterials: ligand-free NPs are embedded in situ in polymers to create nanocomposites with modified surface charge. These innovative biomaterials promote cell growth and are intended for use in tissue engineering and implant design. In addition, the group is developing coated electrodes for neurostimulation: Pt or PtIr NPs are applied to deep brain stimulator electrodes by electrophoretic deposition (EPD), which reduces the interface impedance and improves long-term stability. Our current focus in this field are nanoparticles as radio enhancers in proton therapy.
Alloy nanoparticles
Alloy nanoparticles are composed of two or more metallic elements. They can be easily fabricated from laser ablation of alloy targets or laser fragmentation of alloy microparticles. Dependent on the type, molar fraction, and arrangement of the ements, different properties arise for example a tunable plasmon resonance in AgAu. Research in this field currently focuses on high entropy alloy (HEA) or compositionally complex alloys. Here, more than five elements are combined in one particle, which may yield unique magnetic properties but also enhanced activity in heterogeneous catalysis.
Organic Microparticles -Food and Drugs
Organic microparticles, for example, from pharmaceuticals or food ingredients, are highly relevant in industry. One major challenge is their poor water solubility, restricting their effectiveness. Laser processing in liquid was shown to enhance their solubility. Here, we can either use laser fragmentation in liquids (LFL), reducing particle size and increasing specific surface area, but, also laser extraction in liquids (LEL), which works at low laser energies and without breaking the particles. Currently, we fundamentally examine the LEL process using coffee and curcumin as examples, however, transfer to other material systems and also scale-up for industrial utilization is one focus of our group.
Process scale-up for ceramics based high performance lubricants
High-performance lubricants require particles with high hardness, features best fulfilled by ceramics like boron carbide or titanium nitride. Furthermore, their performance requires them to be in a sub-micrometer size scale and with high sphericity. The only process that optimally meets this standard is laser melting in liquids (LML), which, to date, however, only works in small-scale batches and is not suitable for industry. Hence, we aim to investigate the transferability of this process to continuous scalable reactors, aiming at technical scale production for industrial applications.