prof. RNDr. Bohuslav Rezek, Ph.D.

Semiconductor nanomaterials have been intensively studied with a perspective of novel functional mechanisms and principles for a wide range of applications from quantum electronics and optoelectronic devices to energy conversion, catalysis and biosensors. Surface atoms, chemical groups and interaction of surfaces with organic molecules gives rise to new electronic properties and effects (such as LDOS, polarization, transfer of charge or excitation), which are crucial for these applications. Aim of this PhD work is to investigate structural and electronic properties of selected semiconductor nanomaterials and structures with functional atomic centers, surface chemical groups and adsorbed molecules by computational simulations. It will help us explain available experimental microscopic, electronic and spectroscopic data and provide predictions for further experiments and device designs. Considering a PhD student’s interest and our research directions, the actual work will focus on nanostructures based on ZnO, diamond or graphene with proteins, organic dyes and other molecules of interest. The simulations will be based on appropriate atomistic models and suitable level of theory (DFT, DFTB, TDDFT, MD, FF) using various software packages (incl. licenses for QuantumATK and Gaussian) running on dedicated hi-performance workstation or via access to computational clusters (CVUT, Metacentrum). The work is part of our research projects and international collaborations.

Electrochemical biosensors are widely studied and applied technology because of their quick analysis, high sensitivity, specificity, miniaturization and affordable costs. The specificity is achieved by specific chemical reactions of electrode with analyte or via electrode functionalization by bioreceptors such as antibodies. In both cases, the key mechanisms influencing the biosensor sensitivity are analyte adsorption on electrode and its effect on electron transfer. Use of nanomaterials, in particular carbon-based, is intensively explored to enhance these mechanisms by increasing electrode surface area, its nanostructuring and for exploring novel specific reactions and charge transfer pathways. Considering a PhD student’s interest and our research directions, the actual PhD work will focus on a study of electrochemical immunosensors based on electrode platforms modified with nanodiamonds of various types, carbon nanowalls or metal nanoparticles for detection of molecular biomarkers of current interest such as stress, cancer, or food quality. The work is focused on fabrication of these sensors and analyses of their structural, chemical, electronic properties and functions. It will explore various linking strategies (EDC-NHS, PA) and synergic effects of the materials and structures involved. The analyses will include mainly electrochemical methods (CV, DPV) complemented with electrical measurements (conductivity, impedance), spectroscopy (Raman, FTIR, QCM) and microscopy (SEM, AFM, KPFM, PL). The work is part of our research projects and broader international collaborations.

Diamond as a material has been intensively studied from the perspective of new phenomena for uses in electronics, opto-electronic devices and bio-sensors. Subject of this work is modification and characterization of nanocrystalline diamond thin films in combination with other materials (silicon, gold, graphene, etc.). Influence of composition and arrangement of the resulting composite materials, including surface chemical modifications, on electronic-transport and potential plasmonic properties will be investigated. The aim is application for new, highly sensitive chemical sensors. Plasmatic methods for surface modifications, various techniques of scanning probe microscopy (AFM/KPFM/CAFM), Raman micro-spectroscopy, impedance spectroscopy and other electrical measurements will be used at this work. Electronic interactions with molecules of various substances will be eventually studied at later stage. The work has predominantly experimental character (nevertheless, computing methods can be employed as well). Candidate‘s prior knowledge in electronics and solid state physics is advantageous.

Diamond as a material has been intensively studied from the perspective of new phenomena for uses in electronics, opto-electronic devices and bio-sensors. Aim of this work is characterization and controlled modification of diamond nanostructures and nanoparticles by conjugated systems of organic dyes such as polypyrrole or polyanillin. So far obtained experience with synthesis of organic dyes on diamond substrates, where consequently efficient dissociation of excitons in dyes or charge extraction along the grain boundaries in diamond occurs, will be used as a foundation for creation and characterization of nanoparticle-dye systems. Wet chemical and plasmochemical processes, optical and electron spectroscopy (XPS), electron microscopy (SEM), atomic force microscopy (AFM) and light scattering (DLS) will be used at this work. Opto-electronic properties in modified nanoparticles will be studied at later stage. Candidate‘s prior knowledge in physics and/or chemistry is advantageous.

Diamond with impurities such as silicon and other elements represents an intensively studied material for uses in opto-electronics, quantum communication, and biomedicine due to unique optical properties. Control of properties and spatial distribution of optically active structures on a substrate is crucial for many of these applications. Part of this work is participation on the design and making of such structures on microscopic level by using selected lithographic and plasmatic method employing mainly silicon as optically active center in diamond. Samples will be characterized mainly by methods of AFM, electron microscopy (SEM), and Raman and photoluminescence spectroscopy and micro-spectroscopy, including potential use of modern microscopy in the near field (SNOM). Influence of surface chemical modification (from simple atomic groups to organic and water molecules) on optical properties of diamond structures will be studied. Candidate‘s prior knowledge in physics and optics is advantageous.

Diamond with impurities such as silicon and other elements represents an intensively studied material for uses in opto-electronics, quantum communication, and biomedicine due to unique optical properties. Control of properties and spatial distribution of optically active structures on a substrate is crucial for many of these applications. Part of this work is participation on the design and making of such structures on microscopic level by using selected lithographic and plasmatic method employing mainly silicon as optically active center in diamond. Samples will be characterized mainly by methods of AFM, electron microscopy (SEM), and Raman and photoluminescence spectroscopy and micro-spectroscopy, including potential use of modern microscopy in the near field (SNOM). Influence of surface chemical modification (from simple atomic groups to organic and water molecules) on optical properties of diamond structures will be studied. Candidate‘s prior knowledge in physics and optics is advantageous.

When bacterial strains are repeatedly exposed to antibiotics, survived bacteria gradually develop a defense mechanism that makes their inactivation difficult. Antimicrobial resistance (AMR) is therefore becoming on of the biggest challenges for 21st century healthcare. Due to the problems with development of new antibiotics, new ways to reduce spreading and provide effective treatment of bacterial infections need to be explored. Inorganic nanoparticles have been found to have promising antibacterial effects, and even increase the susceptibility of resistant bacteria to antibiotics. Subject of this PhD work is experimental investigation of the antibacterial effects of various types of nanoparticles (nanodiamonds, graphene, metals, metal-oxides) on non-pathogenic gram-positive and gram-negative bacteria (Staphylococus Aureus and Escherichia coli) and compare inactivation effects with conventional antibiotics. Nanomaterials and their physical-chemical properties and interactions with bacteria will be analyzed by electron and optical microscopies, spectroscopies as well as various microbiological tests and assays. Influence of external effects such as illumination, electrical field and discharges will also be explored with view to physics, chemistry, and biology.

Nanoparticles and nanocrystals are in the recent years intensively studied for demands of electronics, opto-electronic devices and bio-sensors. Electrical potential of nanoparticles and its changes due to effects of surrounding environment plays important role in such applications. Aim of this work is mainly development of experimental method followed by time-resolved characterization of local electrostatic potential of nanoparticles (silicon, diamond, gold, etc.) by using techniques of scanning probe microscopy (AFM/KPFM). Time-resolved opto-electronic phenomena in modified nanoparticles and nanocomposites will be eventually studied at later stage of this work. Candidate‘s prior knowledge in electronics and/or solid state physics is advantageous.