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Nanotechnology

Manager: doc. Ing. Drbohlavová Jana, Ph.D.
Members: Bc. Dzuro Matěj , Ing. Hrdý Radim, Ph.D. , Dr. Mohan Rajneesh

Nanostructured surfaces for electrode modification and sensing

a) Fabrication of nanostructured surfaces covered with hexagonally ordered arrays of metal or semiconducting nanowires, nanopillars, nanodots or even quantum dots. The nanostructures from various materials such as gold, nickel, platinum, palladium, metal oxides (e.g. TiO2, WO3, Ta2O5, and SnO2) or various metal/semiconducting oxide composites are created via advanced non-lithographic template based technique. The fabrication method involves anodization of aluminium layer and subsequent through-mask anodization of the layer below the Al, or galvanic deposition of a metal. The nanostructured surfaces are utilized for the construction of a new type of gas sensors, photocatalytically active surfaces, photovoltaic applications, and electrochemical biosensors (the currently tested model compounds are guanine and glutathione). In addition, the interaction of nanostructures with various biological species is studied as well (currently DNA interactions with intercalating molecules such as doxorubicin).

b) The research group has very strong background in the characterization of nanostructured surfaces as working electrodes, namely using electrochemical impedance spectroscopy of various voltammetry methods.

c) Beside the above mentioned nanostructures fixed on solid support, the anodic oxidation method also serves for the creation of Al2O3 nanoporous membrane with different pore diameters (in the range from 10 nm to 200 nm), which can be prepared using very thin aluminium foil (usually from 10 µm to 50 µm). Similarly to nanostructured surfaces, these self-ordered nanoporous membranes find applications in sensing and biosensing.

 

  

Figure 1: SEM image of gold nanorods (left) and alumina nanoporous template (right).

Colloidal nanoparticles for biosensing and bioimaging

a) Synthesis of fluorescent carbon dots (F-CDs) of nearly spherical geometry with sizes below 10 nm, namely blue and green emitting F-CDs (excitation wavelength 365 nm). The fluorescence behaviour of F-CDs is supposed to be controlled by both, size effects and surface defects. By playing with the different surface functionalization, the properties of the F-CDs can be tuned according to the requirement.

Because of numerous advantages over semiconductor quantum dots, F-CDs offer a promising alternative for a number of applications, such as novel fluorescent probes for bio-imaging, medical diagnosis, photocatalysis, smart sensing and energy conversion/storage devices.

F-CDs offer following obvious advantages: green synthesis; wide excitation spectrum extending from the UV region to the visible region; chemical inertness; low photobleaching meaning that the fluorescence is so stable that after being excited for several continuous hours, the fluorescence intensity remains unchanged; the particle size of only several nanometers resulting in F-CDs strong penetration ability into cells; excellent biocompatibility and low toxicity.

Figure 2: Carbon dots emitting blue and green colour under UV illumination.

Possible applications of F-CDs:

  • Metal ion detection: Depending upon the surface ligands, the F-CDs can selectively detect metal ions like  Hg2+, Fe3+, Cu2+, Cr3+, and Al3+.
  • Glucose detection: F-CDs possess intrinsic peroxidase-like activity and can be used for glucose and H2O2 detection.

b) Synthesis of Cd-based semiconductor quantum dots functionalized with various thiol-containing molecules, namely CdTe-GSH, CdTe-MPA and CdTe-TGA prepared via direct colloidal synthesis. Cu based core-shell quantum dots with ZnSe shell and CdTe/CdS/ZnS core-shell quantum dots.

c) Synthesis of various nanoparticles suitable for application as active electrode layer (transducer): copper (I) oxide nanoparticles, iron oxide based magnetic nanoparticles, and cadmium oxide nanoparticles.

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