Senior Staff with DSc

Ph.D. Sławomir Sęk

email: slasek@chem.uw.edu.pl

room: 4.24, Biological and Chemical Research Centre

www:

Scientific achievements and interests area

Formation of molecular layers with well-defined structure and properties is a fundamental task required for construction of some biosensors, bionanostructures and supported biomimetic membranes. In our group, we use scanning probe microscopy techniques to characterize the structure and the properties of molecular films containing lipids, peptides and more complex proteins. Our research interests include:

  • Molecular resolution imaging of the films immobilized on solid substrates (STM/AFM).
  • Studies of adsorption dynamics and formation of molecular films under electrochemical control (EC-STM/AFM).
  • Electric field induced changes in the structure and the properties of adsorbate layers (EC-STM/AFM).
  • Mechanical properties of the films and model membranes (AFM)
  • Adhesion properties of molecular films (Force Spectroscopy)
  • Electrical properties of molecules immobilized on conductive substrates (STM and Current Sensing AFM).
  • Identification of surface confined molecules using specific interactions and molecular recognition (Chemical Force Microscopy).
  • Two dimensional nanostructures and nanolithography/nanografting using AFM-based approach.

    • Research projects:

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    Ph.D. Agnieszka Więckowska

    email: awiec@chem.uw.edu.pl

    room: 149.3, Faculty of Chemistry

    www:

    Scientific achievements and interests area

    My recent researches focus on synthesis and investigating metal nanoparticles, especially gold nanoparticles. Gold clusters are nanocrystals with sizes ranging from one to several hundred nanometers, which surface is stabilized physically or chemically by adsorbed compounds. Adsorption of compounds on the surface of gold clusters prevents aggregation and allows subsequent modification of surface with chosen molecules. Because of its size, clusters of gold fall between world we know, and the quantum world.

    Monolayer covering the gold cluster core can be modify in any way or replace on the thiols containing end groups such as carboxyl, amino, hydroxyl. This approach opens up many possibilities for anchoring on the surface of colloidal gold different chemical compounds, from simple alkanethiols to DNA and enzymes. From the point of view of their potential applications in miniaturized molecular devices such modified gold clusters can be anchored on solid surfaces using a variety of non-covalent interactions, such as host-guest interactions, p-p, van der Waals interactions, donor-acceptor, the antigen-antibody and other.

    The modified gold clusters can be used in the large number of different applications. Such systems are used both in chemistry (as catalysts, sensors, additives for polymers, substrates for SERS), biological sciences (microscopic markers, biosensors, drug transporting systems) or in materials sciences (electronics at the nanoscale, electroptics, molecular machines, optical filters, switches). Gold nanoparticles, in contrast to metallic gold, show high catalytic activity. Gold clusters are active catalysts used for oxidation of carbon monoxide or hydrogen, the reduction of nitric oxide, the combustion of methanol.

    Gold nanoparticles modified with oligonucleotides are also used to determine the DNA sequence. Nucleic acid strand anchored to colloidal gold retains its ability to bind to the complementary strand. This process is reversible, since after heating to a temperature appropriate for the hybrids, hydrogen bonds between complementary strands break. Electrodes modified in this way are used as biosensors in diagnostics.

    Recently, much attention is paid to the use of gold clusters to identify proteins or immobilization of enzymes. It uses, for example, the interactions of antigen-antibody type. Enzymes immobilized on the surface of metallic clusters retain their catalytic bioactivity in contrast to similar systems prepared on the metallic electrodes. In these systems, gold nanoparticles act not only as a matrix for immobilization of enzymes, but also provide electron transfer between the enzyme and the electrode, which means, that they have the function of mediation, so that created systems often do not require an external mediator.

    Interesting properties and stability of the created systems makes alkanethiols modified gold clusters interesting for researchers who are working ine the "nano" scale science. They can be used to build nanostructures in the strategy of "bottom-up". Systems containing gold nanoparticles are systems easy to modify and change the configuration of the measurement, depending on the aims.

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