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Biophysics Researchers: Constant Calcium Uptake Causes Cancer in Cells

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[2017/Nov/28] Dr. Irene Frischauf and Dr. Rainer Schindl made the cover of Science Signaling with their publication: Calcium regulates many vitally important functions in the body - if the calcium balance is defective, diseases like cancer develop... ...  more of Biophysics Researchers: Constant Calcium Uptake Causes Cancer in Cells (Titel)

Noteworthy Publication in Angewandte Chemie

[2016/Nov/06] Publication in Angewandte Chemie: "Detailed Evidence for an Unparalleled Interaction Mode between Calmodulin and Orai Proteins" ...  more of Noteworthy Publication in Angewandte Chemie (Titel)

Victoria Lunz - Genuinely Passionate about Research

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Tuning membrane protein mobility by confinement into nanodomains

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[2016/11/16] In cooperation with Prof. Peter Pohl (Institute of Biophysics, JKU), lead CBL researchers DI Andreas Karner and Dr. Johannes Preiner have developed a platform to study membrane proteins. ...  more of Tuning membrane protein mobility by confinement into nanodomains (Titel)


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Self-Assembled Monolayers (SAMs) on gold

Gold surfaces are particularly suited for immobilization of biomolecules on biosensor surfaces:

• Gold is chemically inert, thus it can be cleaned under harsh conditions which remove all contaminations. Moreover, gold stays clean for a few minutes under ambient conditions, in contrast to most other inorganic surfaces.

• Only thiols (R-SH) or disulfides (R-S-S-R) form covalent bonds with gold. As a consequence, linear molecules with a terminal thiol or disulfide form densely packed monolayers on gold surfaces. The stability of such a self-assembled monolayer (SAM) is additionally enhanced if the thiol or disulfide is attached to a long alkyl chain (n ≥ 11).

• SAMs from simple alkanethiols [HS-(CH2)n-CH3] are hydrophobic. The methyl group, however, can be replaced by functional groups (e.g. OH, COOH, NH2, etc.) which are polar and chemically reactive. Moreover, mixed SAMs with different functional groups can be formed, thus the chemical and physical properties of SAM surfaces can be fine-tuned as needed.

• SAMs with short polyethylene glycol (PEG, see Fig. 3) chains are repelling to proteins and nucleic acids. Such protein-resistant SAMs are needed for biosensor surfaces because any nonspecific adsorption of protein or nucleic acid would lead to a false-positive signal.

• SAMs with a defined area density of reactive groups are required for covalent immobilization of biomolecules in a number of applications:

o In a biosensor, the immobilized biomolecules (e.g. antibodies) serve as “baits” which capture complementary “prey” molecules (e.g. antigens) from the sample solution. Binding is detected by surface plasmon resonance (SPR, e.g. in a BIAcore® instrument) or by a quartz crystal microbalance (QCM).

o Biosensors are often used for Biological Interaction Analysis (BIA), with one of the interacting components being immobilized on a protein-resistant chip while the second component is offered from solution at different concentrations, and in the presence/absence of further regulatory components. In this way, the mechanism of biomolecular interactions can be analyzed.

o The single molecule version of BIA is recognition force spectroscopy in the atomic force microscope (AFM). Here, one of the interacting components is tethered to the AFM tip while the complementary component must be immobilized on an ultra-flat surface (see Fig. 1 in chapter 1). Freshly cleaved mica is unparalleled in flatness and cleanness, yet chemical derivatization is difficult [4]. A versatile alternative to mica is “template-stripped gold” which is first evaporated onto clean mica, and then stripped from the mica surface [Hegner et al. 1993, Surface Sci. 291, 39-46]. After stripping, the gold surface must be covered with a suitable SAM, before the biomolecules can be immobilized.

Our interest is to provide SAMs for studies of Biological Interaction, both in small ensembles (in the BIAcore), and on the single-molecular level (in the AFM). Our approach has been to create modular SAMs (chapters 2.2.–2.4.) which can be adapted to different immobilization problems (see chapter 2.3.). For a firm basis, we examined the preparation and durability of protein-resistant SAMs, with unexpected findings, as described in chapter 2.1.

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