Researchers at the University of California, Berkeley (USA) have now developed a new strategy for the formation of hybrid materials from synthetic polymers and proteins. They have thus been able to fuse the specific biological functions of proteins with the advantageous bulk and processing properties of plastics. Polymer-protein hybrid materials may be of use in the manufacture of sensors, nanomachine parts, or drug-delivery systems.
As Aaron P. Esser-Kahn and Matthew B. Francis report in the journal Angewandte Chemie, they have successfully synthesized a green-fluorescing biodegradable gel that responds to changes in pH value and temperature.
Previous processes for the production of hybrid materials depended on very specific coupling techniques that could not be used for some protein side-chains. In contrast, the new method developed by the Berkeley researchers is broadly applicable because in principle it is suitable for any protein. The coupling occurs at both ends of the protein chain—and these are the same for all proteins: one amino acid group and one carboxylic acid group.
Initially, two parallel but mutually independent (orthogonal) reactions are used to activate the two ends of the chain. These are then attached to special chemical “anchor points” on the polymer. The proteins thus cross-link the individual polymer chains into a three-dimensional network, forming what is known as a hydrogel. A hydrogel is a solid, gelatinous mass consisting of water incorporated in a polymer network. A well-known example of a hydrogel is the soft contact lens.
Francis and Esser-Kahn chose to use a protein that fluoresces green to cross-link their polymer chains. Because the protein maintains its normal folding pattern even after attachment to the polymer, the fluorescence is also maintained: The entire gel fluoresces green.
This hybrid material has a special trait: the cross-linking of the polymer chains is achieved exclusively by means of the proteins. Because proteins can be attacked by proteases, enzymes that disintegrate proteins, these gels are biodegradable. The green fluorescence of the protein is pH-dependent. The gel correspondingly also reacts to changes in pH. It only fluoresces in the basic range; in a lightly acidic medium, the gel no longer fluoresces. Raising the temperature also elicits a response from the gel. The protein denatures at about 70 °C, which quenches the fluorescence and causes the gel to shrink.
Author: Matthew B. Francis, University of California, Berkeley (USA), http://chem.berkeley.edu/people/faculty/francis/francis.html
Title: Protein-Cross-Linked Polymeric Materials through Site-Selective Bioconjugation
Angewandte Chemie International Edition 2008, 47, No. 20, 3751–3754, doi: 10.1002/anie.200705564
Matthew B. Francis | Angewandte Chemie
World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
17.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering