Scientists create multifunctional protein-polymer films

(Nanowerk News) A team from Lomonosov Moscow State University (MSU) together with foreign and Russian colleagues found that when mixing dendrimers (tree-like polymers) and proteins, multilayer films are spontaneously formed. They are easily formed and retain the activity and function of protein enzymes, which determines their potential as a material for creating biosensors and medical products. The results of the study are published in the journal Polymer ("Spontaneous formation of nanofilms under interaction of 4th generation pyrydylphenylene dendrimer with proteins").
A Dendrimer-Lysozyme Complex
Dendrimer molecule is marked yellow. The surface of the protein molecule is color-coded in accordance with the chemical properties of amino acid residues (red - positive charge, blue -- negative charge, green -- polarized, and white -- hydrophobic). (Image: Vladimir Muronetz)
Today a huge number of polymers is known, with different structure, composition, and properties. One of the most interesting examples are dendrimers - tree-like macromolecules. They are arranged as follows: three chemical groups are attached to the central core, each one branches into two same groups, and so on, and so on. Such a structure is achieved by a multistage synthesis.
The number of branching points determines generation number of the dendrimer: the first generation polymer has one branching point, the second one has two, the third has three, and so on. The further, the denser and more spherical becomes the structure, and its physical and chemical properties are preset by the functional groups on the outer layer. Dendrimers are able to form surface cavities into which molecules can be enveloped, and this property was the main prerequisite for the active study of these polymers. However, MSU scientists have found a completely different application for dendrimers.
"We found that upon mixing of proteins with fourth generation dendrimers the self-assembly of multilayer nanofilms 200-700 nm thick occurs. They can be adjacent to glass or plastic surfaces, as well as be formed at the liquid-air interface," says Vladimir Muronetz, professor of the Faculty of Bioengineering and Bioinformatics and the Faculty of Biology, MSU, and Head of the Animal Cell Biochemistry Department in A.N. Belozersky Institute of Physico-Chemical Biology, MSU.
Scientists have conducted experiments on the incorporation of various enzymes into the composition of nanofilms: lysozyme, which destroys the bacterial cell walls, and several types of proteinases break down proteins. It was concluded that in the composition of nanofilms these proteins are able to preserve activity for about two weeks. This two-component system is resistant to the action of cleaning agents (detergents), to changes in the medium acidity, and is generally stable during storage. However, the main advantage of the produced films is the simplicity of their formation process due to self-assembly.
"We believe that protein-dendrimer films are promising materials for creating biosensors, and can also be used in medicine as bioactive dressing material," concludes Vladimir Muronetz.
Source: Lomonosov Moscow State University