Abstract

Proteins are fascinating macromolecules. Nature evolved ways to accurately control the monomer sequence, making them the ultimate precision polymers. Proteins fold and self-assemble into well-defined three dimensional nanoobjects. Moreover, enzymes efficiently catalyze numerous chemical reactions with high selectivity at mild reaction conditions. Compared to the properties and functions of nature’s macromolecules, even the most sophisticated synthetic polymers still appear to be simple and only offer comparably basic functionality. Therefore, an interdisciplinary approach combining polymer chemistry and protein science creates new opportunities to design and realize functional materials, as well as to support the environmentally friendly synthesis of polymers.

The protein cage thermosome is a hollow nanosphere with gated pores that are so large that macromolecules can diffuse in and out of the cage. By site-directed mutagenesis and chemical conjugation a variety of guests were entrapped into this cage. Thus, thermosome-polymer conjugates were developed into powerful delivery vehicles for small interfering RNA and are useful templates for the synthesis of nanoparticles. Moreover, the thermosome was used as nanoreactor for the controlled synthesis of polymers in a confined reaction space. A second approach to harness the functionality of proteins within synthetic materials is to dope engineering materials with small quantities of proteins. Fluorescent proteins are force-responsive and loose their fluorescence if mechanically perturbed. This effect was exploited to develop fiber-reinforced composites in which fluorescent proteins act as a mechanical sensor on the nanoscale. Such self-reporting materials can detect and report micro damage and could find application as safety feature to avoid catastrophic material failure of load-bearing components. In a third example, the opportunities that arise from enzymatic polymerizations will be highlighted. Our group discovered that some metalloproteins such as horseradish peroxidase and hemoglobin can catalyze atom transfer radical polymerizations (ATRP). This novel enzymatic activity allows to prepare well-defined polymers that are otherwise not accessible through classic ATRP . Moreover, the controlled synthesis of polymer brushes on surfaces can be tuned in unique ways and polymer-filled polymersomes can be prepared by confining the polymerization into polymer vesicles.