Biomimetic synthesis within polyelectrolyte microcapsules: Characterization of enzyme catalyzed polyphenols and polypeptides

An enzyme-catalyzed synthesis of novel polymers within layer-by-layer (LbL) constructed polyelectrolyte microcapsules has been developed. This approach is based on the selective permeability of polyelectrolyte-capsule walls to monomer molecules. Conversely biocatalysts and forming polymeric chains cannot exit the micro-capsule interior because of their characteristic high molecular weight. Horseradish Peroxidase (HRP) was encapsulated into four bilayer PSS (poly-styrenesulfonate)/PAH (poly-allylamine hydrochloride) capsules with an average diameter of 5 μm using pH-driven pore opening. The polymerization of 4-(2-Aminoethyl) phenol hydrochloride (tyramine) catalyzed by HRP produces easily detectable fluorescent polymeric products after the addition of hydrogen peroxide to the system. It is known that proteolytic enzymes that effect hydrolysis can be used for peptide synthesis by manipulating physicochemical conditions such as pH, enzyme concentration, oxygen tension, and temperature. Papain (an endolytic cysteine protease, isolated from papaya latex) was encapsulated into four bilayer Tannic acid/Chitosan capsules with an average diameter of 6 μm. Papain catalyzed polymerization of phenylalanine to its corresponding polymeric form was achieved by heating a mixture of capsules with encapsulated papain within and monomer at 40°C for several hours. The filling of the capsules with polymer was confirmed by AFM (Atomic Force Microscopy), QCM (Quartz Crystal Microbalance), FS (Fluorescence Spectrometry), and CLSM (Confocal Laser Scanning Microscopy). This approach offers a novel biosynthetic pathway for polypeptide synthesis within micron-sized “reactors”, which can have many applications within the field of biotechnology