Coating is a most perfered mothod used in protecting the solid substrates from contamination, corrosion, and wear. Recently, research interest is increasingly focused on developing smart coatings with novel functionalities including self-cleaning, self-healing, self-reporting, antimicrobes and detoxification. So far little has been reported on the use of bioactive enzymes for self-cleaning coatings, though they can target sticky components of stains with high selectivities.

Based on the previous studies on the bioactive enzymes, researchers with Institute of Process Engineering, Chinese Academy of Sciences (IPE) investigated the feasibility and efficacy of using polymer-conjugated enzymes for preparation of enzyme-based self-cleaning coatings.

As a result, PEG conjugation improved the compatibility between enzyme and polyurethane, thus helping to disperse and retain the enzyme in thin film coating. The coated enzyme afforded highly selective surface bioactivity which allowed the coating to selectively degrade stain-forming biomolecules, avoiding formation of stains.

Polyurethane coatings prepared with PEG conjugated α-amylase demonstrated excellent self-cleaning against starch-rich stains such as sandwich sauces. Such self-cleaning coatings may help to reduce water consumption (by shortening the washing time) and environmental contamination (by eliminating the need of chemical detergents) for washing when applied to automobiles or household facilities.

Additionally, the conjugated enzyme showed enhanced retention in the coating and much improved thermal stability with a half life of 20 days detected at 80 °C and over 350 days under room temperature. Combined with the enhanced thermo-stability, such enzyme-based coatings promise a variety of practical applications and, depending on the enzymes applied, may enable smart coatings offering functionalities including self-cleaning, self-reporting, and antibacteria.

The paper was published in APPLIED MATERIALS & INTERFACES.