Triggered release of antimicrobials Biocides are added to building and finishing materials to prevent the growth of microorganisms, but they are relatively ineffective and have negative environmental impact. Novel smart release technology using safer biocides could soon be the solution. Industrial Technologies © Thinkstock A large EU-funded consortium investigated triggered-release concepts to safely extend product service life through the project 'Smart release of biocides in finishing materials for the sector of construction' (AXIOMA). Scientists focused on algal and fungal growth on indoor and outdoor coatings and plasters as well as on fungi growth on kitchen and bathroom tiles and grout. Nanoclays with different surface modifiers were added to the building materials. Scientists demonstrated that nanoclays can be introduced in the conventional production of paints and plasters at concentrations required to achieve desired results. Differences in formulations had important impact on biocide release rate, which was nevertheless significantly improved by the nanoclay technology. BioSwitch technology imparts the ability to switch biocide activity on and off in response to the presence of enzymes secreted by the microorganisms. The biocide zinc pyrithione is already widely used in toiletries and has potential for inclusion under the simplified active substances scheme of the Biocidal Products Regulation 528/2012. Cost effective and active against a broad spectrum of microorganisms, this biocide was the focus of project studies. Notably, restrictions on biocide use became even tighter during the course of the project. The team inserted biocides into two biopolymer classes: proteins and fats. Tests demonstrated that the enzymes can reach the biopolymers in the coatings and release biocide in response to artificial enzymes. Further optimisation will focus on particle size and prevention of leaching and early triggering. Modelling provided important insight into the effects of coating formulation, environmental conditions and subsequent biocide release. A special software tool was developed to predict fungi and algal risk in both indoor and outdoor environments. It is available on the project website. A life-cycle assessment supported a clear positive environmental impact of the novel materials and technology compared to base materials. AXIOMA researchers have significantly advanced the technology for smart release of biocides in construction materials. Extended service life of construction materials using cost-effective and green biocide technology will provide an important boost to a sector facing increasing environmental restrictions and the effects of a prolonged economic crisis. Keywords Biocides, finishing materials, smart release, construction, zinc pyrithione
