Understanding silver nanoparticle leaching behavior from active biodegradable nanocomposites

Abstract

Biobased and biodegradable polyhydroxyalkanoates (PHAs) can be seen as polymers of the future, which can replace fossil equivalents in a circular bioeconomy. Indeed, PHAs can be produced in bacteria from various biomass feedstocks. PHA biopolymers can be used in packaging, agricultural and medical applications, and they fit at least six end-of-life (EoL) scenarios. Incorporation of silver nanoparticles (NP) in bioplastic food contact materials (FCM) shows great potential as active packaging with antimicrobial performance, which can contribute to reduce food waste, as targeted by SDG 12.3. However, the lack of knowledge regarding NP release, associated risks on human health and accumulation in the environment leads to restricting legislation. Before investigating NP migration from biodegradable PHAs, the first objective is to update the dynamic European legislation regarding biobased and biodegradable packaging materials, FCM and active packaging. In Nov 2022, the European Commission proposed the new Packaging and Packaging Waste Regulation to put the packaging sector on track for climate neutrality by 2050 in line with the European Green Deal's Circular Economy Action Plan. The new rules will clarify how bioplastics can be part of a sustainable future. In the meantime, the Commission also intends to modernize the rules on FCM (Regulation 1935/2004) to ensure food safety, while taking account of the latest science and technology, and supporting innovation and sustainability by promoting safe reusable and recyclable solutions. Two PHAs are on the Union List of permitted substances but authorisations for nanomaterials must be assessed on a case-by-case basis. The PHA value-chain from design through manufacture, value enhancement and disposal should be strategic, considering safety and legislation. Therefore, our research will focus on elucidating mechanisms of silver NP migration from PHAs in consumer as well as specific EoL scenarios to estimate the safety and application potential of bio-nanocomposites as active packaging material.