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Effect of Nanoparticle Incorporation on Functional Properties and Migration of Ag/polyhydroxyalkanoate Nanocomposites
No full textEffect of Nanoparticle Incorporation on Functional Properties and Migration of Ag/polyhydroxyalkanoate Nanocomposites
No full textUnderstanding silver nanoparticle leaching behavior from active biodegradable nanocomposites
No full textBiobased 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
Leaching mechanisms of PVP coated silver nanoparticles from anti-microbial bioplastics
No full textSilver based nanocomposites (Ag NC) show great potential as packaging materials, given their antimicrobial performance, protecting food against microbial degradation. The incorporation of silver nanoparticles (Ag NPs) in biobased food contact materials could be considered as an extra opportunity, contributing to a circular bioeconomy with less food waste. However, the lack of knowledge regarding nanoparticle release mechanisms from (biobased) nanocomposites and the fate on the nano-silver in the end-of-life packaging scenario’s (e.g. waste-disposal, recycling…), leads to restrictive legislation. In the case of silver, excessive NP exposure is undesired in terms of health, safety and environmental considerations. Therefore, this study aims to elucidate the NP migration mechanisms and influential factors such as NP size, matrix material (polyhydroxyalkanoate (PHA) vs cellulose) and external migration conditions on the leaching behaviour of Ag NPs and the antimicrobial performance of Ag NCs.
Commercially available spherical Polyvinylpyrrolidone (PVP) coated (~0.2%) Ag NPs are bulk mixed in the PHA matrices using a solvent-based masterblend approach on the one hand, and deposited on cellulose fiber surfaces on the other hand. The processing of these two models allows to differentiate between desorption and diffusion-based migration mechanisms. The internal structure is analysed using scanning electron microscopy (SEM), and the absolute silver loading is quantified via inductively coupled plasma atomic emission spectroscopy (ICP-AES). Subsequently, the NC models are exposed to food simulants (A, B, D2) via full immersion at standardized conditions (EU Regulation 10/2011). To distinguish the silver release in ionized versus nanoparticulate form, the simulant leachate is followed up longitudinally during the immersion by means of single particle inductively coupled plasma mass spectrometry (SP-ICP-MS). In addition, antimicrobial efficiency is tested on Gram-negative and Gram-positive bacteria.
The silver leaching behaviour was found to be dependent on the incorporation mode (bulk vs fiber surface) of the NPs in the NC matrix, rationalized by their different dominant migration mechanisms. In addition, the time- and size (40 vs. 65 nm) dependency of Ag NP leaching could be established and correlated to the NP mobility in two biodegradable matrix systems. A preferential leaching of the smaller NPs was observed. Ultimately, the physicochemical properties of the leaching medium such as acidity (simulant B) play an important role in the extent of silver release and its physical form (dissolved vs. nanoparticulate) in the leachate. Hence, the diffusion, dissolution and desorption release mechanisms of silver are elucidated.
In conclusion, this methodology can be further optimized to quantify potential NP migration from other biopolymers in order to ensure the safety and application potential of bio-nanocomposites as active packaging material
Understanding silver nanoparticle leaching behavior from active biodegradable nanocomposites
No full textBiobased 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
Understanding silver nanoparticle leaching behavior from active biodegradable nanocomposites
No full textBiobased 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
Understanding silver nanoparticle leaching behavior from active biodegradable nanocomposites
No full textBiobased 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
Leaching mechanisms of PVP coated silver nanoparticles from anti-microbial bioplastics
No full textSilver based nanocomposites (Ag NC) show great potential as packaging materials, given their antimicrobial performance, protecting food against microbial degradation. The incorporation of silver nanoparticles (Ag NPs) in biobased food contact materials could be considered as an extra opportunity, contributing to a circular bioeconomy with less food waste. However, the lack of knowledge regarding nanoparticle release mechanisms from (biobased) nanocomposites and the fate on the nano-silver in the end-of-life packaging scenario’s (e.g. waste-disposal, recycling…), leads to restrictive legislation. In the case of silver, excessive NP exposure is undesired in terms of health, safety and environmental considerations. Therefore, this study aims to elucidate the NP migration mechanisms and influential factors such as NP size, matrix material (polyhydroxyalkanoate (PHA) vs cellulose) and external migration conditions on the leaching behaviour of Ag NPs and the antimicrobial performance of Ag NCs.
Commercially available spherical Polyvinylpyrrolidone (PVP) coated (~0.2%) Ag NPs are bulk mixed in the PHA matrices using a solvent-based masterblend approach on the one hand, and deposited on cellulose fiber surfaces on the other hand. The processing of these two models allows to differentiate between desorption and diffusion-based migration mechanisms. The internal structure is analysed using scanning electron microscopy (SEM), and the absolute silver loading is quantified via inductively coupled plasma atomic emission spectroscopy (ICP-AES). Subsequently, the NC models are exposed to food simulants (A, B, D2) via full immersion at standardized conditions (EU Regulation 10/2011). To distinguish the silver release in ionized versus nanoparticulate form, the simulant leachate is followed up longitudinally during the immersion by means of single particle inductively coupled plasma mass spectrometry (SP-ICP-MS). In addition, antimicrobial efficiency is tested on Gram-negative and Gram-positive bacteria.
The silver leaching behaviour was found to be dependent on the incorporation mode (bulk vs fiber surface) of the NPs in the NC matrix, rationalized by their different dominant migration mechanisms. In addition, the time- and size (40 vs. 65 nm) dependency of Ag NP leaching could be established and correlated to the NP mobility in two biodegradable matrix systems. A preferential leaching of the smaller NPs was observed. Ultimately, the physicochemical properties of the leaching medium such as acidity (simulant B) play an important role in the extent of silver release and its physical form (dissolved vs. nanoparticulate) in the leachate. Hence, the diffusion, dissolution and desorption release mechanisms of silver are elucidated.
In conclusion, this methodology can be further optimized to quantify potential NP migration from other biopolymers in order to ensure the safety and application potential of bio-nanocomposites as active packaging material
Processing and Properties of Polyhydroxyalkanoate/ZnO Nanocomposites: A Review of Their Potential as Sustainable Packaging Materials
Full text linkThe escalating environmental concerns associated with conventional plastic packaging have accelerated the development of sustainable alternatives, making food packaging a focus area for innovation. Bioplastics, particularly polyhydroxyalkanoates (PHAs), have emerged as potential candidates due to their biobased origin, biodegradability, and biocompatibility. PHAs stand out for their good mechanical and medium gas permeability properties, making them promising materials for food packaging applications. In parallel, zinc oxide (ZnO) nanoparticles (NPs) have gained attention for their antimicrobial properties and ability to enhance the mechanical and barrier properties of (bio)polymers. This review aims to provide a comprehensive introduction to the research on PHA/ZnO nanocomposites. It starts with the importance and current challenges of food packaging, followed by a discussion on the opportunities of bioplastics and PHAs. Next, the synthesis, properties, and application areas of ZnO NPs are discussed to introduce their potential use in (bio)plastic food packaging. Early research on PHA/ZnO nanocomposites has focused on solvent-assisted production methods, whereas novel technologies can offer additional possibilities with regard to industrial upscaling, safer or cheaper processing, or more specific incorporation of ZnO NPs in the matrix or on the surface of PHA films or fibers. Here, the use of solvent casting, melt processing, electrospinning, centrifugal fiber spinning, miniemulsion encapsulation, and ultrasonic spray coating to produce PHA/ZnO nanocomposites is explained. Finally, an overview is given of the reported effects of ZnO NP incorporation on thermal, mechanical, gas barrier, UV barrier, and antimicrobial properties in ZnO nanocomposites based on poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate). We conclude that the functionality of PHA materials can be improved by optimizing the ZnO incorporation process and the complex interplay between intrinsic ZnO NP properties, dispersion quality, matrix-filler interactions, and crystallinity. Further research regarding the antimicrobial efficiency and potential migration of ZnO NPs in food (simulants) and the End-of-Life will determine the market potential of PHA/ZnO nanocomposites as active packaging material.Funding:
This research was funded by the Special Research Fund (BOF) of Hasselt University, grant number BOF20DOC06.
Acknowledgments:
The authors acknowledge all co-workers of MPR&S, imo-imomec, UHasselt, and beyond, for fruitful discussions on PHA research throughout the years
Effect of Nanoparticle Incorporation on Functional Properties and Migration of Ag/polyhydroxyalkanoate Nanocomposites
No full textSilver-nanocomposites offer great potential as active packaging material due to their antimicrobial properties. However, limited understanding of silver nanoparticle (Ag NP) release mechanisms, especially from biodegradable nanocomposites, poses challenges in terms of human health and environmental risks, resulting in restrictive regulatory measures. This study aims to understand how the incorporation of Ag NPs affects dispersity, functional properties and Ag°/Ag+ migration from Ag/poly(3-hydroxybutyrate-co-3-hydroxyhexanoate (PHBHHx) nanocomposite films. Commercial spherical polyvinylpyrrolidone-coated Ag NPs of 40 nm were incorporated in PHBHHx (0.2-2 wt.%) via melt extrusion (Dry-mix method). Alternatively, a Masterblend method was applied by pre-dispersing the NPs via solvent casting, before extrusion. Nanocomposite films were obtained via subsequent hot-pressing for further characterization. Specific migration was assessed by full immersion tests, using Milli-Q water and food simulants A and B at 40 °C (EU Regulation 10/2011). The leachate was analysed over 10 days via Single Particle Inductively Coupled Plasma Mass Spectrometry to monitor NP size, particle number concentration and dissolved concentrations. The Dry-mix approach seems optimal in terms of time efficiency and NP dispersity. The latter is evidenced by colour, opacity, UV-VIS transmittance and scanning electron microscopy analyses. Interestingly, using both methods, the tensile properties, crystallinity and thermal stability do not change significantly when varying NP loading up to 2 wt.%. In addition, a 30 % reduction in oxygen permeability is achieved for the highest NP loading. Although increasing NP loading did result in an incremental release of Ag°/Ag+, the migration remained under the specific migration limit of 50 µg Ag/kg food for all food simulants, with the highest migration in the acidic food simulant B. So far, we conclude that the fabricated Ag/PHBHHx films show potential as safe, non-transparent active food packaging material with improved oxygen barrier properties
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