Periodic Reporting for period 2 - Triple-A-COAT (Sustainable Development of a Safe and Biobased Antimicrobial, Antifungal and Antiviral Nanocoating Platform)
Berichtszeitraum: 2024-03-01 bis 2025-08-31
Following COVID-19, the world needs to be better prepared for future pandemics, as well as ongoing threats from infectious diseases such as seasonal influenza, hospital superbugs and stomach infections. Many disease-causing microorganisms, including bacteria, viruses and microscopic fungi, are spread through frequently touched surfaces, such as door handles, seat covers and rails. There is an increasing interest in antimicrobial coatings for such surfaces especially in busy areas such as public buildings and on public transport. These can inhibit microbial contamination or growth on surfaces, especially in between cleaning.
Current antimicrobial coatings use biocide chemicals such as silver-based agents to kill microorganisms. However, these can damage the environment, and microorganisms can develop resistance so the chemicals become less effective over time. Also, some microorganisms form a biofilm which protects them and helps them survive longer. We need new antimicrobial strategies that avoid resistance development as well as being effective against multiple kinds of microorganisms, including those that form biofilms.
It is also important that new antimicrobial coatings are safe and sustainable through all stages of production, application and use. New nanomaterials are being investigated in particular as the basis for new antimicrobial coatings. Their safety must be thoroughly tested at every stage of development.
The EU-funded Triple-A-COAT project is developing a new antimicrobial, antifungal and antiviral coatings for frequently touched surfaces, designed for use in buses. The project is using nanocellulose as the basis of its coatings technology. This is a material obtained from renewable forest resources, or can be made by special bacteria in the lab. It has many potential applications, typically as a replacement for plastic, such as in in food packaging. In Triple-A-COAT we are using nanocellulose in place of oil-based materials as a more sustainable option.
Triple-A-COAT is using antibiofilm compounds, antimicrobial peptides, and nanopatterning inspired by antimicrobial surfaces found in nature, such as on dragonfly wings. These new approaches should give us antimicrobial coatings which effectively inhibit micro-organisms while preventing the development of antimicrobial resistance.
The most promising coatings developed in the project will be tested in a lifelike simulation of a bus. We will also conduct a thorough life cycle assessment of the new coatings to measure their environmental performance in comparison with existing coatings. The results of the project will then be developed commercially, with new coatings available for use in public transport, hospitals and other busy places within a few years after the end of the project.
Current antimicrobial coatings use biocide chemicals such as silver-based agents to kill microorganisms. However, these can damage the environment, and microorganisms can develop resistance so the chemicals become less effective over time. Also, some microorganisms form a biofilm which protects them and helps them survive longer. We need new antimicrobial strategies that avoid resistance development as well as being effective against multiple kinds of microorganisms, including those that form biofilms.
It is also important that new antimicrobial coatings are safe and sustainable through all stages of production, application and use. New nanomaterials are being investigated in particular as the basis for new antimicrobial coatings. Their safety must be thoroughly tested at every stage of development.
The EU-funded Triple-A-COAT project is developing a new antimicrobial, antifungal and antiviral coatings for frequently touched surfaces, designed for use in buses. The project is using nanocellulose as the basis of its coatings technology. This is a material obtained from renewable forest resources, or can be made by special bacteria in the lab. It has many potential applications, typically as a replacement for plastic, such as in in food packaging. In Triple-A-COAT we are using nanocellulose in place of oil-based materials as a more sustainable option.
Triple-A-COAT is using antibiofilm compounds, antimicrobial peptides, and nanopatterning inspired by antimicrobial surfaces found in nature, such as on dragonfly wings. These new approaches should give us antimicrobial coatings which effectively inhibit micro-organisms while preventing the development of antimicrobial resistance.
The most promising coatings developed in the project will be tested in a lifelike simulation of a bus. We will also conduct a thorough life cycle assessment of the new coatings to measure their environmental performance in comparison with existing coatings. The results of the project will then be developed commercially, with new coatings available for use in public transport, hospitals and other busy places within a few years after the end of the project.
During the first reporting period, we exchanged the three nanocellulose (NC) materials—CNC, CNF, and BNC—and tested their physical, chemical, toxicological, and antimicrobial properties. Since none of the unmodified materials showed antimicrobial activity, we enhanced them using three strategies: antimicrobial peptides (AMPs), 2-aminoimidazoles (2AIs), and nanopatterning.
During the second reporting period, we improved the antimicrobial properties of the NC. Enhancing NC with AMPs was achieved by simply mixing the NC with the AMPs. Higher concentrations could be retrieved by mixing in different steps (also known as ‘layering method’). Functionalization of the 2AIs was done in two ways. The first way involved mixing of TEMPO-oxidized NC with 2AIs, which lead to electrostatic interactions between the 2AIs and the NC. The second way was reductive amination, where binding sites were created on the NC and the 2AIs could be attached covalently. The first method is simpler and showed the strongest antimicrobial effects, so it was selected for further use.
The antimicrobial properties of the NC were further improved by creating nanopatterns in the NC. This was done using two method. First, spiky structures were introduced in the NC with ion milling. Using this method, ion beams physically push away atoms, creating NC spikes that can pierce the microbes. Second, wet nanoimprint lithography (wet-NIL) was used. Here, a pattern is introduced on the NC using a stamp. Ion milling was successful for all types of NC, whereas wet-NIL only worked well for CNC. However, wet-NIL offers better potential for up-scaling.
Next, different linker methods were tested to make durable NC coatings. Two systems showed the best stability and were applied through standardized spraying: one from our partner SuSoS based on their AziGrip technology and a polydopamine+boric acid linker. We achieved the best mechanical performance when spraying 10 layers.
We tested the modified NC for antimicrobial activity using standard tests and in-house assays that better reflect real-world conditions. AMP- and 2AI-modified NC showed strong antibacterial and antifungal activity in suspension. On coatings, 2AI remained consistently active; AMP coatings showed more variation and are still being optimized.
Based on performance and stability, four coating systems were selected for further validation. A first life cycle assessment was also completed, comparing the environmental impact of the different components of the coatings, identifying where some changes may be made to further improve their sustainability.
In the coming months, the selected coatings will undergo toxicity testing, and concentrations will be further optimized. Up-scaling of all components has started, and current production estimates indicate that we can supply the upcoming bus demonstration. Additional optimization will keep pushing the TRL of both AMPs and 2AIs forward.
During the second reporting period, we improved the antimicrobial properties of the NC. Enhancing NC with AMPs was achieved by simply mixing the NC with the AMPs. Higher concentrations could be retrieved by mixing in different steps (also known as ‘layering method’). Functionalization of the 2AIs was done in two ways. The first way involved mixing of TEMPO-oxidized NC with 2AIs, which lead to electrostatic interactions between the 2AIs and the NC. The second way was reductive amination, where binding sites were created on the NC and the 2AIs could be attached covalently. The first method is simpler and showed the strongest antimicrobial effects, so it was selected for further use.
The antimicrobial properties of the NC were further improved by creating nanopatterns in the NC. This was done using two method. First, spiky structures were introduced in the NC with ion milling. Using this method, ion beams physically push away atoms, creating NC spikes that can pierce the microbes. Second, wet nanoimprint lithography (wet-NIL) was used. Here, a pattern is introduced on the NC using a stamp. Ion milling was successful for all types of NC, whereas wet-NIL only worked well for CNC. However, wet-NIL offers better potential for up-scaling.
Next, different linker methods were tested to make durable NC coatings. Two systems showed the best stability and were applied through standardized spraying: one from our partner SuSoS based on their AziGrip technology and a polydopamine+boric acid linker. We achieved the best mechanical performance when spraying 10 layers.
We tested the modified NC for antimicrobial activity using standard tests and in-house assays that better reflect real-world conditions. AMP- and 2AI-modified NC showed strong antibacterial and antifungal activity in suspension. On coatings, 2AI remained consistently active; AMP coatings showed more variation and are still being optimized.
Based on performance and stability, four coating systems were selected for further validation. A first life cycle assessment was also completed, comparing the environmental impact of the different components of the coatings, identifying where some changes may be made to further improve their sustainability.
In the coming months, the selected coatings will undergo toxicity testing, and concentrations will be further optimized. Up-scaling of all components has started, and current production estimates indicate that we can supply the upcoming bus demonstration. Additional optimization will keep pushing the TRL of both AMPs and 2AIs forward.
At the end of reporting period 2, four Triple-A-COATings were selected based on their promising antimicrobial activity, durability, and applicability. These coatings will be further optimized and validated at laboratory scale, followed by demonstration in a larger-scale setup during reporting period 3.
We have already begun exploring their potential for commercialization by engaging with industry partners, investing in scale-up activities, and reviewing regulatory requirements. If the results of the upcoming work remain encouraging, we will continue to advance these efforts.
Overall, we aim to develop a new platform for antimicrobial coatings with several different options for materials, antimicrobial functions and coating type. This will enable coatings to be designed for different needs, for example long or short term use, broad spectrum or targeting specific kinds of microorganism.
We have already begun exploring their potential for commercialization by engaging with industry partners, investing in scale-up activities, and reviewing regulatory requirements. If the results of the upcoming work remain encouraging, we will continue to advance these efforts.
Overall, we aim to develop a new platform for antimicrobial coatings with several different options for materials, antimicrobial functions and coating type. This will enable coatings to be designed for different needs, for example long or short term use, broad spectrum or targeting specific kinds of microorganism.