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Project Title: „ Large area deposition technologies of multifunctional antibacterial and antiviral nanocoatings”

Funding: European Regional Development Fund (ERDF), Measure “Support for applied research”

Project No.:

Period: 1 January 2022 – 30 November 2023

Project costs: 500 000,00 EUR

Project implementer: Institute of Solid State Physics, University of Latvia

Cooperation partner: Latvian Biomedical Research and Study Centre

Principle Investigator BMC: Dr. biol. A. Zajakina

Project summary:

The aim of this industrial research project is to develop advanced roll-to-roll (hereinafter R2R) physical vapour deposition (PVD) technology for large scale production of a new type of multifunctional antibacterial and antiviral (MABAV) coatings. We propose to produce and investigate MABAV materials in the form of thin films and multilayers with photochromic and transparent conducting multifunctionalities based on rare-earth oxy-hydrides (REHO) as YHO and metal oxides (MO) as ZnO or WO3 (MoO3) in combination with the metal (Cu, Ag, etc.) and deuterium (D) dopants.

Application: smart windows/glass, smart foils/sheets (as partitions and barriers in public places) and transparent electronics applications, including medical devices, with the aim to prevent the diseases in terms of reduction of bacteria and virus prevalence with attention to the SARS-CoV-2 to limit and reduce the spread of this virus and consequently caused illness COVID-19.

Project’s products:

  • Novel R2R deposition technology of MABAV coatings on flexible substrate (results: new technology, patent);
  • Novel REHO and MO thin films and multilayers with advanced MABAV properties (results: scientific articles, new product prototype, patent).

Project’s impact:

The project will contribute to Global R2R Technologies for Flexible Devices Market, Global Smart Glass and Smart Window Market, and Global Semiconductor Market supporting the SARS-CoV-2 spread decline in exploitation of such products as glasses, e-paper, plastic, sheets, foils, touch displays and other devices, where transparent materials must be used, thus having a global impact by sustaining the human health and world economy wellness in general, and ensuring the competitiveness of Latvian science and Industry at the international level.

Information published 03.01.2022.

Progress of the project:

1 January 2022 – 31 March 2022

To evaluate the antibacterial properties of novel nanocoatings  the testing methodology was established and approved. The method is based on biocidal activity testing on surfaces according to EN ISO 1276 and EN ISO 16615 with modifications to improve the efficiency of the screening technology. The tests are performed in 12-well plates and the bacteria cultivation is optimized for 96-well plate incubation, which allows fast and reliable initial screening of tested samples. Currently, the protocol is optimised for gram-negative and gram-positive bacteria cultivation: Escherichia coli, Staphylococcus aureus. Preliminary data on biocidal activity of tungsten oxide containing nanocoatings were obtained. Furthermore, to evaluate the antiviral activity of nanocoatings, several model viruses were selected: Semliki forest virus (mammalian enveloped RNA virus), MS2 bacteriophage (RNA non-enveloped virus), Pf1 bacteriophage (circular single-stranded DNA filamentous virus). The respective viruses were produced and quantified.

Information published 31.03.2022.

Progress of the project

1 April 2022 – 30 June 2022

A set of zinc oxide and copper antimicrobial nanocoatings were analysed using two types of bacteria, including Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. ZnO and ZnOCuZnO coatings did not show a significant antibacterial effect, while Cu coated PET samples showed antibacterial activity. When comparing two bacterial cultures, S. aureus showed a much higher degree of inhibition than E. coli, respectively. When analyzing the viability properties of bacterial cells (MTT test), it was found that copper coatings reduce the viability of cells in both cultures. In addition, the amount of reactive oxygen species (ROS) was measured by cultivating cells on different coatings. As a result, only copper showed an active type of oxygen on the surface, causing a significant antibacterial effect. Similar results were obtained in virus experiments using MS2 bacteriophage and replication defective human SFV virus, where only Cu-coated PET samples showed statistically significant antiviral effects. Innovative digital PCR quantification method was used to determine the SFV virus titre, which was presented at FEBS3+ conference, 16.06 – 18.06.2022, Tallinn, Estonia. The title of the poster presented was “Quantification of alphaviral vectors using droplet digital PCR”, autors: Ksenija Korotkaja and Anna Zajakina.

Information published 30.06.2022.

Progress of the project

1 July 2022 – 30 September 2022

Testing activities for anti-bacterial and anti-viral effects include a wide range of testing methodologies and techniques. Performed activity is not limited to the implementation of traditionally used testing methodologies. The methodologies described in the testing standards were adapted to the optimal number of tested samples in their more suitable sizes. Optimizations led to more effective usage of samples and increased overall accuracy of the experiments. The optimized methodology has been approved on several bacterial species and supplemented with methods for determining anti-viral effects. Molecular testing methodologies are used in order to better understand the mechanisms of action of the tested anti-microbial coatings on microorganisms. Changes in the enzymatic activity of bacteria and the production of reactive oxygen species compounds in contact with the coating surface are determined. The experimental work with a wild-type SARS-CoV2 virus (lineage B1.1.7) has been started at BSL3 biosafety laboratory. The methodology for virus cultivation and testing on the PET surface will be developed.

Information published 30.09.2022.

Progress of the project

1 October 2022 – 31 December 2022

The anti-microbial activity of WO/Cu for a series of large-area nanocoating samples was analysed using two types of bacteria, including Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. One sample showing a high E. coli inhibition effect (>5 log) was selected, as well as other samples with a lower inhibition effect (2-3 log). However, in selected samples, the antimicrobial effect with the S. aureus bacterium was not high (<2 log). The anti-microbial effect was analyzed depending on the amount of bacteria and the incubation time (2 h, 24 h). In general, the highest anti-microbial effect was observed with prolonged incubation time and decreasing the number of bacteria, which was confirmed by two methods (drop micro-dilution assay and standard Petri plate assay). Previously selected samples are tested with an MS2 bacteriophage.

The SARS-CoV2 (line B1.1.7) virus was produced in the BSL3 safety level laboratory. The virus titer obtained was less than 105/ml, which is not sufficient for anti-viral tests. It is planned to optimize the methodology for virus synthesis using modified cell lines.

Information published 30.12.2022.

Progress of the project

1 January 2023 – 31 March 2023

Within the reporting period, the data on the antibacterial (E. coli, S. aureus) and anti-viral (MS2 bacteriophage, SFV virus) properties of WO/Cu/WO and ZnO/cu/ZnO coatings were generalized. Two publications are being prepared. In addition, the experiments to analyze the photoactive properties of coatings were started. ZnO-containing samples were irradiated with 365 nm (5-10 mJ/cm2) light. The results did not show an increase of the antibacterial effect. It is planned to optimize the surface nanostructure to enhance the photocatalytic effect. The results of the anti-SARS-CoV2 testing showed that the amount of the virus was insufficient for analysis. New genetically modified cell lines and virus samples able to efficiently infect the cells were ordered. The SARS-CoV2 virus infection dose (TCID50) under optimized conditions is expected to be sufficient to perform antiviral tests on selected samples.

Information published 31.03.2023.

Progress of the project

1 April 2023 – 30 June 2023

Within the reporting period, a method for testing nanocoatings with wild-type SARS-CoV2 virus was developed and validated. Cell cultures expressing the human SARS-CoV2 ACE2 receptor (angiotensin-converting enzyme-2), as well as the TMPRSS2 serine protease, which both contribute to the infectious process, were used to produce the virus. Virus titers of 10^6-10^7 iu/ml were obtained according to TCID50 data, which is shown to be sufficient to detect a virus titer reduction rate of around 5 Log. The validation of the test was carried out using a Cu nanocoated sample, which showed 99.9% virus inhibition (>4 Log) compared to the PET sample. In addition, the recombinant alphavirus (SFV) was synthesized and purified, the titer of which was determined by the newly established digital PCR quantification method. Synthesized SFV and SARS-CoV2 viruses will be used for testing of antiviral properties of nanocoatings.

Information published 30.06.2023.

Progress of the project

1 July 2023 – 30 September 2023

Within the reporting period, the nanocoatings were assessed with the wild-type SARS-CoV2 virus. One sample of SO2PO6 WO/Cu/WO, which showed higher (>4log) inhibition by bacteria, SFV virus and MS2 bacteriophage, was selected for SARS-CoV2 testing. Incubation of the SARS-CoV2 virus on the test surface was carried out over a period of 30 min and 24 hours. After 30 min incubation, the sample showed no significant inhibition of the virus, while long-term incubation led to a decrease of 2.5 Log, which corresponds to an impressive decrease in viral activity of around 99.67%. It is important to note that the Cu coating showed an effective reduction after just 30 min of incubation. The data obtained indicate a high potential of Cu coating as a fast viral inhibitory surface material and indicate the dynamic nature of the SO2PO6 surface with effects over a longer incubation period. In addition to tests with the SARS-CoV2 virus, standard anti-bacterial tests were performed on new Mo and Y-containing samples, some of which showed >4 log bacterial reductions.

Information published 02.10.2023.

Progress of the project

1 October 2023 – 30 November 2023

Within the final reporting period, we tested the antibacterial activity YHO/Cu and MoO3/Cu/MoO3, which revealed a very high >5 Log reduction rate against E. coli, S. aureus.  Nevertheless, the reproducibility of the results varied significantly for some samples, demonstrating no optimal stability and homogeneity of the samples. In addition, we finished the assessment of nanocoatings with the wild-type SARS-CoV2 virus. A very high anti-SARS-CoV-2 effect was demonstrated for YHO/Cu (YHO4PO2 and YHO4PO4, large area deposited series) samples with TCID50 reduction rate > 5.7 Log.

In summary, the data obtained in this project demonstrate the high potential of transparent conducting WO3/Cu/WO3 and MoO3/Cu/MoO3, and photochromic YHO/Cu coatings as novel biocidal materials for various applications.

Report summary

Information published 30.11.2023.