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. 2023 May 12;14(5):270.
doi: 10.3390/jfb14050270.

Engineered Cross-Linked Silane with Urea Polymer Thin Durable Coatings onto Polymeric Films for Controlled Antiviral Release of Activated Chlorine and Essential Oils

Elisheva Sasson  1 , Omer Agazani  2 , Eyal Malka  1 , Meital Reches  2 , Shlomo Margel  1
Affiliations

Engineered Cross-Linked Silane with Urea Polymer Thin Durable Coatings onto Polymeric Films for Controlled Antiviral Release of Activated Chlorine and Essential Oils

Elisheva Sasson et al. J Funct Biomater. .

Abstract

In March 2020, the World Health Organization announced a pandemic attributed to SARS-CoV-2, a novel beta-coronavirus, which spread widely from China. As a result, the need for antiviral surfaces has increased significantly. Here, the preparation and characterization of new antiviral coatings on polycarbonate (PC) for controlled release of activated chlorine (Cl+) and thymol separately and combined are described. Thin coatings were prepared by polymerization of 1-[3-(trimethoxysilyl)propyl] urea (TMSPU) in ethanol/water basic solution by modified Stöber polymerization, followed by spreading the formed dispersion onto surface-oxidized PC film using a Mayer rod with appropriate thickness. Activated Cl-releasing coating was prepared by chlorination of the PC/SiO2-urea film with NaOCl through the urea amide groups to form a Cl-amine derivatized coating. Thymol releasing coating was prepared by linking thymol to TMSPU or its polymer via hydrogen bonds between thymol hydroxyl and urea amide groups. The activity towards T4 bacteriophage and canine coronavirus (CCV) was measured. PC/SiO2-urea-thymol enhanced bacteriophage persistence, while PC/SiO2-urea-Cl reduced its amount by 84%. Temperature-dependent release is presented. Surprisingly, the combination of thymol and chlorine had an improved antiviral activity, reducing the amount of both viruses by four orders of magnitude, indicating synergistic activity. For CCV, coating with only thymol was inactive, while SiO2-urea-Cl reduced it below a detectable level.

Keywords: COVID-19; N-halamine compounds; T4 bacteriophage; antiviral coatings; canine coronavirus; essential oils.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Oxidative transfer of chlorine from a chlorinated amide to (1) water and (2) pathogens.
Figure 2
Figure 2
Production of SiO2-urea-Cl and SiO2-urea-thymol thin coatings on polycarbonate (PC) films.
Figure 3
Figure 3
Chemical structures of thymol (left) and TMSPU (right).
Figure 4
Figure 4
Mayer rod system.
Figure 5
Figure 5
AFM topography analysis of PC (A), corona-treated PC (B), PC/SiO2-urea (C), PC/SiO2–urea-Cl (D), PC/SiO2–urea-thymol (E) and PC/SiO2-urea-Cl-thymol films (F).
Figure 6
Figure 6
FTIR/ATR spectra of PC (bottom), PC/SiO2-urea (middle) and PC/SiO2-urea-Cl (top) films.
Figure 7
Figure 7
FTIR/ATR spectra of thymol (bottom), PC/SiO2-urea-thymol (middle) and PC/SiO2-urea-Cl-thymol (top) films.
Figure 8
Figure 8
(A) XPS spectra of corona-treated PC (blue), PC/SiO2-urea (orange) and PC/SiO2-urea-Cl (gray) films. Magnification of the PC/SiO2-urea film spectra depicts the peaks corresponding to (B) N 1s and (C) Si 2p, belonging to the SiO2–urea coating. Magnification of the PC/SiO2-urea-Cl film spectrum shows the peaks corresponding to (D) Cl 2p, belonging to SiO2-urea-Cl coating.
Figure 9
Figure 9
Release rates of activated chlorine from PC/SiO2-urea-Cl film at room temperature, 4 °C and −4 °C.
Figure 10
Figure 10
Release rates of thymol from PC/SiO2-urea films at room temperature and −4 °C.
Figure 11
Figure 11
Antiviral activity against CCV (A) showing log(TCID50/mL) on the bare PC and SiO2-urea-Cl-thymol coated surfaces. Microscope images ×100 of CRFK cells incubated with CCV on bare PC (B) and on PC coated with SiO2-urea-Cl (C) or SiO2-urea-Cl-thymol (D). The SD is based on one experiment in triplicate. * represents Student’s t-test at a significance level of p < 0.05.
Figure 12
Figure 12
Antiviral activity against bacteriophage T4. (A) Normalized PFU/mL on bare PC and coated surfaces. Images show a layer of E. coli on wells with 1.75 cm radius after seeding bacteriophages from (B) bare PC and (C) PC/SiO2-urea-Cl-thymol. The SD is based on three experiments performed in triplicate. Each letter represents an insignificant group, using an ANOVA test and Fisher’s least significant difference (LSD) post hoc test, with a significance level of p < 0.05.
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