The disclosure of the present patent application relates to antimicrobial treatments, and particularly to antimicrobial colloidal particles which may be used as additives for acrylate polymers, films, surface finishings, coatings and the like.
Bacterial colonization and subsequent biofilm formation on materials are well known for degrading material properties, such as optical clarity, texture, and the like, as well as affecting the material's normal functioning while simultaneously putting users at risk of infection. Such concerns are particularly relevant with regard to high-touch surfaces, such as personal electronics, portable devices, light switches, door handles, kitchen countertops, stovetops, food appliance surfaces, and lavatory fixtures. Studies on electronic devices have revealed high exposure risks from contamination by environmental pathogens and skin-resident microbes. One study found that more than 80% of bacteria carried by users end up contaminating their mobile device screens. This is of particular concern due to the growing prevalence of drug-resistant organisms. Another study found a 69.9% prevalence of multidrug-resistant microbes on a common portable device screen, with about 50% of identified bacterial species being resistant to ampicillin and trimethoprim-sulfamethoxazole. Hospital patients are particularly susceptible to nosocomial infections from contaminated mobile devices. Studies have also found that poor hand hygiene and contact with electronic devices are responsible for spreading infections among hospital medical staff and people outside the hospital that the hospital staff comes into contact with. Additionally, fomites are considered an important transmission route of COVID-19, especially for high-touch electronic surfaces.
Although common cleaning agents and disinfectants are effective at removing dirt and microbial contaminants, they can corrode, damage, and leave residual harmful chemicals and products on both skin and device surfaces. Electronic devices often need to be treated with manufacturer-approved detergents which require specialized training for proper application in order to avoid surface damage, liquid infiltration, and electrical short-circuiting. Thus, multilevel antimicrobial polymeric colloids and device screens containing the same solving the aforementioned problems are desired.
The multilevel antimicrobial polymeric colloids include colloidal particles which may, as a non-limiting example, be used as antimicrobial additives for acrylate polymers, films, surface finishings, coatings and the like. The colloidal particles may be suspended in a suitable medium, such as, for example, distilled deionized (DDI) water or the like. Each multilevel antimicrobial polymeric colloidal particle includes a polymer scaffold and at least one antimicrobial polymer carried on the polymer scaffold. The polymer scaffold and the at least one antimicrobial polymer form a hollow colloidal particle. As non-limiting examples, the polymer scaffold may be formed from polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP) or a combination thereof. As a non-limiting example, the at least one antimicrobial polymer may be at least one ionic polymer, such as polycationic polymers, polyanionic polymers or mixed ion polymers. As further non-limiting examples, the at least one antimicrobial polymer may be polyethyleneimine (PEI), polyhexamethylene biguanide (PHMB) or a combination thereof.
Each multilevel antimicrobial polymeric colloidal particle may further include a core within the hollow colloidal particle. The core may have antibacterial, antimicrobial, disinfecting, virucidal, fungicidal and/or sporicidal properties. Non-limiting examples of such materials which may be included in the core include, but are not limited to, antimicrobial metals, antimicrobial metal ions, antimicrobial metal oxides, antimicrobial chemicals, plant-derived antimicrobial phytochemicals, silver, silver compounds, silver salts, silver oxides, copper, copper compounds, copper salts, copper oxides, disinfectants, bactericidal short chain polymers, bactericidal short chain oligomers, ionic liquid compounds, alcohols, peracetic acids, essential oils, and combinations thereof.
An antimicrobial screen for use in electronics, for example, may incorporate the multilevel antimicrobial polymeric colloidal particles described above in order to impart antimicrobial properties to the screen. The antimicrobial screen includes a coating formed from an optically clear acrylic material with the multilevel antimicrobial polymeric colloidal particles incorporated therein. The coating may be coated onto a glass, metal or plastic substrate.
The antimicrobial screen may be made by mixing the multilevel antimicrobial polymeric colloidal particles with acrylate syrup to form a mixture. A radical catalyst is added to the mixture. As a non-limiting example, 2-hydroxy-2-methyl-propiophenone (2-HMP) may be used as the radical catalyst. As another non-limiting example, ammonium persulfate (APS) may be used as the radical catalyst. A layer of the mixture is coated onto a glass, metal or plastic substrate, and the layer of the mixture is cured on the substrate using ultraviolet curing. As non-limiting examples, the acrylate syrup may be 2-hydroxylpropyl acrylate (2-HPA), N,N-dimethylacrylamide (DMAA), 1,6-hexanediol diacrylate (HDDA), or combinations thereof.
These and other features of the present subject matter will become readily apparent upon further review of the following specification.
Similar reference characters denote corresponding features consistently throughout the attached drawings.
The multilevel antimicrobial polymeric colloids include colloidal particles which may, as a non-limiting example, be used as antimicrobial additives for acrylate polymers, films, surface finishings, coatings and the like. The colloidal particles may be suspended in a suitable medium, such as, for example, distilled deionized (DDI) water or the like. Each multilevel antimicrobial polymeric colloidal particle includes a polymer scaffold and at least one antimicrobial polymer carried on the polymer scaffold. The polymer scaffold and the at least one antimicrobial polymer form a hollow colloidal particle. As non-limiting examples, the polymer scaffold may be formed from polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP) or a combination thereof. As a non-limiting example, the at least one antimicrobial polymer may be at least one ionic polymer, such as polycationic polymers, polyanionic polymers or mixed ion polymers. As further non-limiting examples, the at least one antimicrobial polymer may be polyethyleneimine (PEI), polyhexamethylene biguanide (PHMB) or a combination thereof.
Each multilevel antimicrobial polymeric colloidal particle may further include a core within the hollow colloidal particle. The core may have antibacterial, antimicrobial, disinfecting, virucidal, fungicidal and/or sporicidal properties. Non-limiting examples of such materials which may be included in the core include, but are not limited to, antimicrobial metals, antimicrobial metal ions, antimicrobial metal oxides, antimicrobial chemicals, plant-derived antimicrobial phytochemicals, silver, silver compounds, silver salts, silver oxides, copper, copper compounds, copper salts, copper oxides, disinfectants, bactericidal short chain polymers, bactericidal short chain oligomers, ionic liquid compounds, alcohols, peracetic acids, essential oils, and combinations thereof.
Table 1 below shows the composition of four exemplary multilevel antimicrobial polymeric (MAP) colloids, referred to herein as “MAP-1”; “MAP-1 2*”; “MAP-P”; and “MAP-P 2*”.
An antimicrobial screen for use in electronics, for example, may incorporate the multilevel antimicrobial polymeric colloidal particles described above in order to impart antimicrobial properties to the screen. The antimicrobial screen includes a coating formed from an optically clear acrylic material with the multilevel antimicrobial polymeric colloidal particles incorporated therein. The coating may be coated onto a glass, metal or plastic substrate.
The antimicrobial screen may be made by mixing the multilevel antimicrobial polymeric colloidal particles with an acrylate syrup under rapid mixing to form a viscous mixture. A radical catalyst is added to the mixture. As a non-limiting example, 2-hydroxy-2-methyl-propiophenone (2-HMP) may be used as the radical catalyst. As another non-limiting example, ammonium persulfate (APS) may be used as the radical catalyst. A layer of the mixture is coated onto a glass, metal or plastic substrate, and the layer of the mixture is cured on the substrate using ultraviolet curing. As non-limiting examples, the acrylate may be 2-hydroxylpropyl acrylate (2-HPA), N,N-dimethylacrylamide (DMAA), 1,6-hexanediol diacrylate (HDDA), or combinations thereof. Ultraviolet (UV) exposure (at, for example, 352 nm) induces 2-HMP photocleavage to produce benzoyl radicals and α-hydroxyalkyl radicals catalyzing acrylate step polymerization.
Table 2 below shows the compositions of exemplary antimicrobial screens prepared as described above, where MAP-P colloids are used in combination with 2-HPA, and MAP-1 colloids are used in combination with DMAA.
In experiments, acrylate-MAP mixtures were prepared with 0.5 mL MAP-1 or MAP-P solutions (made with DDI water) added to 4.4 mL of DMAA or 2-HPA acrylates, followed by vortexing for 1 minute. The prepared acrylate-MAP mixtures were each deposited on a 2.54×2.54 cm2 area of a glass slide with a bar coater. The deposited acrylate-MAP layer was covered with a polyethylene terephthalate (PET) release film to avoid oxidizing the acrylate. Each acrylate-MAP layer was bar coated at a thickness of 50 μm. UV curing was performed in a chamber with a fluence of 2.5 mW/cm2. The main UV wavelength was 352 nm, with an exposure duration of 2 hours˜7 hours, a temperature of 19.2° C.˜19.5° C., and a humidity level of 33% RH˜37% RH.
Following UV curing of DMAA & MAP-1 and 2-HPA & MAP-P samples, the release film was torn off, leaving the acrylate-MAP coating layer intact.
The cured acrylate-MAP samples were examined under an optical microscope, as shown in
The optical transmittance or transparency of the cured acrylate-MAP samples were determined by a Varioscan spectrophotometer according to chapter “5.10 Opacity” of the ISO/IEC 10373-1:2006(E) standard. As shown in
The swelling ratio and gel fraction tests are convenient methods for measuring the quantity of insoluble components in a sample and the degree of crosslinking in polymers. The swelling ratio represents the fraction increase after water adsorption from oligomers and free polymers not crosslinked into the polymer network. The gel fraction measures the quantity of insoluble components after soaking and drying, usually representing the fraction of crosslinked or networked polymers. The cured acrylate-MAP samples were hydrated by soaking in 37° C. water for 36 hours, following the protocols published in the ASTM D2765 and ISO 54759 standards. The swelling ratios were obtained as additional fraction to the initial weight w0. The samples were further dried at 60° C. in an oven until a constant weight was obtained. The gel fraction was the ratio of the dry weight to the initial weight. The swelling ratio and the gel fraction were calculated as follows:
where w0 is the initial weight, wi is the sample weight after immersing it in 37° C. DDI water for 36 hours, and wD is the dry weight after drying at 60° C. for 2 hours.
For the swelling ratio and gel fraction tests, 2-HPA and MAP-P screens were immersed in 37° C. DDI water for 36 hours, as discussed above. Visual inspection showed that the cured acrylate-MAPs were identical in appearance before and after the swelling ratio and gel fraction tests. The swelling ratio of the 2-HPA and MAP-P screen was about 30% and the gel fraction was over 99%, indicating that the samples are insoluble in water and are fully crosslinked. This also confirmed that MAP incorporation does not affect the appearance nor the mechanical properties of the acrylate material.
The antimicrobial properties of cured acrylate-MAP screen samples were tested against S. aureus, E. coli, and Φ6 bacteriophage (a virus surrogate). The Φ6 bacteriophage belongs to the only known family of enveloped phages, Cystoviridae. Its lipid envelope is reported to exert a similar role as human infective virus under survival trials. Tests were conducted on 2.54×2.54 cm2 pieces of cured acrylate-MAP screen at room conditions for contact times of either 60 seconds or 10 minutes. The test conditions and operations complied with the European standard EN 13727, as well as the requirements of ISO 22196, ASTM E3031, JIS L-1902, 2002, and GB-21551.2-2020.
The 2.54×2.54 cm2 pieces of cured acrylate-MAP screen were deliberately challenged with 106 CFU of bacteria and PFU of bacteriophages. After 60 seconds or 10 minutes of contact at room temperature (20° C.) and humidity (ca. 60% R.H.), the samples were vortexed in D/E neutralizing broth containing 3% Tween® 80, 3% saponin and 0.3% lecithin at pH 7.0. As shown in
Tables 3 and 4 shows the results of the bactericidal and virucidal testing of the acrylate-MAP samples after 60 seconds of contact and 10 minutes of contact, respectively.
E. coli
S. aureus
E. coli
S. aureus
It is to be understood that the multilevel antimicrobial polymeric colloids and device screens containing the same are not limited to the specific embodiments described above, but encompasses any and all embodiments within the scope of the generic language of the following claims enabled by the embodiments described herein, or otherwise shown in the drawings or described above in terms sufficient to enable one of ordinary skill in the art to make and use the claimed subject matter.
This application claims the benefit of U.S. Provisional Patent Application No. 63/290,613, filed on Dec. 16, 2021.
Number | Date | Country | |
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63290613 | Dec 2021 | US |