Patent Application
20220386724
The present invention relates to an antimicrobial fabric for healthcare apparel, healthcare apparel comprising said antimicrobial fabric, and a process for treating a fabric suitable for healthcare apparel.
Recently, the cost to society associated with Hospital Acquired Infections (HAI) has significantly increased. There is a general need to control infective agents, especially in healthcare settings. To protect health workers, and to minimise the risk of cross contamination between patients and healthcare workers it is desirable to engender antimicrobial properties to routine protective equipment, such as gowns.
Gowns are typically made up of multiple layers. These layers can be made from a variety of materials such as polyethylene, polypropylene, polyester or polyurethane. Gowns may be used by patients or healthcare workers. The duration of wear may be very short (minutes), or may be multiple hours—for example in a surgical setting. Such gowns provide a basic level of protection by acting as a simple barrier to pathogens, but unless bacterial and viruses are rapidly killed they may grow and become a contaminating source.
WO2010/118180 claims the chemical attachment of photosensitising dyes to fabrics for odor control.
WO93/00815 discusses dyeing of polymers with photosensitising phthalocyanines, but not cationic dyes.
U.S. Pat. No. 5,486,274A details the preparation of pyridyl substituted phthalocyanines for cleaning applications.
JP2005023473 details a robe or gown for medical applications, made from functionalised synthetic fibres coated with typical conventional biocides. It gives an example of quaternary ammonium salts, but claims a wide variety of biocides. It does not claim photosensitisers or activity mediated by singlet oxygen.
JP3247293 (1995) reports cellulose acetate fibres with antimicrobial properties given by metals salts such as silver or zinc.
CN201109221 claims an antimicrobial water resistant fabric for disposable hospital wear. It makes no claims for the antimicrobial action being mediated by photosensitisers.
CN101285220 (2008) describes polyethylene/polypropylene fibres for a wide variety of applications both within and beyond healthcare. Gowns are specifically mentioned. The antimicrobial additive is silver.
KR20140104256 teaches a manufacturing method for an antimicrobial fabric suitable for gowns. A biocide is included in the manufacturing method, but not specifically claimed in the patent.
CN108936892 (2018) reports a nano-modified resin-based operating gown material. The fabric is made from polyurethane/polylactic acid with zinc and bamboo cellulose incorporated to gift antimicrobial activity.
US2018066384 teaches that treatment of any natural or synthetic fibre with a formulated copper sulfide solution produces antimicrobial fibres claimed suitable for industrial, military and healthcare clothing, including gowns.
CN108914610 (2018) specifically claims a disposable hospital gown. The added biocide is claimed to be a quaternary ammonium salt or metal ion.
CN105839410 (2016) details a surgical gown produced from zinc oxide, woven with silver wire and coated with PHMB.
CN106235474 (2016) again details a surgical gown comprising an antimicrobial silver cloth.
US20090081911 details a surgical gown with an outer layer of spunbond polypropylene. This polypropylene layer is stated to have antibacterial properties, potential by acting as a barrier. No additional biocides are claimed.
Singlet oxygen is a highly attractive antimicrobial agent, as due to its potent and non-selective mechanism of action there are no reported examples of the development of resistance by microorganisms.
Commonly used singlet oxygen generators can still present issues of solubility, aggregation, singlet oxygen generating efficiency, overall unsatisfactory antimicrobial activity and stability.
There is therefore a need to develop suitable singlet oxygen generators to engender healthcare apparel with effective and efficient antimicrobial activities which are safe for the user.
The present invention identifies certain dyes that are suitable for depositing on fibres that may be used in healthcare apparel, and demonstrates their antimicrobial properties.
In particular, the present invention provides an antimicrobial fabric for healthcare apparel comprising a singlet oxygen generating photosensitising dye. The present invention further provides a process for treating a fabric suitable for healthcare apparel with a singlet oxygen generating phthalocyanine.
The present invention identifies certain dyes which are suitable for depositing on fibres (for example polyethylene, polypropylene, polyester, nylon, cellulose or polyurethane) that may be used to construct healthcare apparel, and demonstrates their antimicrobial properties. The healthcare apparel can be any of patient gowns, health worker gowns, surgical gowns, all over hazmat (hazardous material) suits, uniforms or scrubs.
The dye of the present invention is cationic or anionic. Cationic dyes are preferred and have been found to have an unexpected affinity for fabrics (e.g. cellulose, polyester, nylon), enabling their efficient deposition without chemical attachment, and additionally sufficient water solubility to enable dyeing.
The antimicrobial fabric or material may comprise at least one layer of nonwoven fabric, for example meltblown or spunbond formed polypropylene, polyethylene, polyester, cellulose or nylon, onto which is deposited a singlet oxygen generating photosensitising dye. Especially preferred is where the facemask comprises or consists of a non-woven fabric.
In this respect, the fabric or material of the apparel may incorporate the singlet oxygen generating photosensitising dye. “Incorporate” may include the concepts of coated, impregnated or dyed.
Most preferably the fabric or material is comprised of multiple layers, which may or may not be identical.
The present invention relates to the application of certain photosensitisers as generators of singlet oxygen, a method for their application to materials suitable for healthcare apparel, and an antimicrobial gown obtainable using the invention.
Dyes may be selected from structural classes such as phthalocyanines, porphyrins, dipyrrole-boron complexes (BODIPY), phenothiazines (e.g. Methylene Blue) and fluoresceins (e.g. Rose Bengal).
Singlet oxygen generators are known to destroy microorganisms. Singlet oxygen has a greater energy than ground-state, triplet oxygen. The singlet and triplet states of oxygen are distinguished by the singlet state having two electrons of anti-parallel spins and the triplet state having an uncoupled pair of electrons with parallel spins. Singlet oxygen is also distinguished from triplet oxygen because it is a highly reactive species with a lifetime from a few microseconds to several hundred microseconds. During its lifetime singlet oxygen has the potential to react before being deactivated, and therefore has a wide number of applications, including antimicrobial applications such as in medical gloves, facemasks, gowns and other healthcare apparel.
Preferred singlet oxygen generating dyes according to the present invention are phthalocyanines. Preferably the phthalocyanine is alpha substituted.
Alternatively preferred is the phenothiazine class of dyes, for example Methylene Blue.
The phthalocyanine nucleus may be aluminium, titanium or zinc. If aluminium or titanium is used, the metal may be further substituted by alkyl, aryl, alkoxy, hydroxy or halogen. Aluminium, titanium and zinc are chosen because they are more efficient in generating singlet oxygen than other metals such as copper or nickel, and they are reasonably small and so can be inserted into the phthalocyanine easily, with the reactions occurring under air, in good yield, as opposed to other metals such as using SiCl4, and are easily available in bulk. The central metal atom also influences the position of the absorption maximum of the phthalocyanine. Zinc, titanium and aluminium are preferred in the compounds because their absorption is in the visible region of the spectrum especially between 600-700 nm. The zinc compounds described herein are especially preferred.
For the phthalocyanines of the present invention each of the pendant organic radicals linked to the phthalocyanine nucleus may be any aromatic or heteroaromatic moiety. Any one phthalocyanine nucleus may carry two or more different organic radicals. This radical may be linked to the phthalocyanine core by a carbon or hetero-atom bridge. Examples include, but are not limited to oxygen linked phenyl, pyridyl and N-alkylated pyridinium, Examples of N-alkylated pyridines are 3-hydroxy-1-methylpyridin-1-ium, 3-hydroxy-1-ethylpyridin-1-ium, 3-hydroxy-1-propylpyridin-1-ium.
Further, the phthalocyanines used in the present invention preferably have substituents to the phthalocyanine nucleus in the alpha position, adjacent to the phthalocyanine nucleus. This alpha substitution decreases aggregation of the phthalocyanine. Aggregation is known to reduce singlet oxygen generation efficiency, and therefore this structure prevents aggregation and increases efficiency singlet oxygen generation and hence antimicrobial and other activity. In addition, after extensive research the present inventors have realised the molecules described herein have other desirable properties. They are more thermally stable, and stable to radical degradation than commercially available analogs such as Tinolux BBS and Tinolux BMC. The phthalocyanine according to the present invention has a structure with the following formula:
wherein:
M is selected from aluminium, titanium or zinc,
X=Cl−, Br−, I−, methanesulphonate, ethanesulphonate, toluenesulfonate, formate, acetate or other inorganic or organic counter-ion or mixture thereof;
and
wherein alkylation on the pyridine nitrogen is optionally branched C1-C8 alkyl. This alkyl chain may be further hydroxylated or fluorinated.
Most preferred are the zinc pthalocyanines illustrated below—
The phthalocyanines used in the present invention are activated by light and offer a sustained release of singlet oxygen onto the gown or other apparel. It is known that singlet oxygen is a strong antimicrobial agent, killing most bacteria. The advantage of singlet oxygen generating dyes is that they are catalytic and not exhausted over time, and the singlet oxygen they release is not persistent, due it its very short half-life of typically a few microseconds. This has major advantages in toxicity and potential for development of resistant organisms. The short lifetime and hence short diffusion range of singlet oxygen gives this invention a significant advantage in safety for users.
Further, the phthalocyanines preferred in the present invention have substituents to the phthalocyanine nucleus in the alpha position, adjacent to the phthalocyanine nucleus (positions 1, 5, 12 and 13 in Formula 1). This alpha substitution decreases aggregation of the phthalocyanine. Aggregation is known to reduce singlet oxygen generation efficiency, and therefore this structure prevents aggregation and increases efficiency singlet oxygen generation and hence antimicrobial and other activity. To demonstrate this, phthalocyanine I was compared to an analogue where the oxypyridinium residue was attached to the phthalocyanine core in the beta position (positions 3, 6, 11 and 14 in Formula 1). 25 mgs of each were dissolved in 1 L water, and the UV/vis absorption compared. It can be seen in the spectra below that the alpha substitution pattern results in much high population of the monomeric phthalocyanine (ca. 675 nm here) compared to the aggregated phthalocyanine (ca. 640 nm here) than is the case for the beta substitution, which favours the aggregate (ca. 635 nm here).
This use of alpha substitution is therefore novel and inventive over beta substitution pattern.
The phthalocyanines of Formula 1 can be prepared by reacting:
(1) a substituted 1,2-dicyanobenzene of Formula 2:
wherein Z is selected from chloro, bromo and iodo or nitro and is in the 3 position (alpha) to one of the CN groups,
with
(2) a compound aryl-OH whereby the group Z, is replaced by aryl-O groups to form a compound of Formula (3). Pyridyl is illustrated for example, but this may be phenyl or other hetero aromatic.
This can then be followed by reaction of one or more 1,2-dicyanobenzene compounds of Formula 3 with an appropriate metal or metal salt optionally in an inert liquid at an elevated temperature to form a phthalocyanine of Formula 1.
Such reactions are fully described in GB 1489394, GB 2200650 and DE 2455675.
If an N-alkyl derivate is desired, then the alkylation of the pyridine groups is done last. If the alkylation process is not done to completion, some of the pyridyl substituents can remain unalkylated and uncharged. The process can be modified by temperature and stoichiometry to give higher or lower degrees of final alkylation.
The antimicrobial phthalocyanines illustrated in present invention can be used to coat fibres suitable for gown manufacture and can provide effective and continuous antimicrobial protection. In addition, the physical properties of the gown are not significantly reduced.
The phthalocyanines used can be applied to any material suitable for gown or healthcare apparel construction. Examples are, but not limited to polyester, polypropylene, polyester or polyurethane. The application of the phthalocyanines to the fibres may be achieved via a wide variety of methods familiar to those skilled in the art of textile dyeing. Examples may include, but are not limited to—
A particular advantage of the pthalocyanines preferred in this invention is their high solubility in selected solvents which allow facile dyeing of the desired fibres.
Without wishing to be bound by theory, the present inventors have realised that application of the photosensitising phthalocyanines as solutions is a particular advantage of the invention as it maintains the phthalocyanine in a de-aggregated state (in contrast to slurries, suspensions or dispersions). Aggregation is known to decrease the generation of singlet oxygen by photosensitisers. As such, the photosensitiser may be applied at a low weight loading per square meter of fabric, whilst still giving high antimicrobial activity.
In addition to the photosensitising dye, a homo or heteropolymer of unsaturated low molecular weight carboxylic acids (or their esters or anhydrides) may also be deposited onto facemask material, such as the non-woven fabric. Example monomers include acrylic, methacrylic or maleic acids, and example polymers include the carbomer class, such as acrylic acid homopolymers, or maleic acid/vinyl ether heteropolymers. Preferably the carboxylic acid polymer is deposited on the same fabric layer as the photosensitiser, being the outer layer of the apparel. Preferably the homo or heteropolymer may be deposited on the fabric first, enabling deposition of the dye without chemical attachment.
Additionally, or alternatively a surfactant may also be included. Preferably the surfactant is an ionic, or alternatively a betaine type surfactant. Preferred is an ionic sulfonated aryl surfactant, such as an alkylbenzene sulfonate, preferably sodium dodecylbenzenesulfonate.
While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements included within scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.
The present invention will now be illustrated, but in no way limited, by reference to the following examples.
To 2-ethylhexanol (242 g) is charged 3-(oxypyridyl)phthalonitrile (145 g, 0.656 moles, 1 eq), and the vessel purged with inert gas. Zinc chloride is charged (21 g, 0.154 moles, 94% of theoretical charge) followed by DBU (51 g, 0.335 moles, 0.51 eq). The reaction is heated to ca. 107° C. (internal vessel temp) for at least 16 hours. The reaction is cooled and isopropyl alcohol (1600 mL) charged to the reaction mixture. After cooling to room temperature, the product is isolated by filtration and washed with further iso-propanol, then dried in an oven.
To NMP (360 g) is charged pyridyl zinc phthalocyanine prepared in Example 1 (140 g, 1 eq, 0.147 mol) and methyl p-tolueneslufonate (120 g, 0.644 mol, 4.4 eq). The reaction is stirred and heated to 107-111° C. (internal vessel temperature) for 20 h, then cooled to 50-60° C. (internal). Meanwhile, to a second vessel is charged iso-propanol (14 vols, 2000 mL) and lithium iodide trihydrate (125 g, 0.668 mol, 4.54 eq). The reaction mixture is transferred to the second vessel to precipitate the crude product, which is isolated by filtration and washed with further iso-propanol. The wet cake of the crude product is recharged to a vessel with iso-propanol (8 vols, 1100 mL) and lithium iodide trihydrate (35 g, 0.187 mol, 1.27 eq). The slurry is heated to 80-83° C. (internal), then cooled to room temperature. The final product is isolated by filtration and washed with further iso-propanol, before being dried in an oven.
To NMP (10 g) is charged pyridyl zinc phthalocyanine prepared in Example 1 (5 g, 1 eq, 0.0053 mol) and 2-ethylhexyl bromide (6.09 g, 0.0315 mol, 6 eq). The reaction is stirred and heated to 110° C. (oil bath temperature) for 27 h, then cooled to 70° C. (bath). Meanwhile, to a second vessel is charged iso-propanol (150 mL) and sodium iodide (3 g, 0.02 mol, 3.8 eq). The reaction mixture is transferred to the second vessel to precipitate the crude product, which is isolated by filtration and washed with further iso-propanol. The wet cake is recharged to a vessel with iso-propanol (150 ml) and sodium iodide (1 g, 0.0067 mol, 1.27 eq). Water (15 ml) is added, and the slurry heated to 40° C. for 3 h, then cooled to room temperature and further stirred. The product is isolated by filtration, then washed with iso-propanol/water, then finally washed with further iso-propanol before being dried in an oven.
To a slurry of potassium carbonate (47.8 g, 0.347 mol, 1.2 eq), 3-nitrophthalonitrile (50 g, 0.289 mol) in ethyl acetate was added 4-tert-butylphenol (45.6 g, 0.303 mol, 1.05 eq). The mixture was heated to reflux for 7 hours, then the organic phase extracted with water. The majority of the ethyl acetate was removed by distillation, and replaced with iso-propanol. The solution of the desired product was allowed to cool slowly until it crystallised. The product was isolated by filtration, washed with further iso-propanol and dried in an oven.
To 3-(4-t-butylphenoxy)phthalonitrile prepared in Example 5 (15 g, 0.054 mol) is added 2-ethylhexanol (30 ml) zinc chloride (1.77 g, 0.013 mol, 0.24 eq) and DBU (4.3 g, 0.028 mol, 0.52 eq). The reaction is heated to 105° C. (internal) for 23 hours, then cooled and slowly dropped into stirred methanol. The product was isolated by filtration, washed with further methanol and dried in an oven.
0.025 g of the phthalocyanine prepared in Example 2 was dissolved in 100 ml of methanol. A 10×10 cm square of polypropylene fabric (suitable for gown construction) was immersed in the solution for 15 seconds with swirling. The sample was carefully removed from the liquid, allowing the excess to run off. The sample was air dried.
0.025 g of the phthalocyanine prepared in Example 2 was dissolved in 100 ml of methanol. A 10×10 cm square of polyethylene fabric (suitable for gown construction) was immersed in the solution for 15 seconds with swirling. The sample was carefully removed from the liquid, allowing the excess to run off. The sample was air dried.
0.025 g of the phthalocyanine prepared in Example 3 was dissolved in 1 ml NMP and made up to 100 ml with acetone. A 10×10 cm square of polypropylene fabric (suitable for gown construction) was immersed in the solution for 15 seconds with swirling. The sample was carefully removed from the liquid, allowing the excess to run off. The sample was air dried.
0.025 g of the phthalocyanine prepared in Example 5 was dissolved in 100 ml of acetone. A 10×10 cm square of polypropylene fabric (suitable for mask construction) was immersed in the solution for 15 seconds with swirling. The sample was carefully removed from the liquid, allowing the excess to run off. The sample was air dried.
An 8.7 cm diameter disc of a polyethylene/polyester laminate fabric (suitable for a gown, apron or “hazmat” suit) was treated with a suspension of 150 mgs of an acrylic acid homopolymer (for example Carbopol 971) and 75 mgs of sodium dodecylbenzenesulfonate in 50 g water. The disc was treated for 1 min, then the sample was carefully removed from the liquid, allowing the excess to run off. The sample was air dried. Next, 0.025 g of the phthalocyanine prepared in Example 2 was dissolved in 100 ml of water. 2.5 g of this solution was made up to 15 g. The disc prepared above was treated with 4 g of this dye solution for 1 min, then the sample was carefully removed from the liquid, allowing the excess to run off. The sample was air dried.
0.025 g of the phthalocyanine prepared in Example 2 was dissolved in 100 ml of water. To 75 ml of this solution was added 150 mgs of an acrylic acid homopolymer (for example Carbopol 971) and 75 mgs of sodium dodecylbenzenesulfonate. The suspension was stirred until fully dispersed. An 18 cm square of non-woven polypropylene fabric was dipped in this suspension for 2 min, then the sample was carefully removed from the liquid, allowing the excess to run off. The sample was air dried.
A 4.3 cm disc of the sample prepared in Example 6 was inoculated with a 0.1 ml presentation of either Staphylococcus aureus or Klebsiella pneumonia. After 1 h at 37° C. under illumination of 1500 lux, a reduction of 5.5 Log was achieved for Staph a and 2.1 Log for Kleb p.
| Number | Date | Country | Kind |
|---|---|---|---|
| 19183704.6 | Jul 2019 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/068562 | 7/1/2020 | WO |
