Field of the Invention

The present invention relates to functionalised metal-organic frameworks (MOFs), and their use as an antimicrobial composition. The present invention also relates to the use of such compositions as a coating or treating material, and in particular, but not exclusively, as a coating or treating material for fabric substrates. The present invention also relates to methods for coating or treating a fabric substrate with such compositions, and to articles, such as cloth masks, made from such materials.

Background

The primary mode in airborne transmission of any respiratory virus, such as SARS-CoV-2, is droplets or aero-sols produced by an infected person from actions, such as breathing, speaking, coughing or sneezing.

Cloth masks are the most common form of protection against airborne microbes, and in particular, viruses. The market value for face masks is estimated to be around $1 ,520, and is expected to grow to $2,455.4 million by 2027.

Face masks are designed to filter virus aerosol or droplets, and their performance can be improved by adding layers and selecting the appropriate fabrics. However, the material/composite should not compromise on breathability, which is another essential parameter for a face mask. Unfortunately, surgical masks are not very effective for viruses of smaller sizes (<100 nm), whilst N95 respirators are expensive and require training, and are only suitable for frontline healthcare workers.

To achieve antiviral activity, the material used for the mask, typically a natural or synthetic fabric material, can be coated with an anti-viral metal coating, typically including metals such as Ag, Cu or Zn.

However, filtration capabilities remain the main factor to prevent virus transmission. In other words, the mask should be able to filter out pathogens, and the material itself may be provided with a metal-containing coating to display anti-viral properties.

Coordination polymers are a class of compounds which are formed from extended chains, sheets or networks of metal ions interconnected by ligands or linkers. Metal-organic frameworks - MOFs - are a type of coordination polymer having extended three-dimensional framework structures.

CN113699600A (Wang et al) discloses a protective product with a mustard gas/bacterium/virus protection function and a preparation method thereof. A functional semiconductor material and a polymer matrix are compounded to prepare fibres or textiles. The functional semiconductor material is one of an HOF-101 material, an HOF-102 material, an Nil-1000 material, an NU-1000-PCBA material, a UiO-66-AA material and a PCN-222 material; and the polymer matrix is polymer particles or fabric.

WO2021245422A2 (Ornstein et al) discloses a photocatalytic system for destroying contagious and infectious, airborne micro-organisms, or used to remove and/or destroy poisonous gases. The system comprises an air inlet, an air outlet, a surface located between the air inlet and the air outlet, and a light source configured to project light onto said surface; said surface having a coating that comprises a metalorganic framework.

CN113106635A (Wu et al) discloses an electrostatic spinning nanofiber nonwoven fabric comprising a non-woven fabric and electrostatic spinning nanofibers, wherein the electrostatic spinning nanofibers comprise in parts by weight 100-500 parts of thermoplastic resin, 10-60 parts of a metal-organic framework material and 120-160 parts of dimethylformamide.

JP5577346B2 (Fujimori et al) discloses a virus inactivation sheet that can inactivate viruses adhering to said sheet. The virus inactivation sheet has a sheet body, and univalent copper compound microparticles and/ or iodide microparticles retained on the sheet body.

JP5504302B2 (Scott et al) discloses a device for immobilizing a virus while maintaining biological activity of the virus, used for prevention and/or treatment of bacterial infection.

JP5291198B2 (Fujimori et al) discloses a mask that can inactivate viruses adhered to the mask. The mask can inactivate adhered viruses, and is characterized by being provided with: a mask body that has a member for mounting; and virusinactivating microparticles that are supported on the mask body, have virus-inactivating properties, and comprise at least one compound selected from the group consisting of titanium (II) iodide, palladium (II) iodide, silver (I) iodide, copper (I) iodide, and copper (I) thiocyanate. Thus, MOFs are known to have been used in the context of facemask. However, such MOFs are metal-containing MOFs, and any interaction with potential pathogens occurs by virtue of biocidal properties of the metal itself.

It is an object of the invention to address and/or mitigate one or more problems associated with the prior art.

The present invention is based on the finding that functionalised MOFs may be particularly well suited for use as a pathogen-blocking material, for example as a coating, on facemasks.

According to a first aspect, there is provided an article comprising: a textile substrate; and a composition comprising a MOF which has been functionalised with an organic functionalising compound capable of interacting with and/or capable of blocking one or more pathogens, wherein at least a portion of the textile substrate comprises, is treated with or coated with the composition.

The composition may be provided as a coating on the textile material.

The textile material may be treated, e.g. impregnated with, the composition.

The term “capable of interacting with” will be herein understood as meaning that the organic functionalising compound has affinity for the one or more pathogens.

The organic functionalising compound may include at least one functional group capable of binding the one or more pathogens. The term “binding” will be understood to include any form of chemical bond between the organic functionalising compound and the one or more pathogens, so long as the one or more pathogens is immobilised on the functionalised MOF due to interaction with the organic functionalising compound. Thus, the term “binding” may include covalent bonds, ionic bonds, or non- covalent bonds such as hydrogen bonds or dipole-dipole bonds.

The one or more pathogens may comprise or may be a virus. The one or more pathogens may comprise or may be a coronavirus, e.g. SARS-CoV-2.

The organic functionalising compound may include at least one functional group capable of interacting with a moiety present on the surface of the pathogen, e.g. virus. Typically, the organic functionalising compound may include at least one functional group capable of binding a moiety, e.g. a protein, responsible for mediating viral entry into a host cell. For example, in the case of a virus, e.g. a coronavirus, the organic functionalising compound may include at least one functional group capable of binding the Spike (S) glycoprotein (also called “spike protein”) on the surface of the virus.

In such instance, the organic functionalising compound may include at least one functional group selected from the group consisting of carboxylic acid, amine, hydroxy and amide, and/or salts or derivatives thereof, such as ester or the like. Advantageously, the organic functionalising compound may include at least two functional groups selected from the group consisting of carboxylic acid, amine, hydroxy and amide, and/or salts or derivatives thereof, such as ester or the like. This may help binding with the one or more pathogens, e.g. virus, which may help immobilise the virus on the composition. Alternatively, or additionally, the organic functionalising compound may include one or more sugars or carbohydrate groups or structures, such as a polysaccharide or glycosaminoglycan structure, e.g. hyaluronic acid.

The organic functionalising compound may include at least one functional group capable of binding to or being incorporated into the MOF. By such provision, the organic functionalising compound may be considered to “functionalise” the MOF.

Typically, the organic functionalising compound may comprise at least one weak acid group. Weak acid groups or salts thereof are believed to be well suited for incorporation into MOFs due to their ability to bind and/or coordinate to metals of the MOF structure. The organic functionalising compound may comprise one or more functional groups selected from the group consisting of a carboxylic acid group, a carboxylate salt, a phosphate, a phosphonate, a sulfate, a sulfonate, an amine, or an imidazolate; typically a carboxylic acid group, a carboxylate salt, or a phosphonate.

Typically, the organic functionalising compound may comprise one or more compounds selected from the group consisting of tenofovir ((R)-9-(2- phosphonomethoxypropyl)adenine), mycophenolic acid, monensin sodium salt, nystatin, hyaluronic acid, folic acid, levomefolic acids, and salts or derivatives thereof.

The MOF may be capable of adsorbing water. MOFs are generally known to display high water adsorption. The water adsorption properties of MOFs may be advantageous to increase the antimicrobial properties of the composition. In particular, it is believed that, once immobilised on the functionalised MOF, the water adsorption properties of the MOFs may cause local dehydration of the one or more pathogens, which in turn may kill, weaken or inactivate the one or more pathogens, thus lowering infectivity.

The MOF may be selected to exhibit a suitable water adsorption uptake profile. Whilst it is known that MOFs tend to display high water adsorption, the water update profile differs between various types of MOFs.

The MOF may be selected to have a water adsorption step (e.g. in its water adsorption isotherm at 25°C) above 20% relative humidity (RH), e.g. above 30% RH, e.g. above 40%RH, e.g. above 50% RH, e.g. above 60%. The MOF may be selected to have a water adsorption step (e.g. in its water adsorption isotherm at 25°C) in the range of about 20-100% RH, e.g. about 50-100% RH, e.g. about 60-100% RH.

Without wishing to be bound by theory, it is believed that, in the context of a face mask, in use, the MOFs of the coating or treating composition may become saturated with water upon a user exhaling due to the high moisture content of exhaled breath. However, the particular step-shape of water adsorption isotherms for MOFs offers the possibility that some MOFs will adsorb water in exhaled breath but may desorb the water again on inhalation, due to the decrease in water vapour pressure upon inhalation, thereby maintaining their ability to dehydrate pathogens.

As explained above, MOFs are typically formed from metal ions interconnected by ligands or linkers. Advantageously, the MOFs may be formed from metals having low toxicity to humans. By such provision, the composition may have low toxicity to humans.

The metal ions may include or may consist of Mg, Al, Ca, Sc, Ti, V, Fe, Cu, Zn, Ga, Ge, Sn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Pt, and/or Au.

In some embodiments, the metal ions may include or may consist of Zr and/or Al. The MOF may comprise a zirconium-based MOF or an aluminium-based MOF.

The MOF may comprise any suitable MOF.

The MOF may be selected from the group consisting of aluminium fumarate, zirconium fumarate, MOF-841 , a UiO-66 MOF such as UiO-66(Zr), UiO-66-NH2(Zr) or UiO-66-NO2(Zr), a porous interpenetrated zirconium-organic frameworks (PIZOF) such as PIZOF-2, or a HKUST-1 MOF or MOF-199, or other suitable MOFs such as Fe- MIL100/MIL101 , or CALI-10. These MOFs were found to offer suitable water adsorption profiles, and to be capable of being functionalised with an organic functionalising compound. Advantageously, the present composition allows the article to exhibit hydrophilic properties and high uptake of water under the conditions displayed as a face mask, whilst improved efficacy in regard of pathogen filtration, immobilisation and/or inactivation.

The MOF may comprise one or more metals that are known to be antimicrobial, such as Ag, Cu and/or Zn. Advantageously, when incorporated within the MOF, the resulting MOF may improve microbial properties.

The MOF itself may further comprise antimicrobial components. For example, the MOF may be modified by incorporating one or more anti-microbial agents within the MOF, for example as disclosed in W02012/020214 (Morris), the content of which is incorporated herein in its entirety.

The textile substrate may be or may comprise a fabric.

The textile substrate may comprise a natural material, e.g. cotton.

The textile substrate may comprise a synthetic material, e.g. polyacrylonitrile, polypropylene, polyester, polyamide, or the like.

The article may be a facemask.

According to a second aspect, there is provided a method of making an article comprising treating, coating on or incorporating in a textile substrate a composition comprising a MOF which includes an organic functionalising compound capable of interacting with and/or capable of blocking one or more pathogens.

The method may comprise preparing a textile composition, e.g. a fibrous material, comprising a textile raw material and the functionalised MOF.

The method may comprise spinning, e.g. electrospinning, the textile composition. In such instance, the textile article may comprises the functionalised MOF incorporated within the textile raw material.

Typically, the textile raw material may comprise or may consist of a synthetic material, e.g. polyacrylonitrile, polypropylene, polyester, polyamide, or the like.

The method may comprise preparing a textile composition, e.g. a fibrous material, comprising a textile raw material and a non-functionalised MOF. The method may comprise spinning, e.g. electrospinning, the textile composition. In such instance, the textile article may comprises the non-functionalised MOF incorporated within the textile raw material.

Typically, the textile raw material may comprise or may consist of a synthetic material, e.g. polyacrylonitrile, polypropylene, polyester, polyamide, or the like.

The method may further comprise functionalising the MOF with the organic functionalising compound.

The method may comprise treating or coating the textile substrate with the composition comprising a non-functionalised MOF.

The method may comprise growing a MOF on the textile substrate, e.g. on a surface thereof.

The method may further comprise functionalising the MOF with the organic functionalising compound.

The method may comprise treating or coating the textile substrate with the composition comprising the functionalised MOF.

The features described in relation to any aspect of the invention may equally apply to any other aspect and, merely for brevity, are not repeated. For example, features described in relation to compositions can apply in relation to methods, and vice versa.

Brief Description of Drawings

Embodiments of the invention are described with reference to the accompanying drawings, in which:

Figure 1 shows an article according to an embodiment;

Figure 2 shows an example of a MOF which can be used as a starting material for the coating of the article of Figure 1 ;

Figures 3a-3e shows examples of organic functionalising compounds that can be used to modify a MOF to be used in the coating of the article of Figure 1;

Figure 4 is an illustration of a possible mechanism of coordination of the organic functionalising compounds with the MOF;

Figure 5 is a graph showing water adsorption isotherms for several suitable MOFs (PIZOF-2, MOF-841, CALI-10 and AIFum (aluminium fumarate)); Figure 6 is a graph showing water adsorption/desorption isotherms for unmodified and functionalised UiO-66-NC>2 MOFs;

Figure 7 shows TEM micrographs of a) pristine Zr-Fumarate and b) after postsynthetic modification with folic acid (Zr-Fumarate-FA): scale bar: a) 10 nm and b) 20 nm;

Figure 8 shows EDS elemental mapping images of a) Zr-Fumarate-FA and b) an overlay of the Zr (green), C (red), N (blue) and O (yellow) compositional maps, and the compositional maps of c) Zr (green), d) C (red), e) N (blue), and O (yellow); scale bar: 10 nm.

Figures 9 shows the effect of the functionalisation of three different MOFs with three different compounds on the binding ability to BSA protein;

Figure 10 shows a graph illustrating the amount of BSA protein binding pristine Fumarate-MOFs and their FA-modified derivatives when treated with 6 pg of BSA in aqueous solution;

Figure 11 shows TEM micrographs of Bovine Serum Albumin (BSA; a and d), as well as pristine UiO-66-NO2 (b and e) and UiO-66-NO2-FA (c and f) after BSA protein binding experiment: scale bar: (a-c) 200 nm and (d-f) 100 nm;

Figure 12 shows electrospun MOF-FA nanofiber mats including 20 wt% MOF- FA: a) Zr-Fumarate-FA@PAN and b) AI-Fumarate-FA@PAN;

Figure 13 shows the amount of BSA protein binding of plain cotton, pristine PAN nanofibers, a surgical face mask and a FFP2 face mask when treated with 6 or 60 pg of BSA in aqueous solution.

Figure 14 shows the amount of BSA protein binding of plain cotton and MOF- FA modified cotton fabric compared to 100 wt% MOF-FA, and 100 wt% MOF when treated with 6 pg of BSA in aqueous solution;

Figure 15 shows the amount of BSA protein binding of PAN nanofibers with 0wt%, 15wt% and 20 wt% MOF-FA compared to 100 wt% MOF-FA and 100 wt% MOF when treated with 6 pg of BSA in aqueous solution;

Figure 16 shows the amount of BSA protein binding of plain cotton, PAN nanofibers and H KU ST- 1 -treated fabrics when treated with 6 and 60 pg of BSA in aqueous solution.

Detailed Description

In the present disclosure, reference is made to a number of terms, which have the meanings provided below, unless a context indicates to the contrary. The nomenclature used herein for defining compounds, in particular the compounds according to the invention, is in general based on the rules of the IIIPAC organisation for chemical compounds, specifically the “IUPAC Compendium of Chemical Terminology (Gold Book)”. For the avoidance of doubt, if a rule of the IUPAC organisation is in conflict with a definition provided herein, the definition herein is to prevail. Furthermore, if a compound structure is in conflict with the name provided for the structure, the structure is to prevail.

The term “comprising” or variants thereof is to be understood herein to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

The term “consisting” or variants thereof is to be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, and the exclusion of any other element, integer or step or group of elements, integers or steps.

The term “about” herein, when qualifying a number or value, is used to refer to values that lie within ± 5% of the value specified. For example, if a temperature is specified to be about 5 to about 13 °C, temperatures of 4.75 to 13.65 °C are included.

Reference to physical states of matter (such as liquid or solid) refer to the matter’s state at 25 °C and atmospheric pressure unless the context dictates otherwise.

As explained above, the present inventors have discovered that it is possible to improve the antimicrobial properties of textile materials such as facemasks, by coating or treating the textile of fabric substrate with a composition comprising a functionalised MOF.

Figure 1 is a schematic cross-sectional view of an article 5 according to an embodiment. The article 5 is a facemask, and includes a textile substrate 10, which in this example is a cotton cloth, but in other examples may be made from a synthetic fabric such as polypropylene. The article 5 also has a coating 20 on an outer surface of the textile substrate 10.

The coating 20 comprises a MOF which has been functionalised with an organic functionalising compound capable of interacting with and/or capable of blocking one or more pathogens, and particularly viruses such as coronaviruses, e.g. SARS- CoV-2. Figure 2 shows an example of a MOF which can be used as a starting material for the coating of the article of Figure 1. In this example, the MOF is an aluminium fumarate MOF, the structure illustrating the three-dimensional framework formed between aluminium ions and fumarate organic ligands, creating pores within the structure.

Figures 3a-3e show examples of organic functionalising compounds that can be used to modify a MOF to be used in the coating of the article of Figure 1.

The moiety highlighted in blue represents the possible binding moiety to the MOF. This includes phosphate in tenofovir (fig 3a), carboxylic acid in mycophenolic acid (fig 3b), caroboxylate salt in monensin sodium salt (fig 3c), and carboxylic acid in nystatin (fig 3d) and folic acid (fig 3e).

Figure 4 is an illustration of a possible mechanism of coordination of the organic functionalising compounds with the MOF. It shows that in the cases illustrated in Figures 3a to 3e, the organic functionalising compound is bound to the MOF via coordination between an oxygen atom of the highlighted binding moieties and a metal of the MOF.

Figure 5 is a graph showing water adsorption isotherms of four MOFs with steps in the amount adsorbed at suitable relative humidity for this application. MOFs with steps below -20% would be unsuitable as it would mostly remain saturated with water both upon inhalation and exhalation, thus not being able to dehydrate pathogens immobilised on its surface

Figure 6 is a graph showing water adsorption isotherms for UiO-66-NO2 MOFs either unmodified (grey, (i)) or functionalised with folic acid (red, (ii)) or tenofovir (green, (iii)). For each MOF type, the set of solid data points corresponds to measurements taken during adsorption (i.e. during an increase in pressure), and the set of hollow data points corresponds to measurements taken during desorption (i.e. during a decrease in pressure).

To examine the accessibility of the pores of the MOFs before and after surface modification, water adsorption isotherms were recorded at 298 K for all the FA- and Tenofovir-functionalised compounds. The general trend of water uptake of the functionalized LliOs was on the order of UiO-66-NC>2 > UiO-66-NC>2-FA > UiO-66-NC>2- Teno.

It can be observed that surface functionalization with FA or Tenofovir retained the S-shaped water uptake curves of UiO.

Each of MOFs-841 and UiO-66 have steps between 20 and 40% Relative Humidity (RH), making them suitable for use in a face mask article. PIZOF-2 has a step in the 70% RH region, also making it suitable. Many MOFs have a step at around 10% RH, (e.g. MOF-801) but would be unsuitable as they would mostly remain saturated with water both upon inhalation and exhalation, thus not being able to dehydrate pathogens immobilised on its surface.

Examples

• Synthesis of MOF Nanoparticles

UiO-66 and its derivatives - LHO-66-NH2 and LHO-66-NO2'.

Zirconium (IV) chloride (0.500 g, 3.084 mmol) was suspended in DMF (20 mL) and concentrated HCI (4 mL). The mixture was sonicated for 20 minutes. Linker (see Table below) and DMF (40 mL) were added to the mixture and further sonicated for 20 minutes. The mixture was heated to 80 °C in an oven for 24 hours. After cooling to room temperature, the solid was collected by centrifugation and washed with DMF (3 x 30 mL), EtOH (30 mL) and hexane (15 mL). The product was then dried in an oven at 80 °C overnight.

The parameters for each MOF variant are shown in Table 1 .

Table 1 :

Zr-Fumarate:

Anhydrous zirconium (IV) chloride (1.2 g, 5.15 mmol) and fumaric acid (1.8 g, 15.5 mmol) were dissolved in H2O (100 mL) in a 250 mL glass autoclave. Then formic acid (10 mL) was added, and the mixture was sonicated for 15 min. The mixture was heated to 120 °C in an oven for 24 hours. After cooling to room temperature, the solid was collected by centrifugation and washed with H2O (100 mL) and EtOH (2x 100 mL). The product was dried in an oven at 80 °C overnight or kept in an ethanolic solution.

Al-Fumarate:

Sodium aluminate (0.45 g, 5.5 mmol) and fumaric acid (0.9 g, 7.75 mmol) in H2O (50 mL) in a 100 mL round bottom flask and stirred under reflux at 90 °C for 1 hour. After cooling to room temperature for 1 hour, the solid was collected by centrifugation and washed with H2O (100 mL) and EtOH (2x 100 mL). The product was dried in an oven at 80 °C overnight or kept in an ethanolic solution.

• Post-synthetic Modification with Antiviral Agents o Folic Acid

UiO-66 and its derivatives’. Parent MOF obtained above (0.125 g) was suspended in MeOH (15 mL) and the mixture was sonicated for 30 minutes. Folic acid (FA) was added to DMF (20 mL) and sonicated until it was fully dissolved. The FA solution was added to the MOF suspension and stirred under room temperature for 24 hours. The solid was collected by centrifugation and washed with DMF (2 x 20 mL), MeOH (30 mL) and hexane (20 mL). The product was dried in an oven at 80 °C overnight.

The parameters for each MOF variant are shown in Table 2.

Table 2:

Fumarate-MOFs: Folic acid (FA, 0.45 g, 1.0 mmol) was dispersed it in a 1:1 mixture of H2O (75 mL) and MeOH (75 mL). Fumarate-MOF nanoparticles (750 mg) were dispersed in the FA solution and the mixture was stirred at room temperature for 24 h. The solid was collected by centrifugation and washed with H2O (2x 100 mL) and EtOH (3x 100 mL) to remove non-bound folic acid. The product was dried in an oven at 80 °C overnight or kept in an ethanolic solution. o Nystatin

UiO-66 and its derivatives’. Parent MOF obtained above (0.125 g) was suspended in MeOH (15 mL) and the mixture was sonicated for 30 minutes. Nystatin (Nys) was added to DMF (5 mL) and MeOH (10 mL) and sonicated until it was fully dissolved. The Nys solution was added to the MOF suspension in MeOH and stirred under room temperature for 24 hours. The solid was collected by centrifugation and washed with DMF (2 x 20 mL), MeOH (1 x 20 mL) and hexane (1 x 20 mL). The product was dried in an oven at 80 °C overnight.

The parameters for each MOF variant are shown in Table 3.

Table 3: o Tenofovir

UiO-66 and its derivatives’. Parent MOF obtained above (0.125 g) was suspended in MeOH (5 mL) and the mixture was sonicated for 30 minutes. Tenofovir (Teno) was suspended in water (15 mL) and MeOH (5 mL) and sonicated. The Teno solution was added to the MOF suspension and stirred under room temperature for 24 hours. The solid was collected by centrifugation and washed with water (2 x 20 mL) and MeOH (2 x 20 mL). The product was dried in an oven at 80 °C overnight.

The parameters for each MOF variant are shown in Table 4.

Table 4:

• Characterisation o Transmission Electron Microscopy

All materials were characterized by PXRD, FT-IR, TGA, solid state UV-Vis, sorption analysis, and also investigated by Transmission Electron Microscopy (TEM).

Figure 7 shows TEM micrographs of a) pristine Zr-Fumarate and b) after postsynthetic modification with folic acid (Zr-Fumarate-FA): scale bar: a) 10 nm and b) 20 nm. It can be seen by comparing Figures 7(a) and 7(b) that there appears to be a thin coating on the surface of the functionalised Zr-Fumarate MOF nanoparticles.

Energy Dispersive Spectroscopy (EDS) elemental mapping was carried out in order to confirm the nature of such coating, as shown in Figures 8(a)-(f). The results verified that the thin coating relates to the folic acid surface modification on the MOF, as it features N as a unique element (Figure 8(e)).

• Protein Binding Experiments

UiO-66 and its derivatives:

Figures 9 shows the effect of the functionalisation of three different UiO-66- based MOFs with three different compounds on the binding ability to BSA protein.

BSA protein solutions were prepared in water and all the compounds were treated with the solution (6 pg), including pristine MOFs for comparison. MOFs with folic acid and tenofovir functionalization had significantly higher affinity over the base MOFs in all cases, while nystatin-functionalized MOFs had significantly higher affinity UiO-66-NO2 and displayed a moderate increase for UiO-66, but did not show the same increase for UiO-66-NH2.

Fumarate-MOFs:

Figure 10 shows a graph illustrating the amount of BSA protein binding pristine Fumarate-MOFs and their FA-modified derivatives when treated with 6 pg of BSA in aqueous solution

It can be seen that, whilst Zr-Fumarate alone does not provide binding to BSA protein, its functionalisation with folic acid generates strong binding properties. On the other hand, whilst Al-Fumarate alone does provide some binding to BSA protein, its functionalisation with folic acid maintains the binding properties of the MOF. Therefore, functionalisation provides strong binding properties both for MOFs which originally already had binding affinity, and for MOFs which originally (in non-functionalised form) had no or low binding affinity. o Post-Binding Transmission Electron Microscopy

Figure 11 shows Transmission Electron Microscopy (TEM) micrographs of Bovine Serum Albumin (BSA; a and d), as well as pristine UiO-66-NO2 (b and e) and UiO-66-NO2-FA (c and f) after BSA protein binding experiment: scale bar: (a-c) 200 nm and (d-f) 100 nm. The results confirmed that pristine UiO-66 and its derivatives do not bind Bovine Serum Albumin (BSA) and their surface, while BSA is present in case of surface-modified UiO-66 and its derivatives.

• Preparation of MOF@Fabrics o Electrospinning

Synthesised and post-synthetically modified Fumarate-FA-MOFs were dispersed in DMF, then Polyacrylonitrile (PAN) was added and the resulting slurry was electrospun to nanofiber mats, containing 15 wt% or 20 wt% MOF-FA. The mats are shown in Figure 12. o In situ MOF-growth on Fabric

Zr-Fumarate@Fabric:

Water soluble Zre-oxoclusters were prepared by dissolving anhydrous zirconium (IV) chloride (20 g, 85.82 mmol) in acetic acid (30 mL), then adding isopropanol (20 mL) and heating the mixture under reflux at 120 °C for one hour. The product was filtered, washed with acetone (3 x 100 mL) and dried in an oven at 80 °C overnight. To promote the MOF growth on the fabric, one piece of plain cotton or electrospun PAN nanofiber mats (2 cm x 2 cm) was kept in 3M NaOH (5 mL) at 80 °C for 20 min. Zre- oxoclusters (0.26 g) were dissolved in H2O (5 mL), then one piece of fabric was added, and kept at 80°C for 1 h. Meanwhile, fumaric acid (0.64 g, 5.5 mmol) was dissolved in ethanol (20 mL) at 80 °C for 1 hour. Subsequently, the piece of fabric with deposited Zre-oxoclusters was dried in an oven at 80 °C and then transferred to the dissolved linker and kept at 80 °C for 4 h. Zr-Fumarate@Fabric was removed and washed thoroughly with H2O (20 mL) and EtOH (2x 20 mL). The product was dried in an oven at 80 °C overnight.

AI-Fumarate@Fabric:

To promote the MOF growth on the fabric, i.e., one piece of plain cotton or electrospun PAN nanofiber mats (2 cm x 2 cm), it was kept in 3M NaOH (5 mL) at 80 °C for 20 min. Sodium aluminate (0.45 g, 5.5 mmol) was dissolved in H2O (10 mL) in a 50 mL glass autoclave (Thermo Fisher), one piece of fabric was added, and kept at 80C for 1 h. Meanwhile, dissolve fumaric acid (0.9 g, 7.75 mmol) in ethanol (20 mL) at 80 °C for 1 hour. Afterwards, the piece of cotton with deposited sodium aluminate was transferred to the dissolved linker and kept at 80 °C for 4 h. AI-Fumarate@Fabric was removed and washed it properly with H2O (20 mL) and EtOH (2x 20 mL). The product was dried in an oven at 80 °C overnight.

H KU ST- 1 ©Fabric:

To promote the MOF growth on the fabric, i.e., one piece of plain cotton or electrospun PAN nanofiber mats (2 cm x 2 cm), it was kept in 3M NaOH (5 mL) at 80 °C for 20 min. Cupric nitrate nonahydrate (1.0 g, 3.4 mmol) was dissolved in H2O (5 mL) in a 50 mL glass autoclave (Thermo Fisher), one piece of fabric was added, and kept at 80C for 1h. Meanwhile, dissolve 1,3,5-benzenetricarboxylic acid (1.6 g, 9.6 mmol) in ethanol (20 mL) at 80 °C for 1 hour. Afterwards, the piece of cotton with deposited sodium aluminate was transferred to the dissolved linker and kept at 80 °C for 4 h. HKUST-1@Fabric was removed and washed it properly with H2O (20 mL) and EtOH (2x 20 mL). The product was dried in an oven at 80 °C overnight. o MOF@Fabric Functionalisation with Folic Acid

Folic acid (FA, 0.45 g, 1.0 mmol) was dispersed in a 1 :1 mixture of H2O (75 mL) and MeOH (75 mL). One piece of MOF@Fabric was placed in the FA solution (10 mL) and the mixture was stirred at room temperature for 24 h. MOF-FA@Fabric was washed with H2O (2x 10 mL) and EtOH (3x 10 mL) to remove unbound folic acid. The product was dried in an oven at 80 °C overnight.

• Protein Binding Experiments

Figure 13 shows the amount of BSA protein binding of plain cotton, pristine PAN nanofibers, a surgical face mask and a FFP2 face mask when treated with 6 or 60 pg of BSA in aqueous solution.

The untreated fabric showed low (cotton) or almost no (PAN) protein binding, while the surgical face mask and the FFP2 face mask showed approximately 50% protein binding, when treated with 6 pg of BSA in aqueous solution. When treated with 60 pg of BSA in aqueous solution, the protein binding of PAN nanofibers increased slightly, while the protein binding of the surgical face mask and the FFP2 face mask stagnated, and corresponded to only a slightly higher total amount of bound protein compared to the treatment with 6 pg of BSA in aqueous solution.

Figure 14 shows the amount of BSA protein binding of plain cotton and MOF- FA modified cotton fabric compared to 100 wt% MOF-FA, and 100 wt% MOF when treated with 6 pg of BSA in aqueous solution. Figure 15 shows the amount of BSA protein binding of PAN nanofibers with 0wt%, 15wt% and 20 wt% MOF-FA compared to 100 wt% MOF-FA and 100 wt% MOF (that is, compared to the powders of non-functionalised and functionalised MOF nanoparticles) when treated with 6 pg of BSA in aqueous solution.

These two figures show that all Al-Fumarate MOF-treated fabrics show high level of binding with BSA proteins. The results also confirm the earlier observation that functionalisation with folic acid dramatically enhances protein binding for Zr-Fumarate MOF-treated fabrics. Compared to the protein binding of a surgical face mask and a FFP2 mask the MOF-treated fabrics show a significantly enhanced binding performance.

Figure 16 shows the amount of BSA protein binding of plain cotton, PAN nanofibers and H KU ST- 1 -treated fabrics when treated with 6 and 60 pg of BSA in aqueous solution.

When treated with 6 pg of BSA in aqueous solution, H KU ST- 1 -treated fabrics showed great protein binding. When treated with 60 pg of BSA in aqueous solution, the H KU ST- 1 -treated cotton only showed twice the total amount of bound protein compared to the treatment with 6 pg of BSA in aqueous solution, while HKUST-1- treated PAN nanofibers still displayed almost complete protein binding.

It will be understood that the present embodiments are provided by way of example only, and that various modifications can be made to the present embodiments without departing from the scope of the invention.