Zinc-based MOF polymorphic nanostructure-based polyester fabric and preparation method thereof

Abstract

The invention relates to a polyester fabric based on a zinc-based MOF (Metal Organic Framework) polymorphic nanostructure and a preparation method. The surface of the polyester fabric forms an MOF material with a polymorphic nanostructure through coordination of L-methionine and zinc ions. According to the invention, L-methionine is innovatively used as a bifunctional ligand, and a zinc-based MOF is anchored on the surface of an ammonolysis polyester fiber through a covalent bond, so that the polyester fabric with spectral pathogen inactivation capability is prepared. And the structure-function relationship between the zinc-based MOF polymorphic nanostructure and the pathogen inactivation efficiency is disclosed for the first time.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of functional textiles, and particularly relates to an antibacterial and antiviral polyester fabric based on a metal organic framework material and a preparation method thereof. BACKGROUND

[0002] Polyester fibers are widely used in clothing, home textiles and medical textiles due to their excellent mechanical properties and low cost, but ordinary polyester lacks antibacterial and antiviral functions and is easy to become a carrier for the spread of pathogens. In the prior art, patent CN119162691B discloses a waterproof antibacterial polyester fiber fabric and a preparation method thereof. N,N'-bis(2-hydroxyethyl)ethylenediamine, N,N'-di-Boc-S-methyl isothiourea and the like are used as raw materials, and dimethyl terephthalate is subjected to esterification and polycondensation to obtain a waterproof antibacterial copolyester polymer having a similar structure to PET polyester. The long-chain structure containing quaternary ammonium salt and guanidine groups in the structure is uniformly distributed in the polyester fiber matrix to play an antibacterial performance. However, such an organic antibacterial agent has the defects of low antibacterial activity and poor inactivation of viruses.

[0003] Metal organic framework (MOF) materials have attracted much attention in the biomedical field due to their high specific surface area and adjustable pore structure. Patent CN116043551B discloses an antiviral bioactive cotton fabric in which Cu-based MOF nanorods are grown in situ on the surface of cotton fibers, which exhibits unique inhibitory activity against H1N1-PR8 influenza virus. However, it is worth noting that such a single morphology of nanomaterials lacks inactivation rate for non-enveloped viruses. SUMMARY

[0004] In view of the problems in the prior art, the application discloses a polyester fabric based on zinc-based MOF multi-morphology nanostructure and a preparation method thereof, aiming to solve the technical bottlenecks such as poor antibacterial performance of organic finishing agent, lack of antiviral performance and single morphology of MOF material existing in traditional antibacterial textiles.

[0005] The technical scheme is specifically implemented as follows:

[0006] An antibacterial and antiviral polyester fabric based on zinc-based MOF multi-morphology nanostructure, wherein the surface of the polyester fabric is formed with multi-morphology nanostructure MOF material through coordination between L-methionine and zinc ions.

[0007] Further, the multi-morphology nanostructure MOF material includes nanoparticles (diameter less than 100 nanometers), nanoflowers (assembled from nanosheets, diameter 300-500 nanometers, containing micropores <4 nanometers and mesopores 2-30 nanometers, specific surface area 650-1000 square meters / gram) and nanoclusters (length 1-3 micrometers);

[0008] Further, the polymorphic zinc-based MOF nanostructured material is prepared by regulating the molar concentration of L-methionine and zinc nitrate and the pH value of the solution to control the crystal growth kinetics.

[0009] Specifically comprising the following operation steps:

[0010] (1) The washed polyester fabric is soaked in 1,6-hexanediamine aqueous solution for ammonolysis treatment, and then the fabric after ammonolysis treatment is immersed in L-methionine solution again, and acylation reaction is carried out after controlling the weight gain.

[0011] (2) The fabric after acylation is soaked in L-methionine solution again, zinc ion solution is added under stirring, and after 10 minutes of continuous stirring, the fabric is washed with ultrapure water for three times and dried in an oven.

[0012] Further, the concentration of the 1,6-hexanediamine solution in step (1) is 43-172 millimoles / liter, the soaking time is 10-30 minutes, the temperature is 150-180℃, and the reaction time is 5-20 minutes; the concentration of the L-methionine solution used for acylation is 33.5-134 millimoles / liter, the soaking time is 60-90 minutes, the acylation reaction temperature is 120-150℃, and the heating time is 30-60 minutes.

[0013] Further, the concentration of the L-methionine solution in step (2) is 0.025-2.5 millimoles / liter, and the pH of the L-methionine solution is adjusted to 4.45-11.45 by using 1 mol / liter hydrochloric acid solution or triethylamine solution.

[0014] Further, the zinc ion solution in step (2) includes one or more of zinc acetate, zinc nitrate, zinc sulfate and zinc chloride aqueous solution, the concentration of the zinc ion solution is 0.015-1.5 millimoles / liter, the reaction temperature is 20-30℃, the time is 5-30 minutes, and the stirring speed is 300-1200 revolutions / minute.

[0015] Further, step (2) is repeated 2-6 times, so that the loading amount of zinc-based MOF reaches 8.2-14.5 wt%.

[0016] The application innovatively uses L-methionine as a bifunctional ligand to anchor zinc-based MOF on the surface of ammonolysis polyester fiber through covalent bond, and prepares polyester fabric with spectrum pathogen inactivation ability. And for the first time, the structure-activity relationship between zinc-based MOF polymorphic nanostructure and pathogen inactivation efficiency is revealed.

[0017] The antibacterial and antiviral polyester fabric based on the zinc-based MOF polymorph nanostructure of the application has the following beneficial effects:

[0018] The application has the following beneficial effects:

[0019] 1) The zinc-based MOF nano material form is controllably synthesized by simple solution concentration and pH value control, and is in-situ grown on the surface of the polyester fiber, thereby realizing high-efficiency and broad-spectrum antibacterial and antiviral capabilities.

[0020] 2) The structure-activity relationship of the zinc-based MOF polymorph nanostructure on the inactivation efficiency of bacteria and viruses is verified, wherein the nano flower structure can simultaneously realize high-efficiency inactivation of bacteria and viruses. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The figure is the morphology of the zinc-based MOF nanoflower prepared in Example 1 of the application;

[0022] Figure 2 The figure is the morphology of the zinc-based MOF nanoparticle prepared in Example 4 of the application;

[0023] Figure 3 The figure is the morphology of the zinc-based MOF nanocluster prepared in Example 5 of the application;

[0024] Figure 4 The figure is the morphology of the zinc-based MOF nanocluster prepared in Comparative Example 3 of the application;

[0025] Figure 5 The figure is the morphology of the zinc-based MOF nanocluster prepared in Comparative Example 4 of the application. DETAILED DESCRIPTION

[0026] The application is further described below in combination with specific examples, so as to better understand the technical solutions.

[0027] Example 1

[0028] A preparation method of an antibacterial and antiviral polyester fabric based on a zinc-based MOF polymorph nanostructure, comprising the following steps:

[0029] (1) The ordinary polyester fabric (10x10 square centimeters) is immersed in 1,6-hexanediamine solution (43 millimoles / liter, 200 milliliters) for 10 minutes, then the soaked fabric is heated to 160°C, reacted for 5 minutes, washed with water, and dried at 60°C to constant weight; the ammonia-activated polyester fabric is immersed in L-methionine solution (134 millimoles / liter, 100 milliliters) for 60 minutes, heated to 150°C after rolling to increase the weight by 110%, reacted for 30 minutes, washed with water, and dried at 60°C to constant weight;

[0030] (2) The polyester fabric treated in step (1) is immersed in L-methionine solution (0.25 millimoles / liter, 40 milliliters), the pH of the solution is adjusted to 10.45 with 1 mole / liter of triethylamine, the solution is stirred at a speed of 400 revolutions / minute, and zinc acetate solution (0.15 millimoles / liter, 10 milliliters) is added, the growth is repeated 2 times, stirring is continued at 25°C for 10 minutes, and then the fabric is washed with water and dried at 60°C to constant weight. Zinc-based MOF nanoflowers (diameter 300-500 nanometers) are formed on the surface of the obtained fabric, and the loading of the zinc-based MOF nanoflowers is 2.7wt%. The morphology diagram is as shown in Figure 1 .

[0031] Example 2

[0032] A preparation method of an antibacterial and antiviral polyester fabric based on zinc-based MOF multi-morphology nanostructure, comprising the following steps:

[0033] (1) The ordinary polyester fabric (10x10 square centimeters) is immersed in 1,6-hexanediamine solution (43 millimoles / liter, 200 milliliters) for 10 minutes, then the soaked fabric is heated to 160°C, reacted for 5 minutes, washed with water, and dried at 60°C to constant weight; the ammonia-activated polyester fabric is immersed in L-methionine solution (134 millimoles / liter, 100 milliliters) for 60 minutes, heated to 150°C after rolling to increase the weight by 110%, reacted for 30 minutes, washed with water, and dried at 60°C to constant weight;

[0034] (2) The polyester fabric treated in step (1) is immersed in L-methionine solution (0.25 millimoles / liter, 40 milliliters), the pH of the solution is adjusted to 10.45 with 1 mole / liter of triethylamine, the solution is stirred at a speed of 400 revolutions / minute, and zinc acetate solution (0.15 millimoles / liter, 10 milliliters) is added, the growth is repeated 4 times, stirring is continued at 25°C for 10 minutes, and then the fabric is washed with water and dried at 60°C to constant weight. Zinc-based MOF nanoflowers (diameter 300-500 nanometers) are formed on the surface of the obtained fabric, and the loading of the zinc-based MOF nanoflowers is 6.3wt%.

[0035] Example 3

[0036] A preparation method of an antibacterial and antiviral polyester fabric based on zinc-based MOF multi-morphology nanostructure, comprising the following steps:

[0037] (1) The ordinary polyester fabric (10x10 square centimeters) is immersed in 1,6-hexanediamine solution (43 millimoles / liter, 200 milliliters) for 10 minutes, then the soaked fabric is heated to 160°C for 5 minutes, washed with water and dried at 60°C to constant weight; the ammonia-activated polyester fabric is immersed in L-methionine solution (134 millimoles / liter, 100 milliliters) for 60 minutes, heated to 150°C for 30 minutes after rolling to increase the weight by 110%, washed with water and dried at 60°C to constant weight;

[0038] (2) The polyester fabric treated in step (1) is immersed in L-methionine solution (0.25 millimoles / liter, 40 milliliters), the pH of the solution is adjusted to 10.45 with 1 mole / liter triethylamine, the solution is stirred at 400 revolutions / minute, and zinc acetate solution (0.15 millimoles / liter, 10 milliliters) is added, and the growth is repeated 6 times, stirred at 25°C for 10 minutes, washed with water and dried at 60°C to constant weight. The zinc-based MOF nanoflower (diameter 300-500 nanometers) is formed on the surface of the obtained fiber, and the loading amount of the zinc-based MOF nanoflower is 10.2wt%.

[0039] Example 4

[0040] A preparation method of an antibacterial and antiviral polyester fabric based on zinc-based MOF polymorph nanostructure, comprising the following steps:

[0041] (1) The ordinary polyester fabric (10x10 square centimeters) is immersed in 1,6-hexanediamine solution (43 millimoles / liter, 200 milliliters) for 10 minutes, then the soaked fabric is heated to 160°C for 5 minutes, washed with water and dried at 60°C to constant weight; the ammonia-activated polyester fabric is immersed in L-methionine solution (134 millimoles / liter, 100 milliliters) for 60 minutes, heated to 150°C for 30 minutes after rolling to increase the weight by 110%, washed with water and dried at 60°C to constant weight;

[0042] (2) The polyester fabric treated in step (1) is immersed in L-methionine solution (0.025 millimoles / liter, 40 milliliters), the pH of the solution is adjusted to 4.45 with 1 mole / liter hydrochloric acid, the solution is stirred at 400 revolutions / minute, and zinc acetate solution (0.015 millimoles / liter, 10 milliliters) is added, and the growth is repeated 6 times, stirred at 25°C for 10 minutes, washed with water and dried at 60°C to constant weight. The zinc-based MOF nanoparticle (diameter less than 100 nanometers) is formed on the surface of the obtained fiber, and the loading amount of the zinc-based MOF nanoparticle is 8.7wt%. The morphology diagram is shown in Figure 2 .

[0043] Example 5

[0044] A preparation method of an antibacterial and antiviral polyester fabric based on zinc-based MOF polymorph nanostructure, comprising the following steps:

[0045] (1) The ordinary polyester fabric (10 x 10 square centimeters) was immersed in a 1,6-hexanediamine solution (43 millimoles / liter, 200 milliliters) for 10 minutes, then the soaked fabric was heated to 160°C for 5 minutes, and after washing with water, it was dried at 60°C to constant weight; the ammonia-activated polyester fabric was immersed in an L-methionine solution (134 millimoles / liter, 100 milliliters) for 60 minutes, and after rolling to increase the weight by 110%, it was heated at 150°C for 30 minutes, and after washing with water, it was dried at 60°C to constant weight;

[0046] (2) The polyester fabric treated in step (1) was immersed in an L-methionine solution (2.5 millimoles / liter, 40 milliliters), and the pH of the solution was adjusted to 11.45 with 1 mole / liter of ethylenediamine, the solution was stirred at a speed of 400 revolutions / minute, and a zinc acetate solution (1.5 millimoles / liter, 10 milliliters) was added, and the growth was repeated 6 times, and the stirring was continued at 25°C for 10 minutes, and after washing with water, it was dried at 60°C to constant weight. The zinc-based MOF nanoclusters (length 1-3 microns) were formed on the surface of the obtained fiber, and the loading of the zinc-based MOF nanoclusters was 11.8 wt%. The morphology diagram is shown in Figure 3

[0047] Example 6

[0048] A preparation method of an antibacterial and antiviral polyester fabric based on zinc-based MOF polymorph nanostructures, comprising the following steps:

[0049] (1) The ordinary polyester fabric (10 x 10 square centimeters) was immersed in a 1,6-hexanediamine solution (43 millimoles / liter, 200 milliliters) for 10 minutes, then the soaked fabric was heated to 160°C for 5 minutes, and after washing with water, it was dried at 60°C to constant weight; the ammonia-activated polyester fabric was immersed in an L-methionine solution (134 millimoles / liter, 100 milliliters) for 60 minutes, and after rolling to increase the weight by 110%, it was heated at 150°C for 30 minutes, and after washing with water, it was dried at 60°C to constant weight;

[0050] (2) The polyester fabric treated in step (1) was immersed in an L-methionine solution (0.25 millimoles / liter, 40 milliliters), and the pH of the solution was adjusted to 11.45 with 1 mole / liter of ethylenediamine, the solution was stirred at a speed of 400 revolutions / minute, and a zinc acetate solution (0.15 millimoles / liter, 10 milliliters) was added, and the growth was repeated 6 times, and the stirring was continued at 25°C for 10 minutes, and after washing with water, it was dried at 60°C to constant weight. The mixture of zinc-based MOF nanoflowers and nanoclusters was formed on the surface of the obtained fiber, and the loading was 12.3 wt%.

[0051] Comparative Example 1

[0052] ​(1) The common polyester fabric (10 x 10 cm2) was immersed in 1,6-hexanediamine solution (43 mmol / l, 200 ml) for 10 minutes, then the immersed fabric was heated to 160°C for 5 minutes, and after washing with water, dried at 60°C to constant weight; the ammonia-activated polyester fabric was immersed in L-methionine solution (134 mmol / l, 100 ml) for 60 minutes, and after roll-pressing with a weight increase of 110%, heated at 150°C for 30 minutes, and after washing with water, dried at 60°C to constant weight.

[0053] Comparative Example 2

[0054] (1) The common polyester fabric (10 x 10 cm2) was immersed in 1,6-hexanediamine solution (43 mmol / l, 200 ml) for 10 minutes, then the immersed fabric was heated to 160°C for 5 minutes, and after washing with water, dried at 60°C to constant weight; the ammonia-activated polyester fabric was immersed in L-methionine solution (134 mmol / l, 100 ml) for 60 minutes, and after roll-pressing with a weight increase of 110%, heated at 150°C for 30 minutes, and after washing with water, dried at 60°C to constant weight.

[0055] (2) The polyester fabric treated in step (1) was immersed in zinc acetate solution (0.15 mmol / l, 10 ml), and the solution was stirred at 400 rpm for 10 minutes at 25°C, and after washing with water, dried at 60°C to constant weight.

[0056] Comparative Example 3

[0057] (1) The common polyester fabric (10 x 10 cm2) was immersed in 1,6-hexanediamine solution (43 mmol / l, 200 ml) for 10 minutes, then the immersed fabric was heated to 160°C for 5 minutes, and after washing with water, dried at 60°C to constant weight; the ammonia-activated polyester fabric was immersed in L-methionine solution (134 mmol / l, 100 ml) for 60 minutes, and after roll-pressing with a weight increase of 110%, heated at 150°C for 30 minutes, and after washing with water, dried at 60°C to constant weight.

[0058] (2) The polyester fabric treated in step (1) was immersed in L-methionine solution (0.025 mmol / l, 40 ml), and the solution was adjusted to pH 3.45 with 1 mol / l hydrochloric acid, and zinc acetate solution (0.015 mmol / l, 10 ml) was added, and the solution was stirred at 400 rpm for 10 minutes at 25°C, and after washing with water, dried at 60°C to constant weight. The surface of the obtained fiber was formed without any particulate matter, and the morphology thereof is shown in Figure 4

[0059] Comparative Example 4

[0060] ​(1) The common polyester fabric (10 x 10 cm2) was immersed in 1,6-hexanediamine solution (43 mmol / L, 200 mL) for 10 minutes, then the immersed fabric was heated to 160°C for 5 minutes, and dried at 60°C to constant weight after washing. The ammonia-activated polyester fabric was immersed in L-methionine solution (134 mmol / L, 100 mL) for 60 minutes, and heated at 150°C for 30 minutes after roll coating to increase the weight by 110%, and dried at 60°C to constant weight after washing;

[0061] (2) The polyester fabric treated in step (1) was immersed in L-methionine solution (2.5 mmol / L, 40 mL), and the pH of the solution was adjusted to 12.45 with 1 mol / L ethylenediamine. The solution was stirred at 400 rpm, and zinc acetate solution (1.5 mmol / L, 10 mL) was added. The growth was repeated 6 times, and stirring was continued at 25°C for 10 minutes. The obtained fabric was washed and dried at 60°C to constant weight. The surface of the obtained fabric was free of any cluster formation, and the morphology thereof is shown in Fig. 2. Figure 5

[0062] Performance test

[0063] The samples provided in Examples 1-6 and Comparative Examples 1-2 above were subjected to the following tests:

[0064] (1) phi-X174 and phi6 bacteriophages were used as enveloped and non-enveloped model viruses, respectively, to evaluate the virus inactivation ability:

[0065] The phi-X174 bacteriophage suspension (5 μL) was dropped on the surface of the fabric, and incubated at 37°C for 10 minutes in a constant temperature incubator. Then, the phi-X174 bacteriophage was eluted and diluted with phosphate buffer, and mixed with host bacteria (TG1). The mixed suspension of phi-X174 and TG1 was dropped on solid culture medium, and incubated at 37°C for 24 hours. The number of plaques was used to evaluate the inactivation ability of the sample on phi-X174 bacteriophage. The mixed suspension of phi-X174 and TG1 without sample was used as a blank control group. The anti-virus efficiency (%) was calculated as follows: anti-virus efficiency (%) = (number of plaques of the control group - number of plaques of the sample) / number of plaques of the control group x 100.

[0066] ​A suspension of phi6 bacteriophage (5 μl) was added to the surface of the fabric, incubated at 25°C for 10 minutes, then eluted and diluted with phosphate buffer, and a suspension of host bacteria P. aeruginosa and culture solution (prepared by mixing tryptone, potassium chloride, sodium chloride and ultrapure water) was added and incubated at 25°C for 10 minutes. Finally, an appropriate amount of the mixture was poured onto a preheated LB agar plate and incubated at 25°C for 24 hours. The plaques formed were observed, and the number of plaques was used to evaluate the inactivation ability of the sample on phi6 bacteriophage. A mixed suspension of phi6 and P. aeruginosa without sample contact was used as a blank control group, and the antiviral efficiency (%) was calculated as (number of plaques in the control group - number of plaques in the sample) / number of plaques in the control group x 100.

[0067] (2) Biological safety performance evaluation: The cytotoxicity of the modified fabric on mouse embryonic fibroblasts (NIH / 3T3) was detected by cell counting kit 8 (CCK-8). The fabric sample was soaked in normal saline (25°C, 10 ml) for 24 hours. The filtered filtrate solution was sterilized by high temperature and high pressure. NIH / 3T3 cells (10 6 / ml) were inoculated in a 96-well plate (100 μl / well) and cultured for 8 hours to adhere, then stimulated with the filtrate for 24 hours, and the blank control was normal saline. Then 10 μl of CCK-8 solution was added to the culture medium and incubated for 1 hour. The absorbance of the sample was detected by an enzyme-labeled instrument (Epoch2, Bio-Tek) at a wavelength of 450 nm, and the cell survival rate was calculated. Next, NIH / 3T3 cells were inoculated in a 12-well plate (100 μl of culture medium per well), cultured for 8 hours, and stimulated with the filtrate for 24 hours. Annexin V-FITC (5 μl) and PI (5 μl) solutions were mixed and added to 100 μl of cell suspension, incubated in the dark for 15 minutes, and the apoptosis rate of NIH / 3T3 cells was calculated by flow cytometry.

[0068] (3) Washing test: The fabric was washed 100 times according to the standard method of AATCC 61-2006 (2A).

[0069] (4) Rubbing test: The fabric was rubbed 200 times according to the standard method of ASTM D4966-2010.

[0070] The specific test results are shown in Table 1:

[0071] Table 1 Test Results

[0072]

[0073]

[0074]

[0075] As can be seen from the data in Table 1, the zinc-based MOF nanoflower (diameter 300-500 nm) connected to the surface of the polyester fiber by covalent bond has high efficient and broad-spectrum antiviral performance, and is resistant to washing and rubbing, and has high biological safety performance. The zinc-based MOFs of other structural morphologies, such as nanoparticles and nanoclusters, have different inactivation effects on different types of viruses, and do not have broad-spectrum pathogen inactivation ability.

Claims

1. A polyester fabric based on zinc-based MOF polymorphic nanostructure, characterized in that: The surface of the polyester fabric is formed by coordination between L-methionine and zinc ions to form a multi-morphological nanostructured MOF material.

2. The polyester fabric based on zinc-based MOF polymorphic nanostructure according to claim 1, characterized in that: The polymorphic nanostructured MOF material includes nanoparticles, nanoflowers and / or nanoclusters.

3. A method for preparing polyester fabric based on zinc-based MOF polymorphic nanostructure, characterized in that: The following steps are involved: 1) The washed polyester fabric is immersed in a 1,6-hexanediamine aqueous solution for aminolysis treatment, and the aminolysis-treated fabric is immersed in an L-methionine solution to control weight gain and then undergo an amidation reaction; 2) The amidated fabric was immersed in L-methionine solution again, and zinc ion solution was added under stirring to induce the growth of zinc-based MOF. After stirring for 10 minutes, the fabric was washed with ultrapure water and dried in an oven.

4. The method for preparing a polyester fabric based on a zinc-based MOF polymorphic nanostructure according to claim 1, characterized in that In step 1), the concentration of the 1,6-hexanediamine aqueous solution is 43-172 mmol / L, the soaking time is 10-30 minutes, the temperature is 150-180° C., and the reaction time is 5-20 minutes.

5. The method for preparing a polyester fabric based on zinc-based MOF polymorphic nanostructure according to claim 1, characterized in that In step 1), the concentration of the L-methionine solution used after the acylation treatment is 33.5-134 mmol / L, the soaking time is 60-90 minutes, the heating amidation reaction temperature is 120-150° C., and the heating time is 30-60 minutes.

6. The method for preparing a polyester fabric based on a zinc-based MOF polymorphic nanostructure according to claim 1, characterized in that In step 2), the concentration of the L-methionine solution is 0.025-2.5 mmol / L, and the pH of the L-methionine solution is adjusted to 4.45-11.45 using 1 mol / L hydrochloric acid solution or triethylamine solution.

7. The method for preparing a polyester fabric based on a zinc-based MOF polymorphic nanostructure according to claim 1, characterized in that In step 2), the zinc ion solution includes at least one of zinc acetate, zinc nitrate, zinc sulfate and zinc chloride aqueous solution, the concentration of the zinc ion solution is 0.015-1.5 mmol / L, the reaction temperature is 20-30° C., the reaction time is 5-30 minutes, and the stirring speed is 300-1200 rpm.

8. The method for preparing a polyester fabric based on zinc-based MOF polymorphic nanostructure according to claim 1, characterized in that Step 2) was repeated 2-6 times to achieve a Zn-based MOF loading of 8.2-14.5 wt%.

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