Self-assembled gel capable of releasing gaseous germicide and method for producing same

Abstract

A self-assembled gel capable of releasing a gaseous germicide, said gel comprising at least one moisture absorbing agent, at least one water absorbing agent, and at least one stable salt capable of releasing the gaseous germicide, and when sealed and stored, moisture in the air continues to release the germicide from the gel via hydrogen ions upon opening the seal.

Description

[Technical field]

[0001] The present invention discloses a method for producing and formulation of a self-activated, sustained release germicidal and antibacterial deodorant gel.

[0002] Microbial growth is the most common cause of odors and allergens in the home. Prolonged exposure to bad odors can lead to depression, nausea and other mental health problems. Uncontrolled microbial growth can also lead to poor home hygiene, which can cause detectable chronic disease and discomfort. In addition to routine cleaning, gaseous germicides are a good alternative to solve the problem of microbial growth, as they can reach hard-to-reach surfaces through the air. Aqueous chlorine dioxide is a well-studied and effective germicide and is often used in water treatment. Gaseous chlorine dioxide is also a fast and effective broad-spectrum germicide and can be used to combat biological warfare agents such as anthrax. Chlorine dioxide decomposes quickly and has a short half-life, so large-scale gas use in unmanned environments can be safely achieved with only 15 minutes of aeration. However, chlorine dioxide's high reactivity, short half-life, and high toxicity are also the reasons why chlorine dioxide faces challenges in continuous disinfection. Continuous production of low-dose chlorine dioxide could be a solution to this problem. Kouji Ab et al. (US8603355B2, US20100086493A1, US8545898B2) [1][2][3] reported that continuous generation of chlorine dioxide can be achieved by adding a pH adjuster. Then, the solution that continuously generates chlorine dioxide can be transformed into various forms by compounding gelling and foaming agents. However, the disadvantage of the above preparations is that the chemicals need to be separated during transportation and storage. These components require the end user to mix the chemicals at the end-use site, which creates an occupational hazard for untrained workers. After mixing, a large amount of chlorine dioxide will also be suddenly released when the reaction starts, further harming the end user. The present invention solves this problem by producing a self-assembled, self-activated, continuously releasing gaseous chlorine dioxide aerogel that can be used to improve hygiene in enclosed spaces and reduce odor problems. Summary of the Invention

[0003] The present invention provides a gel that sustains the release of a gaseous germicide, the composition of which comprises at least one moisture absorbing agent, at least one water absorbing agent, and at least one salt capable of releasing a gaseous germicide. An acidity regulator, i.e., a pH buffer salt, can be included in the composition to regulate the release rate of the gaseous germicide. The composition should be stored in a sealed container until needed.

[0004] The specific contents of the present invention are as follows. A self-assembled gel capable of releasing a globular germicide, the gel comprising: at least one moisture absorbing agent, at least one water absorbing agent, and at least one stable salt capable of releasing a gaseous germicide; The composition comprising the above components is stored in a sealed container, When in use, the sealed container is opened, the moisture absorbent absorbs moisture in the air, and after absorbing the moisture, the moisture absorbent dissolves the salt that releases the gaseous germicide, and the salt that releases the gaseous germicide is activated by the hydrogen ions in the solution and releases the germicide. Further, the moisture absorbent is one or more combinations selected from zinc nitrate, copper nitrate, calcium chloride, magnesium chloride, zinc chloride, iron chloride, magnesium potassium chloride, potassium carbonate potassium phosphate, ferric ammonium citrate, ammonium nitrate, potassium hydroxide, sodium hydroxide, and nano water collectors. Further, the water absorbing agent is one or more combinations selected from sodium polyacrylate, potassium polyacrylate, polyacrylamide copolymer, poly(ethylene-maleic anhydride), carboxymethylcellulose, cross-linked carboxymethylcellulose, polyvinyl alcohol hydrogel, cross-linked polyethylene oxide, starch-grafted polyacrylonitrile hydrolysate, other metal neutralized polyacrylic acid, and starch powder. Additionally, the salt capable of releasing a gaseous germicide may be sodium chlorite, other salts capable of triggering and releasing a gaseous germicide, and combinations thereof. Additionally, it may include an acidity regulator, a pH adjuster, a pH buffer and / or a non-water absorbing inert spacer material. Further, the acidity regulator, pH adjuster, and pH buffer are one or more combinations selected from sodium citrate, citric acid, potassium dihydrogen phosphate, disodium hydrogen phosphate, disodium phosphate, sodium acetate, sodium dihydrogen phosphate, imidazole, sodium carbonate, sodium bicarbonate, sodium hydroxide, other acid salts, and other basic salts. Additionally, the non-water absorbing inert spacer material is selected from talcum powder, titanium powder, and combinations thereof. Further, the gel is a single mixture; First, add and mix a stable dry salt powder capable of releasing a gaseous germicide, a water absorbent, and then add and mix a moisture absorbent. Further, the gel is a single mixture; First, dry powder of stable salt capable of releasing gaseous germicide, water absorbent, acidity regulator, pH adjuster, pH buffer, non-water absorbing inert spacer material are added and mixed, and then the moisture absorbent is added and mixed. Furthermore, the gel comprises: a bottom layer including at least a moisture absorbent; an intermediate layer containing a stable salt capable of releasing a gaseous germicide; and and a top layer which contains at least a water absorbing agent. Furthermore, the gel comprises: a bottom layer including at least a moisture absorbent; an intermediate layer containing a stable salt capable of releasing a gaseous germicide; a top layer including at least a water absorbing agent; Acidity regulators, pH adjusters, pH buffers, non-water absorbing inert spacer materials are added to any of the above layers. Furthermore, the gel comprises: a bottom layer including at least a moisture absorbent; a top layer comprising at least a mixture of a stable salt capable of releasing a gaseous sterilant, an acidity regulator, a pH adjuster, a pH buffer, and a non-water-absorbent inert spacer material.

[0005] When the sealed container is opened, the moisture absorbent absorbs moisture in the air. The moisture is then absorbed by the moisture absorbent to form a hydrogel structure, and at the same time dissolves the salt or any other salt that can release a gaseous germicide. The stable salt that can release a gaseous germicide is then activated by the water molecules or hydrogen ions in the moisture collected by the moisture absorbent. The balance between the moisture absorption amount of the moisture absorbent and the water retention amount of the water absorbent allows the slow and sustained release of the germicide to be achieved by slowly supplying moisture or hydrogen ions. [Brief description of the drawings]

[0006] The present invention will now be further described with reference to the drawings. [Figure 1] Illustrated diagram of aerogel: (a) before moisture absorption and (b) the complete structure formed after moisture absorption. [Diagram 2] Examples of (a) single mixture gels, (b) layer-by-layer composite gels, and (c and (d) a combination of both preparation methods are shown. [Diagram 3] The duration of continuous release of the gel samples is shown. [Figure 4] 1 shows a schematic diagram of a sterilization testing apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The present invention describes a self-assembling gel that releases a gaseous germicide. The invention can be safely stored in its gel form without activating it until the sealed container is opened and moisture in the air is used as a reaction trigger by adding dry chemicals, isolating them from moisture during transport and storage, and introducing water into the system via a hygroscopic compound. The present invention describes a system that uses sodium chlorite to generate chlorine dioxide, but the system is not limited to other biocides that can be activated with water or hydrogen ions.

[0008] Chlorine dioxide is a gaseous disinfectant that kills viruses. [4] 0.05 ppm for bacteria [5] It is effective against chlorine dioxide at low doses of 0.01 ppm. Chlorine dioxide exists in the form of a stable salt of sodium chlorite, which is activated to chlorine dioxide gas by the following chemical reaction: 5NaClO2+4H + →4ClO2+2H2O+5NaCl Therefore, by controlling the supply of hydrogen ions, the release of gaseous chlorine dioxide can be controlled.

[0009] In the present invention, the supply of hydrogen ions is controlled by firstly the lack of water in the system. In the absence of moisture, the acid salt and alkaline salt cannot ionize to provide hydrogen ions and cause the activation of sodium chlorite, which allows safe storage and transportation. (See FIG. 1(a)). When in use, the sealed container is opened and the moisture absorbent absorbs moisture in the air to activate sodium chlorite to generate chlorine dioxide. At the same time, the absorbed moisture is absorbed by the water absorbent to further prevent the supply of water to sodium chlorite to activate the generation of chlorine dioxide, and a hydrogel structure is formed. When moisture is absorbed, the hydrogel structure expands and becomes rigid, which also ensures the structural integrity of the system, and can be fixed to the container without falling off even when turned upside down. (See FIG. 1(b)).

[0010] The moisture absorbent is the main initiator of the chain reaction system. One or more moisture absorbents can be used to control the rate of moisture absorption from moist air. The moisture absorbent(s) can be zinc nitrate, copper nitrate, calcium chloride, magnesium chloride, zinc chloride, iron(III) chloride, potassium magnesium chloride, potassium carbonate potassium phosphate, ammonium ferric citrate, ammonium nitrate, potassium hydroxide, sodium hydroxide, nano water collectors. [6] , other metal nitrates, other metal chlorides, their anhydrous and hydrated forms, and any combination thereof.

[0011] When moisture is absorbed from the air, the absorbed water is either retained in the absorbent or dissolves other materials in the system. Water absorbing agents are used to slow down the reaction rate of system activation and form hydrogels to ensure the structural integrity of the system. The water absorbing agent or agents may be selected from the following materials: sodium polyacrylate, potassium polyacrylate, polyacrylamide copolymer, poly(ethylene-maleic anhydride), carboxymethyl cellulose, crosslinked carboxymethyl cellulose, polyvinyl alcohol hydrogel, crosslinked polyethylene oxide, starch-grafted polyacrylonitrile hydrolysate, other metal neutralized polyacrylic acid, starch powder.

[0012] Other ingredients (e.g., pH adjusters and inert powders that do not absorb water) can be added to the system to further impede the activation of sodium chlorite.

[0013] The gels can be prepared as a single mixture, as shown in Figure 2(a), a layer-by-layer composite, as shown in Figure 2(b), or a combination of both, as shown in Figure 2(c), or using a single mixture as the top layer of the gel, as shown in Figure 2(d). Although the single mixtures are already capable of forming functional gels, the layer-by-layer composites have been found to be even better in terms of storage and sustained release properties.

[0014] When preparing a single mixture gel, firstly, the stable salt capable of releasing gaseous germicide, the water absorbing agent, the pH adjusting agent (if present), and the inert spacer material (if present) are mixed uniformly, and then the moisture absorbing agent is added and mixed uniformly. The moisture absorbing agent should be added last, since adding once may cause a chain reaction and cause premature reaction. Examples 1 to 9 are examples of single mixtures prepared according to the above method.

[0015] When preparing a multi-layer composite gel, the moisture absorbent should be placed in the bottom layer, the stable salt capable of releasing a gaseous germicide in the middle, and the water absorbent in the top layer, so that moisture can be eliminated from the entire system before use. If a pH adjuster is added, it can be incorporated in the bottom layer or the middle layer. If an inert spacer material is added, it can be mixed into the base layer or the middle layer, or mixed between the base layer and the middle layer. A water absorbent layer can also be added between the stable salt capable of releasing a gaseous germicide and the moisture absorbent to increase the structural strength. Examples 10 to 12 are examples of four-layer multi-layer composite gels prepared according to the above method.

[0016] The performance of the gel can be evaluated by its sustained release time. After opening the screw cap and exposing to air, the bottle is held upright to allow the gel to form a rigid structure within a certain time. In Examples 1-9, a rigid structure was obtained after 1 day. In Examples 10-13, a rigid structure was obtained after 3 days. The successful formation of a rigid structure was determined by inverting the bottle and verifying that the gel contents did not fall out within 1 minute. Once a rigid structure was obtained, the bottle was kept inverted throughout the observation period to allow the chlorine dioxide gas, which is denser than air, to escape quickly.

[0017] The presence of chlorine dioxide was then measured using an ATI Porta Sens II gas detector and 00-1004 probe. The gas detector was set to give a minimum detection limit of 0.01 ppm of chlorine dioxide. The inlet of the detector was placed directly under the mouth of the container, and the number of days on which the detector detected chlorine dioxide was recorded.

[0018] Referring to Figure 3, the sustained release time of Examples 1 to 8 is compared. Comparing Example 1 with Examples 2 and 5, it can be seen that reducing the moisture absorbent does not increase the sustained release time of the gaseous sterilant. This is because according to Formulation Method 1, when there is enough moisture to initiate the reaction, moisture will also be generated throughout the activation process of sodium chlorite. Therefore, reducing or increasing the moisture absorbent will not extend the duration of the gel.

[0019] Comparing Example 1 and Example 4, the results show that doubling the amount of gaseous germicide (i.e., sodium chlorite) can extend the durability of the gel to some extent and extend its wear time. Comparing Example 1 with Examples 3, 6, 7, 8 and 9, it can be clearly observed that the more alkaline salt present, i.e. the higher the pH, the longer the gel lasts, while Example 9, which contains only alkaline salt, gives the maximum lasting time of 20 days compared to the previous examples.

[0020] Thus, the release rate and duration of release of the germicide from the gel can be finely controlled by selecting different acid and / or alkaline salt contents and the amount of gaseous germicide added.

[0021] Examples 10-12 were prepared in multiple layers, and their formulations were similar to Example 9. The durability of all multi-layer gels was significantly improved compared to the single mixture gels, and could be extended by 33% from 3 weeks to 4 weeks. This is because the moisture absorbent is separated from the stable salt that can release the gaseous germicide, so moisture must travel a longer path to reach the germicide layer enough to fully initiate the activation of sodium chlorite. Another advantage of multi-layer gels is that by ensuring that the outermost layer is absorbent, the structural integrity is strongest in the outermost layer, providing the strongest support.

[0022] According to a study by Morin et al., chlorine dioxide at a concentration of 0.01 ppm can kill bacteria within 2 to 3 hours. [4]can kill. The minimum detection value of the chlorine dioxide detector used to collect the data in Figure 2 is 0.01 ppm, so the gel sample in Figure 2 was able to kill bacteria throughout the entire release process. To evaluate whether the aerogels can be stored before activation and their performance after storage, Examples 13-17 were stored at room temperature for 36 days. The gels had a longer release time compared to Figure 2. The bottles were tightly capped immediately after the material was added to prevent moisture from entering and activating the system. After storage, the caps were removed and left to ventilate for a sufficient amount of time to allow air to enter and activate (to release any chlorine dioxide that may have accumulated during storage).

[0023] After aeration and activation, the gels were individually placed in 35 L airtight containers. A chlorine dioxide detector and an agar plate pre-seeded with E. coli were also placed in the containers to monitor the chlorine dioxide levels and perform sterility tests. For controls, an empty bottle was placed in the control container instead of the aerogel.

[0024] Referring to Figure 4, after the container is closed and sealed, the system is left for 10 minutes. The system is then reopened and the agar plate is removed to stop the sterilization. The chlorine dioxide concentration data is recorded before the system is turned on. The agar plate is then incubated for one day and counted the next day.

[0025] JPEG2025504875000002.jpg72165Table 1 shows that Examples 13 to 17 can be stored and still achieve high germicidal activity after activation. Example 17 also shows that the concentration of chlorine dioxide released can be controlled to a safe level (>0.3 ppm STEL and >0.1 ppm TWA) while maintaining a high sterilization rate. EXAMPLES

[0026] Example 1 First, sodium polyacrylate (0.4 g), citric acid (1 g), and sodium chlorite (1.5 g) were mixed using a vortex apparatus. Then, copper nitrate trihydrate (1 g) was added to the mixture and further mixed using a vortex apparatus. Example 2 First, sodium polyacrylate (0.4 g), citric acid (1 g), and sodium chlorite (1.5 g) were mixed using a vortex apparatus. Then, copper nitrate trihydrate (0.5 g) was added to the mixture and further mixed using a vortex apparatus. Example 3 First, sodium polyacrylate (0.4 g), citric acid (0.5 g), and sodium chlorite (1.5 g) were mixed using a vortex apparatus, then copper nitrate trihydrate (1 g) was added to the mixture and further mixed using a vortex apparatus. Example 4 First, sodium polyacrylate (0.4 g), citric acid (1 g), and sodium chlorite (3 g) were mixed using a vortex apparatus, then copper nitrate trihydrate (1 g) was added to the mixture and further mixed using a vortex apparatus. Example 5 First, sodium polyacrylate (0.8 g), citric acid (1 g), and sodium chlorite (1.5 g) were mixed using a vortex apparatus. Then, copper nitrate trihydrate (1 g) was added to the mixture and further mixed using a vortex apparatus. Example 6 First, sodium polyacrylate (0.4 g), citric acid (0.32 g), sodium citrate dihydrate (0.68 g), and sodium chlorite (1.5 g) were mixed using a vortex apparatus, then copper nitrate trihydrate (1 g) was added to the mixture and further mixed using a vortex apparatus. Example 7 First, sodium polyacrylate (0.4 g), citric acid (0.21 g), sodium citrate dihydrate (0.78 g), and sodium chlorite (1.5 g) were mixed using a vortex apparatus, then copper nitrate trihydrate (1 g) was added to the mixture and further mixed using a vortex apparatus. Example 8 First, sodium polyacrylate (0.4 g), citric acid (0.12 g), sodium citrate dihydrate (0.88 g) and sodium chlorite (1.5 g) were mixed using a vortex apparatus. Then, copper nitrate trihydrate (1 g) was added to the mixture and further mixed using a vortex apparatus. Example 9 First, sodium polyacrylate (0.4 g), sodium citrate dihydrate (1 g), and sodium chlorite (1.5 g) were mixed using a vortex apparatus, then copper nitrate trihydrate (1 g) was added to the mixture and further mixed using a vortex apparatus. Example 10 First, a premixed mixture of copper nitrate trihydrate (1 g) and sodium citrate dihydrate (1 g) was added to the system as the bottom layer, then another premixed mixture of sodium chlorite (1.5 g) and sodium polyacrylate (0.4 g) was added to the system as the second layer. Example 11 First, copper nitrate trihydrate (1 g) was added to the system as the bottom layer. Then, another premixed mixture of sodium chlorite (1.5 g) and sodium citrate dihydrate (1 g) was added to the system as the second layer. After that, sodium polyacrylate (0.4 g) was added to the system as the top layer. Example 12 First, a premixed mixture of copper nitrate trihydrate (1 g) and sodium citrate dihydrate (1 g) was added to the system as the bottom layer. Sodium polyacrylate (0.4 g) was then added to the system as the spacing layer. A premixed mixture of sodium chlorite (1.5 g) and sodium citrate dihydrate (1 g) was then added to the system as the third layer. Another layer of sodium polyacrylate (0.2 g) was then added to the system as the top layer. Example 13 First, a premixed mixture of copper nitrate trihydrate (1 g) and sodium citrate dihydrate (1 g) was added to the system as the bottom layer. Then, sodium chlorite (1.5 g) was added to the system as the second layer. After that, sodium polyacrylate (0.4 g) was added to the system as the third and top layers. Example 14 First, a premixed mixture of copper chloride trihydrate (1 g) and sodium citrate dihydrate (1 g) was added to the system as the bottom layer. Sodium chlorite (1.5 g) was then added to the system as the second layer. Sodium polyacrylate (0.4 g) was then added to the system as the third and top layers. Example 15 First, a premixed mixture of copper chloride trihydrate (1 g) and sodium bicarbonate (1 g) was added to the system as the bottom layer. Then, sodium chlorite (1.5 g) was added to the system as the second layer. After that, sodium polyacrylate (0.4 g) was added to the system as the third and top layers. Example 16 First, a premixed mixture of anhydrous copper chloride (1 g) and sodium bicarbonate (1 g) was added to the system as the bottom layer. Then, sodium chlorite (1.5 g) was added to the system as the second layer. After that, sodium polyacrylate (0.4 g) was added to the system as the third and top layers. Example 17 First, a premixed mixture of copper nitrate trihydrate (1 g) and sodium bicarbonate (1 g) was added to the system as the bottom layer. Then, sodium chlorite (1.5 g) was added to the system as the second layer. After that, sodium polyacrylate (0.4 g) was added to the system as the third and top layers.

[0027] References [1] K. Abe, "Composition for stabilizing chlorine dioxide", U.S. Patent US8603355B2, March 15, 2007. [2] K. Abe, "Pure chlorine dioxide solution and gel and foam compositions containing the solution", U.S. Patent Application US20100086493A, March 15, 2007 [3] KATSToshiaki Fukuda, "Broad-spectrum antiviral composition with excellent storage stability", US Patent US8545898B2, February 16, 2007 [4] TFTMTSH Morino, "Effect of low concentration chlorine dioxide gas on bacteria and viruses on glass surfaces in humid environments", Journal of Applied Microbiology Letters, vol. 53, no. 6, pp. 628-634, 2011. [5] MFT MaTS Hirofumi Morino, "Effect of very low concentrations of gaseous chlorine dioxide on Escherichia coli, Pseudomonas aeruginosa and Acinetobacter baumannii on the surface of wet glass dishes," BMC ReS Notes, Vol13, 2020 [6] L. Yingjian, "Harvesting water from air using trapped titanium dioxide nanotubes," Hong Kong, Hong Kong University of Science and Technology, 2020

Claims

1. A self-assembling gel capable of releasing a gaseous germicide, said gel comprising: formed from a composition including at least one moisture absorbent, at least one water absorbent, and at least one stable salt capable of releasing a gaseous sterilant; The composition is stored in a sealed container; The composition is configured such that, when the sealed container is opened, the moisture absorbent absorbs moisture in the air, and after the moisture absorbent absorbs moisture, it dissolves a salt capable of releasing a gaseous sterilant, and the salt capable of releasing a gaseous sterilant is activated by hydrogen ions in the solution and releases the sterilant; The gel is characterized in that it is a multi-layer gel including a bottom layer containing the moisture absorbent, the moisture absorbent being separated from a stable salt capable of releasing the gaseous sterilant.

2. The gel according to claim 1, wherein the moisture absorbent is one or a combination of zinc nitrate, copper nitrate, calcium chloride, magnesium chloride, zinc chloride, iron chloride, magnesium chloride-potassium chloride, potassium carbonate, potassium phosphate, ammonium iron citrate, ammonium nitrate, potassium hydroxide, and sodium hydroxide.

3. 2. The gel according to claim 1, wherein the water-absorbing agent is one or a combination selected from the group consisting of sodium polyacrylate, potassium polyacrylate, polyacrylamide copolymer, poly(ethylene-maleic anhydride), carboxymethyl cellulose, cross-linked carboxymethyl cellulose, polyvinyl alcohol hydrogel, cross-linked polyethylene oxide, starch-grafted polyacrylonitrile hydrolysate, other metal-neutralized polyacrylic acid, and starch powder.

4. 10. The gel of claim 1, wherein the salt capable of releasing a gaseous germicide is sodium chlorite, other salts capable of triggering and releasing a gaseous germicide, and combinations thereof.

5. 2. The gel of claim 1, further comprising an acidity regulator, a pH adjuster, a pH buffer and / or a non-water-absorbing inert spacer material.

6. The gel according to claim 5, wherein the acidity regulator, pH adjuster, or pH buffer is one or a combination of sodium citrate, citric acid, potassium dihydrogen phosphate, disodium hydrogen phosphate, disodium phosphate, sodium acetate, sodium dihydrogen phosphate, imidazole, sodium carbonate, sodium bicarbonate, sodium hydroxide, other acid salts, and other basic salts.

7. 6. The gel of claim 5, wherein the non-water-absorbing inert spacer material is selected from talc powder, titanium powder, and combinations thereof.

8. 10. The gel of claim 1, wherein the gel comprises: an intermediate layer containing a stable salt capable of releasing a gaseous disinfectant; and a top layer comprising at least a water-absorbing agent.

9. 6. The gel of claim 5, wherein the gel comprises: an intermediate layer containing a stable salt capable of releasing a gaseous disinfectant; a top layer including at least a water-absorbing agent; A gel characterized in that an acidity regulator, a pH adjuster, a pH buffer, or a non-water-absorbing inert spacer material is contained in any one of the bottom layer, the middle layer, and the top layer.

10. 6. The gel of claim 5, wherein the gel comprises: The gel further comprises a top layer comprising at least a mixture of a stable salt capable of releasing a gaseous sterilant, an acidity regulator, a pH adjuster, a pH buffer, and a non-water-absorbing inert spacer material.

Images