A degradable small molecule double quaternary ammonium salt with high antibacterial activity, its degradation product and a synthesis and degradation method thereof

Abstract

The application provides a degradable small-molecule double quaternary ammonium salt with high antibacterial activity, a degradation product thereof and a synthesis and degradation method thereof, and relates to the technical field of organic small molecules. The synthesis method specifically comprises the following steps: S1, under the catalysis of an organic base, a silane compound and a halogenated alkyl alcohol compound are combined to obtain a condensation intermediate with silicon-oxygen groups and halogen atoms at both ends; S2, the intermediate obtained in the synthesis is subjected to a nucleophilic substitution reaction with a triamine compound, thereby obtaining a silicon-based small-molecule double quaternary ammonium salt. The double quaternary ammonium salt has high antibacterial capacity, the minimum inhibitory concentration of the double quaternary ammonium salt on Staphylococcus aureus can reach 0.1 mu g / mL, the minimum inhibitory concentration of the double quaternary ammonium salt on Escherichia coli can reach 5 mu g / mL, and the double quaternary ammonium salt has low toxicity on human normal cells. In addition, the double quaternary ammonium salt also has the ability of pH response and temperature response controlled degradation. The degradation product, a single quaternary ammonium salt, has almost no bactericidal effect. Thus, the bactericidal toxicity is changed from yes to no through the degradation reaction.

Description

Technical Field

[0001] This invention belongs to the field of organic small molecule technology, specifically relating to a degradable small molecule bis-quaternary ammonium salt with high antibacterial activity, its degradation products, and its synthesis and degradation methods. Background Technology

[0002] With industrial development and improved living standards, people's environmental awareness has gradually increased. Traditional disinfectants are mainly chlorine-containing agents and peroxide compounds, which are difficult to store, highly irritating to the human body, and difficult to degrade after discharge, easily causing environmental pollution. Therefore, the development of a biodegradable and highly efficient antibacterial and bactericide is urgently needed. Quaternary ammonium salts are organic salts with nitrogen ions, which can achieve highly efficient and broad-spectrum antibacterial effects, are stable, and are among the most widely used antibacterial products internationally. Due to electrostatic interactions, the cationic polar head of quaternary ammonium salts can bind to negatively charged phospholipids in the cell membrane. The hydrophobic tail of quaternary ammonium salts embeds into the cell membrane, disrupting cell membrane integrity and causing leakage of intracellular substances, thereby achieving the purpose of sterilization.

[0003] Biquaternary ammonium salts are organic salts containing two nitrogen ions. Compared to monoquaternary ammonium salts, they have a higher positive charge density, making them more readily adsorbed onto the bacterial cell membrane surface. The polar head and hydrophobic tail of the quaternary ammonium salt act on different locations on the bacterial cell membrane, namely the membrane proteins and lipid layers, respectively. Therefore, biquaternary ammonium salts have a stronger bactericidal effect than monoquaternary ammonium salts.

[0004] Compared to monoquaternary ammonium compounds, bisquaternary ammonium salts exhibit bactericidal effects several times, even tens of times, stronger than their monoquaternary ammonium counterparts. Furthermore, bisquaternary ammonium salts demonstrate excellent biocompatibility and low cytotoxicity to human cells, far exceeding the effective inhibitory concentration for bacteria. They are widely applicable in medical disinfection, cosmetics, and personal hygiene products, and are highly safe.

[0005] However, conventional methods for preparing bis-quaternary ammonium salts are complex, have limited antibacterial activity, and the resulting bis-quaternary ammonium salts lack degradability, thus limiting their wider application. Therefore, synthesizing a bis-quaternary ammonium salt that combines highly efficient antibacterial and degradable capabilities is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a method for synthesizing a biodegradable small-molecule quaternary ammonium salt with high antibacterial activity. By modifying the hydrophilic group structure, changing the hydrophobic chain length, and introducing atomic groups with special functions, a two-step method can be used to prepare a quaternary ammonium salt that combines high antibacterial efficiency and biodegradability. Furthermore, according to the method disclosed in this invention, the antibacterial effect and degradation rate can be controlled by adjusting the steric hindrance of the intermediate connecting portion of the quaternary ammonium salt, thereby achieving precise regulation.

[0007] To achieve the above objectives, the present invention provides a method for synthesizing a biodegradable small-molecule bis-quaternary ammonium salt with high antibacterial activity, comprising the following steps:

[0008] S1 dissolves silane compounds and haloalkyl alcohol compounds in an aqueous organic solvent, adds an organic base and stirs the reaction. After the reaction is complete, the product is purified to obtain a condensation intermediate containing siloxy groups with halogen atoms at both ends.

[0009] S2 involves a nucleophilic substitution reaction between the synthesized intermediate and a triamine compound. The product is then purified to obtain a silicon-based small molecule bis-quaternary ammonium salt.

[0010] The silicon-based small molecule bisquaternary ammonium salt has degradation and bactericidal capabilities, with a minimum inhibitory concentration of 0.1–3300 μg / mL against bacteria such as Staphylococcus aureus and Escherichia coli; and a minimum killing concentration of 32–1024 μg / mL against mammalian L929 fibroblasts.

[0011] In a preferred embodiment, in step S1, the mass ratio of the silane compound, the haloalkyl alcohol compound, the organic solvent, and the organic base is 1:(1.5-3.6):(10-15):(1.0-1.6). In this invention, the synthesis of the bis-quaternary ammonium salt requires the construction of a bilateral halosilane intermediate. The molar ratio of the silane compound to the haloalkyl alcohol compound can be 1:2. The role of the organic base is to react with the byproduct hydrochloric acid to generate ammonium chloride, thus shifting the reaction to the right. Therefore, the molar ratio of the haloalkyl alcohol compound to the organic base can be 1:1, and the amount of organic base can be appropriately increased.

[0012] In a preferred embodiment, in step S1, the silane compound contains two halogenated groups and / or alkoxy groups; preferably, the silane compound includes one or more of dichlorodimethylsilane, dichlorodiethylsilane, dichlorodiisopropylsilane, dichlorodi-tert-butylsilane, dichlorodiphenylsilane, dimethoxydimethylsilane, dimethoxydiethylsilane, dimethoxydiisopropylsilane, dimethoxydi-tert-butylsilane, dimethoxydiphenylsilane, diethoxydimethylsilane, diethoxydiethylsilane, diethoxydiisopropylsilane, diethoxydi-tert-butylsilane, and diethoxydiphenylsilane.

[0013] In a preferred embodiment, in step S1, the haloalkyl alcohol compound includes 3-chloro-1-propanol, 4-chloro-1-butanol, 6-chloro-1-hexanol, 8-chloro-1-octanol, 9-chloro-1-nonanol, 12-chloro-1-dodecylol, 3-bromo-1-propanol, 4-bromo-1-butanol, 6-bromo-1-hexanol, 8-bromo-1-octanol, 9-bromo-1-nonanol, 12-bromo-1- One or more of the following: dodecanol, 3-iodo-1-propanol, 4-iodo-1-butanol, 6-iodo-1-hexanol, 8-iodo-1-octanol, 9-iodo-1-nonanol, and 12-iodo-1-dodecanol; preferably, the haloalkyl alcohols such as 3-bromo-1-propanol, 4-bromo-1-butanol, 6-bromo-1-hexanol, 8-bromo-1-octanol, 9-bromo-1-nonanol, and 12-bromo-1-dodecanol.

[0014] In this invention, an intermediate containing a siloxy group is synthesized by condensing a silane compound with a haloalkyl alcohol compound. The controlled breaking of active bonds such as the siloxy group allows for the transformation of the molecular structure from a bis-quaternary ammonium salt to a mono-quaternary ammonium salt. Furthermore, halogen atoms possess excellent bactericidal properties; the synergistic effect of both enhances bactericidal activity while simultaneously achieving biodegradability.

[0015] In a preferred embodiment, in step S1, the organic solvent includes one or more of tetrahydrofuran, acetone, dichloromethane, and trichloromethane.

[0016] In this invention, the organic solvent can fully dissolve the liquid intermediate product and separate it from the precipitated byproduct, thereby improving the product yield. The selected organic solvent should be an ultra-dry solvent, free from water, because water will cause silicon chloride to react preferentially with water rather than haloalkyl alcohols. Furthermore, the presence of water will cause hydrolysis of the silicon-oxygen bonds in the intermediate product, affecting the reaction.

[0017] In a preferred embodiment, in step S1, the organic base includes an aliphatic organic amine compound; preferably, the organic base includes one or more of trimethylamine, triethylamine, diethylamine, and dimethylamine.

[0018] In a preferred embodiment, the organic base is added in step S1 by slow dripping at a rate of 10–30 mg / min. The slow dripping rate is controlled because the reaction is a violently exothermic reaction; slow dripping allows for a more complete reaction and ensures experimental safety.

[0019] In a preferred embodiment, to keep the dehydrated organic solvent dry, the reaction apparatus can be filled with a dry inert gas, and step S1 is completed under an inert gas atmosphere. Preferably, the inert gas is nitrogen or argon.

[0020] In a preferred embodiment, in step S1, the stirring reaction temperature is -10 to 20°C, the stirring reaction time is 6 to 12 hours, and the stirring reaction speed is 50 to 200 rpm; the purification operation is as follows: centrifuge the solid-liquid mixture after the reaction, collect the supernatant and filter it, remove the solvent by rotary evaporation at 40°C, and then evacuate the vacuum for 0.5 to 1 hour.

[0021] In a preferred embodiment, in step S1, the synthesized condensation intermediate containing siloxy groups and halogen atoms at both ends comprises a compound represented by the general structural formula III:

[0022]

[0023] In the general formula of Formula III, the side group R includes one or more of methyl, ethyl, isopropyl, and phenyl; X represents a halogenated group; and n represents the carbon chain length, where n is an integer from 3 to 20.

[0024] In a preferred embodiment, in step S2, the triamine compound includes one or more of trimethylamine, triethylamine, tripropylamine, tributylamine, and tripentamine.

[0025] In a preferred embodiment, in step S2, the mass ratio of the intermediate to the triamine compound is (3-5):1. The triamine compound used in this invention serves to undergo a nucleophilic substitution reaction with the intermediate to form a bisquaternary ammonium salt, i.e., one intermediate molecule is substituted by two triamine compounds in a molar ratio of 1:2.

[0026] In a preferred embodiment, in step S2, the nucleophilic substitution reaction conditions are: at a temperature of -10 to 30°C, the reaction is stirred at 50-200 rpm for 6 to 12 hours; the purification operation is: centrifuging the solid-liquid mixture after the reaction, collecting the solid and evacuating it under vacuum for 0.5 to 1 hour.

[0027] Another objective of this invention is to provide a biodegradable silicon-based small molecule quaternary ammonium salt with high antibacterial activity. Through the above preparation method, this invention can obtain a small molecule quaternary ammonium salt that combines high antibacterial activity and biodegradability. It has been verified that its bactericidal ability can reach 99.999% within 20 to 60 minutes. Moreover, the bactericidal effect becomes stronger as the length n of the hydrophobic carbon chain increases.

[0028] To achieve the above objectives, the present invention provides a biodegradable silicon-based small molecule bis-quaternary ammonium salt with high antibacterial activity, comprising compounds with the general structural formula shown in Formula I:

[0029]

[0030] In the general formula of Formula I, the side group R includes one or more of methyl, ethyl, isopropyl, and phenyl; X represents a halogenated group; n represents the carbon chain length, and n is an integer from 3 to 20;

[0031] In the general formula I, trimethylamino can also be replaced by one or more of triethylamino, tripropylamino, tributylamino, and tripentanamino, as shown in the following structural formula:

[0032]

[0033] In a preferred embodiment, the bactericidal ability of the silicon-based small molecule bis-quaternary ammonium salt increases with the increase of the carbon chain length in the molecular structure. When the silicon-oxygen bond breaks and the bis-quaternary ammonium salt degrades into a mono-quaternary ammonium salt, it has no bactericidal ability.

[0034] In a preferred embodiment, the silicon-based small molecule bis-quaternary ammonium salt can achieve controllable degradation. By adjusting the substituents with different steric hindrances on the silicon atoms, the bactericidal effect and degradation rate can be changed. The greater the steric hindrance of the substituent, the slower the degradation rate.

[0035] Another objective of this invention is to provide a method for degrading highly antibacterial silicon-based small-molecule bis-quaternary ammonium salts. Due to the unique silyl ether linking groups in the structure of silicon-based bis-quaternary ammonium salts, they can achieve controllable degradation at different rates under different pH values ​​or temperatures. By adjusting the hydrophobic chain length *n* and the substituents with different steric hindrances on the silicon atoms, the bactericidal properties and degradation rate of the bis-quaternary ammonium salts can be adjusted. Thus, through the cleavage of siloxy groups, the bis-quaternary ammonium salts can be degraded into mono-quaternary ammonium salts, achieving a complete transformation from having bactericidal properties to having none.

[0036] To achieve the above objectives, the present invention provides a method for degrading silicon-based small molecule bis-quaternary ammonium salts with high antibacterial activity, specifically comprising the following steps:

[0037] The biodegradable silicon-based small molecule bis-quaternary ammonium salt with high antibacterial activity prepared by the aforementioned method can be degraded by dissolving it in an aqueous solution.

[0038] In a preferred embodiment, the pH of the aqueous solution is between 1 and 12; more preferably, the pH of the aqueous solution is between 2 and 10; and most preferably, the pH of the aqueous solution is 2, 3, 4, 5, 6, 7, or 8.

[0039] In a preferred embodiment, the aqueous solution comprises one or more of an acetate-sodium acetate buffer solution, pure water, and sodium bicarbonate solution.

[0040] In a preferred embodiment, the mass-to-volume ratio of the biodegradable silicon-based small molecule bis-quaternary ammonium salt to the aqueous solution is 100 μg:(0.1-100) μL. More preferably, the mass-to-volume ratio of the biodegradable silicon-based small molecule bis-quaternary ammonium salt to the aqueous solution is 100 μg:(0.1-10) μL.

[0041] In a preferred embodiment, the degradation temperature of the solution is 5-300°C, and more preferably, the degradation temperature of the solution is 10-200°C.

[0042] In a preferred embodiment, the biodegradable silicon-based small molecule quaternary ammonium salt with high antibacterial activity, after being dissolved in an aqueous solution, degrades in 0 to 3 months under environmental conditions of pH 2.5 to 7.4 and temperature 25 to 80°C.

[0043] Another objective of this invention is to provide a product derived from the degradation of a silicon-based small-molecule bis-quaternary ammonium salt with high antibacterial activity. Experimental verification shows that, similar to the silicon-based small-molecule bis-quaternary ammonium salt, the degradation product, a mono-quaternary ammonium salt, also exhibits a gradually increasing bactericidal effect with increasing hydrophobic carbon chain length (n). However, compared to the bis-quaternary ammonium salt, the mono-quaternary ammonium salt has almost no bactericidal effect. Specifically, the minimum inhibitory concentration (MIC) of the mono-quaternary ammonium salt against bacteria such as Staphylococcus aureus and Escherichia coli is above 10,000 μg / mL, indicating that it essentially lacks bactericidal ability. Therefore, this characteristic can be utilized to achieve a complete transformation of bacterial toxicity before and after degradation, thereby expanding its application scenarios.

[0044] To achieve the above objectives, the present invention provides a product for degrading highly antibacterial silicon-based small molecule bis-quaternary ammonium salts, comprising compounds represented by the general structural formula II:

[0045]

[0046] In the general formula of Formula II, the side group R includes one or more of methyl, ethyl, isopropyl, and phenyl; X represents a halogenated group; n represents the carbon chain length, and n is an integer from 3 to 20;

[0047] In the general formula II, trimethylamino can also be replaced by one or more of triethylamino, tripropylamino, tributylamino, and tripentamino.

[0048] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0049] 1. From the perspective of preparation method, the present invention obtains a quaternary ammonium salt that combines high-efficiency antibacterial and degradable capabilities in only two steps. The process is simple, has low requirements for reaction equipment and reaction conditions, and the raw materials are cheap and readily available, making it particularly suitable for large-scale industrial production.

[0050] 2. From the product perspective, the quaternary ammonium salt obtained in this invention exhibits significant bactericidal effects, demonstrating high antibacterial activity against bacteria such as Staphylococcus aureus and Escherichia coli. Specifically, the minimum inhibitory concentration (MIC) against Staphylococcus aureus can reach 0.1 μg / mL, and the MIC against Escherichia coli can reach 5 μg / mL, while showing low cytotoxicity to normal human cells. Furthermore, the contained silyl ether groups exhibit good biocompatibility. Therefore, it is suitable for sterilization applications in multiple scenarios.

[0051] 3. From an application perspective, the bis-quaternary ammonium salt provided by this invention offers multiple ways to regulate its bactericidal and degradation capabilities. Specifically, the bactericidal effect and degradation rate can be controlled by substituents with different steric hindrances on the silicon atoms; the strength of the bactericidal ability can be controlled by the length n of the hydrophobic carbon chain; and the degradation rate can be controlled by changing the degradation temperature and pH. Moreover, the degradation product, the mono-quaternary ammonium salt, has almost no bactericidal effect. It is possible to achieve a complete transformation of bacterial toxicity from present to absent before and after degradation. Attached Figure Description

[0052] These and / or other aspects and advantages of the present invention will become clearer and more readily understood from the following detailed description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

[0053] Figure 1 Experimental principle diagram;

[0054] Figure 2 Schematic diagram of the synthesis route for bisquaternary ammonium salts;

[0055] Figure 3 Schematic diagram of the synthesis route for monoquaternary ammonium salts;

[0056] Figure 4 intermediate product Ipr-bis-C3-Br 1 H-NMR (CDCl3, 400MHz, 298K);

[0057] Figure 5 Biquaternary ammonium salt IPR-bis-C3-QAS 1 H-NMR (D2O, 400MHz, 298K);

[0058] Figure 6 Mono-C3-QAS 1 H-NMR (d6-DMSO, 400MHz, 298K);

[0059] Figure 7 Comparison of the bactericidal effects of quaternary ammonium salts before and after degradation;

[0060] Figure 8 Sterilization effect of bis-quaternary ammonium salt IPR-bis-C9-QAS at different times;

[0061] Figure 9 Phytokinetics of bis-quaternary ammonium salt IPR-bis-C9-QAS;

[0062] Figure 10 Effects of different concentrations of quaternary ammonium salts ipr-bis-C3-QAS, ipr-bis-C6-QAS and ipr-bis-C9-QAS on L929 cell viability;

[0063] Figure 11 Controllable degradation of bis-quaternary ammonium salt IPR-bis-C9-QAS under different conditions 1 H-NMR (D2O, 400MHz, 298K);

[0064] Figure 12 Mass spectra comparison of bis-quaternary ammonium salt Ipr-bis-C6-QAS before and after degradation at 60℃ and pH 6.0. Detailed Implementation

[0065] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the following embodiments. Unless otherwise specified, the methods described are conventional methods. Unless otherwise specified, the raw materials are available from publicly available commercial sources. It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in the description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0066] In this invention, the mass fractions can be well-known units of mass in the art such as μg, mg, g, kg, or multiples thereof, such as 1 / 10, 1 / 100, 10 times, 100 times, etc.

[0067] Example 1

[0068] (1) The raw materials used in this embodiment are composed of the following components, in parts by mass:

[0069]

[0070] (2) The specific preparation steps are as follows:

[0071] The round-bottom flask containing the reaction vessel was filled with an inert gas to ensure a dry reaction environment. 3-Bromo-1-propanol was added to tetrahydrofuran, followed by dichlorodimethylsilane, and the mixture was shaken to mix. The reaction vessel was placed at -10°C, and TEA was slowly added dropwise to the mixture at 10 mg / min. The mixture was stirred at 100 rpm for 12 hours. The solid-liquid mixture was centrifuged, and the supernatant was collected and filtered through a 0.45 μm syringe filter. The liquid was then collected. The solvent was removed by rotary evaporation at 40°C, and the mixture was further evacuated under vacuum for 1 hour to obtain the reaction intermediate.

[0072] Example 2

[0073] (1) The raw materials used in this embodiment are composed of the following components, in parts by mass:

[0074] 38 portions of the intermediate prepared in Example 1

[0075] TMA 13 copies

[0076] THF 100 copies

[0077] (2) The specific preparation steps are as follows:

[0078] The round-bottom flask containing the reaction vessel was filled with an inert gas to ensure a dry reaction environment. Tetrahydrofuran was added to the intermediate prepared in Example 1, followed by TMA. The mixture was stirred at 10°C and reacted for 12 hours. The mixture was washed with tetrahydrofuran and centrifuged. The collected solid was then vacuum-sealed to further remove the solvent, yielding the bisquaternary ammonium salt product.

[0079] Examples 3-4

[0080] The steps are the same as in Example 1, except that dichlorodimethylsilane is replaced with dichlorodiethylsilane and dichlorodiisopropylsilane, and the mass fractions are replaced with 9 parts and 10 parts, respectively.

[0081] Examples 5-6

[0082] The steps are the same as in Example 1, except that 3-bromo-1-propanol is replaced with 6-bromo-1-hexanol and 9-bromo-1-nonanol, and the mass fractions are replaced with 20 parts and 25 parts, respectively.

[0083] Examples 7-8

[0084] The steps are the same as in Example 1, except that dichlorodimethylsilane is replaced with dichlorodiethylsilane, and the mass fraction is replaced with 9 parts; 3-bromo-1-propanol is replaced with 6-bromo-1-hexanol and 9-bromo-1-nonanol, and the mass fractions are replaced with 20 parts and 25 parts, respectively.

[0085] Examples 9-10

[0086] The steps are the same as in Example 1, except that dichlorodimethylsilane is replaced with dichlorodiisopropylsilane, and the mass fraction is replaced with 10 parts; 3-bromo-1-propanol is replaced with 6-bromo-1-hexanol and 9-bromo-1-nonanol, and the mass fractions are replaced with 20 parts and 25 parts, respectively.

[0087] Example 11

[0088] The steps are the same as in Example 2, except that the intermediate prepared in Example 1 is replaced with the intermediate prepared in Example 3, and the mass fraction is replaced with 41 parts.

[0089] Example 12

[0090] The steps are the same as in Example 2, except that the intermediate prepared in Example 1 is replaced with the intermediate prepared in Example 4, and the mass fraction is replaced with 44 parts.

[0091] Example 13

[0092] The steps are the same as in Example 2, except that the intermediate prepared in Example 1 is replaced with the intermediate prepared in Example 5, and the mass fraction is replaced with 47 parts.

[0093] Example 14

[0094] The steps are the same as in Example 2, except that the intermediate prepared in Example 1 is replaced with the intermediate prepared in Example 6, and the mass fraction is replaced with 56 parts.

[0095] Example 15

[0096] The steps are the same as in Example 2, except that the intermediate prepared in Example 1 is replaced with the intermediate prepared in Example 7, and the mass fraction is replaced with 50 parts.

[0097] Example 16

[0098] The steps are the same as in Example 2, except that the intermediate prepared in Example 1 is replaced with the intermediate prepared in Example 8, and the mass fraction is replaced with 60 parts.

[0099] Example 17

[0100] The steps are the same as in Example 2, except that the intermediate prepared in Example 1 is replaced with the intermediate prepared in Example 9, and the mass fraction is replaced with 53 parts.

[0101] Example 18

[0102] The steps are the same as in Example 2, except that the intermediate prepared in Example 1 is replaced with the intermediate prepared in Example 10, and the mass fraction is replaced with 63 parts.

[0103] Example 19

[0104] (1) The raw materials used in this embodiment are composed of the following components, in parts by mass:

[0105] 31 parts of 3-bromo-1-propanol

[0106] TMA 13 copies

[0107] THF 100 copies

[0108] (2) The specific preparation steps are as follows:

[0109] The round-bottom flask containing the reaction vessel was filled with an inert gas to ensure a dry reaction environment. 3-Bromo-1-propanol was added to tetrahydrofuran, followed by TMA, and the mixture was shaken to mix. The reaction vessel was placed at 10°C and stirred for 12 hours. The mixture was then rinsed with tetrahydrofuran and centrifuged. The solid was then further desolventized under vacuum to obtain the monoquaternary ammonium salt product.

[0110] Examples 20-21

[0111] The steps are the same as in Example 19, except that 3-bromo-1-propanol is replaced with 6-bromo-1-hexanol and 9-bromo-1-nonanol, and the mass fractions are replaced with 41 parts and 50 parts, respectively.

[0112] The analytical methods described below were used in all embodiments unless otherwise stated. The molecular names and formulas corresponding to the above embodiments are shown in Table 1.

[0113] Table 1

[0114]

[0115]

[0116]

[0117] Mono-quaternary ammonium salts can be obtained by degrading bis-quaternary ammonium salts with corresponding carbon chain lengths. This patent embodiment also provides another mono-quaternary ammonium salt obtained by a synthetic method. Testing showed that the quaternary ammonium salt product after degradation of the bis-quaternary ammonium salt had the same composition as the synthesized mono-quaternary ammonium salt. Taking ipr-bis-C6-QAS as an example, its mass spectra before and after degradation in an acetate-sodium acetate solution at pH 6.0 are shown below. Figure 12 As shown, the mass spectrum peak at m / z = 216.2045 before degradation corresponds to the mass spectrum peak of the bis-quaternary ammonium salt, while the mass spectrum peak at m / z = 160.1695 after degradation corresponds to the mass spectrum peak of the mono-quaternary ammonium salt. Therefore, it can be seen that the quaternary ammonium salt product after the degradation of the bis-quaternary ammonium salt has the same structure as the quaternary ammonium salt synthesized in the embodiments of this patent.

[0118] Example of effect

[0119] (a) Determination of minimum inhibitory concentration (MIC):

[0120] Experimental Method: Add 200 μL of 0.2% (w / w) resporane MH medium to a 96-well plate. The medium was pre-sterilized using an autoclave. Add 40 μL of the quaternary ammonium salt to the first well, then add 160 μL of resporane MH medium to the first well and mix well. Using a pipette, pipette 200 μL of the liquid from the first well of the 96-well plate and add it to the second well, effectively diluting the original solution by two times. Repeat this process to obtain a series of two-fold diluted resporane MH medium containing the quaternary ammonium salt. Add 4 μL of bacteria with an OD600 of 0.15 in PBS buffer to each well. Incubate the 96-well plate at 37°C for 18 hours. Calculate the percentage of surviving bacteria by measuring the absorbance at OD600 using a microplate reader, and determine the MIC value of the quaternary ammonium salt by observing the color change of the medium.

[0121] The minimum inhibitory concentrations (MICs) of the controllable degradable quaternary ammonium salts prepared in the above embodiments in water against *Escherichia coli* (E. coli) and *Staphylococcus aureus* (S. au) are shown in Table 2.

[0122] Table 2

[0123] MIC (μg / mL) S.au E. coli Me-bis-C3-QAS 500-700 2800-3300 Me-bis-C6-QAS 5-40 50-120 Me-bis-C9-QAS 0.5-10 5-30 Et-bis-C3-QAS 400-600 2000-3000 Et-bis-C6-QAS 5-20 50-100 Et-bis-C9-QAS 0.5-5 5-20 ipr-bis-C3-QAS 480-530 2000-2100 ipr-bis-C6-QAS 3-8 60-70 ipr-bis-C9-QAS 0.1-1 5-10 mono-C3-QAS 18000-20000 18000-20000 mono-C6-QAS 15000-18000 15000-18000 mono-C9-QAS 1000-1500 4000-4500

[0124] (II) Determination of inhibition zone:

[0125] Experimental Method: While still hot, sterile nutrient agar solution was poured into petri dishes. After the agar solidified, 300 μL of a 10-fold diluted Staphylococcus aureus bacterial suspension (OD600 = 1) was pipette-added to the surface of the petri dish and spread evenly. A 15 mm diameter hole was punched in the center of the agar medium, and 200 μL of a 0.1 mg / mL drug solution was added to the hole. The petri dishes were incubated at 37°C for 18 hours. The size of the inhibition zone was measured using the inhibition zone detection function of a colony counter. The results are as follows: Figure 7 As shown, from Figure 7 As can be seen, at the same mass concentration, the inhibition zone area formed by bis-quaternary ammonium salts is larger than that of mono-quaternary ammonium salts, and the inhibition zone area also increases with the increase of carbon chain length. Compared with mono-quaternary ammonium salts, bis-quaternary ammonium salts have a higher positive charge density and a greater destructive effect on bacterial cell membranes. The role of the hydrophobic chain is to insert into the phospholipid bilayer of the cell membrane; the longer the hydrophobic chain, the stronger the bactericidal ability.

[0126] (III) Bactericidal kinetics determination:

[0127] Experimental Method: While still hot, pour sterilized nutrient agar solution into petri dishes and allow the agar to cool and solidify. Select *E. coli* bacterial suspension diluted 10-fold (OD600 = 1) for later use. Sterilize the PBS solution for later use. Add 1 mL of 0.01 g / mL quaternary ammonium salt solution to 4 mL of bacterial suspension. Perform serial dilutions at 20-minute intervals. The dilution method is as follows: Take 0.5 mL of the well-mixed liquid and add it to 4.5 mL of PBS solution, mix well to obtain a 10-fold diluted bacterial suspension. Then take another 0.5 mL of this solution and add it to 4.5 mL of PBS solution, mix well to obtain a 100-fold diluted bacterial suspension, and so on, with the highest dilution being 10-fold. 6 Take 200 μL of bacterial culture from each dilution and spread it evenly on an agar plate using a sterilized spreader. Spread the culture on three plates for each dilution to facilitate subsequent counting. Invert the spread plates and incubate at 37°C for 24 hours. Measure the colony count using a colony counter. Take the average value of colonies ranging from 30 to 300, multiply it by the dilution factor, and this value represents the colony count corresponding to that sterilization time. Colony forming units (CFU / mL) = (average value of colonies from 30 to 300) × dilution factor × 5. For the blank control group, replace 1 mL of 0.01 g / mL bisquaternary ammonium salt solution with 1 mL of PBS solution; all other steps are the same.

[0128] The bactericidal effect of bis-quaternary ammonium salt IPR-bis-C9-QAS at different times is as follows: Figure 8 As shown, the bactericidal kinetics are as follows Figure 9 As shown, the quaternary ammonium salt Ipr-bis-C9-QAS can kill 99.99% of bacteria within 20 minutes.

[0129] (iv) Cell viability assay:

[0130] Experimental Methods: L929 mammalian fibroblasts in logarithmic growth phase were collected. The cell suspension concentration was adjusted, and 100 μL was added to each well of a 96-well plate (except the outermost ring) to achieve a cell density of 1000–10000 cells / well. Cells were cultured for 24 hours in a 5% CO2 incubator at 37°C. 100 μL of different concentrations of quaternary ammonium salt aqueous solutions were added to the first row of wells. Using a pipette, 100 μL of the solution was transferred from the first well of the 96-well plate to the second well, effectively diluting the original solution by two times. This process was repeated to obtain a series of two-fold dilutions of cell culture media containing quaternary ammonium salts. 20 μL of CCK-8 solution was added to each well, and the cells were incubated for another hour. The absorbance of each well was measured at 450 nm using a microplate reader. Cell viability = (A... 450nm,实验 -A 450nm,空白 ) / (A 450nm,对照 -A 450nm,空白 ), where A 450nm,实验A represents the absorbance in the wells containing quaternary ammonium salt reagents, cells, and CCK-8 solution. 450nm,空白 A represents the absorbance in wells containing CCK-8 solution but without cells. 450nm,对照 This refers to the absorbance in wells containing cells and CCK-8 solution but without the addition of quaternary ammonium salt reagents. Figure 10 As shown, the minimum concentration at which bisquaternary ammonium salts exert a killing effect on L929 cells decreases with increasing carbon chain length. It can also be seen that at low concentrations, bisquaternary ammonium salts do not produce toxic effects on human cells.

[0131] (v) Degradation performance:

[0132] Experimental methods: When observing degradation under neutral conditions, the synthesized quaternary ammonium salt was completely dissolved in heavy water, sealed in an NMR tube, and subjected to isothermal degradation at different temperatures. When observing degradation under acidic conditions, the sample was completely dissolved in acetate-sodium acetate buffer solutions of different pH values. The dissolved sample was then added to deuterium water, sealed in an NMR tube, and subjected to isothermal degradation in a water bath at different temperatures. Similarly, controlling the degradation temperature can be achieved by adjusting the water bath temperature. Figure 11 As shown, the hydrogen atom on the carbon atom bonded by the silicon-oxygen bond in the bis-quaternary ammonium salt shifted to around 3.62 ppm before hydrolysis. After hydrolysis, the silicon-oxygen bond broke, and the NMR spectrum shift of this hydrogen atom shifted to around 3.45 ppm. The degree of degradation was calculated by observing the changes in NMR spectrum integrals and the shift in peak position.

[0133] The controllable degradable quaternary ammonium salt (0.01 g) prepared in the examples was dissolved in 400 μl of acetate-sodium acetate buffer solution (pH=4.0) and 400 μl of pure water (pH=6.7) at 37 °C. 100 μl of deuterium water was added to each solution and sealed in an NMR tube. The degradation performance of different substituents on silicon atoms in acidic and neutral environments was observed using the aforementioned method. The complete degradation time is shown in Table 3.

[0134] Table 3

[0135]

[0136] As shown in Table 3, under the same temperature conditions, the stronger the acidity, the faster the degradation rate of the bisquaternary ammonium salt. From methyl and ethyl to isopropyl, the greater the steric hindrance of the alkyl group attached to the silicon atom, the slower the silicon-oxygen bond breaks, and the longer the degradation time. Figure 11 As shown, under the same pH conditions controlling the degradation environment, the higher the temperature, the faster the degradation rate. Therefore, the controlled degradation of quaternary ammonium salts can be achieved by changing the temperature and pH of the environment, realizing the transformation of quaternary ammonium salts from bacterially toxic to non-toxic, which can help protect the ecological environment. Similarly, quaternary ammonium salts with different substituents can be selected for sterilization according to specific degradation rate requirements.

[0137] In summary, one application scenario for the biodegradable small-molecule quaternary ammonium salt with high antibacterial activity obtained by this invention is: use under neutral conditions to achieve a good bactericidal effect by utilizing its high antibacterial activity. Before being discharged into the environment, it can be degraded by acid to become non-toxic. Furthermore, different quaternary ammonium salts have different degradation characteristics, allowing them to be applied to different scenarios according to requirements.

[0138] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

[0139] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. Furthermore, various different embodiments of the present invention can also be arbitrarily combined, as long as they do not violate the spirit of the present invention, and should also be regarded as the content disclosed by the present invention.

Claims

1. A degradable silicon-based small molecule bis-quaternary ammonium salt with high antibacterial activity, characterized in that, selected from the following structures: 、 、 、 、 、 、 、 、 。 2. The method for synthesizing the biodegradable silicon-based small molecule bis-quaternary ammonium salt with high antibacterial activity as described in claim 1, characterized in that, comprising the following steps: S1 dissolving a silane compound and a haloalkyl alcohol compound in a water-free organic solvent, adding an organic base to stir the reaction, purifying the product after the reaction is completed, to obtain a condensation intermediate with a silicon-oxygen group and a halogen atom at both ends; S2 performing a nucleophilic substitution reaction between the intermediate obtained by synthesis and a triamine compound, purifying the product after the reaction, to obtain a silicon-based small molecule bis-quaternary ammonium salt; In step S1, the haloalkyl alcohol compound is selected from one of 3-bromo-1-propanol, 6-bromo-1-hexanol, and 9-bromo-1-nonanol; and the silane compound is selected from one of dichlorodimethylsilane, dichlorodiethylsilane, and dichlorodiisopropylsilane. In step S2, the triamine compound is trimethylamine.

3. The method of synthesizing degradable silicon-based small molecule bis-quaternary ammonium salt with high antibacterial activity according to claim 2, characterized in that, In step S1, the mass ratio of the silane compound, the haloalkyl alcohol compound, the organic solvent, and the organic base is 1:(1.5-3.6):(10-15):(1.0-1.6).

4. The method of synthesizing degradable silicon-based small molecule bis-quaternary ammonium salt with high antibacterial activity according to claim 2, characterized in that, In step S1, the organic solvent includes one or more of tetrahydrofuran, acetone, dichloromethane, and trichloromethane. The organic base includes an aliphatic organic amine compound.

5. The method of synthesis of degradable silicon-based small molecule bis-quaternary ammonium salt with high antimicrobial activity according to claim 4, characterized in that, In step S1, the organic base includes one or more of trimethylamine, triethylamine, diethylamine, and dimethylamine.

6. The method of synthesizing degradable silicon-based small molecule bis-quaternary ammonium salt with high antibacterial activity according to claim 2, characterized in that, In step S1, the stirring reaction temperature is -10-20°C, and the stirring reaction time is 6-12 h; and the purification operation is: centrifuging the solid-liquid mixture after the reaction, collecting the supernatant, filtering, evaporating the solvent from the liquid after filtering, and vacuumizing for 0.5-1 h.

7. The method for synthesizing the biodegradable silicon-based small molecule bis-quaternary ammonium salt with high antibacterial activity as described in claim 2, characterized in that, In step S2, the mass ratio of the intermediate to the triamine compound is (3-5):

1.

8. The method for synthesizing the biodegradable silicon-based small molecule bis-quaternary ammonium salt with high antibacterial activity as described in claim 2, characterized in that, In step S2, the nucleophilic substitution reaction conditions are: reacting at a temperature of -10-30°C for 6-12 h; and the purification operation is: centrifuging the solid-liquid mixture after the reaction, collecting the solid, and vacuumizing for 0.5-1 h.

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