one. Inorganic antibacterial agents
Utilizing the antibacterial ability of silver, copper, zinc and other metals, through physical adsorption ion exchange and other methods, silver, copper, zinc and other metals (or their ions) are fixed on the surface of porous materials such as fluorite, silica gel and so on to make antibacterial agents, and then By adding it to corresponding products, materials with antibacterial capabilities can be obtained. Metals such as mercury, cadmium, and lead also have antibacterial abilities, but they are harmful to the human body. Copper, nickel, and diamond ions are colored, which will affect the appearance of the product. Zinc has certain antibacterial properties, but its antibacterial strength is only 1 times that of silver ions. /1000. Therefore, silver ion antibacterial agents occupy a dominant position among inorganic antibacterial agents. Silver ion antibacterial agents are commonly used antibacterial agents. They are in the form of white fine powder and have a heat-resistant temperature of over 1300°C. . The carriers of silver ion antibacterial agents include glass, zirconium phosphate, zeolite, ceramics, activated carbon, etc. Sometimes in order to improve the synergy, some copper ions and zinc ions are added. In addition, there are inorganic antibacterial agents such as zinc oxide, copper oxide, ammonium dihydrogen phosphate, and lithium carbonate.
How antibacterial agents work
Take the antibacterial mechanism of silver ions and their compounds as an example: Contact reaction antibacterial mechanism: Contact reaction of silver ions causes destruction of common components of microorganisms or dysfunction. When trace amounts of silver ions reach the microbial cell membrane, because the latter is negatively charged, they rely on Coulomb attraction to firmly adsorb the two. The silver ions penetrate the cell wall and enter the cell, and react with SH groups to coagulate the protein and destroy cell synthesis. enzyme activity, the cells lose their ability to divide and proliferate and die. Silver ions can also damage microbial electronic transmission systems, respiratory systems and material transmission systems.
two. Organic antibacterial agents
The main types of organic antibacterial agents include vanillin or ethyl vanillin compounds, which are often used in polyethylene food packaging films to play an antibacterial role. In addition, there are acyanilides, imidazoles, thiazoles, isothiazolone derivatives, quaternary ammonium salts, bisphosphonates, phenols, etc. The safety of organic antibacterial agents is still under study. Generally speaking, organic antibacterial agents have poor heat resistance, are easily hydrolyzed, and have a short validity period.
It is generally believed that the mechanism of action of organic antibacterial agents can be summarized in the following three aspects:
1. It acts on the cell wall and cell membrane system;
2. It acts on biochemical reaction enzymes or other active substances;
3. It acts on genetic material or genetic particle structure
Take quaternary ammonium salt antibacterial agents as an example: quaternary ammonium salts can adsorb negatively charged bacteria, causing damage to the cell wall structure and causing the contents to leak out. The bactericidal mechanism of alcohol is to remove lipids in bacterial cell membranes and denature bacterial proteins. Ethanol is commonly used. When its concentration is 70% to 75%, it has strong bactericidal power. When the concentration is too high, it can quickly coagulate the proteins on the bacterial surface. , the bactericidal efficacy decreases instead. Commonly used biguanide fungicides include chlorhexidine. When its concentration is low, it destroys the bacterial cell membrane and causes the cytoplasmic contents to leak; when its concentration is high, it coagulates bacterial proteins. In addition, quaternary ammonium salts also inhibit bacterial dehydrogenase and oxidase.
three. Natural antibacterial agents
Natural antibacterial agents are mainly extracted from natural plants, such as chitin, mustard, castor oil, wasabi, etc. They are easy to use, but have limited antibacterial effect, poor heat resistance, low bactericidal rate, cannot be used in broad spectrum and long-term use and are in small quantities. .
Plant-derived natural antibacterial agents and their antibacterial mechanisms:
At present, plant-derived antibacterial agents are the most studied type of natural antibacterial agents. my country’s traditional Chinese herbal medicine has a long history, and the development potential of this type of antibacterial agent resources is huge, such as Andrographis paniculata, garlic, golden buckwheat, quassipa, coptis and berberine, Houttuynia cordata and Houttuynia cordata, etc., which are all commonly used antibacterial agents. drug. There are many reports on related research on plant antimicrobials abroad (see Table 1). At present, the development of natural plant antibacterial agents has just started, and the research on its antibacterial mechanism needs to be in-depth.
Microbial-derived natural antibacterial agents and their antibacterial mechanisms
Microorganisms themselves can also be used as antibacterial agents. Its antibacterial mechanisms include the following: First, secretion of antibiotics. Y.Ouhdouch et al. reported that non-polyene antibiotics extracted from several strains of actinomycetes isolated in Morocco have strong inhibitory effects on yeasts, molds and bacteria. Through research, G.M. Thorne et al. found that daptomycin, the fermentation product of Streptomyces roseosporus, is a lipopeptide antibiotic that can inhibit almost all Gram-positive pathogens without producing cross-resistance [40]; M. Morita et al. The anti-Gram-negative bacteria activity is related to the structure. Experiments have confirmed that the C2 end and N2 end of this endolysin molecular chain are related to antibacterial activity. H. Tsubery et al. studied the antibacterial properties of the deamidated derivative of polymyxin B (PMB) (PMBN). Although the antibacterial properties of PMBN are weaker than those of PMB, it can penetrate the cells of Gram-negative bacteria. outer membrane and neutralize lipopolysaccharide (LPS) toxicity. The second is to participate in competition for nutrition and living space. By occupying living space, consuming oxygen, etc., we weaken or even eliminate certain pathogens in the same living environment. The third is to induce disease resistance in the host. Microorganisms can induce host defense responses or directly parasitize pathogenic bacteria and inhibit them. The fourth is direct action on pathogenic bacteria. L.L. Wilson et al. found that Trichoderma and yeast can parasitize pathogenic bacteria and secrete an enzyme that can destroy the fungal cell wall. Therefore�, Research on the antibacterial effects of microorganisms provides important theoretical basis and practical guidance for the development of new natural polymer antibacterial agents.
Animal-derived natural antibacterial agents and their antibacterial mechanisms
Most of these antibacterial agents act on the cell wall of bacteria to achieve antibacterial and bacteriostatic effects. Here we will explain the representative chitosan antibacterial agent. Chitosan is the deacetylation product of chitin and can be dissolved in many dilute acids. The smaller the relative molecular weight of chitosan, the greater the degree of deacetylation, and the greater the solubility. Chitosan has strong antibacterial activity, and its MIC value against Escherichia coli, Bacillus subtilis and Staphylococcus aureus reaches (250~500)×10-6. In addition, chitosan also has an inhibitory effect on plant pathogenic bacteria. For example, 1% chitosan has a complete inhibitory effect on F. oxysporum (F. Solani) and F. oxysporumcepae (F. oxysporumcepae). The antibacterial effect of chitosan is believed to have the following two mechanisms: one is that -NH3+ in the chitosan molecule is positively charged and adsorbed on the cell surface. On the one hand, it may form a polymer film to prevent nutrients from entering the cells. Internal transport, on the other hand, causes uneven distribution of negative charges on the cell wall and cell membrane, destroys the balance of synthesis and dissolution of the cell wall, dissolves the cell wall, thereby playing a bactericidal and bactericidal effect; the other is to enter the cell through penetration and adsorb into the cell body Substances containing anions disrupt the normal physiological activities of cells, thereby killing bacteria. Chitosan has different mechanisms of action for Gram-positive and Gram-negative bacteria with different cell wall structures. Gram-positive bacteria have a thick cell wall structure, and chitosan mainly acts on their cell surface, so the former mechanism is the leading role in killing such bacteria; Gram-negative bacteria have thin cell walls and small molecules Chitosan can enter its cells and act, so the latter mechanism plays a leading role. Research results show that as the degree of deacetylation and concentration increase, the antibacterial activity of chitosan increases. As for the influence of relative molecular mass, there is no consistent conclusion yet. The reason is that on the one hand, the relative molecular mass of chitosan cannot be well controlled during the production process, and on the other hand, because chitosan with different relative molecular masses It has different effects on different strains of bacteria. It is generally believed that as the relative molecular weight of chitosan decreases, the inhibitory effect on E. coli increases, while the inhibitory effect on Staphylococcus aureus weakens. In addition, some alkaloids can also be used as antibacterial agents. For example, Y.R. Torres and others found that alkaloids extracted from a sponge invertebrate have strong antibacterial effects on both Gram-negative and Gram-positive bacteria.
As an ideal antibacterial agent, it should have immediate, broad-spectrum, long-lasting, stable and safe antibacterial effects. However, existing antibacterial agents, whether inorganic, organic, or natural biological, have not met the ideal requirements. All types of existing antibacterial agents have unique antibacterial mechanisms. Only by conducting comprehensive and in-depth research on the antibacterial mechanisms and integrating the characteristics of various antibacterial agents can the effectiveness of antibacterial agents be further improved.
Extended reading: https://www. china-fire-retardant.com/post/9400.html
Extended reading: https ://www.alltextile.cn/product/product-30-663.html
Extended reading: https://www.yingjietex.com/product/Twist-Satin-with-Jacquard-Fabric.html
Extended reading:https://www.china-fire-retardant.com/post/9409.html
Extended reading:https://www.yingjietex.com/product/Two-way-stretch-satin-Printing- fabric.htm
