Current status and progress of domestic research

Research and development status of inorganic antibacterial materials Since the 1990s, China has been researching and developing inorganic antibacterial materials for plastics, and has achieved rapid development. In 1998, the output of antibacterial agents in China was only 50 tons, sales were 4 million yuan, and sales of antibacterial products were 7 billion yuan. By 2004, the output value of inorganic antibacterial materials and products in China had exceeded 100 billion yuan. This speed of development shows the strong market demand for such products and the industry. At present, inorganic antibacterial materials have been successfully applied in household appliances, building materials, decorative materials, fibers and textiles, daily necessities, sanitary products, food packaging and other industries. A remarkable feature of the development of inorganic antibacterial materials in China is the rapid follow-up and strong intervention of famous enterprises and famous brand products, which has effectively promoted the development of this product and related industries. Haier Group is the first large-scale brand-name enterprise to use inorganic antibacterial materials for the production of antibacterial appliances. Then, a large number of leading and leading enterprises in the industry put forward the requirements for the development of antibacterial products, and quickly introduced to the market. Haier Kehua Company (National Engineering Research Center for Engineering Plastics), backed by the Institute of Physics and Chemistry of the Chinese Academy of Sciences, has studied a variety of porous carrier silver ion antibacterial agents, silver-zinc composite antibacterial agents and nano antibacterial agents. Southwest Jiaotong University began research on preparation and functional control of four-needle ZnO whiskers (T-ZnOw) in the 1990s, invented the preparation technology of T-ZnOw antibacterial materials with independent intellectual property rights, and obtained a number of national invention patents. Applying for European patents, passing the Sichuan Provincial Achievements Appraisal, reaching the international advanced level and successfully achieving industrialization. Since 1999, the Institute of Metals of the Chinese Academy of Sciences has carried out research on antibacterial stainless steel and its structural control. It has obtained two types of antibacterial stainless steels, namely ferrite and austenite with independent intellectual property rights. Through the identification of results, it has reached the advanced level of international similar products.

Research Status of Related Mechanisms Domestic research on inorganic antibacterial materials began with the porous material silver-loaded system. In solving the discoloration of silver-ion antibacterial materials, more than ten units have done relevant basic research work. For example, after the silver-loaded or zinc-zeolite composite antibacterial agent is treated by a certain surface coating, the color stability can be improved; the prepared silver-loaded zirconium phosphate type antibacterial agent is prepared by adding a color stabilizer and strict control of the preparation process. The color is relatively stable. The research group led by Professor Zhou Yiwan of Southwest Jiaotong University has proposed and established the control technology for the preparation of zinc oxide whisker antibacterial materials, and proposed the basic principle and method of in-situ symbiotic and solid solution doping of zinc oxide whiskers. The energy levels and luminescent excitons were studied and the relationship between characteristic luminescence and antibacterial activity was found and explained. On this basis, the effects of structure, morphology, size, doping and energy level control and surface state on the antibacterial effect were studied. The antibacterial activity mechanism of zinc oxide inorganic antibacterial materials was studied. The basic framework and academic ideas of the antibacterial activity center theory. The research team led by Professor Yang Ke of the Institute of Metals of the Chinese Academy of Sciences has carried out some research work on the composition design, smelting and hot processing, antibacterial heat treatment, microstructure and precipitation phase, and antibacterial durability of antibacterial stainless steel. The copper-rich precipitate phase (ε-Cu) in the antibacterial stainless steel was observed under transmission electron microscopy and considered to be a key material characteristic for killing bacteria. Bioelectron microscopy was also used to directly observe the relationship between Escherichia coli and Staphylococcus aureus in contact with antibacterial stainless steel, from time to time from bacterial body to dehydration, dryness and death. This is the first direct observation of antibacterial stainless steel killing bacteria. In summary, inorganic antibacterial materials have formed a considerable industrial scale at home and abroad, and have attracted the attention of the business community and governments. Compared with the fast-growing industry, relevant basic research is obviously lagging behind, especially the antibacterial mechanism and persistence of inorganic antibacterial materials, human and environmental safety, microbial genetic variation and how to selectively and selectively prepare and use inorganic antibacterial materials. The key basic scientific issues are urgently needed for further study. With the increasing use of inorganic antibacterial materials, the use of surface is expanding, and many deep scientific and environmental safety issues must be highly valued.

In recent years, inorganic antibacterial materials have gained an extremely rapid development and an increasingly widespread application, playing an increasingly important role in protecting human living environment and improving people's health. The antibacterial material is generally a functional material prepared by adding an antibacterial agent to a matrix material through a certain process, and has the function of killing and inhibiting the growth of microorganisms, and the main function thereof is to inhibit the microbial reproduction and propagation of the surface of the material and the product, and cut off the source of the harmful microorganisms. . Antibacterial agents mainly include inorganic, organic and natural. The main components of organic antibacterial agents are quaternary ammonium salts, alcohols, biguanides and other compounds containing reactive functional groups. They have the characteristics of quick effect and strong bactericidal ability, but they are prone to microbial resistance (anti-drug) and have a role. Short-term, poor heat resistance and secondary pollution; natural antibacterial agents from natural extracts, such as chitosan, berberol, etc., the main antibacterial mechanism is considered similar to organic quaternary ammonium salts, but the effect is not as good as organic Antibacterial agents, and the products are not yet mature. Inorganic antibacterial agents in the initial industrialization mainly adopt physical adsorption or ion exchange methods, and metal ions such as silver, copper and zinc are carried in the micropores of porous materials, and the antibacterial ability of metal ions is utilized to achieve long-acting antibacterial action through sustained release. purpose. In recent years, inorganic antibacterial agents such as nano silver, zinc oxide and photocatalytic materials have appeared. Inorganic antibacterial agents and various antibacterial composite materials prepared by using them as functional additives are generally referred to as inorganic antibacterial materials.

Foreign research status and development trend

Research Status of Metal Ion Inorganic Antibacterial Materials and Related Mechanisms In metal ion antibacterial materials, considering the factors of safety, usability and antibacterial effect, the antibacterial metal ions that can be applied mainly include silver, zinc and copper ions. Since copper b has a darker color, the zinc ion effect is relatively poor. Therefore, the research on silver-based antibacterial agents in metal ion antibacterial agents is the most systematic and in-depth. The main varieties are molecular sieve silver, glass silver, fluorite silver, aluminosilicate silver, phosphate silver. Solving the problem of discoloration of silver-loaded inorganic antibacterial materials has always been the focus and difficulty of research on such antibacterial materials. Controlling the pore size of the support or using a material that forms a stable chelate with the metal ions can make the silver ions more stable and reduce the chance of discoloration. S. Ohsumi studied the relationship between the preparation process and the color stability of the silver-loaded antibacterial agent. It was found that high-temperature baking can delay the discoloration of the silver-loaded antibacterial agent to some extent. The use of glass as a carrier to load silver ions into the glass chemical structure not only solves the durability, but also can be applied to some transparent matrix materials. Using nanomaterials as carriers, research and preparation of various silver-based antibacterial materials is also a development trend in recent years. There are two main hypotheses about the mechanism of action of metal ion-based antibacterial materials, namely, the ion-release antibacterial mechanism and the active oxygen antibacterial mechanism. The basic idea of ​​the metal ion sustained-release antibacterial mechanism is that during the use, the antibacterial active ions are slowly released, and the metal ion activity destroys the bacterial cell membrane or binds to the sulfhydryl group of the bacterial enzyme protein to destroy the activity of the enzyme, thereby exerting an antibacterial effect. The silver-loaded inorganic antibacterial agent exerts a long-lasting antibacterial effect due to the slow release of metal ions. The antibacterial mechanism of reactive oxygen species believes that under the action of light, Ag+ reacts with water or air to form active oxygen O2- and high activity (strong oxidative or reducing). OH, destroying microbial structure and activity. A. Amanatido experimentally confirmed that ACF (Ag) can be produced? O2 and H2O2, and inferred that it may be produced? OH. In Y. Inoue et al., it is believed that Ag+ requires light and dissolved oxygen to produce antibacterial activity. Recent research has controlled the oxidation state of silver by electrochemical methods. When Ag+ becomes Ag, there is no antibacterial activity; when Ag becomes Ag+, antibacterial activity occurs. Therefore, it is considered that the antibacterial activity is caused by oxidation rather than by reduction. On the other hand, dissolved oxygen is reduced in the oxidation state of silver, and the silver-loaded zeolite solution is determined by a cell staining method. It has been detected that the product of oxygen molecule reduction is active oxygen. O2. Therefore, active oxygen is considered to be the antibacterial active center of the silver-loaded zeolite.

Active oxide antibacterial materials and their antibacterial activity mechanism The active oxide represented by ZnO is one of the first inorganic b to be applied. From bactericidal ointments to patch patches, from cosmetics to drugs, they are used in large quantities. Studies have shown that ZnO has a peculiar killing and inhibiting effect on various skin diseases, especially various specific rashes and eczema caused by Staphylococcus aureus. Zinc oxide is an inorganic antibacterial material with good biocompatibility, environmental coordination and safe antibacterial properties. However, due to the limitation of antibacterial activity, its development was once stagnant. O. Yamanoto studied the effect of ZnO particle size on antibacterial activity and found that in the range of 0.1-0.8 μm, its antibacterial activity increased significantly with the decrease of particle size. It is found that the ZnO/activated carbon composite system has a strong antibacterial effect, and the antibacterial activity increases significantly with the increase of ZnO content (52-65%) and carbonization temperature in the system, while the ZnO-free activated carbon does not have antibacterial properties. Matsushita Co., Ltd. found that a four-needle ZnO whisker (T-ZnOw) has better antibacterial activity than general zinc oxide, and has successfully applied it to the fields of antibacterial, mildewproof, sewage treatment, decomposition of harmful chemicals, etc. effect. Regarding the antibacterial mechanism of active oxide inorganic antibacterial materials, early studies have suggested that antibacterials of metal oxides such as ZnO, CaO, MgO are caused by metal ions ionized in the medium, but with 10 times the concentration of corresponding metal ion salts. , did not achieve the desired antibacterial effect. Studies have suggested that the antibacterial property of ZnO is due to its strong affinity with bacteria, which can destroy the survival and reproduction of bacteria by inhibiting the formation of bacterial fibrin. A study by J. Sawai of Japan found that the antibacterial activity of ZnO is derived from the release of active oxygen, and the presence of H2O2 is detected in its slurry system. The H2O2 content in the 100 mg/ml ZnO slurry system is 50 μg/ml. However, further experiments showed that the antibacterial activity of the aqueous solution containing 62 μg/ml of H 2 O 2 was significantly lower than that of the ZnO containing 100 mg/ml. Obviously, there is still an unclear mechanism of activity. The work of the research team also showed that ZnO has a significant effect on improving the sensitivity of E. coli to chloramphenicol, but no further study. The antibacterial activity of metal oxides against Escherichia coli and Staphylococcus aureus was evaluated by measuring the change of conductivity of bacterial culture medium, and the chemical kinetics of the experimental results were simply simulated by using the organobacterial bactericidal kinetic model. analysis. Regarding the problem of antibacterial difference between ZnO and CaO, MgO, in-depth research found that it is caused by different antibacterial active centers of ZnO, CaO and MgO. The former is H2O2 (active oxygen), and the latter two oxides are O2-.

Research progress on antibacterial stainless steel materials Antibacterial stainless steel not only maintains the high strength and toughness, thermal conductivity and electrical conductivity, temperature and wear resistance, plasticity and machinability of metal materials, but also the corrosion resistance and beautification of stainless steel itself. The new bactericidal and bacteriostatic function is a new type of structural/functional integrated material. The application of antibacterial stainless steel can be extended to many fields that cannot be covered by existing organic antibacterial agents and inorganic antibacterial agents, especially requiring high strength and resistance. High-temperature, wear-resistant applications provide new materials for the manufacture of medical devices, catering equipment, food processing equipment and utilities. The research and development of antibacterial stainless steel is also derived from Japan. In the late 1990s, some Japanese steel companies such as Nippon Steel, Aichi Steel, and Kawasaki Steel began research and development of antibacterial stainless steel materials with special application significance. They have been reported to have good manufacturing processability and antibacterial properties. Cu-ferritic antibacterial stainless steel, austenitic antibacterial stainless steel and martensitic antibacterial stainless steel, and formed several patents. Limited research has focused on the composition design and organization and properties of materials, and has speculated on the antibacterial mechanism from the perspective of materials research.

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