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Synthesis of Nanomaterials and Their Applications in Agriculture and Medicine
Nanotechnology has formed a research and development boom in the world. All countries in the world regard the development of nanotechnology as a part of the strategic goal of national science and technology development, and have invested heavily in the research and development of nanotechnology and materials. Nanomaterials are an important part of nanotechnology, and more and more countries pay attention to them. Countries (regions) have formulated corresponding development strategies and plans to guide and promote the development of nanotechnology and nanomaterials, and take supporting research and development in the field of nanotechnology and materials as the main driving force for technological innovation in the 2 1 century. Nanotechnology and materials show their broad development prospects and trends.

Strategic plans and key research areas of nanotechnology/materials development in various countries

At present, more than 30 countries in the world are engaged in the research and development of nanotechnology, and their investment in nanotechnology has increased rapidly, from $432 million in 1997 to $2 174 billion in 2002. In 2002, the investment ratio of governments in nanotechnology increased by 503% compared with 1997 (see table 60). From the table 1, it can be seen that since 2000, the growth rate of R&D funds invested by governments in various countries (regions) has accelerated. The United States, Japan and Western Europe are big countries (regions) that invest in nanotechnology, and the sum of investment of other countries and regions is not as much as that of the United States and Japan.

Since February 2000, the United States put forward the National Nanotechnology Plan (NNI), and the R&D expenditure of nanotechnology increased from $422 million in fiscal year 2000/KLOC-0 to $849 million in fiscal year 2004 (see Table 2). In 2000, the NNI Implementation Plan identified five strategic areas for key development (see Table 3), and the research contents contained in these five strategic research areas have been adjusted in recent years. Key research areas involved in major challenge projects in fiscal year 2003:

1) "design" stronger, lighter, harder, self-repairing and safe nano-materials: 10 times the strength of industrial, transportation and construction steel; Polymer materials and multifunctional intelligent materials whose strength is three times that of the materials used in the automobile industry melted at the current high temperature of 100 degrees Celsius;

2) Nano-electronics, nano-optoelectronics, nano-magnetism: improve the running speed of computers and improve the storage efficiency of chips by a million times; Increase the storage capacity of electrons to several thousand terabits. The storage capacity per unit surface area increases 1 thousand times; Bandwidth is increased by hundreds of times, and communication mode is changed;

3) In terms of medical care, reduce the expensive medical care expenses and enhance its effectiveness through diagnostic and therapeutic equipment; Using gene rapid sequencing and intracellular sensors for diagnosis and treatment; Detect early cancer cells and deliver drugs; Study on biosensor which can reduce the rejection rate of artificial organs by 50% and detect early diseases; Develop small medical devices with minimal damage to human tissues;

4) In terms of nano-scale treatment and environmental protection, the pollution particles smaller than 300 nanometers in water and 50 nanometers in air are removed to promote the cleanliness of the environment and water;

5) improve energy conversion and storage efficiency, and the energy efficiency of solar cells is improved by 1 times;

6) Developing small-power micro spacecraft to explore the outer space of the solar system;

7) Study nano-biological devices to alleviate the pain caused by treatment: a quick and effective biochemical detector; Nano-electronic/mechanical/chemical devices for protecting health and repairing damaged tissues;

8) Introduce the concepts of new materials, electronics, energy and environment in economic and safe transportation;

9) In terms of national security, pay close attention to the major challenges of nano-electronics, multifunctional materials and nano-biological devices.

In fiscal year 2003, the Ministry of Energy added three basic research projects on the characteristics of nanomaterials:

In the synthesis and treatment of nano-materials, we have a basic understanding of nano-processing involving material deformation and fracture. In order to synthesize nano-materials, we use fixed-die technology to arrange nano-particles. Synthesis of larger size nanomaterials by using nanomaterials with uniform size and shape;

● Research on nanomaterials in condensed matter physics, focusing on how to make macromolecules balance and self-organize into larger nanostructure materials;

● Engage in basic research to understand the role played by the characteristics of nano-materials in the transformation and control of catalytic changes.

The five key development strategic areas supported by NNI in fiscal year 2004 are the same as those in 2003 (see Table 3). Focus on supporting long-term research on manipulating substances at atomic and molecular levels, and exert creativity to build advanced new devices such as molecules and human cell sizes, so as to further improve electronic devices applied to information technology; Research and development of high performance and low maintenance materials); Used in manufacturing, national defense, transportation, aerospace and environment; Accelerate the application of nanotechnology in biotechnology, health care and agriculture. Key areas of research and development: biological-chemical-radiation-explosion detection and protection? Innovative solution of CBRE nanotechnology: nano-manufacturing research; Nanobiological system; Development of nanometer standard instruments: Educate and train a new generation of workers to meet the needs of future industrial development; Expand the industrial lineup participating in the nanotechnology revolution.

In the second Basic Plan for Science and Technology (200 1-2006), the Japanese government regards nanotechnology and materials, life sciences, information and communication, environmental protection, etc. As the most important field of national science and technology development strategy. In 20001year, the research funds invested in nanotechnology in this plan reached 142 billion yen, an increase of 8.8 billion yen over 2000. Key research areas of nanotechnology and materials determined by the plan: nano-materials and materials and their applications in electronics, electromagnetism and optics; Nano-materials and materials and their applications in structural materials: nano-information elements; Application of nanotechnology in medical treatment, life science, energy science and environmental science; Substances and materials related to surface and interface control; Nanometer measurement and standard technology; Nano-processing, synthesis and engineering technology; Calculation, theory and simulation technology of nanotechnology; Materials and technologies that form a safe space, etc.

In 200 1 year, the Ministry of International Trade and Industry of Japan formulated the "Nanomaterials Program" (NMP), with an annual funding of 35 million US dollars for seven years (200 1-2007), which was jointly studied by government departments, government research institutions, universities and industries, with the aim of establishing a new nano-functional material research and development and industry-oriented education function. In 200 1 year, the Ministry of Trade and Industry also formulated and implemented the "Next Generation Semiconductor Technology Development Plan" to develop the next generation semiconductor processing basic technology of 50-70 nanometers, and the government invested 60 million US dollars every year.

Japan's "exploratory research on advanced technology" involves many exploratory studies such as nanoparticles, nanostructures, nanobiology and nanoelectronics. The research period of this project is set at five years, all of which are funded by the government. During the five-year period, the average amount of government funding for the project was 654.38 million Canadian dollars +6 million pounds. Each project usually consists of 15-25 scientists and technicians, and is divided into three research groups. The plan encourages domestic and foreign industries, universities and research institutions to cooperate in research. The plan has completed many projects, mainly in research.

The Ministry of Education, Culture, Sports, Science and Technology of Japan released the budget for science and technology in 2003, in which the budget for nanotechnology and materials totaled 1, 496,5438+0 billion yen (see Table 6). On July 14, 2003, the 6th meeting of "Research and Development Promotion Project of Nanotechnology and Materials" was held at the Comprehensive Science and Technology Conference of Cabinet Office of Japan, and the key areas of research and development were determined: nano drug delivery system, nano medical equipment and innovative nano-structured materials. These projects, led by the Cabinet Office and jointly promoted by many government departments, were implemented in 2004.

Europe strives for the international status of nanotechnology. On the one hand, it actively creates new nanotechnology industries in Europe; On the other hand, it urges existing industrial sectors to improve their nanotechnology capabilities. In the Sixth Framework Plan (2002-2006), the EU took nanotechnology and nanoscience as one of the seven key development strategic areas, with a funding of US$ 6,543.80+2 billion, and identified specific strategic objectives and key research areas:

I nanotechnology and nanoscience

Transforming long-term interdisciplinary research into understanding new phenomena, mastering new technologies and developing research tools: paying attention to molecular and mesoscopic phenomena; Self-organizing materials and structures; Molecular and biomolecular mechanics and motors; A new method for comprehensive development of interdisciplinary research on inorganic, organic and biological materials and processes.

Nano-biotechnology: Its goal is to support the comprehensive research of living and non-living, and there are widely used nano-biotechnology, such as nano-biotechnology that can be used in processing, medical treatment and environmental analysis systems. The main research fields involve the lab on a chip, the interface of biological entities, the surface repair of nanoparticles, advanced drug delivery methods and nanoelectronics; Treatment, operation and detection of biomolecules or complexes, electronic detection of biological entities, microfluidics, promoting and controlling cell growth based on enzyme action.

Creating nano-engineering technology of materials and components: By controlling nano-structures, we can develop new functional and structural materials with ultra-high performance, including developing production technology and processing technology of materials. Pay attention to nanostructured alloys and composites, advanced functional polymers and nanostructured functional materials.

Develop operation control devices and instruments: develop a new generation of nanometer measurement and analysis instruments with a resolution of 10 nm. The key research fields involve various advanced nano-measurement technologies; Break through the technology, method or means to explore the self-organization characteristics of matter and develop nano-machinery.

Application of nanotechnology in health, chemistry, energy, optics and environment. Focus on computational simulation and advanced production technology; Develop innovative materials that can be modified.

Second, intelligent multifunctional materials

New materials with high knowledge content, new functions and modifications will be the key to technological innovation, devices and systems.

Develop basic knowledge: the goal is to understand the complex physical, chemical and biological phenomena related to materials, and to master and deal with intelligent materials that are helpful to experiments, theories and simulation tools. Main research areas: design and development of new structural materials with specific characteristics; The development of supramolecular and small molecular engineering focuses on the synthesis, exploration and potential application of new high-complexity molecules and their complexes.

The combination of technology and production: the transportation and processing of knowledge-based multifunctional materials and biomaterials: the goal is to produce new multifunctional "intelligent" materials, which can build larger structures. Key research areas: new materials; Self-repairing engineering materials; Including surface technology and engineering technology.

Engineering support for material development: the goal is to build a bridge between knowledge production and knowledge use and overcome the weakness of European homogeneous industries in the integration of materials and production. By developing new tools, new materials can be produced in a stable competitive environment. Key research areas: optimizing material design, processing and tools; Material testing; Make the material into a larger structure, considering biocompatibility and economic benefits.

Third, new production technology and equipment.

The concept of new production includes greater flexibility, higher integration, safer and cleaner, which will depend on organizational innovation and technological development.

In the five-year plan (1999-2003) of "nanotechnology information device initiative", Council of Europe has set three goals: to design devices with performance exceeding that of complementary metal oxide semiconductor silicon compatible devices; On the basis of chemistry, electronics, optoelectronics, biology and mechanics, new devices and systems at atomic or molecular scale are designed to solve special calculation problems by using the characteristics of molecules. The European Science Foundation put forward a five-year plan of "self-organized nanostructures", which was implemented in 2003. Molecular self-organization, soft matter or supramolecular research related to mechanical mechanism, and the function and preparation of self-organized nanostructures are listed as the first stage of research.

Among the scientific research priorities, the British government has determined the scientific research strategy and research priorities for 200 1-2004. Among them, materials science (research funding is 444 million pounds) and basic technology (research funding is 265,438 pounds +000 pounds) involve the research focus of nano-materials and nano-technology: promoting forward-looking material simulation research; Promote nanotechnology research and the development of interdisciplinary nanotechnology research cooperation centers (IRC) managed by different institutions. The British Engineering and Materials Science Research Council invested about US$ 7 million in the five-year plan for the development of materials science (1994- 1999), of which about US$ 1 10,000 was devoted to the research of nanoparticles. In 2000, the plan continued to support the research in the field of nano-materials. In 2003, the British government invested about 30 million pounds in nanotechnology.

In June, 2002, after investigating hundreds of scientists and inventors, the consultant expert group of the British government's Subcommittee on Nanotechnology Application outlined the development strategy of British nanotechnology in its report entitled "Development Strategy of British Nanotechnology" (see Table 7), and selected six areas of nanotechnology with research advantages and industrial development opportunities in Britain: electronics and communications; Drug delivery system; Biological tissue engineering, drug implantation and devices; Nanomaterials, especially biomedical and functional interface nanomaterials; Nano-instruments, tools and measurements; Sensors and actuators.

At present, the French government mainly supports three nanotechnology projects: "French micro-nano technology network" (65.438 million euros); "Nanostructured materials" (2.3 million euros); "Independent nano-objects" (6.5438+0.2 million euros).

The German Federal Ministry of Education and Research and the German Federal Ministry of Economic Affairs have funded six nanotechnology competence centers, with an annual investment of 65 million German marks. The main areas of funding are: ultra-thin functional films; Application of nanostructures in the field of optoelectronics: development of new nanostructures: ultra-fine surface measurement; Analytical methods of nanostructures.

In 2002, the German Federal Ministry of Education and Research issued a new strategy to enhance the research capacity of nanotechnology, which increased the research funding of nanotechnology from 65,438+27.6 million euros in 0998 to 8,850 euros in 2002, an increase of 200% in four years. Key research areas include strengthening the security of nanotechnology research infrastructure; Rebuilding comprehensive and innovative research institutions; Commercialization of nanotechnology; Promote the establishment of innovative enterprises; Strengthen the role of small and medium-sized enterprises and evaluate opportunities for cooperation with other countries; Shorten the term of relevant patents or authorizations; Science and technology laws related to promoting the next generation of science and technology research and development. Funding for the next generation of materials research reached 75 million euros, including funding for nanostructured materials.

Britain, France, Germany and other EU countries, in addition to the nanotechnology research supported by their governments, will also participate in the EU projects on nanomaterials in the Sixth Framework Plan mentioned above.

In the Basic Plan for the Development of Science and Technology from 2002 to 2006, the Korean government took nanotechnology and biotechnology, information technology and aerospace technology as the key strategic areas for the development of national science and technology. The "Nanobiotechnology Development 10 Year Plan" formulated in 2000 focuses on the research and development of nanodiagnostic devices, nanotherapeutic systems and nanobionic devices. "200 1-20 10tb Nanodevices Plan" identified TB nanoelectronics, spintronics, molecular electronics and core technologies as key research areas. The government's total investment in this plan is USD 6543.8+EUR 420 million. The Ministry of Science and Technology actively encourages private enterprises to set up special investment funds for nanotechnology as matching funds. The budget of "Action Plan for Nanotechnology Development in 2002" is 203 1 billion won, which is 9.310/%higher than that of 200 1 year. It aims to develop nano-core technology, establish a new national nano-manufacturing research center (25 billion won) and a fusion center of information technology and nano-technology. By 20 10, South Korea will have13,000 experts in the field of nanotechnology, ranking among the top 10 in the world.

In fiscal year 2003, Australia took nano-materials and biomaterials as key strategic research areas, mainly studying the formation of bulk materials through nano-self-organization of atoms and molecules.

Since 1999, Taiwan Province Province of China has successively formulated the Advanced Research Plan for Nanomaterials (1999). The "Nanotechnology Research Plan" (200 1-2005) is expected to invest NT$ 1 billion every year for five years. From 2002 to 2007, Taiwan Province Province of China plans to invest a total of 600 million US dollars in nanotechnology-related fields, with a steady growth every year, reaching an average of 654.38 billion US dollars per year.

Development of Nanotechnology/Materials in the World

Countries (regions) have made great progress in nano-materials and technology by implementing nano-science and technology plans.

As for nano-materials, the development of nano-technology/materials is obvious, taking some international research results in recent two years as an example. In 2002, IBM and Cornell University successively developed carbon nano-transistors. Wisconsin State University has developed an atomic silicon storage material, the storage density of which is 6,543.8+0,000 times that of the current CD.

The Institute of Nanotechnology established by MIT and the US Army has developed a kind of nano-coating with waterproof and bactericidal effects. The materials research group led by Stupp of Northwestern University in Illinois, USA designed and prepared bone-like nanofibers for the first time (Science, 23, 1 1, 2002). The research team led by Joshua Goldberger, Department of Chemistry, University of California, cooperated with scientists from Lawrence National Laboratory to successfully synthesize gallium nitride with single crystal structure for the first time by using a new epitaxial coating technology. GaN nanotubes, a new technology, can also be applied to the synthesis of single crystal nanotubes of other materials. Gallium nitride? GaN nanotubes can also be used in nano-capillary electrophoresis, biochemical nanofluid induction, nano-electronic and photoelectric elements (Nature 422? 599 2003)。

Alumina nanotubes were first developed by the Department of Chemistry, Moscow University, Russia. The Institute of Electrochemistry of Russian Academy of Sciences has successfully developed a new type of nano-coating, which has good sterilization and environmental protection performance.

Japan Industrial Research Institute has developed a single electron semiconductor, which uses carbon nanotubes to work at room temperature. On this basis, Nagoya University developed carbon nanotubes with controllable conductivity. Toshiba R&D Center in Japan used hydrocarbon catalytic decomposition method to coat a layer of iron-aluminum composite oxide on zinc oxide (ZnO2 _ 2) porous dielectric material as a catalyst, and prepared five layers of high-density filled carbon nanofibers with a diameter of 5-8 nanometers, and formed about 40,000 nanofibers per square millimeter on its surface energy. The purpose of studying this material is to develop a hydrogen storage energy material to absorb hydrogen and other fuels. Hitachi Research Institute uses nanotechnology to mix soft magnetic metal and high-resistance ceramics at atomic level under the action of mechanical force, thus forming a high-resistance ceramic structure around soft magnetic metal nanocrystals. Nanoparticles of soft magnetic metal are separated by high barrier to form high resistance, which can reduce the loss caused by high-frequency eddy current, thus successfully synthesizing high-frequency electromagnetic wave absorbing nanomaterials. The electromagnetic wave absorbing nano-materials prepared by this method can reduce the thickness of electromagnetic wave absorbing materials by about 50%, and are expected to be put into practical application as coated electromagnetic wave absorbing materials. The research team led by Yoshio Bando of Japan National Institute of Materials has successfully developed magnesium oxide single crystal nanotubes filled with liquid gallium with an inner diameter of about 20 ~ 60 nanometers. Gallium nano-composite thermometer, using the physical characteristics of magnesium oxide's high temperature resistance and stable structure at high temperature, greatly increases the temperature measuring range of nano-thermometer, and its measuring temperature is expected to reach 1000 degrees Celsius (APP. Physical communication 83999, 2003). This measuring temperature is much higher than the measuring temperature of 50-500℃ of carbon nanotube thermometer studied by Yoshio Bando's research group in 2002 (Nature 4 15 599, 2002).

In cooperation with the Department of Astrophysics of Alhos University, the Toulouse Center for Structural Research and Materials Manufacturing of the French National Scientific Research Center has designed a nano "mold" molecule that can automatically aggregate atomic lines on the copper surface, which opens a channel for the electronic interconnection of molecular components of future single-molecule circuits.

Nano-technology has also made new progress and breakthrough in medical application, nano-electronics, nano-processing and nano-devices. This article is not listed here.

Through the implementation of "National Key Plan", "863 Plan" and "973 Plan" in China, nanomaterials and nanotechnology have made outstanding achievements and attracted international attention. For example, in nano-electronics, waveguide single electron device transistor and coulometer which are super-sensitive to charge have been successfully developed; A semiconductor quantum wire mesa with a width of 6 nm and a wire metal gate with a width of 6 nm are realized, and various "nano-electrode pairs" with a spacing of only 10 nm are prepared. The prototype of high sensitivity sensor and hard disk head is developed by using giant magnetoresistance effect. In the aspect of nano-materials, the State Key Laboratory of Artificial Microstructure and Mesoscale Physics of Chinese Academy of Sciences cooperated with the State Key Laboratory of Artificial Microstructure and Mesoscale Physics of Peking University to construct C60 nanotubes directly from C60 powder. The obtained C60 nanotubes were grown from C60 crystals at 500℃, which kept the structure and properties of C60 molecules. At the same time, as a new aggregation structure, they had the characteristics of quasi-one-dimensional nanomaterials (J. AM. Chemistry. SOC, 2002, 165438+ 10 month, 13). Quasi-one-dimensional nanomaterials and non-hydrothermal synthesis nanomaterials of carbon nanotubes and their arrays have been developed. The research in the fields of super-ductility of nano-copper metal, bulk metal alloy, nano-multiphase ceramics, giant magnetoresistance, magnetocaloric effect, optical properties of mesoporous assembly system, nano-bio-bone repair materials, binary synergistic nano-interface materials and so on has certain influence in the world. Many important and influential achievements have also been made in the construction and self-assembly of nano-devices, ultra-high density information storage, nano-molecular electronic devices and so on.

Future development trend of nanotechnology/materials

Judging from the history of scientific and technological development, the development of new technologies often needs the support of new materials. If there is no optical fiber made by 1970, so that the light intensity is hardly attenuated, there may be no modern optical communication; Without high-purity and large-diameter silicon single crystal, it is difficult to imagine the rapid development of integrated circuits, advanced computers and communication equipment. Nano-materials are nano-scale materials with new characteristics and behaviors controlled by nano-scale. Nano-materials are an extremely important material basis for future social development. Nano-materials are the units to construct two-dimensional and three-dimensional complex functional nano-systems, and many new nano-devices and functional devices can be produced on this basis. Many breakthroughs in new fields of science and technology urgently need the support of nano-materials and nano-technologies, and the technological upgrading of traditional industries also needs the support of nano-materials and technologies. Nano-materials and technology will have a great impact and influence on many fields. From the bibliometric point of view, nanotechnology involves as many as 87 research fields.

From a global perspective, with the strong support of governments of various countries (regions) and the efforts of all walks of life in research and development, nanotechnology and technology have been continuously developed, and many new nano materials, new characteristics and new applications will be continuously discovered. The development of nanotechnology/materials shows attractive prospects. As mentioned above, nanotechnology/materials involve a wide range of research fields and have a wide impact on science, technology, economy and society, and its future development direction involves many aspects. This paper focuses on the future development trend of nano-materials.

● Nano-materials and their properties are developing in the direction of higher quality, which will make more nano-powders, nano-particles and nano-composite materials with superior performance and low price more widely used. For example, nanoparticles can be used to make new optical films and new functional materials with optics and magnetism. Magnetic nanoparticles and quantum dots will be used to produce subminiature optical disk drives. The storage capacity is 10 times that of current chips, and the speed is several hundred GHz.

● In terms of nano-materials and processing, new functional structural materials will be created by controlling nanocrystals, nano-films, nano-particles and carbon nanotubes; Develop ultra-light and super-strong structural materials; Develop long-life materials, materials supporting energy conversion and electronic materials with new functions; Understand the nano-technology involved in material deformation and fracture, and arrange nano-particles by imitation technology to synthesize nano-materials;

● Nanomaterials will become highly selective and effective catalysts in the process of chemical and energy conversion. This is not only very important for energy and chemical production, but also has great economic value for energy conversion and environmental protection.

The development of nano-materials will have a great impact on the biomedical field, such as implantable and compensatory biocompatible materials, diagnostic devices and therapeutics, and nano-materials will have more opportunities to be used in drug delivery systems. New biocompatible nano-materials and nano-mechanical components will create more implantable new materials, artificial organ new materials and nano-components.

● Develop new nano-polymer fiber materials with environmental compatibility based on natural fiber materials to ensure human health and safety: develop bacterial fine fiber nano-ecological materials; Wheat biopolymer (starch) composites used in food and other industries; Combining nanoparticles with biodegradable polymers to improve the physical and chemical properties of polymers; Developing nanocrystalline reinforcing agent from sugar to purify waste products; Development of locally chemically modified plant cellulose nanoparticles for polymer composites: development and utilization of rice husk to produce nano-silicon carbide; development of self-organized plant cellulose membrane with surface separation.

In a word, nanotechnology/materials will develop in the direction of integration with information technology, modern life science and cognitive science, and their integration will promote innovation and new discovery in all scientific and technological economic fields.