| Due to the rapid development of nanotechnology and the flourish of synthetic techniques for nanomaterials, a variety of high quality nanomaterials and their related nanocomposites in different dimensions have been prepared via a number of chemical or physical methods. For practical applications, it is of great significance for the micro/nano blocks to be assembled into functional macro-scale materials. Most of the reported assembling strategies are only suitable for certain nano blocks, difficult to scale up, and moreover, producing the assemblies with relatively monotonefunctions and simple structures. From such perspective, general, efficient, low-cost, environmentally friendly and rapid scale-up assembly methods are desired to solve the problems of nanomaterials in the practical applications.Inspired by Nature, microorganism-based techniques have drawn extensive attention for the synthesis and assembly of nanomaterials. Compared to the traditionally chemical or physical methods, these techniques possess many advantages, such as environmental compatibility, low cost, high efficiency, and hierarchical/multi-dimensional structure processability. This thesis focuses on the syntheses of macro-scale nanomaterials by assembling various micro/nano blocks based on the inductive microorganism approach. Through investigating the influence of the growth and physiological metabolism of the selected microbials, we successfully realize the assembly of micro/nano blocks into macro-scale nanocomposites and explore their performances in a couple of practical applications, such as drug delivery, catalysis, absorption of heavy metal ions, cytotoxicity and so on. Our studies show that this technique of microorganism-induced assembly has wide adaptability in the assembly of micro/nano units with various dimensions and components. It is simple, universal, economical, safe to environment, and easy to scale up. This work broadens the research scope of micro/nano units by bioassembly technology and is of value for the practical applications of nanomaterials. The results are summarized as below.1. We developed a general, environmentally friendly, and scalable fungal mycelia growth method for in-situ assembly of zero-dimensional, one-dimensional, and two-dimensional nanoparticles to prepare macroscopic hypha sphere-based nanocomposites with novel structures. It is shown that the hyphae induce the assembly of micro/nano units mainly by surface charge, functional groups and surface adhesive force. Under theinteraction of shear force in water, during the somatic cell growth, the hyphae of bacteria winds together and finally forms the macro-scale hyphae nanocomposite spheres. By regulating the content of micro/nano units and culture time, we can control the size and performance of the hyphae nanocomposite spheres. This method has the advantages of good biocompatibility, certain mechanical strength, and stable integration between hyphae and micro/nano units. These materials show good properties in magnetic response, thermal treatment, pollutant adsorption and drug-sustained release.2. By the use of fungal hyphae (FH) growth induced ordered assembly of several kinds of micro/nano units, we prepared a series of core-shell structured hypha nanocomposite spheres in a programmed manner. This method can be applied in theintegration of different kinds of nanoparticles into the hyphae spheres simultaneously, and therefore, possessing multifunctionality. By this method, we have prepared two layered and three layered core-shell structured multifunctional hypha nanocomposite spheres, such as FH/GO/Fe3O4NPs, FH/Fe3O4NPs/GO, FH/Fe3O4NPs/Au NPs, FH/GO/Au NPs/CNT, FH/CNT/Au NPs/GO, etc. From color distribution and SEM analysis, the results showed that all of the programmedly-added nanoparticles were adhered on the surface of mycelium, forming hypha spheres with relatively orderly spatial distribution. This kind of multifunctional composite shows excellent properties in water treatment, catalysis, and photothermal effect.3. We developed a microorganism secreting bacterial cellulose-induced assembly method to construct biological nanospheres incorporated with graphene oxide (GO). It showed that GO interacted with bacterial cellulose effectively by hydrogen bonding, forming stable spherical structure under the shear force of water flow. Moreover, GO nanosheets distributed evenly in the net structure of bacterial cellulose. In particular, this material can effectively promote cell proliferation, anticipating to be used as a scaffold material in tissue engineering with good biocompatibility. In addition, the bacterial cellulose/GO spherical nanocomposite showed improved performance of fixation and release of doxorubicin hydrochloride compared with the pure bacterial cellulose, demonstrating great potential to be applied in drug delivery.4. We achieved the immobilization of simulated nuclide Sr2+and formation of stable SrCO3crystals by using the decomposed urea as carbonate sources from the secretion of carbonate mineralization bacteria in the metabolism process. We investigated the influences of pH value, temperature, inoculation quantity, culture time, and concentrations of Sr2+and urea on the rate of Sr2+consolidation and the morphologies of mineralized materials. It was found that bacteria and metabolites played important roles in the mineralization of SrCO3. Through this mineralization process, the Sr2+consolidation rate can reach98%. As a new, economical, radionuclide processing technology, microbial mineralization is very useful for the enrichment, regeneration or geological disposal of nuclide. |
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