Development And Research For Ordered Arrangement Of Microbes In Micro/nano Biofabrication

Microbes have great potential in micro/nano fabrication technology.They can be used in micro scale,nano scale and multi-level hierarchical assembly as natural basic units and chassis cells.They have various shapes and sizes,which can become primary structrual units in micro/nano fabrication.On the other hand,microbes also have different biological functions,different metabolic pathways and products,which means they can also become primary functional units,‘micro/nano robots' to realize their functions in fabrication processes.How to control the movement and arrangement of microbes in micro/nano fabrication is the core problem to be solved,in order to design and assemble novel functional materials and devices.In this thesis,a method based on magnetic control and another method based on microfluidic technique have been raised and researched to solve this problem.A method based on magnetic control was set up to control movement and arrangement of microbes.Microbes were modified by polymers and then got a biomimetic mineralization shell through chemical reaction,so that magnetic nano-particles could be attached to microbial cell surface to provide the cell magnetic property.Saccharomyces cerevisiae was used as typical strain,treated respectively by two kinds of polymer modification methods,layer-by-layer self-assembly through charge effect and cohesive adsorption through the viscosity of sodium alginate.And then the modified yeast cells were processed by bimimetic mineralization method doped with magnetic nano-particles to become magnetic controllable microbes.The microstructure,magnetic property and viability of this magnetic controllable yesat were studied.Both of the two kinds of modification methods before mineralization step can provide magnetic property to cell,and sodium alginate modified yeast could maintain cell viability as well.Besides,Flavobacterium heparinum was employed as a functional strain to study the influence on heparinase metabolism by sodium alginate — biomimetic mineralization modification.The result indicated that the heparinase metabolism was delayed to begin,but the reaction rate was nearly the same as control group.A magnetic template with stripe pattern of 50 ?m width was designed and custom-made in order to study the ordered arrangement of magnetic controllable microbes in a patterned magnetic field.The result proved that after the modification yeast cells could be aligned along the pattern on the template very well.Another method based on microfluidic technique was developed as well.A patterned Si wafer template with 5 ?m and 10 ?m width of stripe and grid pattern was etched by KOH wet etching method and photolithography technique.We designed and prepared a two-level nesting patterned polydimethylsiloxane(PDMS)template based on the etched Si wafer template.And its structure was observed.We also attempted to use the 5 ?m pattern to induce the synthesis of bacterial cellulose.The stripe patterned bacterial cellulose film was synthesized through the patterning arrangement of Gluconacetobacter xylinus which produced bacterial cellulose in the PDMS template.