Preparation Of Chloroplast/SiO 2 Composites And Study Of Light Trapping Properties

Living cells are highly intricate structure with multiple function, for instance, red blood cells take up oxygen in the lungs or gills and release it into body tissues via blood flow through the circulatory system, the produced carbon dioxide also transported by red blood cells to the lungs and be out of the body; chlorop lasts convert the solar energy into chemical energy via so-called photosynthesis. The function of living cells continues to fascinate scientists, including chemists. Living cell assay, liveing cell therapy, living cell converting energy and other emerging technologies are becoming hot research fields, accordingly leading to the design and prepararion of a wealth of bio-inspired hybrid materials. To date, these materials have already been realized in the design of biocatalysts, bioreactors, and bioartificial organs. However, the application of living cells is limited due to their sensitivity to environmental conditions. Therefore great efforts have been made to prolong their biological functions, and one of the most important ways is to select a suitable matrix to confer protection. Among the commonly used matrix for cell entrapment, e.g., silica, calcium alginate or alumina, amorphous silica promises to be an excellent choice because of its chemical durability, optical transparency, mechanically strong, and the important property is biocompatibility. In fact, the widespread existence of silica wall in nature has provided evidence for designing silica shell for cell protection, which has really quality and universality. In recent years, organic modified silicone as a kind of cell entrappment matrix entrapped with an adjustable micro-structure has aroused wide attention, at the same time, it also further expand the application in the field of silicon in the biological matrix. Silica-based materials made of organically modified siloxanes via sol-gel process have been widely applied in the fields of environmental monitoring, drug carrier, laser materials, optical devices, and biomimetic materials.Based on the above research background, we simulated the natural structure of the diatom and designed chlorop last/silica and chlorop las t/organo silicone composite in order to preserve the function of photosynthesis of chloroplast and enlarge application range in vitro apply the function of photosynthesis of chlorop last. Combining with the interface guiding role of chloroplast to siloxanes during sol-gel process, monodisperse microspheres and composite gel were prepared the monodisperse microspheres and composite gel. A variety of characterization techniques were jointly used including scanning electron microscopy, transmission electron microscopy, X-ray diffraction. The micro structure of materials were characterized, and the electrostatic attraction between chloroplast surface and silica sol was deeply investigated by Zeta potential analysis. Subsequently the light-harvesting ability of chloroplast/silica microspheres investigated via UV-Visible spectrophotometer. With emphasis on the insights above mentioned, we carried out the researches in this thesis mainly including two parts below:The natural chloroplast extracted from spinach was used to direct the surface deposition of silica using mild sol-gel process. The results from SEM, TEM show that those chloroplast/silica microspheres have good dispersion, uniform particle size, spherical structure without reunion phenomenon. The energy dispersive x-ray (EDX) and structural characterization using XRD provide evidence for the formation of silica coating. To investigate the interaction between chloroplast surface and silica sol, zeta potential analysis was exploited, the charge of chloroplast surface helps attract negative charged silica sol generated from subsequent hydrolysis and condensation of the TEOS, then realized single-chloroplast encapsulation within silica shell. That is to say, Zeta potential analysis yields information regarding the electrostatic attraction between chloroplast surface and silica sol, which provides theoretical feasibility of single-chloroplast encapsulation. Prolonged plant cell viability combined with visible-light absorption of chlorophyll might enable stand-alone chloroplast-based harvesting light as photo-catalytic microreactors.On the basis of above work, the chloroplast/ormosil composite gel were prepared by exploiting functional 3-methacryloxypropyltrimethoxysilane(MAPTMS) in situ sol-gel process at the outer surface of chloroplast. The results from SEM, EDX, XRD show those hybrid materials have good dispersion, maintained chloroplast morpholody. The EDX also confirmed the silica shell coated on the surface of chloroplast. Compared with the free chloroplast, the light absorption function of chlorophyll in chloroplast/ormosil composite gel was extended.The original intention of designing these silica-base materials in the present thesis was "bio-inspired" of diatoms, combining the light absorption property of chloroplast with sol-gel process of silica process. Such material design concept is not only explaining the interaction between silica and the chloroplast in theory, but also enriched relevant theoretical knowledge of chlorop last-directed silica interfacial deposition and gel material.