Short Peptide Self-Assembling Hvdrogel Doped Porphyrin And Their Photoelectric Properties

Efficient use of solar energy is one of the hot topics that people have been studying for a long time.Although important research results have been achieved,there are still problems such as low efficiency and high cost,which restricts the efficient using of solar energy.However,the protein/pigment complex formed by molecular self-assembly in nature is the key light capture unit,which completes the light energy harvesting,electron and energy transfer and final material synthesis.Therefore,biomimicking the natural light conversion process is one of the effective ways to improve light conversion efficiency and reducing cost.How to realize the efficient utilization of light energy through simple molecular design and structure assembly has become a hot and challenging research topic at present.In this thesis,short peptides consisting of several amino acids were selected as the self-assembling building unit,and the self-assembly behavior of the peptides was regulated by changing the assembly conditions,so as to achieve the precise design and preparation of the self-assembly structure.Based on the understanding of the self-assembly rule of short peptides,the ordered assembly ability of porphyrin and other pigment molecules was further studied,and the assembly with similar structure and function as that of natural photosynthetic system was constructed.The main results of the study are as follows:(1)A short peptide cage with hierarchical organization was constructed by using porous CaCO3 microparticles as templates in combination with enzyme-catalyzed condensation reaction.The porous CaCO3 microparticles were used as the carrier of thermolysin,which could be used as catalyzers for the condensation of Fmoc-Y and L-NH2 in water/n-hexane emulsion to yield the short peptide Fmoc-YL-NH2 for self-assembly.The condensation of Fmoc-Y and L-NH2 in the confined space of water/n-hexane emulsion allow the resulting Fmoc-YL-NH2 for self-assembly only confined on the surface of CaCO3.The peptide cage composed of nanofibrils can finally be obtained by removing the CaCO3 template,which has great potential application in the encapsulation of active cargos(such as porphyrin).(2)Light-harvesting hybrid hydrogels were prepared by self-assembly of aromatic short peptides with porphyrin as a dopant,and effective solar energy conversion was achieved.The long-range ordered assembly of aromatic short peptides can act as photoelectron receptor and conductor and promote photoelectron generation from light-harvesting antenna(porphyrins).At the same time,the doping of porphyrin can effectively reduce the impedance of peptide hydrogels and promote photoelectron transfer.The results of photocurrent measurement show that the porphyrin-doped peptide hydrogels have good photo-response properties.