In-Situ Controllable Synthesis Of Nanocomposites On Silk Fibroin Fiber

Recently, nanostructured metal oxide semiconductors (MOS) and noblemetals, e.g. ZnO and Au nanoparticles, have drawn more attention due totheir valuable optical properties and relevant applications in biological andmedicine fields and biocompatibility. There are many researches on ZnO andAu nanoparticles mainly focusing crystal growth, crystal structure controland nanoscience. Nowadays, ZnO and Au crystals of different shapes andsizes have been fabricated successfully. However, the high temperature, highpressure or some additives employed in the synthesis processes may bringsome problems, such as higher cost and complex operation process.Therefore, controllable synthesis of ZnO and Au nanoparticles with differentmorphology and good biocompatibility are high of significance.Nature has provided us with valuable solutions via millions of years’evolution. Evolvement of bioinspired techniques for the construction ofwell-ordered nanomaterials is a crucial intersection of branches of materialsscience and biotechnology. Soft chemistry technique is presently developed tofabricate a variety of functional nanostructures through appropriate biogenic approaches. In particular, Silk fibroin fiber (SFF), one of natural fibers withgood toughness, intensity and biocompatibility, has been used in many fields,such as synthesis of optical nanomaterials and biomedical nanomaterials, dueto the particular configurations and the special functional groups.Based on these investigations, ZnO and Au nanostructures with variousmorphology and size, have been successfully prepared and encrusted ondegummed silk fibroin fibers (SFF) respectively, through in situ biotemplatesoakage approaches at room temperature. With the mild reduction ability, thegrowth mechanisms of the crystals have also been analyzed. The maincontents and results are as follows:1. The optimization of degumming processAn optimized degumming process has been designed to obtaindegummed SFF as the active biotemplate, which involved boiling thecocoons in alkaline solution for about one hour, then rinsing with deionizedwater.2. The controllable synthesis of ZnO/SFF compositesReactive silk fibroin fibers (SFF) were chosen as the biotemplates todirect the in-situ synthesis and assembly of ZnO nanoparticles. Without anyadditives, flower-like ZnO nanoparticle was obtained with specially modifiedprocess. Through the research on the optical properties of products, it can be found that the solid products presented orange-red phosphorescence centeredabout600nm, which guarantees the products with the potential of bioimagelabels in the medicine field.3. The controllable synthesis of Au/SFF nanocompositesTwo kinds of Au/SFF composites have been obtained, sphere Au/SFFnanocomposites with the size of5nm and13nm, and Au/SFF microparticles.The degummed SFF were immersed in HAuCl4solution at room temperature,to actualize the extracellular nucleation of Au nanocrystallites and in situassembly into nanostructures on the biofibers. Furthermore, without anyadditives, gold nano-and microparticles with different sizes and shapes havebeen fabricated by adjusting the parameters. After resolved in CaCl2solution,Au/SF nano-and microparticles have been obtained as well. Due tonon-toxicity and biocompatibility, the products can be used in the medicineand biological cells fields.