Bovine Serum Albumin Assisted Synthesis Of Gold Nanomaterials And Their Properties

Gold nanomaterials are extremely promising in fields of biological and chemical sensing,biolabeling and bioimaging etc.due to their unique optical properties such as localized surface plasmon resonance and fluorescence.Proteins,the most abundant biological macromolecules with multiple functions,are widely used to mediate the synthesis of gold nanomaterials.Among various proteins,cheap and abunbant bovine serum albumin(BSA)is one of the idealest ligands due to its good biocompatibility,abunbant functional groups and biodegradability.In this thesis,we used BSA to assist the synthesis of many kinds of gold nanomaterials,and systemly investigated the roles of BSA played in the synthesis.We tuned the optical properties of gold nanomaterials and explored their application in surface enhanced Raman scattering(SERS)and sensing of glutathione and copper ions.Firstly,we developed a facile approach for preparation of ultra-stable Au nanoflowers by using BSA as ligand at room temperature.The role of BSA in the formation of gold nanoflowers was investigated.Increased concentration of BSA or decreased concentration of the reductant contributed to reduced activity or reduced reduction of the gold precursor,leading to the formation of Au nanoflowers with increased size.The BSA capped on surface of the gold nanoflowers not only contributed to the superior stability of the Au nanoflowers against ripening,but also endowed them with the ability to recognize oppositely charged dyes by SERS measurements according to the isoelectric point of the protein.Secondly,we fabricated a kind of novel BSA@Au core-shell particles by using110 nm BSA aggregate as a template,onto which gold shells composed by Au nanoparticles(NPs)were grown through seeded growth approach.Morphology of the Au shells deposited on the BSA aggregates was tuned from sparse to dense distribution of Au NPs by increasing concentration of silver ions contained in the growth solutions.Surface plasmon resonance(SPR)peaks of the BSA@Au particles were tunable in the range from 550 to 620 nm,corresponding to evolution in color from red to blue.The blue BSA@Au particles were responsive to glutathione(GSH).With increased amount of GSH presented,color of the BSA@Au particles evolved from blue to red attributed to gradual swelling of the BSA@Au particles and thus increased distance among the Au NPs in the shell.Based on this,a colorimetric method for detection of GSH was established with good selectivity and anti-interference capability,suitable for analysis of GSH in real samples.Moreover,the method was expanded to the synthesis of BSA@Ag core-shell particles using sodium citrate and histidine as the ligand respectively.The SPR peak of the BSA@Ag particles was tuned by varying the amount of seeds added into the growth solution.The as-prepared BSA@Ag particles were optically responsive to both surfactants and GSH.Thirdly,we re-examined the classical synthesis of BSA-Au nanoclusters(NCs)using BSA as the reductant and ligand.The effect of Na OH addition time and concentrations on the reducing ability of BSA and the resultant fluorescence intensity of BSA-Au NCs was systemly investigated.We found the change in addition time and concentrations of Na OH both influenced the solution p H and thus reducing ability of BSA.In a certain range,the fluorescence intensity of BSA-Au NCs increased with the reducing ability of BSA.According to this,we optimized the synthesis of BSA-Au NCs and improved their fluorescence response to copper ions.Finally,we prepared BSA-Au NCs fluorescence hydrogels in-situ using BSA as the matrix,reductant and ligand.The effect of Na OH and BSA concentrations on the formation of hydrogels was studied,and the result showed the genergation of Au NCs promoted the formation of hydrogels.The as-prepared BSA-Au NCs hydrogels were injectable and self-sealed,which is promising in fields of tissue engineering,biolabeling etc.