Study On SERS Properties Of Gold-based Alloy Nanomaterials And Their Biosensing Applications

Surface-enhanced Raman scattering（SERS）is a fast,sensitive,analytical method that can provide fingerprints of samples.It shows a unique advantage in material analysis and is widely used in the fields of interface chemistry and life sciences.In this paper,the gold-based alloy nanomaterials as SERS active substrate materials,a SERS biosensor is constructed based on the detection of acetylcholinesterase activity and the combination method of DNA and different alloy nanomaterials have been explored.1.In this work,a novel SERS system is constructed based on supramolecular assembly.To facilitate the interfacial supramolecular assembly,para-sulfonatocalix[4]arene（p SC₄）is directionally assembled onto Au Cu nanocrystals（NCs）through Cu-OH bonds.Due to the host-guest interaction between methylene blue（MB）and p SC₄,MB is captured by surface-tethered p SC₄ of Au Cu NCs,which enhancing the Raman scattering signal of MB up to 468 times.Moreover,by analyzing the difference between simulated and measured spectrum of MB,Raman enhancement of distinct groups is resolved with different mechanisms.Raman scattering of phenothiazine breathing mode and nitrogen-benzene stretching mode is dominated by proximity effect-induced electromagnetic mechanism and hydrogen bond-induced chemical mechanism respectively.Meanwhile,by introducing Nile blue or thionine as the second guest molecule,Raman scattering of MB can be replaced with that of Nile blue or thionine,which endowing the SERS system with a reporter-tunable feature.In addition,by further introducing enzymatic catalysis,a SERS system is employed to design a biosensing platform for enzyme detection and drug evaluation.Overall,this work establishes a supramolecular assembly-enabled SERS system,providing a strategy of resolving Raman enhancement mechanism and tuning Raman reporters.2.Au Ag alloy and Au Cu alloy with different morphologies were synthesized by the same preparation method,and were used as surface-enhanced Raman substrate materials.Introducing multiple single-stranded DNA（30A,30G,30C,30T）to explore the effect of DNA on the Raman activity of metals.During the experiment,we found an interesting phenomenon,the addition of DNA has two opposite effects on the Raman activity of Au Ag and Au Cu alloys.After the introduction of DNA,the Raman activity of Au Ag alloy is reduced.While,for Au Cu alloy,the existence of DNA is helpful to improve its SERS activity.Based on this phenomenon,we proposed the follwing guesses and conducted a series of experiments to verify,the combination method of DNA to different Raman substrates is diverse,which show a centain group orientation.It turns out that when Au Ag reacts with DNA,the phosphate skeleton of DNA preferentially binds to metal;When Au Cu reacts with DNA,the base of DNA preferentially binds to metal,and these two combination methods were obtained under different excitation light sources.The discovery of this phenomenon provides a new idea for the design of Raman biosensing systems,and will have profound influence in various fields of life sciences.