A Dual-Mode Detection Of Monosaccharide Based On Sers And Fluorescence Techniques

Glycomics has increasingly attracted our attention besides the development of genomics and proteomics. With the deepening research of glycomics and glycobiology, the identification and detection of monosaccharide has become a research focus. D-mannose, playing a vital role in organisms, is a kind of hexose which is significant to the fields of medicine, cell biology and so on. On the other hand, metal nanoparticles have been the subjects of the development of optical sensing, photocatalysis, medical diagnosis and treatment, due to that the optical properties of metal nanoparticles are strongly dependent on the size, shape and environment of the particles. Under irradiation of lights with a proper wavelength, the surface plasmon in metal particles can be excited. As a result, the local electric field close to the particles can be greatly enhanced. This is the foundation of various spectroscopic techniques sensitive to the electromagnetic fields, particularly of surface-enhanced Raman spectroscopy (SERS) and fluorescence spectroscopy.This thesis preparates a SERS and fluorescence dual-mode nanoprobe by the combination of fluorescence analysis and SERS on the basis of the unique optical and electrical properties of metal nanomaterials and the specific binding between monosaccharide and lectin, which is of great significance to the improvement of sugar molecules detection technology. First, we prepare a fluorescent-carbohydrate probe AuNP@MUA@GOx@Con A-TRITC using gold nanoparticles functionalized with 11-mercaptoundecanoic acid, glucose oxidase, and plus the binding between the mannoside chain on the surface of GOx and concanavalin A, which could successfully quantitative detect D-mannose through the reversible increase and decrease of fluorescent intensity. Besides, we combinate fluorescent molecules and Raman molecules with gold nanorodes to prepare a dual carbohydrate nanoprobe AuNR@4MBA@PAA@GOx@Con A-TRITC possessing two spectral signals. If the solution environment exists D-mannose, Con A will bind with D-mannose in the first place, causing the change of aggregation state of metal nanpparticles and then the distance between nanoparticles. On the one hand, the value of the SERS intensity changes with the concentration of D-mannose to make the qualitative detection of D-mannose. Specifically, the value of the maximum fluorescence intensity changes rugularly to quantitative detection of D-mannose.