The Application Of Core-shell Nanomaterials In Raman Analysis

Surface enhanced Raman scattering?SERS?technology has the advantages of high sensitivity,wide application range and rapid detection.However,in the application of actual biological samples,environmental interference is likely to cause desorption of Raman molecules and affect the stability and reproducibility of SERS detection.Core-shell structure nanomaterials have the advantages of multi-function,tunability,biocompatibility,controllability,etc.,and have been widely used in drug delivery and release,biological imaging,spectroscopy and other fields.In order to improve the stability of the nanoprobe,we placed Raman molecules inside the core-shell material and prepared core-Raman molecule-shell nanomaterials.In addition,we have developed a new SERS detection method,which realizes the contactless detection of the target by Raman molecules.The detection mechanism is different from the previous direct contact detection.Instead,it uses the external shell as a signal switch to control the signal switch.It does not affect the nature and structure of the internal Raman molecule and maintains its high stability.This method regulates the signal of Raman molecule,realizes SERS analysis in living cells and blood.The main research contents are as follows:?1?By discussing the effect of shell thickness and type on SERS performance,it is proved that the shell structure can hinder the penetration of laser or SERS signals,which greatly reduces the detection signal.First,based on the gold core labeled with Raman signal molecules,a variety of core-shell nanomaterials were constructed,and the relationship between shell thickness,type and SERS signal intensity was explored.Two Raman signal molecules 4-mercaptopyridine?SH-Mpy?and 4-mercaptobenzoic acid?SH-MBA?were bonded to the surface of the gold core through gold-sulfur bonds,and a variety of shell structures?Au,Ag,ZnO,MnO₂?.For noble metal shells,as the shell thickness becomes larger,the SERS signal will show a tendency to increase first and then decrease.However,for non-noble metal shells,as the shell thickness becomes larger,the SERS signal will gradually weaken.?2?Intracellular glutathione ratio type SERS detection was realized based on manganese dioxide and double gold nanoparticles.Firstly,Au-Mpy-Au@MnO₂nanoprobe was synthesized by embedding Mpy-SH molecules between Au nuclei and Au shells.The SERS nanoprobe generated a strong SERS“hot spot”and avoided the interference of external environment on Mpy Raman molecules.MnO2 shell has a characteristic signal peak around 610 cm-1,which can not only be used as a blocker to weaken the SERS signal strength of internal Mpy,but also be used as a Raman reference value to correct the interference from working conditions.When glutathione?GSH?is added,GSH reacts with MnO2,where the signal strength of MnO2 decreases and the signal of Mpy increases.The linear relationship between the signal ratio of Mpy and MnO₂ and the concentration of GSH was plotted.The greater the concentration of GSH,the greater the ratio.In addition,the SERS technology based on capillary sampling required only 2?L samples to conduct uniform SERS analysis.?3?Based on the above mentioned manganese dioxide and gold-coated shell-core nanoparticles,the ALP in serum was determined.Rapid ultraviolet and Raman detection of ALP enzyme was realized by redox reaction of MnO2 and ascorbic acid?AA,ALP enzymatic hydrolysis product?.In the presence of ALP,the manganese dioxide shell is gradually degraded,and the Uv absorption peak position of the nanoprobe is gradually blued.The Uv absorption peak position can be used as a signal to realize the Uv detection of high concentration of ALP.In addition,using the Raman intensity ratio of Mpy and MnO2 as a signal,SERS detection of ALP with low concentration and high agricultural speed could be realized.With the help of this ratio nanoprobe and capillary SERS technology,our analysis system realized rapid SERS detection of ALP in trace samples and ALP detection in serum.