Preparation Of New Magnetic Molecularly Imprinted Polymer And SERS Application Reserach

Surface-enhanced Raman Spectroscopy(SERS)has been widely recognized and applied to the analysis and detection of various fields due to its advantages of high sensitivity,simple operation,fast and trace detection,etc.Traditional precious metals such as gold,silver and copper can significantly enhanced the Raman spectrum of the measured material when they were used as the substrate.However,they have some disadvantages such as unstable chemical properties,difficulty in enrichment,poor spectral reproducibility and no selectivity,which restricte the application of SERS.By introducing magnetic particles and combining with molecular imprinting technology(MIT),we successfully prepared molecular imprinted polymer(MIPs)with stable properties,good repeatability and can specifically recognize and adsorb the target molecules.At the same time,we uesd SERS technology to analyze and detecte the target molecules.The main contents and results are as follows:1.We prepared the core-shell composite magnetic nanoparticles Fe₃O₄@Si O₂@Ag by the seed method,and characterized by Scanning electron microscopy(SEM),Transmission electron microscopy(TEM),Energy dispersive spectroscopy(EDS),X-ray diffraction(XRD)and Fourier transform infrared spectroscopy(IR).The results showed that the prepared composite magnetic nanoparticles Fe₃O₄@Si O₂@Ag were spherical and uniformly dispersed core-shell structure.Using 4-mercaptobenzoic acid(4-MBA)as probe molecule,it was found that Fe₃O₄@Si O₂@Ag had significant enhancement effect on Raman spectra of 4-MBA.The detection limit of 4-MBA could reach to 10^-13mol/L by S/N?3.Further studies showed that the Raman spectra of norfloxacin(NOFX)were enhanced by Fe₃O₄@Si O₂@Ag.The detection limit of Raman was 10^-9mol/L when the signal-to-noise ratio was S/N?3.The concentration of NOFX showed a good linear relationship between 10^-3?10^-8mol/L with the intensity of Raman peak at 1420 cm^-1,and the linear equation was y=3719.3x+30933,R²=0.986.Parallel determination of 10^-3mol/L NOFX for 15 times,the RSD was 3.34%,which indicated that the method had good repeatability.The above results indicated that Fe₃O₄@Si O₂@Ag could be used as a good magnetic SERS substrate for SERS detection of NOFX.2.Based on dopamine(DA)can self-polymerize under weak base conditions without heating and initiator,we used Fe₃O₄@Si O₂@Ag as matrix material,dopamine hydrochloride as functional monomer and Ciprofloxacin(CIP)as template molecule,presented a simple and rapid method for the preparation of magnetic molecularly imprinted polymers.It was characterized by Scanning electron microscopy(SEM),Transmission electron microscopy(TEM),Energy dispersive spectroscopy(EDS)and X-ray diffraction(XRD).Applying polymer Fe₃O₄@Si O₂@Ag-MIPs to SERS detection,it was found that Fe₃O₄@Si O₂@Ag-MIPs had good repeatability and uniformity.Fe₃O₄@Si O₂@Ag-MIPs had strong enhancement effect on Raman spectra of CIP.The detection limit of Raman could reach to 10^-9mol/L when S/N was greater than 3.The concentration of CIP showed a good linear relationship between 10^-3?10^-8mol/L at 1404cm^-1.The linear equation was y=705.37x+6352.5,R²=0.998;Investigated the selectivity of magnetic molecularly imprinted polymers with different drugs as interfering agents,we can found that MIPs had good selection properties.The results of the standard addition test showed that the recovery rate was between 83.3%and 93.4%,and the RSD was?1.61.The above results showed that the method was simple,fast,efficient,and selective,and can be used for specific detection of actual drugs.3.Based on the reversible covalent binding between borates and target glycoproteins,we proposed a scheme that can specifically recognized and detected immunoglobulin G(Ig G).MIPs was synthesized using 4-vinylphenylboronic acid(VPBA)as functional monomer,ethylene dimethacrylate(EGDMA)as cross-linking agent,2-methylpropionitrile(AIBN)as initiator,ethylene glycol(EG)and cyclohexanol as binary porogen,Ig G as template molecule,and using magnetic Fe₃O₄@Si O₂@Ag-Boronic acid particle as SERS probe to capture the target glycoprotein,and the"MIPs-target molecule-magnetic SERS probe"sandwich-like complex was successfully constructed.The results showed that the prepared sandwich-like complex showed high sensitivity and excellent selectivity for Ig G.The Raman peak intensity showed a good linear relationship in the concentration range of 1.0 mg/m L?1.0 ng/m L.The linear equation was y=657.93x+2963.9,R²=0.996.Parallel testing of this sandwich-like complex proved to have excellent repeatability.This method provided a new possibility for clinical non-immunity and quantitative detection of Ig G.4.GO has a large specific surface area,which can stabilize the adsorption of metal particles and improving the stability of the substrate.Thus we used Fe₃O₄/GO/Ag as matrix material,dopamine hydrochloride as functional monomer and NOFX as template molecule.It was characterized by Scanning electron microscopy(SEM),Transmission electron microscopy(TEM),Energy dispersive spectroscopy(EDS)and X-ray diffraction(XRD).Applying polymer Fe₃O₄/GO/Ag-MIPs to SERS detection,it was found that Fe₃O₄/GO/Ag-MIPs had strong enhancement effect on Raman spectra of NOFX.The detection limit of Raman could reach to 10^-9mol/L when S/N was greater than 3.The concentration of NOFX showed a good linear relationship between 10^-3?10^-8mol/L at1420 cm^-1.The linear equation was y=811.14x+6715.3,R²=0.991;the RSD was 3.32%for 10^-4mol/L NOFX determined 10 times in parallel,indicating that the recycling performance was good;the selectivity of magnetic molecularly imprinted polymers(MIPs)was investigated by using different drugs as interfering substances,and good selectivity was found.The method was simple,rapid,efficient and selective,and can be used for the specific detection of actual drugs.