Development Of Nanomaterials Modified Molecularly Imprinted Photochemical Sensors

Molecular imprinting technology（MIT）refers to the preparation of a polymer that has specific selectivity for a particular target molecule（template molecule/imprint molecule）,the molecularly imprinted polymers（MIPs）.It was widely used in a number of applications because of its specific characterization and recognition and practicability for target molecules due to molecularly imprinted polymers.In addition,quantum dots（QDs）have a high fluorescence intensity,good stability and long fluorescence life,so that it has been wide range of attention in the some field,such as materials and sensing.Mn:ZnS QDs have quantum size effect,surface effect and quantum tunneling effect,so they can be used as an ideal material for constructing fluorescent probe.The advantages of QDs and molecular imprinting techniques were combined to build sensors with rapid,sensitive,and highly selective to detect many substances in the environment.The research work of this paper is as follows:1.A newly fluorescence probe for detection of Serotonin based on a Mn-doped ZnS quantum dots@silica nanoparticle@molecularly imprinted polymers（QDs@SiO₂@MIPs）was successfully created.QDs@SiO₂@MIPs were characterized by scanning electron microscope,transmission electron microscope,Fourier transform infrared spectroscopy,UV spectroscopy,X-ray powder diffraction,Energy Dispersive Spectrometer,and fluorescence spectroscopy.A complex was produced between the amino group of QDs@SiO₂@MIPs and the hydroxyl group of 5-HT when 5-HT rebinding,the energy of the QDs would be transferred to the complex,which led to its fluorescence quenching.The composite material has a high selectivity with an imprinting factor of 5.96.The linear regression equation is F₀/F=0.0036Cq-0.0512,with a correlation coefficient of 0.9928 in a liner range from 50 to 500ng/mL.The limit of detection（LOD）was 0.69 ng/mL.The probe exhibited simple preparation process,high sensitivity,good selectivity,low detection limit,short analysis time and could be applied to detect 5-HT in human serum successfully.2.A flexible magnetic and fluorescent sensing for the recognition and detection of bisphenol A（BPA）based on a hybrid magnetic ferriferrous oxide nanoparticles@silica nanoparticles@quantumdots@molecularlyimprintedpolymersnanoparticles（Fe₃O₄@SiO₂@QDs@MIPs NPs）was established.Due to the high selectivity of MIPs,the strong fluorescence property of Mn:ZnS QDs,the excellent magnetism of Fe₃O₄ NPs and eximious water-solubility of SiO₂ NPs,the Fe₃O₄@SiO₂@QDs@MIPs NPs can detect BPA effectively in aqueous solution.In the presence of BPA,a new compound was generated via the amino group of Fe₃O₄@SiO₂@QDs@MIPs NPs with the hydroxyl group of BPA,the energy of QDs would be transferred to the compound,which led to fluorescence quenching.And the relative fluorescence intensity decreased linearly with the increasing of BPA concentration within the scope of 50 to 700 ng/mL,and the detection limit was 0.16 ng/mL.In addition,the sensor showed distinguished selectivity to BPA over other possibly competing molecules and with an imprinting factor（IF）of 8.7.On the basis of the merits of the Fe₃O₄@SiO₂@QDs@MIPs NPs,the sensor could be applied to determine BPA in human urine sample successfully.3.A novel fluorescent probe for detection Quercetin based on QDs@SiO₂@Qu-MIPs was built successfully,and the probe quenched by photo induced electron transfer mechanism.We chose Qu as template,AM as functional monomer,ICPTES as auxiliary functional monomer,CTAB as surfactant structure guide,NH₃.H₂O as catalyst,and EDMA as crosslinking agent,and the SiO₂@Qu-MIPs was prepared by sol-gel method,that is,the surface of the SiO₂ modified by MIPs.The composite material has high selectivity with molecularly imprinted.The linear regression equation was F₀/F=0.0041Cq-0.0661,with a correlation coefficient of 0.9894 in a liner range from 30 to 450 ng/mL.The limit of detection（LOD）was 0.14 ng/mL and could be applied to detect Qu in actual sample successfully.