The Study On The Surface Plasmon Resonance Sensor Based On Double-layer Molecularly Imprinted Polymer Films

Surface plasmon resonance(SPR) is a new biochemical analytical technology which has been widely employed in the studies of environmental monitoring, medical diagnosis and food safety. SPR sensors have the advantages of label-free, real-time monitoring and high sensitivity. However, biomolecular recognition elements(BRE) have been employed for the SPR biosensor because of no selectivity of SPR technology. Molecularly imprinted polymers(MIPs) can be as a good chioce as BRE because the advantages of high stability and high selectivity. Therefore, it has been developed the SPR sensor based on molecularly imprinted film(MIF) for the sensitive detection of small molecules.Traditional molecularly imprinted membrane can only detect the template molecules in organic phase, but most of the template molecules are present in the water. In order to solve this problem, we synthesized double-layer molecularly imprinted films combining SPR to detect template molecules in water samples. This method can detect low concentration of template molecules, prepared simplely, fast response and good reusability.The main contents are as the following:1. We synthesized double-layer molecularly imprinted films(MIF) to detect17β-estradiol(E2). The film was synthesized by in-situ UV photo polymerization. The imprinted surfaces were characterized by atomic force microscopy(AFM), scanning electron microscope(SEM) and contact angle measurements. Analysis of surface plasmon resonance(SPR) spectroscopy showed that the imprinted sensing film displayed good selectivity for E2 compared to other analogue molecules and NIF. A good linear relationship was obtained between the SPR angle and E2 concentrations over a range of2.50×10-13-2.50×10-9mol/L with the lowest measurable concentration of 2.50×10-13mol/L.The sensor can be regenerated over tens of times without significant deterioration of the sensor performance. This portable sensor system can be successfully applied for on-site real-time inexpensive and easy-to-use monitoring of E2 in environmental samples.2. A novel double-layer structure MIF on the SPR sensor chips for detection of testosterone in aqueous media. Analysis of SPR spectroscopy showed that the imprintedsensing film displayed good selectivity for testosterone compared to other analogues.Within the concentrations range of 10-12-10-8mol/L, the coupling angle changes of SPR were linear with the negative logarithm of testosterone concentrations. Based on a signal/noise ratio of three, the detection limit was estimated to be 10-12mol/L. The sensor can be regenerated over seven times without significant deterioration of the sensor performance. This portable sensor system can be successfully applied for detection of testosterone in aqueous media.3. In order to detect estrone in water, we synthesized a novel double-layer MIF.Analysis of SPR spectroscopy showed that the imprinted sensing film displayed good selectivity for estrone compared to other analogue molecules. A good linear relationship was obtained between the SPR angle and estrone concentrations over a range of2.50×10-12-2.50×10-8 mol/L with the lowest measurable concentration of 2.50×10-12 mol/L.The sensor can be regenerated over tens of times without significant deterioration of the sensor performance. This portable sensor system can be successfully applied for monitoring of estrone in environmental samples.4. Finally this paper studied the mechanisms of the double-layer MIF. We found that two factors affect the adsorption, one is the cross-linker concentration of the double layer.In the MIF, the cross-linker concentration of the pre-polymerization solution which used in the 2nd layer was higher, so that the 2nd layer can solid enough to detect the template in water solution. The other is the thickness of the MIF. The 1stlayer MIF was thicker and contained more specific recognition sites than the 2nd layer.