Sensor Of Tumor Biomarker Based On Local Field Enhanced Up-conversion Luminescence

It is very important to design a simple and efficient method for predictive diagnosis of tumor,especially in the case of self-examination.FRET-based detection system has advantages in stability and detection procedures,and it is also one of the optimization directions emerging in recent years in order to make tumor marker detection platform portable,simple,and real-time.The characteristics of the up-conversion nanoparticles perfectly meet the requirements of biosensor.However,low fluorescence quantum yield limits their application.Enhancing the intensity of up-conversion fluorescence is the most important research content in the application of up-conversion nanoparticles.The optical stop band of opal photonic crystal can block the light of specific wavelength and make it scatter between the cracks of the photonic crystal,so that the energy density of electromagnetic wave at the cracks of opal photonic crystal is greatly improved and significantly improve the emission intensity of up-conversion nanoparticles on the surface of opal photonic crystal.In this paper,we designed a new-style photonic crystal to enhance the up-conversion fluorescence,and on this basis,we constructed a FRET-based PSA sensor,and obtained the following results:[1]In this paper,a novel bilayer of poly（methyl methacrylate）opal photonic crystal（PMMA OPC）with double photonic stop bands was fabricated to match the excitation field and emission field of the up-conversion nanoparticles（UCNPs）at the same time,and greatly enhance their up-conversion fluorescence intensity.In this paper,core-shell up-conversion fluorescent nanoparticles Na YF₄:Yb³⁺,Er³⁺@Na YF₄:Yb³⁺,Nd³⁺were used.Under the excitation of 808nm light,the up-conversion emission intensity was increased by more than 170 times through the double stop bands photonic crystal structure designed in this paper.A FRET PSA sensor chip was constructed on the basis of up-converted nanoparticle/double stop bands photonic crystal composite film,it showed a good linear relationship in the range of 0.1～10ng/m L.The excitation light power density was as low as 1.7W/cm².[2]In order to make opal photonic crystals truly widely used,this paper designed a strategy of using polymer layer to modify photonic crystal film to enhance its water stability and mechanical stability.Existing methods for preparing opal photonic crystal film will inevitably generate a large number of aperture,a large area of photonic crystal film is essentially composed of fragments of photonic crystals with size of 5～10 microns,resulting in the poor water stability and mechanical stability of opal photonic crystals.In this paper,the polymer layer is used to fix the fragmentary photonic crystal film,and the modified photonic crystal film is inverted as a whole,so that the opal structure is exposed,and the water stability and mechanical stability of the photonic crystal film are greatly improved without affecting the fluorescence enhancement effect of photonic crystal.