三种稀土离子掺杂的nayf4上转换都荧光生物传感器的构建及应用-分析化学专业毕业论文.docx

ABSTRACTOwing ABSTRACT Owing to the unique photo—physical properties，rare-earth ions doped upconversion nanoparticles(UCNPs)have attracted extensive aRention in the recent few years．Compared with conventional fluorescent labels，the unique luminescence mechanism of UCNPs possess several advantages such as improved detection sensitivity owing to no autofluorescence， deeper NIR light penetration into biological causing minimum photodamage to living organisms，good chemical and physical stability， and low toxicity which endow their potential applications in bio-medical field，biological luminescent labels and drug delivery carriers．In this work，we prepared upconversion fluorescent materials and built three biosensors for ultrasemitive detection of biomolecule．The main work iS as follows： 1．A nanosensor based on fluorescence resonance energy transfer (FRET)between upconversion nanoparticles(UCNPs)and gold nanoparticles(AuNPs)was developed for melamine detection．The positively charged UCNPs as donor and the negatively charged AuNPs as acceptor bound together via electrostatic interaction，which caused the fluorescence quenching of UCNPs．Upon addition of melamine，AuNPs were released from the surface of UCNPs and aggregation due to the III 万方数据 N-Au N-Au interaction between melamine and AuNPs，which results in the fluorescence of UCNPs gradually recovered．Under the optimal conditions including media pH(7．O)，the concentration of AuNPs(1．23 nM)and incubation time(1 2 min)，the fluorescence enhanced efficiency shows a linear response to the melamine concentration ranging from 32 to 500 nM with a detection limit of 1 8 nM．Compared with other fluorescence methods，the fluorimetric nanosensor shows high sensitivity of O．9677，ease of operation and can be used for the determination of melamine in raw milk samples． 2．A novel nanosensor for tyrosine based on photoinduced electron-transfer(PET) between NaYF4：Yb，Tm upconversion nanoparticles(UCNPs)and melanin-like polymers．Melanin．1ike film