Preparation Of Functionalized Upconversion Luminescent Nano-probes And Their Bio-application

Lanthanide—based upconversion nanoparticles (UCNPs) that emit high-energy,short-wavelength photons under excitation by near-infrared (NIR) low-energy light. UCNPs possessmany advantages, such as excellent light stability, high chemical stability, long luminescencelifetime, narrowband emission, a large anti-Stocks shift, low toxicity; moreover, using near-infraredlight as the excitation source has many advantages, such as non-biological background fluorescence,deep light-penetration.We synthesized various kinds of UCNPs through solvo-thermal methods. We further obtainedexcellent water-soluble and bio-compatible UCNPs with low toxicity by different surfacemodification and functionalization. Finally, the UCNPs can be used as probe in bioimagingapplication and biomedical field.Chapter1: A brief overview of the research progress of UCNPs for biomedical applications.Chapter2: We first synthesized UCNPs through the solvo-thermal methods and coated silicaon its surface. and further amino functional, After coupling with the acid-base indicator (XO) ontothe surface of amino-functionalized silica, the upconversion luminescence nano-sensor for pH havebeen synthesized.The nano-sensor has good water solubility, low toxicity, and well penetration tothe cell membrane. In addition, the probe material can be applied to the detection of pH level in theliving cells.Chapter3: With coating mesoporous silica on the surface of the UCNPs and adsorbing organicfluorescent dye molecules into mesoporous silica, a kind of conversion on the HS-nano-sensorbased on upconversion luminescence has been synthesized. and can be used for detecting HS-inpure water and in living cells.In summary, this thesis illustrates synthesis of UCNPs, surface modification, Our findingspromoted the function of UCNPs for further applications in the biomedical field.