Controlled Synthesis Of Persistent Luminescence Nanoparticles For Biomedical Applications

Persistent luminescence nanoparticles(PLNPs)can remain luminescent after excitation ceases.In the past years,PLNPs have attracted widespread attention in various fields.Especially,PLNPs show many advantages in biomedicine.PLNPs can remain luminescent after excitation ceases,but the background fluorescence of complex biological samples disappeared rapidly as its short lifetime.So,the background fluorescence interference can be efficiently avoided by simply capturing the persistent luminescence of PLNPs in optical detection and bioimaging.In addition,since in situ excitation is not involved,PLNPs can reduce tissue light scattering interference of complex biological samples,leading to significant enhancement of signal-to-noise ratio and sensitivity of detection and imaging.Moreover,PLNPs have also made great progress in disease therapy.On the one hand,the long-lasting luminescence of PLNPs can serve as a persistent light source in vivo to excite photosensitizers and photothermal agents for continuous photodynamic and photothermal therapy.On the other hand,PLNPs can be used as a photosensitizer with energy storage capacity.After excitation ceases,the stored energy in PLNPs will be continuously released to produce reactive oxygen species for persistent disease therapy in the dark.While considerable achievements in biomedicine have been made,PLNPs remain face considerable challenges to be solved.The controlled synthesis of PLNPs is one of the important challenges.To better realize biomedical applications,PLNPs are required to have good dispersibility,surface modifiability,controllable size,excellent persistent luminescence,morphology matching with organisms,and excellent biocompatibility.At present,most of the PLNPs are prepared by a “top-down” method such as the hightemperature solid-state method,which requires synthesizing of bulk materials first,and then obtain PLNPs through grinding.The particles produced by “top-down” methods are not suitable for biological systems as their poor dispersibility,uneven size,and they are difficult to chemically modification,which severely limits the biomedical applications of PLNPs.Therefore,developing of a synthetic method for the controlled synthesis of PLNPs is of great significance for promoting the biomedical applications of PLNPs.In this work,we developed a synthetic strategy based on the hydrothermal method to synthesize PLNPs,and the morphology of PLNPs was well regulated by changing the reaction conditions of the hydrothermal synthesis process.Furthermore,we explored applications of PLNPs in background-free bioimaging and disease therapy based on their optical properties and structural characteristics.The main research contents of this dissertation are as follows:(1)A controlled synthesis method of PLNPs based on coordination chemistry was proposed.By changing the coordination ability of amino ligands in the hydrothermal reaction system,topological PLNPs with different morphologies were obtained.As the coordination ability of the ligands changed from weak to strong,the morphology of the PLNPs changes from rod-like to dumbbell-like,and finally to flower-like.In addition,the obtained PLNPs with different morphologies show excellent persistent luminescence properties.(2)A background-free latent fingerprint imaging method based on PLNPs was developed.Under a certain acidic p H range,the negatively charged PLNRs modified with carboxy can specifically bind to the positively charged amino groups in the fingerprint via electrostatic interaction.The interference from background fluorescence in the fingerprint substrates can be efficiently eliminated by collecting the persistent luminescence of PLNRs after the background fluorescence decayed completely.This imaging method can enhance the sensitivity and resolution of fingerprint imaging,and a clear fingerprint image without background interference can be obtained.(3)The photodynamic antibacterial properties of persistent luminescence nanoflowers with topological structure in the dark were studied.The topological persistent luminescence nanoflowers exhibited strong bacterial adhesion capacity and good persistent photocatalytic activity,thus showed excellent antibacterial properties under dark conditions.Furthermore,antibacterial fabrics coated with persistent luminescence nanoflowers can also kill bacteria effectively.The antibacterial mask and towel fabricated with antibacterial fabrics displayed well bacterial inhibition ability,and have great potential in personal health protection.