Controllable Synthesis And Biological Applications Of Near-Infrared Persistent Luminescence Nanomaterials

Persistent luminescence nanomaterials（PLNPs）are a kind of materials that can store excitation light energy through defects and remain luminescent after stopping the excitation.Emission bands of PLNPs are mainly located in the ultraviolet region,visible region and near-infrared（NIR）region.Among the well-developed PLNPs,NIR PLNPs exhibit excellent properties such as low scattering background and high tissue penetration.These merits make NIR PLNPs show great potential in the fields of bioimaging with a high signal-to-noise ratio.Bioimaging applications require NIR PLNPs to have high afterglow intensity and long afterglow time to achieve deep tissue penetration.However,most of the current NIR PLNPs have low afterglow intensity and short afterglow time due to the limited excitation light energy stored in a few internal defects.There is an urgent need to regulate the optical performance of the NIR PLNPs.Ion doping is an important method for the property tuning of luminescent materials.The doping of specific ions in the host materials to introduce defects can regulate the optical performance of materials.Benefiting from their energy level structures,the introduction of suitable lanthanide ions into NIR PLNPs is expected to regulate the optical performance such as afterglow intensity,afterglow time and emission wavelength of the materials.In this thesis,a series of lanthanide ion-doped NIR PLNPs were synthesized.Then,the afterglow intensity,afterglow time,and emission wavelength of the NIR PLNPs were regulated by changing the type and content of doped ions.Further,the imaging ability of NIR PLNPs in deep tissues was investigated.The main research contents of this thesis are as follows:（1）Controllable synthesis and bioimaging applications of PLNPs with emission in the first biological window（NIR-Ⅰ,650-900 nm）.The Zn_1.2Ga_1.6Ge_0.2O₄:Cr（ZGGO:Cr）NIR-Ⅰ PLNPs were synthesized by hydrothermal method.The optical performance of ZGGO:Cr PLNPs was regulated by adjusting the type and content of the doped ions.The results showed that Zn_1.2Ga_1.6Ge_0.2O₄:Cr,Tm（ZGGO:Cr,Tm）PLNPs exhibited the strongest afterglow intensity and the longest afterglow time（about 90 minutes）when the doped content of Tm³⁺ions was 0.1%（molar ratio）.Subsequently,the applications of ZGGO:Cr,Tm PLNPs in deep tissue imaging were further investigated.The ZGGO:Cr,Tm PLNPs could achieve an optical penetration depth of 1.2 cm in biological tissues after a short ultraviolet excitation.This work provides a new way for the controllable synthesis of NIR-Ⅰ PLNPs.（2）Controllable synthesis of PLNPs with emission in the second biological window（NIR-Ⅱ,900-1700 nm）.We introduced Ni²⁺and Yb³⁺ions into Zn_1.2Ga_1.6Sn_0.2O₄ and La₂O₂S host materials,and synthesized Zn_1.2Ga_1.6Sn_0.2O₄:Ni（ZGSO:Ni）and La₂O₂S:Yb（LOS:Yb）NIR-ⅡPLNPs by hydrothermal method.The emission wavelengths of ZGSO:Ni and LOS:Yb PLNPs were 1350 nm and 980 nm,respectively.Further studies showed that both ZGSO:Ni and LOS:Yb PLNPs possessed good dispersibility and homogeneous size.The two NIR-ⅡPLNPs possessed average sizes of 10 nm and 20 nm,respectively.Subsequently,the imaging ability of two NIR-Ⅱ PLNPs in intralipid was investigated.The ZGSO:Ni and LOS:Yb PLNPs could reach an optical penetration depth of 0.2 cm in the intralipid after a short ultraviolet excitation.This work further extends the emission wavelengths of PLNPs to the NIR-Ⅱ region,and it is expected to further broaden the applications of PLNPs.