Preparation,Functionalization,and Properties Of Cr³⁺-doped Near Infrared Persistent Luminescence Materials

Persistent luminescence(PersL)materials doped with Cr³⁺owns long afterglow lifetime,and the emission wavelength of them are in the“optical transparent window”(650-900 nm)of biological tissues,which can avoid autofluorescence and penetrate deeper tissues.Therefore,they have broad application prospects in biomedical imaging,diagnosis and treatment.In this paper,aiming at the problems of short emission wavelength,unadjustable emission wavelength and high preparation cost of existing PersL materials,we developed a long-wavelength tunable near infrared(NIR)emission PersL materials based on Ba Ga₂O₄with Cr³⁺as the luminescence center,and optimized the luminescence and luminescence properties by co-doping rare earth or non-rare earth ions.At the same time,aiming at the problems of large particle size,poor water solubility and single function of PersL materials synthesized by solid-state method,persistent luminescence nanoparticle(PLNPs)with small size were prepared by hydrothermal reaction combined with subsequent high-temperature calcination method when Cr³⁺as the luminescent center,?-Ga₂O₃as the matrix and Ba²⁺as the co-doped ion.Through surface modification,polydopamine(PDA)with photothermal effect was wrapped on the surface of PLNPs,and the integrated probes with good photothermal for diagnosis and treatment was prepared.Ba Ga₂O₄:Cr³⁺NIR PersL materials were prepared by solid-state method with BaCO₃,Ga₂O₃and Cr₂O₃as raw materials.The of Ba Ga₂O₄:Cr PersL materials owns high crystallinity when the calcination temperature is 1100?and the calcination time is 2 h.The emission wavelength of Ba Ga₂O₄:Cr PersL materials is 731 nm,and the PersL materials owns the strongest luminescence intensity,and the afterglow time was 6 days when the composition of the PersL materials is Ba Ga₂O₄:Cr_0.06,and they can be repeatedly excited by red LED light.The emission wavelength of PersL materials were red-shifted to 739 nm by changing the Ba/Ga ratio in Ba Ga₂O₄:Cr PersL materials.At the same time,and the luminescence intensity of the PersL materials was enhanced.When the composition of PersL materials is Ba_0.14Ga₂O₄:Cr_0.06,the luminescence intensity of it reached the strongest.The emission wavelength of PersL materials can be adjusted from 715 nm to 739 nm by changing the doping amount of Cr³⁺and Ba/Ga ratio in Ba Ga₂O₄:Cr PersL materials.At room temperature,the specific information could still be clearly read out after 1 h of excited by 254 nm UV light for 5 min when Ba Ga₂O₄:Cr_0.06PersL materials were applied to information storage.Ba Ga₂O₄:Cr,Sm PersL materials with good crystallinity were prepared by solid-state method with BaCO₃,Ga₂O₃,Cr₂O₃and Sm₂O₃as the raw materials,calcination temperature is1100?and the calcination time is 2 h,and the afterglow property of Ba Ga₂O₄:Cr were enhanced.When the composition was Ba Ga₂O₄:Cr_0.06,Sm_0.004,the luminescence intensity reached the maximum.The electron trap energy level depth is estimated to be about 0.553 e V by the half-width method thermoluminescence spectra.Studies have shown that Ba Ga₂O₄:Cr,Sm PersL materials have good thermal stability,and have a potential as red LED raw material.Meanwhile,Ba Ga₂O₄:Cr,M(M=Eu³⁺,Gd³⁺,Al³⁺,Sn⁴⁺or Si⁴⁺)PersL materials with good crystallinity were prepared,the luminescence intensity of Ba Ga₂O₄:Cr³⁺was enhanced,and the luminescence properties of Ba Ga₂O₄:Cr PersL materials were optimized.Ba Ga₂O₄:Cr,M PersL materials have strong and persistent luminescence by co-doping,and have potential applications in night vision surveillance and medical imaging. ?-Ga₂O₃:Cr,Ba PLNPs with NIR emission were prepared by ethylene glycol assisted hydrothermal reaction combined with subsequent calcination method with Ga₂O₃,Cr(NO₃)₃·9H₂O,(CH₃COO)₂Ba as raw materials.The PLNPs owns high crystallinity and complete crystal growth when the p H of the solution is 7,the calcination temperature is 600?,the calcination time is 3 h,and the auxiliary agent is 2 m L ethylene glycol in the solution.The emission wavelength of?-Ga₂O₃:Cr,Ba NIR PLNPs is 701 nm.The luminescence intensity reaches the strongest when the PLNPs are composed of?-Ga₂O₃:Cr_0.0025,Ba_0.0012,and the particle size of thems are about 36.71 nm.The PLNPs owns good luminescence and afterglow properties.The average luminescence lifetime is 65.98s by three exponential fitting of afterglow decay curve.The electron trap depth of?-Ga₂O₃:Cr,Ba PLNPs was estimated to be about 0.379e V by half-width method.?-Ga₂O₃:Cr,Ba PLNPs with small-sized prepared by hydrothermal reaction have good luminescent properties and glow performance,which are expected to be used for in vivo bioimaging.Surface modification witn Hydroxy(-OH)and(3-Aminopropyl)triethoxysilane(APTES),and further wrapped PDA on its surface to construct PLNPs-PDA with photothermal properties.The TEM results show that the prepared nanomaterials has good dispersion and the particle size is about 33.89 nm.The emission wavelength of PLNPs-PDA is 701 nm.After excitation by 808nm laser,the temperature of PLNPs-PDA solution increases obviously,indicating thatPLNPs-PDA has good photothermal properties.When the excitation source density is 2W·cm^-2and the solution concentration is 300 ug·m L^-1,the temperature of 1 m L PLNPs-PDA solution increases by nearly 6?after 10 min excitation,and the photothermal properties of PLNPs-PDA can be further improved by prolonging the reaction time between dopamine hydrochloride and PLNPs-APTES.It provides a possibility for subsequent photothermal therapy guided by tumor imaging.