Synthesis And Bioapplication Of The Second Near-Infrared NaNdF₄ Nanoprobes

The excellent physical and chemical stability,narrow absorption and emission bands,and long fluorescence lifetime of rare earth nanoparticles(referred to as RE NPs)make them very attractive for multimodal imaging and therapy of cancer.Their narrow absorption requires the careful selection of laser wavelength to achieve the desired purpose,particularly for RE NPs simultaneously with both photothermal and photoluminescent properties(e.g.Nd-based nanoparticles).Herein,we prepared a series of different sized NaNdF4 nanoparticles(referred to as NNF NPs)(i.e.4.7,5.9,12.8,and 15.6 nm)and investigated their in vitro and in vivo size-dependent photothermal conversion and photoluminescence under 808 nm and 793 nm laser irradiation,respectively.We found that the photothermal conversion was better under the 808 nm laser,and better under the 793 nm laser in the near-infrared region II imaging.Therefore,we selected 12.8 nm NNF nanocrystals with the best photothermal effect and the second imaging performance as the probe for further experiments.We then modified 12.8 nm NNF NPs with phospholipid carboxyl PEG and functionalized them with RGD to actively target tumors for better imaging results.The NaNdF4@PEG@RGD nanoparticles(referred to as NNF-P-R NPs)have good biocompatibility,stability and excellent targeting capability.This work demonstrated the significance of selection of proper laser wavelength and great potential of NNF NPs in the diagnosis and treatment of cancer.Objective:The advantages of nanocrystals in photothermal conversion and photoluminescence are realized by tuning the size of nanocrystals and selecting lasers of different wavelengths for the diagnosis and treatment of breast cancer.Methods:The dependence of nanocrystal properties on the particle size and excitation wavelength of laser was investigated to select better experimental conditions for diagnosis and treatment of breast cancer.First,the size of NNF nanocrystals was controlled by a simple method(control the heating time),and then NNF nanocrystals of different sizes were prepared and characterized.Lasers with different wavelengths were selected to study the photoluminescence and photothermal conversion properties of NNF nanocrystals.Finally,NNF nanocrystals and lasers were selected to diagnose and photothermally treat mice with breast cancers.Results:We synthesized monodispersed size tunable NaNdF4 nanoparticles,which in vitro and in vivo photothermal conversion and NIR-? fluorescence imaging showed size and irradiation(or excitation)wavelength dependence.12.8 nm NNF-P-R nanocrystals can not only be used as a good NIR-II fluorescent probe under the exciation of 793 nm laser,but also can be labeled with 99mTc for SPECT/CT imaging to achieve accurate diagnosis of tumors.At the same time,under 808 nm laser irradiation,it can be used as a photothermal transducer for photothermal therapy of tumors.Conclusion:Our work reveals the wavelength-dependent photoluminescence and photothermal conversion property of rare-earth(RE)nanoparticles,and provides insights into the choose of different lasers to realize advantages and avoid disadvantages of RE nanoparticles.