Design And Optimization Of Optical Thermometric Materials For Photo-thermal Therapy

Photo-thermal therapy?PTT?refers to the effective conversion of near-infrared?NIR?photon energy into a large amount of heat by using photo-thermal therapy agent?PTA?Appropriate high temperature can destroys cancer cell membranes in tumor tissues and denatures the protein to induce irreversible cancer cell damage.thereby PTT as a treatment could achieve effective thermal ablation and optical minimally invasive of tumor cells in the lesion area.Photo-thermal therapy has received great attention from researchers as a method of minimally invasive treatment of cancer based on optical nanoparticles Compared with surgery,chemical and radiotherapy traditional treatment,photo-thermal therapy has the advantages that shorter treatment time and fewer side effects.In the process of photo-thermal therapy,the therapeutic effect depends on the heat generated by the photo-thermal therapeutic agent under the irradiation of near infrared light,and excessive heat or insufficient heat will affect its therapeutic effect.Therefore,real-time temperature detection is essential during photo-thermal therapy.The temperature detection of the lesion area can effectively intervene positively during the photo-thermal treatment process to avoid the therapeutic effect reduced by insufficient heat or excessive temperature.And real-time temperature feedback can improve the safety and efficiency of photo-thermal therapy.Traditional thermometers?such as mercury thermometers,thermo-couple thermometers,and thermal imaging cameras,etc.?are limited by the internal environment of the biological tissue lesion area,and their internal temperature cannot be measured accurately and non-invasively.Therefore,it is crucial to realize non-contact temperature detection with high accuracyLuminescent materials based on rare earth as a new generation of non-contact optical temperature sensing probe can effectively solve the above problems.The temperature measurement principle based on the fluorescence intensity ratio?FIR?of lanthanide rare earth ions under different temperature environments,the fluorescence intensity ratios of different energy levels of rare earth ions have a corresponding function relationship with temperature,so the ratio of the emitted light intensity of rare earth ions can be tested to determine the ambient temperature where the emission center is located.As a new type of non-invasive,non-contact nano-thermometer,rare earth ion temperature probe has excellent spatial,temperature resolution and high thermal sensitivity.Lanthanide rare earth ion luminescent materials also have unmatched optical characteristics by other materials,such as rich energy levels,long luminescence life,narrow emission lines,high color purity,and their special electrons.It can obtain rich luminescence from ultraviolet to visible to near infrared light based on rare earth ions doped arrangement.Visible and near-infrared emission light exhibits the following advantages in organisms:it has low auto-fluorescence and deep optical penetration depth,and can be used as an imaging agent in the photo-thermal treatment to achieve visual imaging in the lesion area.Therefore,this paper uses temperature monitoring technology based on the lanthanide ion fluorescence intensity ratio and luminescence characteristics to achieve real-time temperature monitoring and imaging during photo-thermal therapy.Achieving the organic combination of photo-thermal therapeutic agent and rare earth doped luminescent material to construct a multi-functional with optic image,photo-thermal therapy and temperature detection nanomaterial is of great research significance.In order to explore the optical temperature sensing characteristics of rare earth ion-doped materials,the third chapter uses the bulk material Na2Ln2Ti3O10?Ln=Gd,La?as the matrix,and uses 2H11/2/4S3/2?4I15/2 green light emission of Er³⁺as the main research object to realize a temperature sensing probe with strong visible light,and explore the sample Na2La2Ti3O10?Ln=Gd,La?:0.01Er³⁺,0.12Yb³⁺visible light temperature sensing characteristics,which is laid the foundation for the rare earth ion FIR temperature detection technology.Considering that the sample of bulk material does not have a uniform morphology and the size is too large,which limits its application prospects in biological tissues.Chapter four uses co-precipitation to synthesize Y₂O₃:Yb³⁺/Er³⁺nanocrystals with uniform morphology,nanoscale and good dispersion,and explore their visible light emission characteristics and temperature sensing characteristics.At the same time,the photo-thermal properties of the bio-compatible SiO₂@Cu₂S photo-thermal therapeutic agent and its ablation effect of bacteria were studied.In order to further improve the photo-thermal effect of sample,this research designed and developed a core-shell structured high-efficiency photo-thermal treatment system Y₂O₃:Nd³⁺/Yb³⁺@SiO₂@Cu₂S,systematically studied its ablation effect on bacteria,cancer cells and the effect of near infrared light on penetration of biological tissue.Based on the temperature monitoring system and photo-thermal treatment system,multifunctional visible light temperature self-monitoring photo-thermal treatment system Y₂O₃:Nd³⁺/Yb³⁺/Er³⁺@SiO₂@Cu₂S was built.The relevant research results provide a new research ideas that combination of photo-thermal agent and rare earth luminescent material.Visible light temperature sensing has greater limitations for biological tissue applications,and the broad-spectrum absorption characteristics of the photo-thermal agent Cu₂S affect the accuracy of FIR-based temperature detection.Chapter five optimizes the performance of the multifunction temperature self-monitoring photo-thermal therapy system.From the perspective of temperature measurement in biological tissues,a near-infrared optical temperature probe is realized and a photo-thermal therapeutic agent IR-780 with narrow-band absorption characteristics was selected.The near infrared emission performance of temperature sensing probe located in biological window area from 4F3/2????4I9/2 and 4F3/2????4I9/2(Nd³⁺),and the 4F3/2?4I11/2 emission of Nd³⁺and 2F5/2?2F7/2 near infrared emission from Yb³⁺were explored,respectively.Using 808 nm located in the first biological window area as the excitation light source,a multifunctional temperature self-monitoring photo-thermal therapy system was designed based on near infrared NaYF₄:Yb/Er@NaYF₄:Nd@mSiO₂-IR780.This NIR to NIR multifunctional temperature self-monitoring photo-thermal therapy system is of great significance for biological applications and provides a basis for subsequent related research.