Temperature Self-monitored Photothermal Therapy Of Cancer Cells Based On Integrated Nanosensors

Photothermal trerapy is based on the heat generated by photothermal agents under laser irradiation,and then kills tumor cells at high temperature.In order to avoid damage to normal tissue cells caused by photothermal trerapy,real-time monitoring of microscopic temperature changes in photothermal process plays a very important role in optimizing the therapeutic effect.However,up to now,thermocouples and infrared thermal camera are mainly used to record the apparent temperature,and excess or insufficient heating would probably take place,which result in serious side effects.Herein,in order to monitor temperature variation at microscopic levels during PTT,we present a in-situ reduction method to construct a gold nanospheres-attached Eu(TTA)3(TPPO)2-loaded functional nanomaterials(Eu@Au-NPs)and a one-step facile modified polymerization method to prepare polypyrrole-rhodamine B nanoparticles(PPy-RhB NPs).Under laser irradiation,functional nanoparticles can produce photothermal effects,and real-time temperature monitoring of photothermal process can be performed based on its own temperature sensitivity.The main research and results of this thesis are shown as follows:(1)Firstly,rare-earth chelates Eu(TTA)3(TPPO)2 were synthesized via a solvothermal method.Then Eu(TTA)3(TPPO)2 nanoparticles(Eu-NPs)were prepared via a one-step reprecipitation-encapsulation method.Finally,the gold nanoparticles-attached nanospheres(Eu@Au-NPs)were synthesized by the in-situ reduction of HAuCl4 in the presence of Eu-NPs.Europium(Ⅲ)chelates display a highly temperature-dependent emission,and were easily quenched of luminescence by water.Hence,we prepared the hybrid nanoparticles to improve the water solubility and luminescence stability.The surface amino groups in the PLL shell provided positive charges,and allows AuCl4-attach on Eu-NPs via strong electrostatic attractions.Afterwards,the gold nanoparticles were synthesized by the in-situ reduction of HAuCl4 on the surface of Eu-NPs.The nanomaterials possess uniform nanostructures in the form of nanospheres,and can be easily dispersed in water.The average diameter of NPs(nanoparticles)is calculated to be around 120 nm,while the gold nanoparticles had spherical size of 5-10 nm.The fluorescence emission intensity decreases rapidly with increasing temperature.The intensity at 615 nm fell about 52.7%when temperature increases from 25℃ to 60℃,indicating that Eu-NPs can realize good fluorescence temperature-sensing property.Upon photoexcitation at localized surface plasmon resonance(LSPR)band of gold nanospheres,Eu@Au-NPs can efficiently convert the excited state photon energy into heat at 520 nm.Under a 520 nm laser irriadiation for 18 minutes,the temperature of the Eu@Au-NPs dispersion increased from 30℃ to 41.9℃,suggesting that Eu@Au-NPs can realize good photothermal effect.Therefore,the local heat can be monitored in real time and in situ by Eu@Au-NPs.(2)Polypyrrole-rhodamine B nanoparticles(PPy-RhB NPs)were prepared via a one-step modified polymerization method in the presence of PVP as a capping reagent or stabilizer and ferric oxide as an oxidant for the synthesis,and rhodamine B was rapidly added during the cationic radical polymerization process of pyrrole via a pseudo-polycondensation mechanism.PPy-RhB NPs possess high near-infrared absorption property,photothermal effect for photothermal therapy and luminescence stability.These nanoparticles were uniformly dispersed in water and had spherical size of 70 nm.Under 808 nm laser irriadiation for 15 minutes,the temperature of PPy-RhB NPs dispersion increased from 23.7℃ to 61.4℃,indicating that PPy-RhB NPs performs excellent photothermal effect.In addition,PPy-RhB NPs possess superior temperature sentitivity based on the fluorescent intensity response of rhodamine B at about 576 nm.The emission intensity normalized at 580 nm fell about 57%when temperature increases from 20℃ to 70℃.Due to the significant temperature-dependent changes of emission intensity,PPy-RhB NPs are certified to be a favorable optical thermometer with a relatively high temperature sensitivity of-1.4%/℃.In vitro cellular based on the PPy-RhB NPs,the biocompatibility of nanoparticles towards HeLa cells is measured by MTT assay.After exposing by 808 nm laser for 10 minutes,obvious cellular viability inhibition is observed,and the cell mortality rate is up to about 80%.The data demonstrates that PPy-RhB NPs exhibit high photothermal ablation efficiency for tumor cells.The fluorescence intensity changes of rhodamine B in vitro was performed by laser confocal fluorescence imaging under various irradiation time intervals.After irradiating by 808 nm laser for 5 minutes with confocal fluorescence imaging,the fluorescence signals are quenched by about 90%,suggesting that PPy-RhB NPs can perform real-time microscopic temperature monitoring during photothermal ablation of tumor cells.