Peptide Mediated Noble Metal Nanomaterials For Photothermal Therapy Of Tumors And Construction Of Electrochemical Biosensors

Cancer is one of the leading causes of high morbidity and mortality worldwide.In order to reduce the mortality caused by cancer,the development and improvement of cancer treatment and early diagnosis techniques have been the focus of research in cancer treatment field.Photothermal therapy induced by near-infrared?NIR?light irradiation is a remarkable strategy of anti-tumor therapy using multi-channel interactive plasma nanomaterials as probe.Because it can cause targeted thermal damage in the tumor area,which has a good application prospect in the therapy of tumors.In clinical treatment,the NIR laser is used as a light source in photothermal therapy because of its high penetration rate in human tissues and minimal damage.In addition,electrochemical biosensor combined electrochemical signal response with biomolecular recognition,as a kind of detection platform,has the advantages of high sensitivity,simple operation,low cost and good stability,which has attracted wide attention in the field of tumor detection.Based on the above research background,the polypeptide mediated by noble metal composite nanomaterials were developed and applied to the field of photothermal tumor therapy.The application of the electrochemical biosensor in the detection of tumor cells was also explored.The main contents of this paper include the following three parts:?1?The preparation of silver based nano-cage and its application in photothermal therapy of tumorInorganic nano-noble metal photothermal agent as a substitute material has attracted extensive attention in recent years because of its high photothermal conversion efficiency and easy preparation and modification.However,inorganic nano-noble metal materials usually have potential biological toxicity or toxic reagents were used in the synthesis process,which restricted the application of inorganic materials to a great extent.In view of this challenge,based on the principle of biomimetic mineralization,a green and mild synthesis strategy of silver nanocages was developed using octreotide as a biological template.The study found that the synthesis method can control the growth kinetics of silver nanocages by adjusting the incubation time and the dose of silver nitrate,thereby regulating the size and morphology of the silver nanocages.At the same time,the optimized silver nanocages had high photothermal conversion efficiency of 46.1%and molar extinction coefficient of1.6×10¹¹ M^-1 cm^-1,showing an excellent photothermal conversion performance.After being irradiated by 808 nm laser for 5 min,the temperature of the silver nanocage dispersion system can raise from ambient temperature to 80.3°C,demonstrating the remarkable photothermal ablation of the tumor under 808 nm laser irradiation.The use of biological templates and the synthesis of no additional toxic surfactants resulted in no apparent toxicity within the therapeutic dose of Ag nanocages.The successful preparation of silver nanocages is helpful to understand the reaction mechanism of metal surface plasmas,which can be used as an efficient photothermal therapy reagent for tumor photothermal treatment.?2?Preparation of gold based branched nanoshells?BGSs?and its application in photothermal therapy of tumorAnisotropic gold nanocrystals exhibited strong plasmon resonance in the visible and near infrared region due to the enhancement of the electromagnetic field at the dendritic end.However,some disadvantages of traditional preparation methods have limited the application of branched gold nanoparticles,such as Long duration,complex procedure,or the morphology of the prepared nanoparticles is multiple,the absorption region is difficult to tune,the high cytotoxic surface capping agent is difficult to clear,and the poor stability.Based on this research background,we used green silver nanocages as sacrificial template,adding excessive gold precursor solution to trigger the replacement reaction between gold and silver,and finally adding ascorbic acid to reduce the residual gold ions.Thus,the biofriendly branched gold nanoshells with strong light response were prepared.This method was a seedless method without toxic surfactants,which not only shortened the synthesis time,but also avoided the removal procedure of surfactant.It was found that the structure of the branched gold nanoshells was strongly absorbed in the NIR region.The temperature of the aqueous dispersion system can increase to 72.6°C after the irradiation of 808 nm laser with 1.5 W cm^-2 for 5 min.Meanwhlie,the nanoparticles had favorable physiological stability,photothermal conversion property and biocompatibility.The generated hyperthermia of the nanoparticles upon NIR laser irritation,as a potential nanomaterial,was enough to ablate tumor cells,which can be used for further in vivo and in vitro cancer treatment and future biological applications.?3?Electrochemical biosensor constructed by platinum-based 2D nanosheets for the detection of tumor cellsElectrochemical biosensors,which had the advantages of fast response,low detection limit,high sensitivity,simple operation and low manufacturing cost,have become a major method for detecting tumor cells.However,the sensitivity of most electrochemical detection methods was not high enough.Therefore,a kind of platinum nanocrystals was prepared in this paper,and the OCT was adsorbed on the surface of platinum nanocrystals by in situ synthesis to form an adsorption probe.It can be anchored on the cell surface to amplify the electrochemical signal of the sensor by reducing H₂O₂.At the same time,the graphene BGSs and OCT were modified onto the glassy carbon electrode by layer-by-layer assembly,so as to improve the ability of electron transfer to the electrode surface.Owing to the excellent characteristics of graphene and BGSs,the surface conductivity of the electrode was increased by 7.1 times.It was found that the constructed electrochemical biosensor had good stability,higher sensitivity and wider detection range.Its detection limit can be effectively reduced to 10 cell mL^-1,and it has an inestimable application prospect in early diagnosis of tumor.