| At present,humans usually use surgical resection,chemotherapy or radiotherapy for tumor treatment in the clinical aspect,but these treatments are often accompanied by poor treatment effects,large toxic and side effects and tumor recurrence and other adverse consequences,bringing endless to patients Pain,so it is imperative to seek a new and efficient treatment.In recent years,photothermal therapy?PTT?and photothermal-chemo combination therapy?PCT?are widely regarded as highly effective and minimally invasive tumor treatment methods due to their advantages of high efficiency,low side effects,and low recurrence,and looking for an ideal photothermal preparation become an indispensable part of photothermal therapy.Fluorescent carbon dots with near-infrared absorption?NIR-CD?are considered to be an emerging nanomaterial for photothermal therapy applications due to their good biocompatibility and excellent photothermal properties.However,most of the carbon dots are too small in size and have no targeting,and it is difficult to achieve large-scale aggregation of tumor sites.Therefore,it is worth trying to use appropriate nanomaterials as drug carriers to improve the tumor targeting of carbon dots.Among many nanomaterials,Mo S2 nanosheets,as a new type of two-dimensional nanomaterials,also have certain photothermal properties in the near infrared region.At the same time,their huge specific surface area makes them have great application potential in drug carriers.In addition,studies have shown that the Mo element in the Mo S2 nanosheets has a strong X-ray attenuation capability and can be used as a contrast agent for CT imaging.Therefore,this paper designed and synthesized a 0D/2D/0D sandwich heterojunction as a photothermal agent using 0D carbon dots with near-infrared response and 2D Mo S2 nanosheets as a photothermal agent,and explored its application in tumor photothermal therapy and photothermal-chemo combination therapy.The main research contents and conclusions are as follows:1.Preparation of near-infrared response carbon dots and its application in bio-imaging and tumor photothermal therapy.First,acid-activated pyrene and polyethyleneimine were used as precursors to prepare carbon dots?NIR-CDs?with optical response in the near infrared region by hydrothermal method.NIR-CDs are uniform in size and have an average diameter of about 5.3±1.3 nm.Infrared spectroscopy shows that NIR-CDs contain hydroxyl and amino functional groups,so they have good water solubility and positive charge in aqueous solutions.Under the excitation of ultraviolet light,it showed bright blue-cyan fluorescence.It was found that NIR-CDs have obvious light absorption in the near infrared region,and the photothermal conversion efficiency is as high as 38.3%.Therefore,the application of NIR-CDs in the fields of bio-imaging and photothermal therapy was further explored.Cell uptake experiments show that NIR-CDs show a bright blue fluorescent signal in the cytoplasm,indicating that NIR-CDs can be used as bioluminescent probes.In addition,NIR-CDs were injected intratumorally into the tumor site of mice,and the tumors of the mice were completely eliminated after irradiation treatment with a power density of 0.8 W cm-2,indicating that NIR-CDs have a good photothermal treatment effect.2.Preparation of NIR-CD/Mo S2 heterojunction and its application in CT imaging and photothermal therapy.We prepared PEG-functionalized Mo S2nanosheets as a carrier using hydrothermal method.According to the principle of mutual attraction between positive and negative charges,we successfully loaded positively charged NIR-CDs onto the surface of negatively charged Mo S2 nanosheets to form NIR-CD/Mo S2 heterojunction.The results show that NIR-CDs with good water solubility are dispersed on the surface of the Mo S2 nanosheets,which further improves the characteristics of the Mo S2 nanosheets to be easily settled and makes them stable in aqueous solutions.In the near-infrared region,the NIR-CD/Mo S2heterojunction has synergistically enhanced photothermal performance,and its photothermal conversion efficiency is as high as 78.2%.Subsequently,in vivo CT imaging was performed using a Micro-CT imager.There was significant material accumulation in the tumor site of the mice,indicating that the NIR-CD/Mo S2heterojunction has a certain passive targeting effect.Finally,the effect of photothermal treatment in mice was explored.Experiments showed that compared with NIR-CDs,the NIR-CD/Mo S2 heterojunction can also completely eliminate tumors at an ultralow and safe laser exposure(0.2 W cm-2),and achieved the CT imaging-guided photothermal therapy.3.The chemotherapeutic drug doxorubicin?DOX?is further loaded on the basis of the NIR-CD/Mo S2 heterojunction to achieve a combination of photothermal therapy and chemotherapy at lower power.Drug release experiments show that the release of DOX in the complex is p H-responsive.Under acidic conditions,the DOX release rate reaches 40%.Using confocal microscopy,it can be clearly found that under acidic conditions,DOX is further released from the NIR-CD/Mo S2heterojunction and enters the nucleus,causing apoptosis.At the same time,in vivo experiments showed that the NIR-CD/DOX/Mo S2 composite achieved the same therapeutic effect at a lower power density of 0.1 W cm-2 compared to the NIR-CD/Mo S2 heterojunction,indicating that NIR-CD/DOX/Mo S2 complex does have a synergistic therapeutic effect. |
PDF Full Text Request