Synthesis And Application Of Multifunctional Theranostics Probes Based On Polydopamine

In recent years,with cancer-related mortality increasing year by year,the prevention,diagnosis and treatment of cancer have attracted wide attention.Due to the complexity,diversity and heterogeneity of the tumor,single modal therapy cannot completely cure the tumor and prevent cancer metastasis.With the rapid development of nanotechnology,it has become possible to assemble several types of diagnostic reagents into a nanostructure through physical adsorption and chemical combination,and realize the mission of multi-modal synergistic therapy.Among them,photothermal therapy?PTT?is a new non-invasive cancer treatment technology,which has the advantages of strong selectivity,low toxicity and side effects.The main content of this study is to explore the synthesis and application of multifunctional theranostics probes based on polydopamine.The nanoprobes have multimodal therapy and bioimaging function induced by a near-infrared laser,enabling iamging guided cancer combination therapy.In this work,a gold nanorod@polydopamine?Au NRs@PDA?composite nanoprobe loaded with DOX and a platinum@polydopamine?Pt@PDA?composite nanoprobe modified by chlorin dihydrogen?Ce6?were prepared.The following work was performed:1.The gold nanorods@Zinc Oxide?Au NRs@ZnO?with core-shell structure was prepared by hydrothermal synthesis.Then a certain amount of dopamine hydrochloride?DA?was added and the abundant catechol groups on the surface of DA were used to coordinate with Zn²⁺to promote the disassembly and disappearance of the ZnO template.At the same time,DA could spontaneously oxidize and polymerize into PDA in a weak alkaline environment,and finally form a yolk-shell structure of Au NRs@PDA composite nanoprobe.The nanoprobe has good dispersibility,stability,excellent light absorption and photothermal conversion ability in the near infrared region.In addition,the nanoprobe exhibits good photoacoustic imaging effects and can be used as an excellent magnetic resonance imaging T1 contrast agent after surface modification of strontium ions(Gd³⁺).Therefore,the combination therapy of chemotherapy and PTT guided by photoacoustic imaging and magnetic resonance imaging can be achieved after loading DOX drugs.2.Based on the similar preparation process,a yolk-shell Pt@PDA composite nanoprobe was synthesized.The nanoprobe also has good biocompatibility,photothermal heating and photoacoustic imaging effects.In addition,based on the catalytic properties of Pt,oxygen can be produced by catalyzing the decomposition of hydrogen peroxide,which can effectively alleviate the problem of hypoxia in the tumor site.Under the irradiation of NIR laser,the photodynamic therapeutic effect of Ce6 can be increased while the yield of singlet oxygen is improved.The nanoprobe can realize the combined treatment of PTT and enhanced PDT under the guidance of photoacoustic imaging.