Construction Of Organic/inorganic Multifunctional Theranostic Platform Based On Gold Nanoparticles

It is of great significance to develop multifunctional imaging-guided therapeutic platforms with ideal resolution and sensitivity.It is worth noting that the gold nanoparticles are attractive candidates in the field of biomedical research.Because of the large atomic number,gold has a higher X-ray absorption coefficient,which enables gold nanoparticles to be used as CT contrast agents.In addition,due to their absorption in the near-infrared(NIR)region,the gold nanoparticles such as gold nanorods and gold nanoshells can be uesd as photoacoustic imaing(PA)contrast agents and photothermal therapeutic agents.So,these nanoparticles integrate with the functions of imaging and therapy.Considering the poor biocompatibility of the inorganic nanoparticles,modified with organic polymers will be favorable for their use in the biomedical research.Herein,we constructed the organic-inorganic multifunctional theranostic platforms based on the gold nanostructures to realize the imaging-guided therapy of tumors.The main researches are included as follows:1.Due to the unique optical and magnetic properties,rare-earth(RE)nanoparticles are the promising candidates for multimodal imaging.In this chapter,we exploit a new design of RE-Au core-shell nanostructures.We adopted the one-dimensional RE nanorods as the cores because it would favor cell internalization.After coating a layer of gold nanoshells,they could be used as photothermal therapeutic agents.The RE-Au-PGEA nanohybrids with good gene transfection capacity were constructed by grafting hydroxyl-rich polycations PGEA(ethanolamine-functionalized poly(glycidyl methacrylate))with low cytotoxicity onto the surface of RE-Au nanorods.Given the unique characteristics of all the components,the feasibility of RE-Au-PGEA for multifunctional photoacoustic(PA),computed tomography(CT),magnetic resonance(MR),and up-conversion luminescence(UCL)imaging and complementary photothermal therapy(PTT)/gene therapy(GT)therapy was investigated in details in vitro and in vivo.The visualization of the therapeutic processes with comprehensive information renders RE-Au-PGEA nanohybrids intriguing platforms to realize enhanced antitumor performances.Natural polysaccharides have great advantages such as non-toxic,biocompatibility,biodegradability and other unique bioactive properties.After some hydroxyl groups of neutral polysaccharides activated by CDI and functionalized by ED,we obtained cationic polysaccharides with amine groups.Through the nonsolvent-aided counterion complexation method,we prepared the Au@PSa hybrid nanospheres.With the introduction of Schiff base covalent bonds and the formation of Au-S bonds between Au and GSH in tumor microenvironment,Au@PSa nanospheres present pH-and GSH-responsive ability and can be self-destructed in the tumor site.Notably,natural polysaccharide pullulan also has the liver-targeting ability.Targeted therapy can reduce the overall dosage of the patient and minimize the side effects.At the same time,combined the CT and PA imaging properties and hyperthermia function of gold nanorods,we can achieve the imaging-guided targeted therapy of tumors.