Application Of Organic Semiconducting Materials In Photoacoustic Theranostics

Photoacoustic imaging(PAI)is a newly emerging medical imaging paradigm with the combination of ultrasound and optics.It permits light focusing and imaging deep inside strongly scattering media with high resolution.With these merits,PAI holds tremendous promise in functional imaging various physiological functions(such as blood flow and oxygenation)and molecular imaging to identify specific cancer cells.However,most endogenous materials usually have a lower photoacoustic signal,and thus exogenous photoacoustic contrast agents(such as carbon nanotubes,gold nanorods and other inorganic materials)are required to improve the quality of photoacoustic imaging.In consideration of the potential biotoxicity of these inorganic nanomaterials,organic semiconducting materials have attracted widespread attention in the field of photoacoustic imaging owing to their good photoelectric properties and biocompatibility.This paper mainly focused on the preparation of organic semiconducting materials and theirs applications in photoacoustic therapy.1.In this section,we designed and synthesized an amphiphilic perylene-3,4,9,10-tetracarboxylic acid imide(PDI)organic semiconducting materials with strong near infrared absorption,and targeting group Arg-Gly-Asp(c RGD),which can be self-assembled into organic semiconducting nanoparticles(c RGD-PDI NP)through its own amphiphilic structure.cRGD-PDI NP exhibits strong near-infrared absorption,good light stability,high targeting,low cytotoxicity and longer blood circulation half-life,which show a good application prospects in the field of photoacoustic imaging.Real-time imaging of jugular vein thrombosis in mice by photoacoustic imager demonstrated that cRGD-PDI NP can be used as an effective PA contrast agent to achieve specific targeted diagnosis of early thrombosis in mice.More importantly,c RGD-PDI NP not only provides accurate information including the contours,size and conformation of the thrombus,as well as the spatial distribution,but also real-time monitor the degree of thrombosis obstruction,effectively distinguish early thrombosis from late thrombosis,provide first-hand information for post-clinical treatment intervention.2.In this chapter,cancer cell-targeting and near-infrared absorptive organic semiconducting nanoparticles were engineered via typical nanoprecipitation method for photoacoustic therapy in living mice.Water-insoluble BODIPY conjugated molecules were encapsulated into amphiphilic biomacromolecule DSPE-mPEG-FA(MW:5000)to form water-soluble organic semiconducting nanoparticles(FA-BODIPY NP).As-prepared FA-BODIPY NP exhibited superior photothermal conversion ability compared with traditional photothermal therapeutic age nts(gold nanorods,GN R).Furthermore,the photoacoustic imaging of live mice demonstrated that FA-BODIPY NP could achieve efficient photoacoustic imaging in vivo.The photothermal experiments demonstrated that FA-BODIPY NP exhibited a more excellent efficiency of photothermal therapy than conventional GNR.3.In this chapter,molecular brush-type cationic conjugated polyelectrolytes were used as a multi-functional organic semiconducting material(photoacoustic contrast agent and drug carrier).The photoacoustic imaging system was used to study the enrichment of organic semiconductor materials and the constraints of optimization of materials in tumor area.By using PEG2000-PFNa to modify conjugated polyelectrolyte,polymer@PEG2000-PFNa was prepared as a transport carrier of siRNA,not only reduces its cytotoxicity and increases the cycle time of the ploymer@PEG2000-PFNa/siPlk1 complex in the blood,but also increases the efficiency of the gene silence.We then use 20 nM polymer@PEG2000-PFNa/siPlk1(100 M)to reduce the expression level of the target gene Plk1 mRNA by 85%,and then the same molar ratio of polymer/siPlk1 was injected into A549 tumor-bearing mice by tail vein,and its interference efficiency was 25%.The results showed that Polymer@PEG2000-PFNa could be used as a multi-functional carrier for siRN A to achieve effective gene therapy,and has bright application prospect in the development of new nucleic acid-based therapy.