Computed Tomography Imaging-Guided Tandem Catalysis-Enhanced Photodynamic Therapy with Gold Nanoparticle Functional Covalent Organic Polymers

Tandem catalysis from hydrogen peroxide (H2O2) to oxygen (O-2) and then to singlet oxygen (O-1(2)) is a convenient way to overcome the hypoxic environment of the tumor for efficient cancer therapy. In this work, meso-tetrakis(4-carboxyl)-21H,23H-porphine (TCPP) and beta-cyclodextrin (beta-CD) functional gold nanoparticles (CD-AuNPs) are integrated together with a brushy covalent organic polymer (COP-8) to form COP@Au@TCPP nanocomposites. The brushy red emissive COP-8 was prepared with 9,9-dioctyl-2,7-diaminofluorene and 2,4,6-triformylphloroglucinol through a simple Schiff base reaction and acts as a sensor to monitor the material transfer and location in tumor cells. The n-octyl groups on the surface of COP-8 act as hooks to load CD-AuNPs via hydrophobic interaction, while the beta-CD improves the biocompatibility of the whole COP@Au@TCPP. The COP@Au@TCPP nanocomposites aggregate efficiently in the tumor site through enhanced permeability and retention effect. The CD-AuNPs act as catalyzers to decompose H2O2 into O-2 in tumor cells. Then, TCPPs on COP@Au@TCPP sensitize O-2 to form O-1(2) under 655 nm radiation for efficient photodynamic therapy (PDT). In combination with the X-ray computed tomography (CT) imaging capacity of CD-AuNPs, the CT-imaging-guided PDT system was successfully prepared. The imaging information, in turn, shows the tandem catalysis PDT efficiency of the COP@Au@TCPP. This work paves the way for the preparation of an imaging-guided therapy system with COP as a matrix to ingrate various biocompatibility components.