Facile Hydrothermal Synthesis of an Iodine-Doped Computed Tomography Contrast Agent Using Insoluble Triiodobenzene

Synthesis of theranostic covalent organic framework for Tumor-targeted Chemo-photodynamic therapy

Covalent organic frameworks (COFs) are a novel class of organic porous materials that, in recent years, have gained much attention for their applications as nanocarriers toward nanomedicine development. Inspired by this, we introduce for the first time a novel theranostic nanoplatform that combines iodine ligand 5-amino-2,4,6-triiodoisophthalic acid (ATIPA)-decorated porphyrin-based covalent organic frameworks (pCOF-I) designed for effective photodynamic therapy (PDT), doxorubicin (DOX) encapsulation, and computed tomography (CT) imaging toward melanoma treatment. In the design of this COF, we have successfully integrated the iodine ligand with porphyrin. The synthesized mesoporous nanoplatform was loaded with DOX and further modified by COOH-PEG-NH2, which was conjugated with the AS1411 aptamer to be targeted to B16F0 melanoma cells. Comprehensive characterizations verified the successful synthesis and controlled release of DOX from the synthesized COF. In vitro evaluation against B16F0 showed combined chemo-PDT therapy. In addition, higher cellular uptake and toxicity were observed for the targeted platform compared to the non-targeted one towards B16F0. The porphyrin molecules imparted to the pCOF-I nanoparticles (NPs) a significant capacity for light-induced reactive oxygen species (ROS) generation, demonstrating remarkable PDT efficacy in both in vivo and in vitro environments. An in vivo investigation on B16F0 ectopic tumor model of melanoma in mice confirmed the potential for showed combined chemo-PDT therapy chemo-PDT in preclinical stage while approving guided delivery and tumor accumulation of AS1411 aptamer-tagged systems. On the other hand, the prepared platform demonstrated desirable CT-scan imaging of B16F0 tumorized mice 6 and 24 h post-injection. Notably, this is the first report of an AS1411 aptamer-targeted pCOF-I system for CT imaging-guided combined chemo-PDT, marking a significant step forward in multimodal cancer treatment strategies.

Biocompatible carbonized iodine-doped dots for contrast-enhanced CT imaging

Background

Computed tomography (CT) imaging has been widely used for the diagnosis and surveillance of diseases. Although CT is attracting attention due to its reasonable price, short scan time, and excellent diagnostic ability, there are severe drawbacks of conventional CT contrast agents, such as low sensitivity, serious toxicity, and complicated synthesis process. Herein, we describe iodine-doped carbon dots (IDC) for enhancing the abilities of CT contrast agents.

Method

IDC was synthesized by one-pot hydrothermal synthesis for 4 h at 180 ℃ and analysis of its structure and size distribution with UV–Vis, XPS, FT-IR, NMR, TEM, and DLS. Furthermore, the CT values of IDC were calculated and compared with those of conventional CT contrast agents (Iohexol), and the in vitro and in vivo toxicities of IDC were determined to prove their safety.

Results

IDC showed improved CT contrast enhancement compared to iohexol. The biocompatibility of the IDC was verified via cytotoxicity tests, hemolysis assays, chemical analysis, and histological analysis. The osmotic pressure of IDC was lower than that of iohexol, resulting in no dilution-induced contrast decrease in plasma.

Conclusion

Based on these results, the remarkable CT contrast enhancement and biocompatibility of IDC can be used as an effective CT contrast agent for the diagnosis of various diseases compared with conventional CT contrast agents.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40824-022-00277-3.