A Facile and Highly Efficient Approach to Obtain a Fluorescent Chromogenic Porous Organic Polymer for Lymphatic Targeting Imaging.

Man Duan,Wenbin Shen,Dongmei Han,Kun Chang,Xinyu Wang,Nan Gao,Jianshi Du

doi:10.3390/molecules27051558

Abstract

Porous organic polymers have an open architecture, excellent stability, and tunable structural components, revealing great application potential in the field of fluorescence imaging, but this part of the research is still in its infancy. In this study, we aimed to tailor the physical and chemical characteristics of indocyanine green using sulfonic acid groups and conjugated fragments, and prepared amino-grafted porous polymers. The resulting material had excellent solvent and thermal stability, and possessed a relatively large pore structure with a size of 3.4 nm. Based on the synergistic effect of electrostatic bonding and π–π interactions, the fluorescent chromogenic agent, indocyanine green, was tightly incorporated into the pore cavity of POP solids through a one-step immersion method. Accordingly, the fluorescent chromogenic POP demonstrated excellent imaging capabilities in biological experiments. This preparation of fluorescent chromogenic porous organic polymer illustrates a promising application of POP-based solids in both fluorescence imaging and biomedicine applications.

Highlights

Porous organic polymers (POPs), emerging as a novel functional porous solid, have attracted a great deal of attention due to their open architecture, large surface area, and adjustable pore size [1–3]
indocyanine green (ICG) molecules were incorporated into the porous channels of POP architecture through a onestep immersion process to obtain the fluorescent chromogenic POP product (ICG-POP)
The Fourier-transform infrared spectroscopy (FT-IR) spectrum for 2,5-diethynylaniline shows two characteristic signals located at 619 and 672 cm−1 ascribed to the asymmetric and symmetric stretching vibrations of the C-Br bond

Summary

Introduction

Porous organic polymers (POPs), emerging as a novel functional porous solid, have attracted a great deal of attention due to their open architecture, large surface area, and adjustable pore size [1–3]. Thanks to state-of-the-art coupling approaches, great efforts have been made in, for example, crystalline networks of COFs (covalent organic frameworks) and CTFs (covalent triazine-based frameworks) and amorphous networks of PIMs (polymer of intrinsic microporosity), CMPs (conjugated microporous polymers), and PAFs (porous aromatic frameworks) [4–15]. In addition to their porous nature, the tunable structural composition of POP samples is a rare quality, which has been widely used to realize custommade skeletons for the satisfaction of unique requirements in the areas of molecular capture, gas storage, and catalysis [16–27]. Their medical fluorescence effect still needs to be improved

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