Red and near infrared fluorescent conjugated polyelectrolytes for biomedical applications

Abstract

Red and near infrared (NIR) fluorescent conjugated polyelectrolytes (CPEs) have attracted increasing attention in the past few years due to their potential applications in biomedical fields. Specifically, red and NIR fluorescent CPEs with special functionalities exhibit great promises in targeted tumor cell imaging and detection of disease‐related biomarkers. In addition, smart agents combining image and therapeutic actions have also been successfully demonstrated for some red and NIR emissive CPEs. In this mini review, we attempt to offer a brief description of the synthetic methods for red and NIR CPEs, and focus predominantly on the rationale behind the molecular design and their applications in biomedical research. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 519–532

A Perspective Looking Backward and Forward on the 25th Anniversary of Conjugated Polyelectrolytes

“…63,64 Therefore, there is clearly room for the development of low-band-gap CPEs which retain the high brightness fluorescence that is characteristic of the wider bandgap analogs. 57 Another aspect of importance is understanding and control of the interchain aggregation that is typical of CPEs due to their amphiphilic nature.…”

“…Since these early reports, there have been a plethora of studies using CPEs as intracellular probes, as anticancer agents, and for gene delivery, among other applications. The interested reader is referred to some excellent review articles for a more detailed overview. ,− …”

Development of Meso‐Substituted Heterocyclic BODIPY‐Based Polymeric Nanoparticles for Pathogen Inhibition using Photodynamic Therapy**

“…In PDT, reactive oxygen species (i. e., singlet oxygen or radicals) have been generated through photosensitizers (PSs) upon irradiation of light which causes eradication of target tumor or microbial cells. [8][9][10][11] In the past few years, a new class of PSs with potential applications in PDT has intensified significantly. [12][13][14][15][16][17][18] The non-porphyrin molecules (synthetic dyes) have also been evaluated for their photosensitizing abilities.…”

“…[4–7] Recently, PDT has revived interest in the treatment of localized infections. In PDT, reactive oxygen species (i. e., singlet oxygen or radicals) have been generated through photosensitizers (PSs) upon irradiation of light which causes eradication of target tumor or microbial cells [8–11] . In the past few years, a new class of PSs with potential applications in PDT has intensified significantly [12–18] .…”

Intramolecular Charge Transfer-Based Conjugated Oligomer with Fluorescence, Efficient Photodynamics, and Photothermal Activities

“…Conjugated polymers/oligomers have emerged as a competitive class of photoactive agents for phototriggered inactivation of cancer cells or microorganisms. − Due to its large π-conjugated structure, conjugated polymers/oligomers possess strong light-harvesting abilities which can motivate a cascade of photochemical reactions. Through radiative transition from singlet excited state, they display favorable fluorescence properties with high quantum yields, which makes them excellent probes for biological imaging and diagnosis. − Meanwhile, the excited triplet state formed by intersystem crossing can interact with the surrounding oxygen and other substrates to produce toxic ROS. − Moreover, their capacity to serve as photothermal agents has also been explored, which mainly focus on nonfluorescent polydopamine (PDA), polyaniline (PANI), polypyrrole (PPy), and poly­(3,4-ethyl-enedioxythiophene) (PEDOT), as well as some conjugated polymers/oligomers with a narrow bandgap that shifted their absorption into the NIR region. ,− In these cases, photon energy has been transferred into heat through nonradiative transition, and the radiative channel and ISC process are inhibited.…”