Multifunctional Phosphorescent Conjugated Polymer Dots for Hypoxia Imaging and Photodynamic Therapy of Cancer Cells

Abstract

Molecular oxygen (O2) plays a key role in many physiological processes, and becomes a toxicant to kill cells when excited to 1O2. Intracellular O2 levels, or the degree of hypoxia, are always viewed as an indicator of cancers. Due to the highly efficient cancer therapy ability and low side effect, photodynamic therapy (PDT) becomes one of the most promising treatments for cancers. Herein, an early‐stage diagnosis and therapy system is reported based on the phosphorescent conjugated polymer dots (Pdots) containing Pt(II) porphyrin as an oxygen‐responsive phosphorescent group and 1O2 photosensitizer. Intracellular hypoxia detection has been investigated. Results show that cells treated with Pdots display longer lifetimes under hypoxic conditions, and time‐resolved luminescence images exhibit a higher signal‐to‐noise ratio after gating off the short‐lived background fluorescence. Quantification of O2 is realized by the ratiometric emission intensity of phosphorescence/fluorescence and the lifetime of phosphorescence. Additionally, the PDT efficiency of Pdots is estimated by flow cytometry, MTT cell viability assay, and in situ imaging of PDT induced cell death. Interestingly, Pdots exhibit a high PDT efficiency and would be promising in clinical applications.

Recent Advances in the Development of Highly Luminescent Semiconducting Polymer Dots and Nanoparticles for Biological Imaging and Medicine

“…The list of topics include narrow emissive Pdots for multiplexing, 21–26 near-infrared (NIR) emissive Pdots and CPNs, 23,26–35 long luminescence lifetime emissive Pdots and CPNs, 22,24,32 single-chain and monovalent Pdots, 36,37 photoswitchable Pdots and CPNs, 38–43 electro-/chemiluminescent Pdots and CPNs, 44–54 CPNs with aggregation-induced emission (AIE), 52,55–60 luminescent Pdots and CPNs for dual modality imaging, 61–65 and Pdots and CPNs developed for biosensing 66–81 and photodynamic cancer therapy. 82–86 …”

Compact Conjugated Polymer Dots with Covalently Incorporated Metalloporphyrins for Hypoxia Bioimaging

“…However, the red emission is significantly higher than the blue emission of the fluorene moieties, and the luminescence color is also red. Conversely, although the hydrophilic polyelectrolytes have higher platinum contents (9.8 and 7 %), the blue emission attributed to the fluorene energy donors is higher than that of the porphyrin acceptors. This is mainly because hydrophilicity and electrostatic repulsion of the side chain make the nanoparticles pack relatively loosely and the interchain energy transfer is weakened.…”

“…However, ionic side chains in polyelectrolytes can result in nonspecific absorption in labeling by electrostatic interactions. The hydrophilia and electrostatic repulsion of ionic side chains also make nanoparticles relatively loose and decrease the energy‐transfer efficiency . Herein, we synthesized a kind of hydrophobic polymer (i.e., PFPtTFPP) as an oxygen sensor with fluorene as a donor and Pt II porphyrin decorated with fluorobenzene as an acceptor (Scheme ) .…”

Therapeutic Considerations and Conjugated Polymer‐Based Photosensitizers for Photodynamic Therapy

“…As photosensitizer‐doped conjugated polymer nanoparticles have been developed for PDT, the photosensitizer can probably leach out from the nanoparticles. Our group developed photo‐crosslinkable nanoparticles doped with photosensitizer Chlorin e6 (Ce6) to construct a nanoparticle platform for PDT .…”