Fluorination Enhances NIR‐II Fluorescence of Polymer Dots for Quantitative Brain Tumor Imaging

Abstract

Here, we describe a fluorination strategy for semiconducting polymers for the development of highly bright second near‐infrared region (NIR‐II) probes. Tetrafluorination yielded a fluorescence QY of 3.2 % for the polymer dots (Pdots), over a 3‐fold enhancement compared to non‐fluorinated counterparts. The fluorescence enhancement was attributable to a nanoscale fluorous effect in the Pdots that maintained the molecular planarity and minimized the structure distortion between the excited state and ground state, thus reducing the nonradiative relaxations. By performing through‐skull and through‐scalp imaging of the brain vasculature of live mice, we quantitatively analyzed the vascular morphology of transgenic brain tumors in terms of the vessel lengths, vessel branches, and vessel symmetry, which showed statistically significant differences from the wild type animals. The bright NIR‐II Pdots obtained through fluorination chemistry provide insightful information for precise diagnosis of the malignancy of the brain tumor.

Tailored Engineering of Novel Xanthonium Polymethine Dyes for Synergetic PDT and PTT Triggered by 1064 nm Laser toward Deep‐Seated Tumors

“…In recent years, many efforts have been devoted to amplifying the photothermal conversion and enhancing fluorescence brightness of NIR-II dyes. [26][27][28][29][30][31][32] But, searching for PDT-effective dyes excitable by >1000 nm light remains a blank field. The key challenge is not just simply pushing the dyes' absorption into NIR-II regions, but more importantly lies in how to rationally modulate their excited state energy distributions, so as to simultaneously achieve NIR-II fluorescence, PDT, and PTT in a subtle and balanced fashion.…”

Surgical Navigation for Malignancies Guided by Near‐Infrared‐II Fluorescence Imaging

“…[ 76 ] first reported the organic SPNPs, pDA‐PEG (Figure 2) nanoparticles for cell imaging and blood flow tracking in NIR‐II region. After this, SPNPs have garnered wide attention and been exploited for several biomedical applications in NIR‐II region, including tumor imaging, [ 77–81 ] vascular imaging, [ 82–84 ] and phototherapy. [ 85–88 ] However, since the majority of SPNPs are binary micelles after encapsulated hydrophobic SPs into amphiphilic polymers, [ 76,84,88 ] SPNPs may suffer from dissociation in the blood circulation when concentrations are below critical micelle concentrations, causing aggregation of SPs and poor bio‐distribution of SPNPs.…”

“…After this, SPNPs have garnered wide attention and been exploited for several biomedical applications in NIR‐II region, including tumor imaging, [ 77–81 ] vascular imaging, [ 82–84 ] and phototherapy. [ 85–88 ] However, since the majority of SPNPs are binary micelles after encapsulated hydrophobic SPs into amphiphilic polymers, [ 76,84,88 ] SPNPs may suffer from dissociation in the blood circulation when concentrations are below critical micelle concentrations, causing aggregation of SPs and poor bio‐distribution of SPNPs. [ 89,90 ] To address these issues, grafted semiconducting polymer amphiphiles have been developed by introducing hydrophilic groups to SP side chains, such as PFTQ‐PEG, which can assemble in aqueous solutions without dissociation.…”

Recent Advances in Polymeric Nanoparticles for Enhanced Fluorescence and Photoacoustic Imaging

“…Recently, a new fluorination strategy to increase the NIR‐II emission signals and QYs of SNPs was reported by Liu et al [52] . Their results revealed that the fluorination of SPs reduces non‐radiative relaxation by maintaining molecular planarity and minimising structural distortions between the excited and ground state.…”