Far‐Red/Near‐Infrared Conjugated Polymer Nanoparticles for Long‐Term In Situ Monitoring of Liver Tumor Growth

Abstract

The design and synthesis is reported for a fluorescent conjugated polymer (CP), poly{[4,4,9,9‐tetrakis(4‐(octyloxy)phenyl‐4,9‐dihydro‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene)]‐alt‐co‐[4,7‐di(thiophen‐2‐yl)‐2,1,3‐benzothiadiazole]} (PIDT‐DBT), with absorption and emission profiles fallen within far‐red/near infrared (FR/NIR) region and further demonstrate its application in long‐term in vitro cell tracing and in vivo imaging of liver tumor growth. PIDT‐DBT‐Tat nanoparticles (NPs) have an absorption maximum at ≈600 nm with an emission maximum at ≈720 nm in water. In vitro cell tracing studies reveal that PIDT‐DBT‐Tat NPs can trace HepG2 liver cancer cells over 8 d. In vivo imaging results indicate that PIDT‐DBT‐Tat NPs can monitor liver tumor growth for more than 27 d in a real‐time manner. Both in vitro and in vivo studies demonstrate that PIDT‐DBT‐Tat NPs are superior to commercial Qtracker 705 as fluorescent probes. This study demonstrates for the first time the feasibility for long‐term in vivo imaging of tumor growth by utilizing CP‐based fluorescent probes, which will encourage the development of NIR fluorescent CPs for in vivo bioimaging.

π-Conjugated nanostructured materials: preparation, properties and photonic applications

“…These features make them good candidates for a wide range of biomedical applications, and thus there are already numerous studies of their applications in nanobiotechnology. [104][105][106][107][108][109][110][111][112][113][114][115][116][117][118] A number of review articles [20][21][22] have been published giving an overview of the biomedical applications of these nanostructured conjugated materials; therefore, we present a brief summary of recent work on their biomedical applications to complete this review.…”

“…CPNs can be used in long-term cell imaging and as a drug/ biomolecules carrier because they are ideal nanocarriers in image-guided drug and biomolecule delivery due to their good photo stability and intrinsic luminescence properties. [104][105][106][107][108][109][110][111][112] The nanoparticle surfaces can be decorated with a variety of functional groups to allow the attachment of biologically relevant species for targeting and recognition. Moreover, carefully selecting the structure of the oligomer or polymer can produce stimuli-responsive nanoparticles [105][106][107] suitable for controlled cargo release or as light-induced sensitizers to generate reactive oxygen species for use in photodynamic therapy and antibacterial applications.…”

Conjugated Polymer Nanoparticles for Bioimaging

“…The introduction of the bulky polyhedral oligomeric silsesquioxane (POSS) side chain increased the PLQY of poly{[9,9-di(hexyl)fluorene]- alt -[4,7-bis(thiophen-2′-yl)-2,1,3-benzothiazole]} (PFDBT, 14 ) NPs from 2 to 14% (PFDBT-POSS 15 ) [ 45 ]. A 4-octyloxyphenyl side chain was introduced by the same group onto the indacenothiophene units of polymer 16 [ 46 ]. The bulkiness of those side chains hinders efficient π–π stacking, which is beneficial for the fluorescence efficiency due to the inhibition of charge transfer induced fluorescence quenching.…”

“…Liu et al [ 45 , 46 ] designed CPNPs synthesized from polymers 14 , 15 and 16 ( Figure 4 ) in a matrix of 1,2-distearoyl- sn -glycero-3-phosphoethanolamine- N -[methoxy(polyethyleneglycol)-2000] (DSPE-PEG 2000 ) and its maleimide modified derivative DSPE-PEG 2000 -Mal. A hydrophobic core consisting of the conjugated polymer ( 14 , 15 or 16 ) was formed, while the hydrophilic PEG and PEG-Mal point outwards.…”

The biocompatibility studies of polymer dots on pregnant mice and fetuses

“…All these good characteristics enabled polymer dots to be a potential for nanoparticles in biomedical applications. Liu et al had successfully traced the in vitro cell and monitored the in vivo liver tumor growth by utilizing the near-infrared conjugated polymer dots 14 , 15 . We have already used polymer dot in cellular imaging and obtained clear cellular morphology and structure 16 .…”