Color-Tunable Amphiphilic Segmented π-Conjugated Polymer Nano-Assemblies and Their Bioimaging in Cancer Cells

Abstract

We report a unique color tunable amphiphilic segmented π-conjugated polymer design and their π-stack driven diverse self-assembled nanostructures and demonstrate their application as a new classes of aqueous luminescent nanoparticle probes for bioimaging in cervical and breast cancer cells. Oligo-phenylenevinylene (OPV) was employed as rigid luminescent π-core and oligo-ethyleneoxy chains were used as flexible spacers to construct new amphiphilic segmented π-conjugated polymers by Witting–Horner polymerization route. The rigidity of the π-core was varied using tricyclodecanemethyleneoxy, 2-ethylhexyloxy or methoxy pendants and appropriate π-core geometry was optimized to achieve maximum aromatic π-stacking interactions. Solvent-induced chain aggregation of the polymers exhibited a morphological transition from one-dimensional helical nanofibrous to three-dimensional spherical nanoassemblies in good/bad solvent combinations. This morphological transformation was accompanied by the fluorescence color change from blue-to-white-to-yellow. CIE color coordinates exhibited x = 0.25 and y = 0.32 for the white light followed by the collective emission from aggregated and isolated OPV chromophores. Electron and atomic microscopes, steady state photophysical studies, time-resolved fluorescent decay analysis, and dynamic light scattering method enabled us to establish the precise mechanism for the self-assembly of segmented OPV polymers. The polymers produced stable and luminescent aqueous nanoparticles of <200 nm diameter in water. Cytotoxicity studies in cervical and breast cancer cells revealed that these new aqueous luminescent polymer nanoparticles are highly biocompatible and nontoxic to cells up to 60 μg/mL. Cellular uptake studies by confocal microscope further exposed that these nanoparticles were internalized in the cancer cells and they were predominantly accumulated in the nucleus. The present investigation opens up new amphiphilic segmented π-conjugated polymer design for producing diverse supramolecular assemblies and also demonstrates their new application as biocompatible fluorescent nanoprobes for imaging in cancer cells.

Synthesis of novel fluorescent molecule and its polymeric form with aniline as fluorescent and supercapacitor electrode materials

“…Immense interest has been shown in the development of fluorescent materials due to their promising and diverse applications, ranging from optoelectronics to biology, especially in the rapidly growing bionanotechnology field . Among the fluorescent materials, conjugated polymers have attracted great attention due to their unique fluorescent emission, adjustable electronic properties and extensively tunable electrical conductivities between insulators and metals while maintaining light weight, mechanical flexibility, low temperature processing, stability and good processability of polymers . Tuning by controlling the conjugation length of the conjugated polymers, and also the use of different dopants for conjugated polymers increase or decrease the band gaps, which leads to a red or blue shift.…”

“…Tuning by controlling the conjugation length of the conjugated polymers, and also the use of different dopants for conjugated polymers increase or decrease the band gaps, which leads to a red or blue shift. Conductive fluorescent‐conjugated polymers have attracted great attention owing to their potential applications such as medical diagnosis, sensors, drug delivery, energy storage, photocatalyst, etc. Among the conducting polymers, polyaniline (PANI) has been considered as the most encouraging material because of its low cost, simple synthesis, high conductivity, great redox reversibility and stability .…”

Fluorescent-Tagged Biodegradable Polycaprolactone Block Copolymer FRET Probe for Intracellular Bioimaging in Cancer Cells

“…On the other hand, the polymers showed 50 nm red-shift in water (maxima at 495 nm) followed by strong aggregation. Aromatic π-conjugated chromophores such as OPV are well known to undergo π–π stacking depending upon the solvent environment. , Thus, the large red shift in the emission maxima was attributed to the emission from the J-type aggregates by the hairpin-like micellar self-assembly of OPV chromophores. Further, the emission spectra in thin film showed maxima at 495 nm which was almost identical to that of their emission spectra in water.…”

Cationic Polythiophene-based Colorimetric Assay for Probing the Activity of Protein Kinase A

“…Conjugated polymers, with robust light-harvesting ability and optical signal amplification effect, 18,19 has been utilized in bioimaging 20,21,22 and biosensing. 23,24 Water-soluble polythiophene derivatives display irregular curly conformation and exbibits yellow color in its natural state.…”