Conjugated Polyelectrolyte-Based New Strategy for in Situ Detection of Carbon Dioxide

CO2-Responsive Water-Soluble Conjugated Polymers for In Vitro and In Vivo Biological Imaging

Water-soluble conjugated polymers (WCPs) composed of a hydrophobic polythiophene main chain with hydrophilic tertiary amine side-chains can directly self-assemble into sphere-like nano-objects in an aqueous solution due to phase separation between the hydrophilic and hydrophobic segments of the polymeric structure. Due to the presence of gas-responsive tertiary amine moieties in the spherical structure, the resulting polymers rapidly and reversibly tune their structural features, surface charge, and fluorescence performance in response to alternating carbon dioxide (CO₂) and nitrogen (N₂) bubbling, which leads to significantly enhanced fluorescence and surface charge switching properties and a stable cycle of on and off switching response. In vitro studies confirmed that the CO₂-treated polymers exhibited extremely low cytotoxicity and enhanced cellular uptake ability in normal and tumor cells, and thus possess significantly improved fluorescence stability, distribution, and endocytic uptake efficiency within cellular organisms compared to the pristine polymer. More importantly, in vivo assays demonstrated that the CO₂-treated polymers displayed excellent biocompatibility and high fluorescence enhancement in living zebrafish, whereas the fluorescence intensity and stability of zebrafish incubated with the pristine polymer decreased linearly over time. Thus, these CO₂ and N₂-responsive WCPs could potentially be applied as multifunctional fluorescent probes for in vivo biological imaging.

Development of A Thermo-Responsive Conjugated Polymer with Photobleaching-Resistance Property and Tunable Photosensitizing Performance

A thermo-responsive conjugated polymer, PFBT-gPA is synthesized by grafting the poly(N-isopropylacrylamide) (PNIPAAm) to the side chains of a conjugated polyfluorene derivative through atom transfer radical polymerization (ATRP). PFBT-gPA undergoes a reversible phase transition in water below and above the lower critical solution temperature (LCST) and the process is studied by differential scanning calorimetry (DSC) analysis and UV/vis absorption spectra. PFBT-gPA shows a good photostability under UV light irradiation especially above the LCST. Moreover, the photosensitizing performance of PFBT-gPA could be tuned simply by changing temperature. The unique properties of PFBT-gPA promise its potential applications in sensing and photodynamic therapy.

Inhibition and disaggregation of amyloid β protein fibrils through conjugated polymer–core thermoresponsive micelles

The micelles (CPMs) have a thermoresponsive surface and reactive oxygen species (ROS) generating core. At 37 °C, CPMs captured Aβ aggregates to inhibit and disaggregate aggregates under white-light irradiation, reducing Aβ-induced cytotoxicity.

Synergy of CO2 Response and Aggregation-Induced Emission in a Block Copolymer: A Facile Way To "See" Cancer Cells

Carbon dioxide (CO₂), an important gas molecule metabolite produced by the tricarboxylic acid cycle, is a direct signal for identifying cancers in cells and tissues. Herein, design and synthesis of a novel "breathable" block polymer supramolecular assembly probe consisting of a hydrophilic block, an amidine-containing CO₂-responsive block, and an aggregation-induced emission (AIE) luminescence block to detect CO₂ metabolized by cancer cells is reported. The triblock copolymer poly-(4-undecoxy tetraphenyl ethylene methacrylate)-b-poly-((N-amidino)-(2,3-dihydro-1H-1, 4-methyl-1, 2,3-triazole)-(ethenylbenzene))-b-poly(ethylene oxide) (PTPE-b-PAD-b-PEO) was successfully synthesized and characterized. This triblock copolymer could be self-assembled into "breathable" aqueous solution vesicles. In the presence of CO₂, the amidine-containing CO₂-responsive block (PAD block) of the vesicle "inhales" an amount of CO₂, which causes the volume of the vesicle to expand. The expansion of the vesicle induces the aggregation of the AIE luminescence block (PTPE block), which resulted in the fluorescence intensity enhancement. The supramolecular vesicles "exhale" CO₂, and the volume and AIE phenomenon of the vesicles decrease when N₂ is passed into the solution. On the basis of this reversible change of fluorescence intensity, HeLa cervical cancer cells, CNE1 nasopharynx cancer cells, 5-8F nasopharynx cancer cells, 16HBE human bronchial epithelial cells, and GES-1 human gastric mucosa epithelial cells have all been successfully detected and identified.

Conjugated polymer nanoparticles-based fluorescent biosensor for ultrasensitive detection of hydroquinone

This work describes a simple and sensitive fluorescent method for detection of hydroquinone utilizing conjugated polymer nanoparticles (CPNs). The CPNs serve both as a catalyst to accelerate the conversion of hydroquinone to benzoquinone and a fluorescent probe. In the presence of hydroquinone, the fluorescence of CPNs can be effectively quenched by benzoquinone. The detection limit of hydroquinone was down to 5 nM and excellent selectivity toward possible interferences was obtained. This method was successfully applied for hydroquinone detection in lake water and satisfactory results were achieved.

A Multiple-Stimulus-Responsive Biomimetic Assembly Based on a Polyisocyanopeptide and Conjugated Polymer

An assembly was fabricated and was revealed to be a multiple-stimulus-responsive biomimetic hybrid polymer architecture. It was constructed by the hydrophobic interactions between a conjugated polyfluorene that contained 2,1,3-benzothiadiazole units (PFBT) and a tri(ethylene glycol)-functionalized polyisocyanopeptide (3OEG-PIC). The introduction of PFBT to the polyisocyanopeptide (PIC) network allowed for the incorporation of responsiveness to multiple stimuli including temperature, CO₂ , carbonic anhydrase, and nonlinear mechanics, which mimics natural processes and interactions. Furthermore, the light-harvesting and signal amplification characteristics of PFBT endowed the supramolecular assembly with the essential function of fluorescence monitoring for biological processes.

Control of electrostatic interaction between a molecular beacon aptamer and conjugated polyelectrolyte for detection range-tunable ATP assay

A new strategy is suggested to fine-tune the detection range by controlling the ionic density of CPEs in the MBA/CPE-based ATP assay.