Conjugated-Polymer-Amplified Sensing, Imaging, and Therapy

Biocompatible SWCNT Conductive Composites for Biomedical Applications

The efficiency of devices for biomedical applications, including tissue engineering and neuronal stimulation, heavily depends on their biocompatibility and performance level. Therefore, it is important to find adequate materials that meet the necessary requirements such as (i) being intrinsically compatible with biological systems, (ii) providing a sufficient electronic conductivity that promotes efficient signal transduction, (iii) having "soft" mechanical properties comparable to biological structures, and (iv) being degradable in physiological solution. We have developed organic conducting biocompatible single-walled carbon nanotubes (SWCNT) composites based on bovine serum albumin, carboxymethylcellulose, and acrylic polymer and investigated their properties, which are relevant for biomedical applications. This includes ζ-potential measurements, conductivity analyses, and SEM micrographs, the latter providing a local analysis of SWCNT distribution in the base material. We observed the development of the electrical conductivity of the SWCNT composites exposed to 1 mM KCl electrolyte for 40 days, representing a high stability of the samples. The conductivity of samples reaches 1300 S/m for 0.45 wt.% nanotubes. Moreover, we demonstrated the biocompatibility of the composites via cultivating fibroblast cell culture. Finally, we showed that composite coating results in the longer lifespan of cells on the surface. Overall, the SWCNT-based conductive composites might be a promising material for extended biomedical applications.

Rational Design of DNA Framework-Based Hybrid Nanomaterials for Anticancer Drug Delivery

Engineered DNA frameworks have been extensively exploited as affinity scaffolds for drug delivery. However, few studies focus on the rational design to comprehensively improve their stability, internalization kinetics, and drug loading efficiency. Herein, DNA framework-based hybrid nanomaterials are rationally engineered by using a molecular docking tool, where the framework acts as a template to support conjugated polymers. The hybrid materials exhibit high stability in biofluids owning to the multiple interactions between DNA and cationic conjugated polymer. Through molecular docking, it is found that a specific structure of the conjugated polymer at major grooves of DNA gives rise to a unique pocket for small-molecular drug doxorubicin (DOX) yielding lower binding energy than conventional DOX binding sites. This increases the binding affinity of DOX, allowing for high drug loading content and efficiency, and preventing drug leakage under physiological condition. As a proof of concept, the hybrid nanomaterials equipped with aptamer are used to carry DOX and antisense oligonucleotide G3139, which effectively inhibits solid tumor growth and shows negligible side effects on mice. It is anticipated that this approach would find broad applications in hybrid materials design and precise medicine.

Hydrophobic Interaction: A Promising Driving Force for the Biomedical Applications of Nucleic Acids

The comprehensive understanding and proper use of supramolecular interactions have become critical for the development of functional materials, and so is the biomedical application of nucleic acids (NAs). Relatively rare attention has been paid to hydrophobic interaction compared with hydrogen bonding and electrostatic interaction of NAs. However, hydrophobic interaction shows some unique properties, such as high tunability for application interest, minimal effect on NA functionality, and sensitivity to external stimuli. Therefore, the widespread use of hydrophobic interaction has promoted the evolution of NA-based biomaterials in higher-order self-assembly, drug/gene-delivery systems, and stimuli-responsive systems. Herein, the recent progress of NA-based biomaterials whose fabrications or properties are highly determined by hydrophobic interactions is summarized. 1) The hydrophobic interaction of NA itself comes from the accumulation of base-stacking forces, by which the NAs with certain base compositions and chain lengths show properties similar to thermal-responsive polymers. 2) In conjugation with hydrophobic molecules, NA amphiphiles show interesting self-assembly structures with unique properties in many new biosensing and therapeutic strategies. 3) The working-mechanisms of some NA-based complex materials are also dependent on hydrophobic interactions. Moreover, in recent attempts, NA amphiphiles have been applied in organizing macroscopic self-assembly of DNA origami and controlling the cell-cell interactions.

Polythiophenes with Cationic Phosphonium Groups as Vectors for Imaging, siRNA Delivery, and Photodynamic Therapy

In this work, we exploit the versatile function of cationic phosphonium-conjugated polythiophenes to develop multifunctional platforms for imaging and combined therapy (siRNA delivery and photodynamic therapy). The photophysical properties (absorption, emission and light-induced generation of singlet oxygen) of these cationic polythiophenes were found to be sensitive to molecular weight. Upon light irradiation, low molecular weight cationic polythiophenes were able to light-sensitize surrounding oxygen into reactive oxygen species (ROS) while the highest were not due to its aggregation in aqueous media. These polymers are also fluorescent, allowing one to visualize their intracellular location through confocal microscopy. The most promising polymers were then used as vectors for siRNA delivery. Due to their cationic and amphipathic features, these polymers were found to effectively self-assemble with siRNA targeting the luciferase gene and deliver it in MDA-MB-231 cancer cells expressing luciferase, leading to 30-50% of the gene-silencing effect. In parallel, the photodynamic therapy (PDT) activity of these cationic polymers was restored after siRNA delivery, demonstrating their potential for combined PDT and gene therapy.

Cellular uptake and targeting of low dispersity, dual emissive, segmented block copolymer nanofibers

Polymer-based nanoparticles show substantial promise in the treatment and diagnosis of cancer and other diseases. Herein we report an exploration of the cellular uptake of tailored, low dispersity segmented 1D nanoparticles which were prepared from an amphiphilic block copolymer, poly(dihexylfluorene)-b-poly(ethyleneglycol) (PDHF13-b-PEG227), with a crystallizable PDHF core-forming block and a 'stealth' PEG corona-forming block with different end-group functionalities. Segmented C-B-A-B-C pentablock 1D nanofibers with varied spatially-defined coronal chemistries and a selected length (95 nm) were prepared using the living crystallization-driven self-assembly (CDSA) seeded-growth method. As the blue fluorescence of PDHF is often subject to environment-related quenching, a far-red BODIPY (BD) fluorophore was attached to the PEG end-group of the coronal B segments to provide additional tracking capability. Folic acid (FA) was also incorporated as a targeting group in the terminal C segments. These dual-emissive pentablock nanofibers exhibited uptake into >97% of folate receptor positive HeLa cells by flow cytometry. In the absence of FA, no significant uptake was detected and nanofibers with either FA or BD coronal groups showed no significant toxicity. Correlative light and electron microscopy (CLEM) studies revealed receptor-mediated endocytosis as an uptake pathway, with subsequent localization to the perinuclear region. A significant proportion of the nanofibers also appeared to interact with the cell membrane in an end-on fashion, which was coupled with fluorescence quenching of the PDHF core. These results provide new insights into the cellular uptake of polymer-based nanofibers and suggest their potential use in targeted therapies and diagnostics.

Rational design of semiconducting polymer brushes as cancer theranostics

Photonic theranostics (PTs) generally contain optical agents for the optical sensing of biomolecules and therapeutic components for converting light into heat or chemical energy. Semiconducting polymer nanoparticles (SPNs) as advanced PTs possessing good biocompatibility, stable photophysical properties, and sensitive and tunable optical responses from the ultraviolet to near-infrared (NIR) II window (300-1700 nm) have recently aroused great interest. Although semiconducting polymers (SPs) with various building blocks have been synthesized and developed to meet the demands of biophotonic applications, most of the SPNs were made by a nanoprecipitation method that used amphiphilic surfactants to encapsulate SPs. Such binary SP micelles usually exhibit weakened photophysical properties of SPs and undergo dissociation in vivo. SP brushes (SPBs) are products of functional post-modification of SP backbones, which endows unique features to SPNs (e.g. enhanced optical properties and multiple chemical reaction sites for the conjunction of organic/inorganic imaging agents and therapeutics). Furthermore, the SPB-based SPNs can be highly stable due to supramolecular self-assembly and/or chemical crosslinking. In this review, we highlight the recent progress in the development of SPBs for advanced theranostics.

Near-Infrared-Light-Assisted in Situ Reduction of Antimicrobial Peptide-Protected Gold Nanoclusters for Stepwise Killing of Bacteria and Cancer Cells

Biomolecule-protected gold nanostructures show good performance in biomedical applications. However, precise control over gold nanocluster (AuNC) preparation with biomolecules remains challenging. Here, we develop a simple near-infrared (NIR)-light-assisted method for in situ reduction of antimicrobial peptide (AMP)-protected AuNCs. Take advantage of the high photothermal conversion efficiency of the conjugated polymer (CP) upon NIR light irradiation, we promote the rapid reduction of AuNCs by the AMP on the surface of the CP. The fluorescent properties of the AuNCs were improved owing to the formation of a unique Au(0)NC@Au(I)AMP core-shell nanostructure. This nanostructure is attributed to the rapid reduction of Au(0) and collision and fusion of Au(0) at high temperatures. Integrating antibacterial AMPs, fluorescent AuNCs, and photothermal CPs, the composites facilitated different killing mechanisms for both bacteria and cancer cells. This material system provides an all-in-one strategy for the stepwise killing of cancer cells and bacterial infection.

Oligonucleotide-Polymer Conjugates: From Molecular Basics to Practical Application

DNA exhibits many attractive properties, such as programmability, precise self-assembly, sequence-coded biomedical functions, and good biocompatibility; therefore, DNA has been used extensively as a building block to construct novel nanomaterials. Recently, studies on oligonucleotide-polymer conjugates (OPCs) have attracted increasing attention. As hybrid molecules, OPCs exhibit novel properties, e.g., sophisticated self-assembly behaviors, which are distinct from the simple combination of the functions of DNA and polymer, making OPCs interesting and useful. The synthesis and applications of OPCs are highly dependent on the choice of the polymer block, but a systematic summary of OPCs based on their molecular structures is still lacking. In order to design OPCs for further applications, it is necessary to thoroughly understand the structure-function relationship of OPCs. In this review, we carefully categorize recently developed OPCs by the structures of the polymer blocks, and discuss the synthesis, purification, and applications for each category. Finally, we will comment on future prospects for OPCs.

Recent advances in porphyrin-based nanocomposites for effective targeted imaging and therapy

Porphyrins are organic compounds that continue to attract much theoretical interest, and have been called the "pigments of life". They have a wide role in photodynamic and sonodynamic therapy, along with uses in magnetic resonance, fluorescence and photoacoustic imaging. There is a vast range of porphyrins that have been isolated or designed, but few of them have real clinical applications. Due to the hydrophobic properties of porphyrins, and their tendency to aggregate by stacking of the planar molecules they are difficult to work with in aqueous media. Therefore encapsulating them in nanoparticles (NPs) or attachment to various delivery vehicles have been used to improve delivery characteristics. Porphyrins can be used in a composite designed material with properties that allow specific targeting, immune tolerance, extended tissue lifetime and improved hydrophilicity. Drug delivery, healing and repairing of damaged organs, and cancer theranostics are some of the medical uses of porphyrin-based nanocomposites covered in this review.

Size-dependent fluorescence of conjugated polymer dots and correlation with the fluorescence in solution and in the solid phase of the polymer

Three conjugated polymers (CPs) were synthesized to obtain CPs with the same backbone but with different compositions of repeat units (phenylene and benzoselenadiazole (BSD)). The dominant composition of phenylene units and a smaller amount of BSD in the CP backbone enabled the CPs to emit different fluorescence colors according to their condition (solution or solid), which was caused by the difference in intermolecular electron transfer between CP backbones. Inspired by this, we fabricated polymer dots (Pdots) with various sizes using the CPs to control the number of CP chains within a spherical Pdot. This implied that smaller Pdots, where the chance of intermolecular electron transfer would be at a minimum, would accommodate fewer polymer chains than larger ones. The minimum chance for intermolecular electron transfer resulted in a short-wavelength emission, which was the identical emission color encountered in liquid CP solution. A more frequent intermolecular electron transfer was expected in larger Pdots, exhibiting long-wavelength emission, which was the same as observed in solid CPs. White-light-emitting Pdots that showed Commission Internationale de 1'Eclairage (CIE) coordinates of (0.34, 0.31) were fabricated simply by controlling the Pdot size.

Fluorescent chemosensors based on conjugated polymers with N-heterocyclic moieties: two decades of progress

A brief summary of representative fluorescent chemosensors based on conjugated polymers with N-heterocyclic moieties, followed by a discussion on the limitations and challenges of current systems, as well as possible future research directions.

A sensor array for the discrimination of polycyclic aromatic hydrocarbons using conjugated polymers and the inner filter effect

The inner filter effect and multivariate array sensing using conjugated polymers are combined for the detection and challenging discrimination of closely related polycyclic aromatic hydrocarbons.

Natural and anthropogenic activities result in the production of polycyclic aromatic hydrocarbons (PAHs), persistent pollutants that negatively impact the environment and human health. Rapid and reliable methods for the detection and discrimination of these compounds remains a technological challenge owing to their relatively featureless properties, structural similarities, and existence as complex mixtures. Here, we demonstrate that the inner filter effect (IFE), in combination with conjugated polymer (CP) array-based sensing, offers a straightforward approach for the quantitative and qualitative profiling of PAHs. The sensor array was constructed from six fluorescent fluorene-based copolymers, which incorporate side chains with peripheral 2-phenylbenzimidazole substituents that provide spectral overlap with PAHs and give rise to a pronounced IFE. Subtle structural differences in copolymer structure result in distinct spectral signatures, which provide a unique “chemical fingerprint” for each PAH. The discriminatory power of the array was evaluated using linear discriminant analysis (LDA) and principal component analysis (PCA) in order to discriminate between 16 PAH compounds identified as priority pollutants by the US Environmental Protection Agency (EPA). This array is the first multivariate system reliant on the modulation of the spectral signatures of CPs through the IFE for the detection and discrimination of closely related polynuclear aromatic species.

Self-Amplified Fluorescent Nanoparticles for Rapid and Visual Detection of Xylene in Aqueous Media

Pollutant detection is of great importance for quality control of drinking water and environmental protection. The common methods of pollutant detection suffer from time-consuming procedures, bulky and expensive instruments, and complicated sample pretreatment. Herein, a type of conceptually new self-amplified fluorescent nanoparticle (SAFN) is constructed based on aggregation-induced emission (AIE) luminogens for rapid and visual detection of xylene in aqueous media. AIE luminogens are self-assembled into SAFNs in aqueous media, which emit efficiently due to the aggregation of luminogen molecules. The SAFNs of AIE luminogens stick xylene molecules from aqueous media through multiple interactions including hydrophobic and π-π interactions. Upon capturing xylene, SAFNs swell, which quench the fluorescence of the whole SAFNs, showing the self-amplification effect. Such a self-amplification effect is entirely different from that of conjugated polymers in the literature. Importantly, fluorescence quenching of SAFNs by xylene can be readily observed by the naked eye, which enables visual xylene sensing. The SAFNs enable rapid and visual detection of xylene in aqueous media with a low detection limit (5 μg/L) in the order of seconds. Given high sensitivity, rapid response, simple and easy operation, and low cost, SAFNs of AIE luminogens present a promising platform for visual detection of organic pollutants in aqueous media.

Highly Selective Fluorescence Sensing and Imaging of ATP Using a Boronic Acid Groups-Bearing Polythiophene Derivate

A boronic acid groups-bearing polythiophene derivate (L) was designed and synthesized for highly sensitive fluorescence detection of ATP based on a multisite-binding coupled with analyte-induced aggregation strategy. L has a polythiophene backbone as fluorophores and two functional side groups, i.e., quaternary ammonium group and boronic acid group, as multibinding sites for ATP. When various structural analogues such as ADP, AMP, and various inorganic phosphates were added into the aqueous solution of L, only ATP caused a remarkable fluorescence quenching of about 60-fold accompanied by obvious color changes of solution from yellow to purple. The detection limit is estimated to be 2 nM based on 3σ/slope. With the advantage of good water solubility, low toxicity, and highly selective response to ATP, L was successfully utilized as a probe to real-time assay activity of adenylate kinase (ADK) and map fluorescent imaging of ATP in living cells.

Photophysical and Electroluminescence Characteristics of Polyfluorene Derivatives with Triphenylamine

In this work, polymers of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-triphenylamine] with side chains containing: pyrene (C1), diphenyl (C2), naphthalene (C3), and isopropyl (C6) structures were synthesized via a Suzuki coupling reaction. The structures were verified using NMR and cyclic voltammetry measurements provide the HOMO and LUMO of the polymers. The polymer with pyrene (C1) and naphthalene (C3) produced photoluminescence in the green while the polymer with the side chain containing diphenyl (C2) and isopropyl (C6) produce dual emission peaks of blue-green photoluminescence (PL). In order to examine the electroluminescence properties of the polymers, the solutions were spin-coated onto patterned ITO anode, dried, and subsequently coated with an Al cathode layer to form pristine single layer polymer LEDs. The results are compared to a standard PFO sample. The electroluminescence spectra resemble the PL spectra for C1 and C3. The devices of C2, C3, and C6 exhibit voltage-dependent EL. An additional red emission peak was detected for C2 and C6, resulting in spectra with peaks at 435 nm, 490 nm, and 625 nm. The effects of the side chains on the spectral characteristics of the polymer are discussed.

Precisely Defined Conjugated Oligoelectrolytes for Biosensing and Therapeutics

Conjugated oligoelectrolytes (COEs) are a relatively new class of synthetic organic molecules with, as of yet, untapped potential for use in organic optoelectronic devices and bioelectronic systems. COEs also offer a novel molecular approach to biosensing, bioimaging, and disease therapy. Substantial progress has been made in the past decade at the intersection of chemistry, materials science, and the biological sciences developing COEs and their polymer analogues, namely, conjugated polyelectrolytes (CPEs), into synthetic systems with biological and biomedical utility. CPEs have traditionally attracted more attention in arenas of sensing, imaging, and therapy. However, the precisely defined molecular structures and interactions of COEs offer potential key advantages over CPEs, including higher reliability and fluorescence quantum efficiency, larger diversity of subcellular targeting strategies, and improved selectivity to biomolecules. Here, the unique-and sometimes overlooked-properties of COEs are discussed and the noticeable progress in their use for biological sensing, imaging, and therapy is reviewed.

Influence of side chain isomerism on the rigidity of poly(3-alkylthiophenes) in solutions revealed by neutron scattering

Using small-angle neutron scattering, we conducted a detailed conformational study of poly(3-alkylthiophene) solutions in deuterated dichlorobenzene.

Converging the Hole Mobility of Poly(2-N-carbazoylethyl acrylate) with Conjugated Polymers by Tuning Isotacticity

Nonconjugated electroactive polymers (also known as pendant or side-chain electroactive polymers) promise several potential advantages relative to conjugated polymers including enhanced mechanical durability, greater stability and synthesis via living polymerization techniques. However, most previous examples suffer from low charge carrier mobility. Here, using poly(2-N-carbazoylethyl acrylate) (PCzEA) as a model polymer, we investigate the ability of side-chain tacticity to influence hole mobility. Specifically, we investigated polymers with dyad isotacticity (m) ranging from ∼45 to ∼95% synthesized by several methods including free radical polymerization and anionic polymerization. We found that the hole mobility (μ_h) measured via the space charge limited current (SCLC) technique increased proportionally to the increasing isotacticity from 2.11 × 10^-6 cm² V^-1 s^-1 (m = 45.5%) to 4.68 × 10^-5 cm² V^-1 s^-1 (m = 94.7%) in unannealed samples and that mobilities could be boosted as high as 2.74 × 10^-4 cm² V^-1 s^-1 (m = 94.7%) with thermal annealing, which rivaled the well-known conjugated polymer poly(3-hexylthiophene) (P3HT) (μ_h = 5.8 × 10^-4 cm² V^-1 s^-1). As such, we report here clear experimental evidence that control of side chain tacticity can enhance charge carrier mobility in nonconjugated pendant electroactive polymers, converging with mobilities typically only observed in conjugated polymers.

Ultrasmall Hyperbranched Semiconducting Polymer Nanoparticles with Different Radioisotopes Labeling for Cancer Theranostics

Exploiting ultrasmall nanoparticles as multifunctional nanocarriers labeled with different radionuclides for tumor theranostics has attracted great attention in past few years. Herein, we develop multifunctional nanocarriers based on ultrasmall hyperbranched semiconducting polymer (HSP) nanoparticles for different radionuclides including technetium-99m (^99mTc), iodine-131 (¹³¹I), and iodine-125 (¹²⁵I) labeling. SPECT imaging of ^99mTc labeled PEGylated HSP nanoparticles (HSP-PEG) exhibit a prominent accumulation in two-independent tumor models including subcutaneously xenograft and patient derived xenograft model. Impressively, 5,6-dimethylxanthenone-4-acetic acid (DMXAA), as tumor-vascular disrupting agent (VDA), significantly improves the tumor accumulation of ¹³¹I labeled HSP-PEG nanoparticles, further leading to the excellent inhibition of tumor growth after intravenous injection. More importantly, SPECT imaging of ¹²⁵I labeled HSP-PEG indicates that ultrasmall HSP-PEG nanoparticles could be slowly excreted from the body of a mouse through urine and feces in 1 week and cause no obvious toxicity to treated mice from blood analysis and histology examinations. Our finding from the different independent tumor models SPECT imaging shows that HSP-PEG nanoparticles may act as multifunctional nanocarriers to deliver different radionuclides for monitoring the in vivo behaviors of nanoparticles and cancer theranostics, which will provide a strategy for cancer treatment.

Conjugated Nanowire Sensors via High-Energy Single-Particle-Induced Linear Polymerization of 9,9'-Spirobi[9 H-fluorene] Derivatives

Nanostructures composed of conjugated polymers or π-conjugated molecules provide sensing platforms with large specific surface areas. One of the feasible approaches to accessing such nanostructured miniaturized sensors with ultrahigh sensitivity is to develop a network of organic nanowires with optical/electronic properties that can measure signals upon interacting with the analytes at their surfaces. In this work, organic nanowires with controlled number density and uniform length were fabricated by one-dimensional solid-state polymerization of 9,9'-spirobi[9 H-fluorene] (SBF) derivatives triggered by high-energy single particles. SBF was chosen as a conjugated molecular motif with the interplay of high density of π-electrons, high solubility, and uniform solid-state structures, allowing us to fabricate sensing platforms via solution processing. The as-deposited energy density in linear polymerization nanospace was theoretically analyzed by a collision model, interpreting nanowire sizes at subnanometer levels. The substitution of bromine atoms was confirmed to be effective not only for the higher collision probability of the incident particles but also for the remarkable increase in radiolytic neutral radical yield via C-Br cleavages or electron-dissociative attachments onto the bromine atoms. The fluorescence spectra of SBF-based nanowires were different from those of SBF derivatives due to extended bond formation as a result of polymerization reactions. Fluorescence was quenched by the addition of nitrobenzene, indicating the potential use of our nanowires for fluorometric sensing applications. Microwave-based conductivity measurements revealed that the SBF-based nanowires exhibited charge carrier transport property upon photoexcitation, and that the conductivity was changed upon treatment with nitrobenzene vapors. The presented strategy of bromination of aromatic rings for efficient fabrication of controlled nanowire networks with favorable fluorescent and charge transport properties of nanowires advances the development of nanostructured sensing systems.

DNA-Functionalized Dye-Loaded Polymeric Nanoparticles: Ultrabright FRET Platform for Amplified Detection of Nucleic Acids

Going beyond the limits of optical biosensing motivates exploration of signal amplification strategies that convert a single molecular recognition event into a response equivalent to hundreds of fluorescent dyes. In this respect, Førster Resonance Energy Transfer (FRET) with bright fluorescent nanoparticles (NPs) is an attractive direction, but it is limited by poor efficiency of NPs as FRET donors, because their size is typically much larger than the Førster radius (∼5 nm). Here, we established FRET-based nanoparticle probes that overcome this fundamental limitation by exploiting a phenomenon of giant light harvesting with thousands of strongly coupled dyes in a polymer matrix. These nanoprobes are based on 40 nm dye-loaded poly(methyl methacrylate- co-methacrylic acid) (PMMA-MA) NPs, so-called light-harvesting nanoantennas, which are functionalized at their surface with oligonucleotides. To achieve this functionalization, we developed an original methodology: PMMA-MA was modified with azide/carboxylate bifunctional group that enabled assembly of small polymeric NPs and their further Cu-free click coupling with oligonucleotides. The obtained functionalized nanoantenna behaves as giant energy donor, where hybridization of target nucleic acid (encoding survivin cancer marker) with ∼23 grafted oligonucleotides/Cy5-acceptors switches on/off FRET from ∼3200 rhodamine-donors of the nanoantenna, leading to 75-fold signal amplification. In solution and on surfaces at single-particle level, the nanoprobe provides sequence-specific two-color ratiometric response to nucleic acids with limit of detection reaching 0.25 pM. It displays unprecedented brightness for a FRET biosensor: it outperforms analogous FRET-based molecular probe by >2000-fold and QDot-605 by ∼100-fold. The developed concept of amplified sensing will increase orders of magnitude sensitivity of fluorescent probes for biomolecular targets.

White light-induced cell apoptosis by a conjugated polyelectrolyte through singlet oxygen generation

A cationic conjugated polyelectrolyte (CPE) PPET3 with a poly(p-phenylene ethynylene terthiophene) backbone and quaternary ammonium side chains was designed and synthesized. It serves as an efficient photosensitizer for photodynamic therapy under white light irradiation and induces cell death through the mitochondrial apoptosis pathway.

A Highly Efficient and Photostable Photosensitizer with Near-Infrared Aggregation-Induced Emission for Image-Guided Photodynamic Anticancer Therapy

Photodynamic therapy (PDT), which relies on photosensitizers (PS) and light to generate reactive oxygen species to kill cancer cells or bacteria, has attracted much attention in recent years. PSs with both bright emission and efficient singlet oxygen generation have also been used for image-guided PDT. However, simultaneously achieving effective ¹ O₂ generation, long wavelength absorption, and stable near-infrared (NIR) emission with low dark toxicity in a single PS remains challenging. In addition, it is well known that when traditional PSs are made into nanoparticles, they encounter quenched fluorescence and reduced ¹ O₂ production. In this contribution, these challenging issues have been successfully addressed through designing the first photostable photosensitizer with aggregation-induced NIR emission and very effective ¹ O₂ generation in aggregate state. The yielded nanoparticles show very effective ¹ O₂ generation, bright NIR fluorescence centered at 820 nm, excellent photostability, good biocompatibility, and negligible dark in vivo toxicity. Both in vitro and in vivo experiments prove that the nanoparticles are excellent candidates for image-guided photodynamic anticancer therapy.

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.