Conjugated polymer nanoparticles are highly versatile nano-structured materials that can potentially find applications in various areas such as optoelectronics, photonics, bio-imaging, bio-sensing and nanomedicine. Their straightforward synthesis in desired sizes and properties, biocompatibility and non-toxicity make these materials highly attractive for the aforementioned applications. This feature article reviews the recent developments in the synthesis, characterization, properties and application of these exciting nanostructured materials.

Water soluble [5]rotaxane and [5]pseudorotaxane based on cucurbit [6]uril and anchored to a meso-tetraphenyl porphyrin have been synthesized and characterized by spectroscopic methods ( 1 H-NMR, 13 C-NMR and UV), and by elemental analysis, and mass spectrometry. The preliminary results of the pH-driven switching properties of [5]rotaxane investigated through 1 H-NMR spectroscopy are reported. These results were compared with those obtained from a model porphyrin, which was prepared by the de-threading cucurbit[6]uril from [5]pseudorotaxane under basic conditions.

Main chain and branched polyrotaxanes have been synthesized in which polymerization and rotaxane formation occur simultaneously, due to the presence of the catalytically active self-threading macrocycle cucurbit[6]uril. Using monomers that contain stopper groups to prevent the catalytic macrocycle from noncatalytic threading, it was possible to prepare polyrotaxanes in high yields with molecular weights up to 39000. These polyrotaxanes are structurally perfect in the sense that exactly two macrocycles are threaded onto each structural repeat unit. Investigations into the polymerization mechanism have demonstrated that the catalyst cucurbit[6]uril is highly sensitive toward the structure of the monomers employed and a poorly designed monomer may result in complete inactivity. Features of the mechanism are discussed in some detail.

High quality white light generation with high colour rendering index (CRI) was achieved by integrating a cross-linkable azide functionalized polyfluorene derivative, namely poly[(9,9-dihexylfluorene)-co-alt-(9,9-bis(6-azidohexyl) fluorene)] (PFA), as a down-converting fluorescent material on the inorganic n-UV InGaN/GaN LED platform. For comparison, two other polyfluorene based polymers, namely poly[(9,9-dihexylfluorene)-co-alt-(9,9-bis(6-bromohexyl) fluorene)] (PFB) and poly[9,9-dihexyl-9H-fluorene] (PF), were tested for white light generation. While PFA and PF both led to white light generation, PFB fell out of the white region on the chromaticity diagram. Compared to PFA, both of the control groups (PF and PFB) exhibited much lower CRI. To gain a better insight into the mechanisms playing a key role for the generation of such high quality white light in PFA, all of these polymers were further subjected to a series of experiments such as controlled exposure to heat at 220 °C for 2 h under Ar and in air. The polymers PFA and PFB, which include cross-linkable groups, produced broad emission spectra in the region of 430-650 nm upon annealing in the absence of oxygen under Ar atmosphere while almost no change was observed in the emission spectrum of PF without any cross-linkable groups. PFA undergoes cross-linking through the decomposition of azide leading to reactive nitrene species, whereas in PFB cross-linking probably occurs via debromination. This result clearly proved that the broadening can not be attributed only to photo or thermal oxidation, but it is also due to cross-linking. PFA was also exposed to n-UV light from the InGaN/GaN LED to investigate its photostability. In these experiments, the spectral changes in absorbance and emission properties and thermal transitions of these polymers were monitored by FT-IR, UV-Vis and fluorescent spectrometry, and differential scanning calorimetry (DSC). These experiments indicated that PFA provides high quality white light opportunely via cross-linking and remains stable once cross-linking is formed in a solid film. © 2008 The Royal Society of Chemistry

A mainchain polyrotaxane is formed in which polymerisation and rotaxane formation occur simultaneously, due to the presence of the catalytically-active self-threading macrocycle cucurbituril.

Carbon nanotubes (CNTs) are interest to many different disciplines including chemistry, physics, biology, material science and engineering because of their unique properties and potential applications in various areas spanning from optoelectronics to biotechnology. However, one of the drawbacks associated with these materials is their insolubility which limits their wide accessibility for many applications. Various approaches have been adopted to circumvent this problem including modification of carbon nanotube surfaces by non-covalent and covalent attachments of solubilizing groups. Covalent approach modification may alter the intrinsic properties of carbon nanotubes and, in turn make them undesirable for many applications. On the other hand, a non-covalent approach helps to improve the solubility of CNTs while preserving their intrinsic properties. Among many noncovalent modifiers of CNTs, conjugated polymers are receiving increasing attention and highly appealing because of a number of reasons. To this end, the aim of this feature article is to review the recent results on the conjugated polymer-based non-covalent functionalization of CNTs with an emphasis on the effect of conjugated polymers in the dispersibility/solubility, optical, thermal and mechanical properties of carbon nanotubes as well as their usage in the purification and isolation of a specific single-walled nanotube from the mixture of the various tubes. IntroductionEver-increasing demand for materials with defined functions and properties urge researchers to seek for ways to design and synthesize novel materials. To this end, nanostructured-materials are getting increasing attention owing to their interesting and unusual properties. Among them, the carbon nanotubes (CNTs) are of particular interest to researchers from different disciplines such as chemistry, physics, biology, medicine and engineering because of their extraordinary structural, mechanical and electronic properties and also for their potential applications in many areas including optoelectronics, nanotechnology, nanomedicine, chemical and biological sensing and etc. 1-8CNTs having a cylindrical nanostuctured-shape consist of seamless rolls of graphitic sheets and can be classified as singlewalled nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) depending on the number of graphene sheets they contain as shown in Fig. 1. Diameter of SWCNTs could vary between 0.4 nm and 3 nm while a diameter range of 2-30 nm is characteristic for MWNTs. The length of both SWCNTs and Deparment of Chemistry and Institute of Materials Science and Nanotechnology, Bilkent University, Bilkent, Ankara, Turkey 06800. E-mail: dtuncel@fen.bilkent.edu.tr D€ on€ us Tuncel D€ on€ us Tuncel graduated from University of North London. Then she went on to study her PhD degree at Cambridge University in the Melville Polymer Synthesis Laboratory and after a while she moved to Imperial College, London and completed her study in 1999 under the supervision of Dr Joachim Steinke in the area of supramolecular c...

Here we report the synthesis of nanoparticles based on a conjugated oligomer which is synthesized through Heckcoupling of divinylfluorene and dibromobenzothiodiazole monomers. These water dispersible nanoparticles emit in the region of red tailing to the near-infrared region of the spectrum with high fluorescent quantum yield and brightness. The nanoparticles were found to be stable in water for a prolonged time without forming any aggregates and could carry camptothecin, an anticancer drug with high loading efficiency. MTT cell viability studies performed with breast cancer cell lines showed that halfmaximal inhibitory concentration (IC 50 ) values of nanoparticles for MCF7 and MDA-MB-231 were 44.7 μM and 24.8 μM, respectively. In order to further decrease the cytotoxicity and increase the stability of nanoparticles, amine groups were disguised by capping with cucurbit [7]uril (CB7). Drug release studies showed that drugs were released at low pH (at 5.0) faster than physiological pH (7.4) confirming the pH-responsive nature of the nanoparticles. On the other hand, CB7-capped drug-loaded nanoparticles regulated the release rate by providing slower release at pH 7.4 than the nanoparticles in the absence of CB7s. IC 50 values for camptothecin in the presence of nanoparticles with or without CB7 were significantly reduced in MCF7 and MDA-MB-231 cells. ■ INTRODUCTIONConjugated polymer nanoparticles (CPNs) are highly appealing for various advanced applications such as in vivo imaging, cell labeling, and delivery of therapeutic agents, as well as nanophotonics, owing to their high quantum yields and molar absorptivity, tunable properties, easy functionalization, photostability, and so forth. 1−7 To date, the use of CPNs has been demonstrated successfully in cell imaging, oxygen sensing, drug delivery, and nucleic acid delivery. 8−16 When these nanostructures are judiciously designed, they can be utilized in theranostic applications by combining more than one functionality to deliver therapeutic and imaging agents. 17−21 For the controlled delivery of therapeutic agents to the targets the nanoparticles could also include responsive groups that will respond to stimuli such as pH, oxidation−reduction, and enzymes. However, in the literature, examples are scarce regarding the multifunctional conjugated polymer nanoparticles (CPNs) and even less with conjugated oligomer-based nanoparticles (CONs). 22,23 Recently, Schenning et al. compared the capabilities of conjugated polymer nanoparticles to selfassembled oligomer-based nanoparticles in terms of their fluorescent quantum yields, stabilities, molar absorptivity, guest-holding, and releasing. 24 They demonstrated that oligomer nanoparticles have higher fluorescent quantum yields and comparable stabilities and molar absorptivity, but they release the guest faster than the conjugated polymer nanoparticles. Thus, this feature should be considered for the further design of oligomer-based nanoparticles for theranostic applications. CONs also offer some useful addi...

W ater-soluble conjugated polymers have been receiving increasingly greater attention owing to their potential applications in the areas of biosensing, bioimaging, and optoelectronics. For example, they have been successfully utilized in the biosensor applications to detect proteins, nucleic acids, and sugars. 1À6 These polymers can be prepared by attaching ionic side groups to the polymer backbone. However, their synthesis is tedious and their solubility is still limited in the water. Good water solubility or dispersibility of the conjugated polymers can alternatively be achieved by converting them into nanoparticles. 7À13 Such water-dispersible conjugated polymer nanoparticles (CPNs) have been exploited in different applications. For example, Landfester, Sherf, List, and coworkers have demonstrated the use of CPNs in optoelectronic applications including light-emitting diodes and photovoltaics and also as inks in inkjet printing. 14À19 Foulger and co-workers demonstrated the use of hybrid conjugated polymer nanoparticles composed of blue-and green-emitting polymers in the construction of organic light-emitting diodes (OLEDs). 20 The color tuning of the electroluminescence for the devices was achieved through energy transfer. These nanoparticles have also been used in biological applications such as fluorescent images, biosensors, and oxygen sensors. 21À27 Apart from these applications, color tuning is important for the optoelectronic applications, especially for energyefficient indoor and outdoor lighting. 28,29 Water-dispersible conjugated polymer nanoparticles can be prepared mainly by two methods, which are miniemulsion and reprecipitation. In the miniemulsion method, a two-phase system (oil-in-water) is used. 7,8 The polymer is dissolved in an organic solvent, which is not miscible with water, and added into a surfactant containing aqueous solution while sonicating. After the nanoparticle formation, the organic solvent is evaporated off to leave behind the conjugated nanoparticles stabilized by the surfactant. In the reprecipitation method, the polymer is dissolved in an organic * Address correspondence to dtuncel@fen.bilkent.edu.tr, volkan@bilkent.edu.tr.Received for review July 9, 2010 and accepted March 28, 2011. Published online 10.1021/nn103598qABSTRACT We report on the synthesis and characterization of water-dispersible, mechanically stable conjugated polymer nanoparticles (CPNs) in shelled architecture with tunable emission and controllable photometric properties via cross-linking. Using a reprecipitation method, whiteemitting polymer nanoparticles are prepared in different sizes by varying the concentration of polymer; the emission kinetics are tuned by controlling the shell formation. For this purpose, polyfluorene derivatives containing azide groups are selected that can be decomposed under UV light to generate very reactive species, which opportunely facilitate the inter-and intra-cross-linking of polymer chains to form shells. Nanoparticles before and after UV treatment are characterized by v...