A novel type of quantum dot (Ph-CN) is manufactured from graphitic carbon nitride by "lining" the carbon nitride structure with phenyl groups through supramolecular preorganization. This approach requires no chemical etching or hydrothermal treatments like other competing nanoparticle syntheses and is easy and safe to use. The Ph-CN nanoparticles exhibit bright, tunable fluorescence, with a high quantum yield of 48.4 % in aqueous colloidal suspensions. Interestingly, the observed Stokes shift of approximately 200 nm is higher than the maximum values reported for carbon nitride based fluorophores. The high quantum yield and the large Stokes shift are related to the structural surface organization of the phenyl groups, which affects the π-electron delocalization in the conjugated carbon nitride networks and induces colloidal stability. The remarkable performance of the Ph-CN nanoparticles in imaging is demonstrated by a simple incubation study with HeLa cells.

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Rapid and effective differentiation and killing of microbial pathogens are major challenges in the diagnosis and treatment of infectious diseases. Here, we report a novel system based on the conjugated polymer poly[(9,9-bis{6′-[N-(triethylene glycol methyl ether)-di(1H-imidazolium)methane]hexyl}-2,7-fluorene)-co-4,7-di-2-thienyl-2,1,3-benzothiadiazole] tetrabromide (PFDBT-BIMEG), which enables efficient microbial pathogen discrimination and killing. The functional side chains of PFDBT-BIMEG enabled both electrostatic and salt bridge interactions with microorganisms. Microorganism binding events caused a change in the aggregation structure of PFDBT-BIMEG, which could be recognized by a change of its fluorescence signal by intramolecular Forster resonance energy transfer (FRET). This sensing strategy allowed rapid and sensitive distinction of microbial pathogens within 15 min. We performed linear discrimination analysis that featured this advance to confirm that the polymer PFDBT-BIMEG could accurately classify microbial pathogens. Owing to the different adhesion mechanism of PFDBT-BIMEG to the surface of the microorganisms, we applied different sterilization strategies for each kind of microbial pathogen. The microbial pathogens could be efficiently killed by reactive oxygen species produced from PFDBT-BIMEG under irradiation, avoiding the use of any other antibacterial agents. This methodology, which combines pathogen discrimination and killing, represents a promising alternative to current diagnostic platforms.

Fluorescent conjugated polymer nanoparticles have attracted great interest for applications in biological imaging owing to their excellent optical properties and low cytotoxicity; however, a lack of effective targeting limits their use. In this work, we design and synthesize a fluorescent conjugated polymer modified with a phenylboronic acid group, which can covalently bind with cis-diol-containing compounds, such as sialic acid (SA), by forming a cyclic ester. However, the obtained conjugated polymer nanoparticles failed to discriminate between cancer cells, with or without SA overexpressed surfaces (such as DU 145 and HeLa cells, respectively). To address this problem, we introduced SA template molecules into the polymer nanoparticles during the reprecipitation process and then removed the template by adjusting the solution pH. The SA-imprinted nanoparticles showed a uniform size around 30 nm and enhanced fluorescence intensity compared with unmodified polymer nanoparticles. The SA-imprinted nanoparticles exhibited selective staining for DU 145 cancer cells and did not enter HeLa cells even after long incubation times. Thus, we present a facile method to prepare fluorescent nanoparticles for applications in targeted cancer cell imaging.

Fluorescent organic nanoparticles have attracted increasing attentions for chemical or biological sensing and imaging due to their low-toxicity, facile fabrication and surface functionalization. In this work, we report novel fluorescent organic nanoparticles via facile self-assembly method in aqueous solution. First, the designed water-soluble fluorophore shows a weak and negligible intrinsic fluorescence in water. Upon binding with adenosine-5'-triphosphate (ATP), fluorescent nanoparticles were formed immediately with strongly enhanced fluorescence. These fluorescent nanoparticles exhibit high sensitivity and selectivity toward Fe(3+) sensing with detection limit of 0.1 nM. In addition, after incubation with HeLa cells, the fluorophore shows excellent imaging performance by interaction with entogenous ATP in cells. Finally, this fluorescent system is also demonstrated to be capable of Fe(3+) sensing via fluorescence quenching in cellular environment.

Here, we present an Au@Pt core-shell multibranched nanoparticle as a new substrate capable of in situ surface-enhanced Raman scattering (SERS), thereby enabling monitoring of the catalytic reaction on the active surface. By careful control of the amount of Pt deposited bimetallic Au@Pt, nanoparticles with moderate performance both for SERS and catalytic activity were obtained. The Pt-catalyzed reduction of 4-nitrothiophenol by borohydride was chosen as the model reaction. The intermediate during the reaction was captured and clearly identified via SERS spectroscopy. We established in situ SERS spectroscopy as a promising and powerful technique to investigate in situ reactions taking place in heterogeneous catalysis.

Binding of biomolecules or probes to the plasma membrane is of great importance to investigate cell morphology and various biological processes. Herein, a water-soluble conjugated polymer is designed as a membrane probe. The probe shows a strong affinity towards lipid membranes owing to the high charge density from abundant imidazolium moieties together with the moderate rigidity and hydrophobicity derived from the conjugated backbone. Upon binding with a membrane, the inter-chain FRET of the probe was substantially enhanced, which resulted in the emission of both blue and red fluorescence. This is favorable for dual-color imaging. Finally, cellular experiments demonstrate the excellent performance of this macromolecular probe on the stable binding with cell membranes without the appearance of cell endocytocysis even after a long retention time.

Currently, many organic materials are being considered as electrode materials and display good electrochemical behavior. However, the most critical issues related to the wide use of organic electrodes are their low thermal stability and poor cycling performance due to their high solubility in electrolytes. Focusing on one of the most conventional carboxylate organic materials, namely lithium terephthalate Li 2 C 8 H 4 O 4 , we tackle these typical disadvantages via modifying its molecular structure by cation substitution. CaC 8 H 4 O 4 and Al 2 (C 8 H 4 O 4 ) 3 are prepared via a facile cation exchange reaction. Of these, CaC 8 H 4 O 4 presents the best cycling performance with thermal stability up to 570 °C and capacity of 399 mA·h·g -1 , without any capacity decay in the voltage window of 0.005-3.0 V. The molecular, crystal structure, and morphology of CaC 8 H 4 O 4 are retained during cycling. This cation-substitution strategy brings new perspectives in the synthesis of new materials as well as broadening the applications of organic materials in Li/Na-ion batteries.