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Abstract: Conjugated polymer dots (Pdots, also named polymer nanoparticles, PNPs), which consist of π‐conjugated organic polymers, are novel organic nanomaterials with size in the range of 1–100 nm. Compared with traditional organic small molecules, semiconductor quantum dots and inorganic nanomaterials, the Pdots exhibit significant potential applications in biological imaging, sensing and detection, drug delivery and theranostics, due to their advantages of special optical properties, diverse structure, easy surface modification and good biocompatibility. In this short review, we present a brief summary of the current development in Pdots as phototheranostic agents, including fluorescence imaging, photoacoustic imaging, photodynamic therapy and photothermal therapy. Current challenges in Pdot research and future directions in the field are proposed. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Currently, solid‐state fluorescent carbonized polymer dots (CPDs) have attracted attention increasingly due to their applications for optoelectronic display. However, designing CPDs possessing solid‐state fluorescence and clarifying the fluorescence mechanism remain challenging. Herein, we initially synthesized a novel type of polythiophene derivatives CPDs, poly‐4,4'‐(thiophene‐3,4‐diyl)dibenzoic acid carbonized polymer dots (PDBA‐CPDs) with solid‐state fluorescence. Subsequently, the structural and optical characterization revealed that the solid‐state fluorescence originated from the aggregation induced emission of the CPDs. In brief, in aggregation state, the remaining polymer structure groups on the surface of the CPDs overlapped and weakened the non‐radiative transition, enhancing solid‐state fluorescence emission. Thirdly, three polythiophene‐derived CPDs were designed to further demonstrate the aggregation induced solid‐state fluorescence mechanism. Finally, owing to their unique properties of solid‐state fluorescence, the white LEDs (light emitting diodes) were fabricated with high color rendering index (CRI) of 82.7 and CIE coordinates of (0.37, 0.39) using commercial 460 nm chip. This work facilitates the development of CPDs' solid‐state fluorescence mechanisms and advances the application of CPDs in the field of optoelectronics. [ABSTRACT FROM AUTHOR]

Peroxalate CL as an energy source to excite photosensitizers has attracted tremendous attention in photodynamic therapy (PDT). In this work, peroxyoxalate CPPO and hypocrellin B (HB)‐based nanoparticles (CBNPs) for ultrasound (US)‐enhanced self‐exciting PDT were designed and prepared. CBNPs showed an excellent therapeutic effect against cancer cells with the assistance of US. This US‐enhanced‐chemiluminescence system avoids the dependence on external light and provides an example for inspiring more effective and precise strategies for cancer treatment. [ABSTRACT FROM AUTHOR]

Hypocrellin B (HB) derived from naturally produced hypocrellins has attracted considerable attention in photodynamic therapy (PDT) because of its excellent photosensitive properties. However, the weak absorption within a "phototherapy window" (600–900 nm) and poor water solubility of HB have limited its clinical application. In this study, two HB derivatives (i. e., HE and HF) were designed and synthesized for the first time by introducing two different substituent groups into the HB structure. The obtained derivatives showed a broad absorption band covering the near‐infrared (NIR) region, NIR emission (peaked at 805 nm), and singlet oxygen quantum yields of 0.27/0.31. HE‐PEG‐NPs were also prepared using 2‐distearoyl‐sn‐glycero‐3‐phosphoethanolamine‐N‐[methoxy(polyethyleneglycol)‐2000] (DSPE‐mPEG2000) to achieve excellent dispersion in water and further explored their practical applications. HE‐PEG‐NPs not only retained their 1O2‐generating ability, but also exhibited a photothermal conversion efficiency of 25.9%. In vitro and in vivo therapeutic results revealed that the synergetic effect of HE‐PEG‐NPs on PDT and photothermal therapy (PTT) could achieve a good performance. Therefore, HE‐PEG‐NPs could be regarded as a promising phototheranostic agent. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs), a kind of phototheranostic agent with the capability of simultaneous bioimaging and phototherapy [i.e. photodynamic therapy (PDT) or photothermal therapy (PTT)], have received considerable attention because of their remarkable properties, including flexibility for surface modification, high biocompatibility, low toxicity and photo‐induced activity for malignant tumor cells. Among numerous carbon sources, it has been found that natural biomass are good candidates for the preparation of CD phototheranostic agents. In this study, pheophytin, a type of Mg‐free chlorophyll derivative and also a natural product with low toxicity, was used as a raw carbon source for the synthesis of CDs by using a microwave method. The obtained hydrophobic CDs exhibited a maximum near‐infrared (NIR) emission peak at approximately 680 nm, and high singlet oxygen (1O2) generation with a quantum yield of 0.62. The self‐assembled CDs from the as‐prepared CDs with DSPE‐mPEG2000 retained efficient 1O2 generation. The obtained carbon dot assembly was not only an efficient fluorescence (FL) imaging agent but also a smart PDT agent. Our studies indicated that the obtained hydrophilic CD assembly holds great potential as a new phototheranostic agent for cancer therapy. This work provides a new route for synthesis of CDs and proposes a readily available candidate for tumor treatment. [ABSTRACT FROM AUTHOR]

During the past decade, increasing attention has been paid to fluorescent carbon dots (CDs) due to their unique photoluminescence (PL) properties. As synthetic methods gradually develop, many post‐functionalization strategies have been developed to enhance the PL of CDs. However, in most cases, the PL enhancement was less than 10‐fold with multistep modification processes. In this work, a facile and efficient post‐functionalization strategy was successfully applied to enhance the PL intensity of CDs dramatically up to 69 times by surfactants at room temperature for the first time. Furthermore, the mechanism of surfactant‐induced PL enhancement of CDs was investigated and in vivo bioimaging was performed. The results demonstrated that electrostatic/non‐electrostatic interactions between CDs and surfactants could effectively lower the vibration and rotation of CDs, increase radiative decay processes and, thus, enhance the PL of CDs. This finding may provide new insights into the strategies for enhancing the PL of CDs, further broadening their potential applications. Brighter Carbon Dots: The effect of different types of surfactants on the photoluminescence of carbon dots (CDs) was investigated. The results show that interactions between carbon dots and surfactants enhance the photoluminescence of CDs. [ABSTRACT FROM AUTHOR]

Abstract: Constructing complex nanoarchitectures via self‐assembly with nanoparticle building blocks is a practical strategy that produces nanostructures with properties that are absent in the individual unit. In this work, we used hydrophilic carbon dots (C‐dots) as building blocks to form C‐dot assemblies. Compared to the individual C‐dot, the self‐assembled C‐dots showed about 30 nm red‐shift of absorption, resulting in the 5.1% increasing of photothermal conversion efficiency upon a 671 nm laser irradiation. More importantly, the C‐dot assemblies enable them can be efficiently uptaken by cancer cells. Meanwhile, in vitro study demonstrated the C‐dot assemblies can efficiently kill cancer cells than that of individual C‐dot upon irradiation for 5 min at equivalent C‐dot concentration. Our study may provide a new strategy for the efficient photothermal therapy of cancer based on C‐dots. [ABSTRACT FROM AUTHOR]

The development of a fluorescent probe to distinguish between cysteine (Cys) and homocysteine (Hcy) is always a challenge owing to their structural similarity, and the simultaneous detection of Cys and Hcy by utilizing different emission channels is especially difficult. In this work, we designed and synthesized a new fluorescent probe to differentiate between Cys and Hcy on the basis of a coumarin derivative with a chlorine atom and an α,β-unsaturated aldehyde. Cys and Hcy induced different cascade reactions with the probe, which led to different products with distinct photophysical properties. The nonfluorescent probe responded to Cys and emitted strong blue fluorescence, whereas it reacted with Hcy and generated yellow fluorescence without interference from glutathione. In addition, the probe was successfully applied to distinguish between Cys and Hcy in living cells. [ABSTRACT FROM AUTHOR]

Fluorescence imaging is a promising tool for the visualization of biomolecules in living systems and there is great demand for new fluorescent dyes that absorb and emit in the near-infrared (NIR) region. Herein, we constructed three new fluorescent dyes ( NBC dyes) based on keto-benzo[ h]coumarin ( k-BC) and benzopyrilium salts. These dyes showed large Stokes shifts (>100 nm) and NIR emission (>800 nm). The relationship between the structures and optical properties of these dyes was further investigated by using density functional theory calculations at the B3LYP/6-3G level of theory. Fluorescence images indicated that the fabricated dyes exhibited good photostability and low cytotoxicity and, thus, have potential applications as imaging agents in living cells and animals. [ABSTRACT FROM AUTHOR]