A systematic review of tea pigments: Prevention of major diseases, protection of organs, and potential mechanisms and applications.

With the growing awareness of a healthy life, tea pigments (TPGs) are in focus for their health benefits. TPGs not only provide specific color to tea liquor but also possess health benefits such as anti-obesity, anti-tumor, anti-inflammatory, anti-viral, anti-oxidative, and bacteriostatic properties. Also, TPGs can benefit bone, liver, kidney, cardiovascular, gut microbiome, and sleep health. Based on previous reports, this review provides a brief introduction to the health benefits of TPGs, focusing on the prevention of human diseases and the protection of organs. Also, the latest research on the functional mechanism(s), practical application, and development strategies of TPGs is discussed.

Red-Emitting Carbon Nanodot-Based Wide-Range Responsive Nanothermometer for Intracellular Temperature Sensing.

Precise sensing of intracellular temperature can provide plenty of information on disease-related cell states and promote the development of a diagnostic method. Fluorescence-based nanothermometers, as the "noncontact" sensors, exhibit great advantages over traditional thermometers due to the dual function of imaging and sensing at the molecular level. Herein, we report a red-emitting carbon nanodots (RCDs)-based nanothermometer for intracellular temperature sensing. Results indicate that RCDs exhibit favorable temperature-responsive fluorescence property with a good linear relationship, reversibility, and reproducibility under heating and cooling treatments in a wide range from 4 to 80 °C. Meanwhile, the RCDs possess satisfactory thermal sensitivity and temperature resolution, which are superior or comparable to the current nanothermometers. The low cytotoxicity and excellent temperature-responsive fluorescence property of RCDs have also been verified in living cell studies. Therefore, the RCDs will be a promising nanothermometer for intracellular temperature sensing in diverse areas.

Efficient suppression of amyloid-ß peptide aggregation and cytotoxicity with photosensitive polymer nanodots.

The deposition of amyloid plaques resulting from the aggregation of amyloid-ß (Aß) peptides is closely related to Alzheimer's disease (AD). With the development of various therapeutic methods, the oxidative modification of Aß has emerged as a fascinating noninvasive photo-therapeutic intervention for treating AD by altering the Aß aggregation tendency. Herein, we report the photo-triggered inhibition of Aß aggregation and cytotoxicity by utilizing polymer nanodots (Pdots) modified with rose bengal (RB), methylene blue (MB), and riboflavin (RF). Experimental results demonstrate that these functionalized Pdots manifest a superior suppression effect on Aß aggregation under irradiation. This can be attributed to the formation of reactive oxygen species (ROS) (i.e., singlet oxygen (1O2)), resulting in the oxygenation of Aß and the change of Aß aggregation tendency. Especially, RB-Pdots manifest better biocompatibility and higher 1O2 productivity. In a word, this hybridized nanostructure will provide a promising platform for the noninvasive photo-therapeutic treatment of AD in the future.

Wurtzite CuNi2InS4 Nanocrystals: A Quaternary Chalcogenide Magnetic Semiconductor.

For the first time, quaternary chalcogenide CuNi2InS4 nanocrystals with a wurtzite structure have been designed and fabricated as a new magnetic semiconductor. The phase structure analysis suggests that the synthesized wurtzite CuNi2InS4 phase has a disordered structure in which Cu+, Ni2+, and In3+ ions share the same lattice site of the unit cell with a random cation distribution. The prepared CuNi2InS4 nanocrystals have uniform bullet-like morphology, small size distribution, good monodispersity, and high crystallinity. The magnetic properties investigation reveals that the wurtzite CuNi2InS4 nanocrystals can exhibit a weak ferromagnetic moment with the blocking temperature at around 13 K thanks to the disordered wurtzite structure and the high content of magnetic Ni2+ ions. As for the semiconducting properties, the as-obtained wurtzite CuNi2InS4 nanocrystals show a strong and broad visible light absorption and have a direct bandgap of 1.45 eV. Due to their favorable optical properties, the fabricated thin film of CuNi2InS4 nanocrystals exhibits a good photoelectric response to the solar spectrum, which makes the obtained new phase potential candidate for applications in the photovoltaics. This work demonstrates a new metastable I-II2-III-VI4 chalcogenide that can be used to render multiple functionalities and applications.

Fabrication of Bi19S27I3 nanorod cluster films for enhanced photodetection performance.

Thin-film photodetectors built from one-dimensional nanostructures have attracted extensive attention due to their significance in basic scientific research and potential technological applications. It is still desirable to develop new materials with a wide response range for application in photodetectors. In this work, a Bi19S27I3 nanorod cluster film has been successfully fabricated on various rigid substrates by a facile solvothermal method. The component nanorods exhibit an oriented growth along the [001] direction. The UV-Vis-NIR absorption spectrum shows a continuous strong absorption spanning the whole visible light to near-infrared region and presents a direct band gap of 0.83 eV for the prepared Bi19S27I3 nanorod clusters. The spectral photoresponse of the Bi19S27I3-based photodetector device demonstrates a broad photoresponse ranging from ultraviolet to near infrared. The photocurrent results reveal that the photodetector exhibits a more sensitive response towards near-infrared light than visible light. Furthermore, the photodetector based on the Bi19S27I3 nanorod cluster film shows significantly enhanced photodetection performance compared to Bi19S27I3 nanorod powder. The photocurrent and on-off ratio of the prepared nanorod cluster film are respectively up to 400 times and several times higher than those of the powder sample. The on-off ratios are about 265 and 66 under NIR illumination and 48 and 11 under visible light for the film and powder samples, respectively. These results suggest a great potential application of the prepared Bi19S27I3 nanorod cluster film in optoelectronic devices.

Temperature responsive fluorescent polymer nanoparticles (TRFNPs) for cellular imaging and controlled releasing of drug to living cells.

Recent studies have demonstrated that drug delivery by using functional nanomaterials with imaging capability could afford plenty of insightful information for the better control of the delivery process. In this work, we developed temperature responsive fluorescent nanoparticles (TRFNPs) for drug delivery and cellular imaging. The TRFNP was fabricated by one-pot co-precipitation of thermal sensitive amphiphilic block copolymers polystyrene-b-poly(N-isopropyl acrylamide) (PS-b-PNIPAM) and fluorescent conjugated polymer poly [(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(1,4-benzo(2,1',3)-thiadiazole)] (PFBT) in the presence of desired small guest molecules. The dynamic light scattering (DLS) measurements verified that this functional nanoparticle exhibited temperature dependent size variation, which could therefore regulate the releasing rate of loaded guest molecules (e.g. drugs) inside the polymer core. Besides, the TRFNPs displayed good photostability in terms of optical characterization. The cellular cytotoxicity characterization demonstrated that this nanoparticle exhibited good biocompatibility even under the mass concentration of 10µg/mL. By using Nile Red as a model molecule, the temperature-controlled releasing process from TRFNPs in solution as well as inside living cells was monitored directly according to the spectroscopic and microscopic characterizations. Furthermore, anti-cancer drug was successfully delivered into living cells via TRFNPs and released in a temperature dependent manner. As a consequence, owing the attractive merits as mentioned above, this nanostructure would find broad applications in nanomedicine in the future.

A bright carbon-dot-based fluorescent probe for selective and sensitive detection of mercury ions.

In this work, we demonstrated a convenient and green strategy for the synthesis of bright and water-soluble carbon dots (CDs) by carbonizing sodium citrate and glutathione together in a hydrothermal method for the first time. Without post surface modification, the as-synthesized CDs display fluorescence quantum yield (QY) as high as 21.03% and show superior stability not only in concentrated salt solutions but also in neutral and alkaline media. The probe exhibits selective and sensitive recognition capability towards mercury ion (Hg2+) in aqueous solution. The fluorescence of CDs can be quenched by Hg2+ through an effective electron energy transfer process. It displays a linear quenching effect toward mercury ion in the concentration range of 0-15µM with a correlation coefficient (R2) of 0.99. The limit of detection is determined to be 25nM at the signal to noise ratio of 3. These attractive merits would enable the extensive applications of this probe in environmental science and analytical chemistry in the future.

Quantification of Cancer Biomarkers in Serum Using Scattering-Based Quantitative Single Particle Intensity Measurement with a Dark-Field Microscope.

In this work, we developed a simple yet robust single particle scattering intensity measurement method for the quantification of cancer-related biomarkers. The design is based on the plasmonic coupling effect between noble metal nanoparticles. First, the primary and secondary antibodies were conjugated onto the surface of 60 nm gold nanoparticles (AuNPs, act as capture probes) and 50 nm silver nanoparticles (AgNPs, act as signal amplification probes) respectively. In the presence of corresponding antigen, a sandwiched immunocomplex was formed, resulting a significantly enhanced scattering intensity in contrast to that of individual probes. By measuring the intensity change of the particles with a dark-field microscope (DFM), the amount of target protein could be accurately quantified. As a proof of concept experiment, quantification of three types of antigens, including carcinoembryonic antigen (CEA), prostate-specific antigen (PSA) and alpha fetoprotein (AFP) by this platform was demonstrated with limit of detection (LOD) of 1.7, 3.3, and 5.9 pM, respectively, with a linear dynamic range of 0 to 300 pM. Furthermore, to elucidate the potential in clinical application, the content of antigens in a serum sample was also quantified directly without additional sample pretreatment. In order to validate the reliability of this method, the measured result was also compared with that obtained by regular enzyme-linked immunosorbent assay (ELISA) kit, showing good consistency between these two data sets. Therefore, owing to the simplicity and accuracy of this method, it could be potentially applied for massive disease screening in clinical assay in the future.

Nanoprecipitation of Fluorescent Conjugated Polymer onto the Surface of Plasmonic Nanoparticle for Fluorescence/Dark-Field Dual-Modality Single Particle Imaging.

In this work, a hybridized nanoparticle with fluorescence/dark-field dual-modality imaging capability was prepared by nanoprecipitation of fluorescent conjugated polymer onto the surface of silica-coated rod-shape plasmonic nanoparticle. According to the spectroscopic and microscopic characterizations, the fluorescence intensity of conjugated polymer poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(1,4-benzo(2,1',3)-thiadiazole)] (PFBT) could be enhanced around 2-fold after assembling onto the silica-decorated metal nanorod surface compared with the fluorescence intensity of regular PFBT polymer dots without the metal core. The in situ nanorod etching experiment further confirmed this result at the single particle level. In addition to the fluorescence enhancement effect, improved fluorescence stability was obtained from the single particle fluorescence intensity characterizations. As a consequence, this self-assembled functional nanoparticle could be extensively applied to biological imaging such as cellular labeling and single particle tracking owing to the novel and unique optical features, for example, the superior optical stability and specific identification capability from the scattering and fluorescence domain, respectively. Furthermore, the amendable peripheral polymer surface of this nanostructure will promote its applications in biological sensing and imaging-guided functional molecule delivery in the future.

Single Particle Tracking of Peptides-Modified Nanocargo on Lipid Membrane Revealing Bulk-Mediated Diffusion.

Understanding the detailed diffusion behavior of the nanocargo on lipid membrane can afford deep insight into the surface chemistry controlled translocation mechanism for the rational design of an efficient delivery system. By tracking the diffusion trajectory of transacting activator of transcription (TAT, a cell penetrating peptide) peptides-modified nanocargo on lipid membrane, bulk-mediated (intermittent hopping) diffusion was observed for the first time after a blended modification of TAT peptides and polyethylene glycol (PEG) molecules onto the nanoparticle surface. In contrast to random walk or confined diffusion, the nanoparticles could be temporarily confined for random waiting times between surface displacements produced by excursions through the bulk fluid, which was not noted before. Non-Gaussian distributed step length (with a stretched power law like tail) was observed, making large displacements much more probable than one would predict for regular Gaussian decay. This kind of larger displacement would therefore significantly facilitate a kinetically controlled surface searching process like heterogeneous penetration site recognition on a fluidic membrane with suitable spatial orientation.

Construction of a polyhedron decorated MOF with a unique network through the combination of two classic secondary building units.

A novel decorated metal-organic polyhedron (MOP) based metal-organic framework with a unique 4,9-connected network is successfully constructed, which displays a relatively strong interaction toward H2 and CO2 probably due to the existence of open metal sites in the secondary building units.