Combined effect of polystyrene nanoparticles and chlorpyrifos to Daphnia magna.

Microplastics and nanoplastics (MPs/NPs) are emerging contaminants ubiquitous in the environment. These particles can act as carriers of hydrophobic organic compounds (HOCs), such as chlorpyrifos (CPF), an organophosphorus insecticide. This study investigates the acute toxicity of CPF combined with model polystyrene nanoplastics (PS-NPs) using Daphnia magna as a model organism.

Daphnia magna uptake and excretion of luminescence-labelled polystyrene nanoparticle as visualized by high sensitivity real-time optical imaging.

The environmental and ecological consequences of nanoplastics (NPs) draw increasing research interests and social concerns. However, the in situ and real-time detection of NPs from living organisms and transferring media remains as a major technical obstacle for scientific investigation. Herein we report a novel time-gated imaging (TGI) strategy capable of real-time visualizing the intake of NPs by an individual living organism, which is based on the polystyrene NPs labelled with lanthanide up-conversion luminescence.

Influence of Two- and Three-Dimensional Engineering on the Trap State Distribution and Photophysical Properties of Lead Halide Perovskite Polycrystals.

Constructing a two- and three-dimensional (2D/3D) heterojunction structure on the surface of a 3D perovskite film, termed 2D/3D engineering, is effective in elevating the stability of perovskite polycrystal-based photovoltaic and photoelectronic devices; however, it remains controversial whether this protocol is favorable or detrimental to the device performance. Here, we prepare a series of 2D/3D perovskite films by post-treating the perovskite polycrystalline film with different concentrations of phenethylammonium iodide (PEAI). Systematic spectroscopy and electrochemical studies illustrate that PEAI can penetrate the 3D perovskite network and eliminate the intrinsic trap states of perovskite polycrystals, while the 2D perovskite nanosheets enriched on the top of the polycrystalline film may introduce additional trap states, which manipulate the photoluminescence performance and dynamics of the as-prepared perovskite films in an opposite manner.

Photoinduced chlorophyll charge transfer state identified in the light-harvesting complex II from a marine green alga .

The light-harvesting complex II of (-LHCII), a green alga, differs from that of spinach (-LHCII) in chlorophyll (Chl) and carotenoid (Car) compositions. We investigated ultrafast excitation dynamics of -LHCII with visible-to-near infrared time-resolved absorption spectroscopy. Absolute fluorescence quantum yield ( ) of LHCII and spectroelectrochemical (SEC) spectra of Chl and were measured to assist the spectral analysis.

Spatial effects of photosensitization on morphology of giant unilamellar vesicles.

Singlet oxygen (O) formed through photosensitization may initiate oxidative destruction of biomembranes, however, the influence from the spatial organization of photosensitizers (PS) relative to membranes remains unclear. To clarify this issue, we loaded riboflavin 5'-(dihydrogen phosphate) monosodium (FMN-Na) as a hydrophilic PS into the lumen of halloysite nanotubes (HNTs), and attached the nanoassemblies (FMN-Na@HNTs), via Pickering effects, to the outer surfaces of giant unilamellar vesicles (GUVs) of phospholipids. We also prepared GUVs dopped with lumiflavin (LF) as a lipophilic PS having a O quantum yield comparable to FMN-Na.

A Spontaneous Membrane-Adsorption Approach to Enhancing Second Near-Infrared Deep-Imaging-Guided Intracranial Tumor Therapy.

Herein, a functional class of microenvironment-associated nanomaterials is reported for improving the second near-infrared (NIR-II) imaging and photothermal therapeutic effect on intracranial tumors via a spontaneous membrane-adsorption approach. Specific peptides, photothermal agents, and biological alkylating agents were designed to endow the nanogels with high targeting specificity, photothermal properties, and pharmacological effects. Importantly, the frozen scanning electron microscopy technology (cryo-SEM) was utilized to observe the self-association of nanomaterials on tumor cells.

Thermally Activated Delayed Fluorescence from d -Metal Carbene Complexes through Intermolecular Charge Transfer and Multicolor Emission with a Monomer-Dimer Equilibrium.

A series of two-coordinate Au and Cu complexes (3 a, 3 b and 5 a, 5 b) are reported as new organometallic thermally activated delayed fluorescence (TADF) emitters, which are based on the carbene-metal-carbazole model with a pyridine-fused 1,2,3-triazolylidene (PyTz) ligand. PyTz features low steric hindrance and a low-energy LUMO (LUMO=-1.47 eV) located over the π* orbitals of the whole ligand, which facilitates intermolecular charge transfer between a donor (carbazole) and an accepter (PyTz).

Noninvasive and real-time pharmacokinetics imaging of polymeric nanoagents in the thoracoepigastric vein networks of living mice.

Noninvasive and real-time visualization of the thoracoepigastric veins (TVs) of living mice was demonstrated by using two-photon excitation (TPE) optical imaging with a Eu-luminescent polymeric nanoagent as the angiographic contrast. The spatiotemporal evolution of the polymeric nanoagent in TVs was monitored for up to 2 h by TPE time-resolved (TPE-TR) bioimaging, which is free from the interference of tissue autofluorescence. A wide field-of-view covering the thoracoabdominal region allowed the visualization of the entire TV network with an imaging depth of 1 to 2 mm and a lateral resolution of 80 μm at submillimeter.

Excitation Energy-Transfer Processes in the Sensitization Luminescence of Europium in a Highly Luminescent Complex.

The excitation energy transfer (EET) pathways in the sensitization luminescence of Eu and the excitation energy migration between the different ligands in [Eu(fod)dpbt] [where fod=6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione and dpbt=2-(,-diethylanilin-4-yl)-4,6-(3,5-dimethylpyrazol-1-yl)-1,3,5-triazine], exhibiting well-separated fluorescence excitation and phosphorescence bands of the different ligands, were investigated by using time-resolved luminescence spectroscopy for the first time. The data clearly revealed that upon the excitation of dpbt, the sensitization luminescence of Eu in [Eu(fod)dpbt] was dominated by the singlet EET pathway, whereas the triplet EET pathway involving T(dpbt) was inefficient. The energy migration from T(dpbt) to T(fod) in [Eu(fod)dpbt] was not observed.

Charge carrier recombination dynamics in a bi-cationic perovskite solar cell.

The compositional engineering is of great importance to tune the electrical and optical properties of perovskite and improve the photovoltaic performance of perovskite solar cells. The exploration of the corresponding photoelectric conversion processes, especially the carrier recombination dynamics, will contribute to the optimization of the devices. In this work, perovskite with mixed methylammonium (MA) and formamidinium (FA) as organic cations, MA0.

Uptake and Translocation of Styrene Maleic Anhydride Nanoparticles in Murraya exotica Plants As Revealed by Noninvasive, Real-Time Optical Bioimaging.

This work reports the in vivo uptake and translocation of PNPs in the one-year grown terrestrial plant, Murraya exotica ( M. exotica), as investigated by two-photon excitation and time-resolved (TPE-TR) optical imaging with a large field of view (FOV, 32 × 32 mm) in a noninvasive and real-time manner. The PNPs (⟨ R⟩ = 12 ± 4.

Naturally occurring nanotube with surface modification as biocompatible, target-specific nanocarrier for cancer phototherapy.

Phototherapy has drawn increasing attention including the use of nanocarriers with high drug loading capacity and delivery efficacy for target-specific therapy. We have made use of naturally-occurring halloysite nanotubes (HNTs) to build a biomimetic nanocarrier platform for target-specific delivery of phototherapeutic agents. The HNTs were decorated with poly(sodium-p-styrenesulfonate) (PSS) to enhance the biocompatibility, and were further functionalized by lumen loading the type-II photosensitizer indocyanine green (ICG).

Wide field of view, real time bioimaging apparatus for noninvasive analysis of nanocarrier pharmacokinetics in living model animals.

Understanding nanocarrier pharmacokinetics is crucial for the emerging nanopharmacy, which highly demands noninvasive and real-time visualization of the dynamics of nanocarriers. To this end, we have developed a 2-photon excitation and time-resolved (TPE-TR) bioimaging apparatus for the analysis of the spatial distribution and temporal evolution of nanocarriers in living model animals. The specific polymeric nanocarrier, Eu@pmma-maa doped with Eu-complexes luminescing in long persistence at ∼615 nm upon near-infrared 2-photon excitation, allows the complete rejection of tissue autofluorescence by selective luminescence detection.

Cooperative Photoprotection by Multicompositional Carotenoids in the LH1 Antenna from a Mutant Strain of Rhodobacter sphaeroides.

To explore the photoprotection role of multicompositional carotenoid (Car) in photosynthetic purple bacteria, we investigated, by means of triplet excitation profile (TEP) combined with steady-state optical spectroscopies, the core light-harvesting complex-reaction center of a mutant strain of Rhodobacter sphaeroides (m-LH1-RC) at room temperature. TEP spectra revealed that spheroidene and derivative (Spe) preferentially protect bacteriochlorophylls (BChls) of relatively lower site energy by quenching the triplet excitation (BChl*); however, spirilloxanthin (Spx) does so irrespective to the site energy of BChls. Triplet excitation results showed the triplet excitation energy-transfer (EET) reaction in a timescale of ∼0.

Characterization of the influences of morphology on the intrinsic properties of perovskite films by temperature-dependent and time-resolved spectroscopies.

Organic-inorganic halide perovskites have attracted enormous attention owing to their promising application in photovoltaic devices. The morphology of the perovskites is the key to driving the performance of perovskite devices, which necessitates a systematic study. In this work, two typical morphologies, i.

Integrity of Membrane Structures in Giant Unilamellar Vesicles as Assay for Antioxidants and Prooxidants.

We have attempted to evaluate, on the basis of optical microscopy for a single giant unilamellar vesicle (GUV), the potency of antioxidants in protecting GUV membranes from oxidative destruction. Photosensitized membrane budding of GUVs prepared from soybean phosphatidylcholine with chlorophyll a (Chl a) and β-carotene (β-Car) as photosensitizer and protector, respectively, were followed by microscopic imaging. A dimensionless entropy parameter, ΔE, as derived from the time-resolved microscopic images, was employed to describe the evolution of morphological variation of GUVs.

Multiple-Trapping Model for the Charge Recombination Dynamics in Mesoporous-Structured Perovskite Solar Cells.

The photovoltaic performance of organic-inorganic hybrid perovskite solar cells has reached a bottleneck after rapid development in last few years. Further breakthrough in this field requires deeper understanding of the underlying mechanism of the photoelectric conversion process in the device, especially the dynamics of charge-carrier recombination. Originating from dye-sensitized solar cells (DSSCs), mesoporous-structured perovskite solar cells (MPSCs) have shown many similarities to DSSCs with respect to their photoelectric dynamics.

Carotenoid Singlet Fission Reactions in Bacterial Light Harvesting Complexes As Revealed by Triplet Excitation Profiles.

Carotenoids (Cars) in bacterial photosynthesis are known as accessory light harvesters and photoprotectors. Recently, the singlet fission (SF) reaction initiated by Car photoabsorption has been recognized to be an effective excitation deactivation channel disfavoring the light harvesting function. Since the SF reaction and the triplet sensitization reaction underlying photoprotection both yield triplet excited state Cars (Car*), their contribution to the overall Car* photoproduction are difficult to disentangle.

Study on the Fluorescent Activity of N²-Indolyl-1,2,3-triazole.

A new type of blue emitter, ²-Indolyl-1,2,3-triazoles (NITs), with the λ ranging from 420-480 nm and the Stokes shift from 89-143 nm, were synthesized through the coupling reaction of indoles with triazole derivatives. The influence of different substitution patterns on the optical properties (efficiency, excitation, and emission wavelengths) of the NITs was investigated. In addition, one palladium complex were synthesized by using NITs as the ligands, which, however, exhibited no fluorescent activity, but did show the enhanced co-planarity.

Power output and carrier dynamics studies of perovskite solar cells under working conditions.

Perovskite solar cells have emerged as promising photovoltaic systems with superb power conversion efficiency. For the practical application of perovskite devices, the greatest concerns are the power output density and the related dynamics under working conditions. In this study, the working conditions of planar and mesoscopic perovskite solar cells are simulated and the power output density evolutions with the working voltage are highlighted.

Dependence of the hydration status of bacterial light-harvesting complex 2 on polyol cosolvents.

Low molecular weight (MW) polyols are organic osmolytes influencing protein structure and activity. We have intended to investigate the effects of low MW polyols on the optical and the excited-state properties of the light-harvesting complex 2 (LH2) isolated from the photosynthetic bacterium Thermochromatium (Tch.) tepidum, a thermophile growing at ∼50 °C.

The Influence of Morphology and PbI on the Intrinsic Trap State Distribution in Perovskite Films Determined by Using Temperature-Dependent Fluorescence Spectroscopy.

Perovskite films with different particle sizes and PbI contents were prepared by using a controlled single or sequential method. By means of temperature-dependent fluorescence spectroscopy, the energetic distribution of intrinsic intragap trap states in perovskite was quantitatively determined, and the radiative charge recombinations through the band edge and via trap states were studied. Furthermore, a series of thermodynamic parameters, such as the demarcation energy between radiative and nonradiative recombination regions, detrapping activation energy, and characteristic temperature, were extracted based on which of the possible radiative and nonradiative recombination mechanisms were proposed.

A femtosecond transient absorption study of charge photogeneration and recombination dynamics in photovoltaic polymers with different side-chain linkages.

A pair of 9-arylidene-9H-fluorene and benzothiadiazole based, low-bandgap copolymers differing merely in the para or meta substitution of alkoxy groups to the arylidene linkages, i.e. p-PAFDTBT and m-PAFDTBT respectively, were comparatively investigated by using morphological characterization, ultrafast spectroscopy and quantum chemical calculations.

Nanoprobes for two-photon excitation time-resolved imaging of living animals: In situ analysis of tumor-targeting dynamics of nanocarriers.

Great challenges remain in the noninvasive luminescence imaging analysis of tumor-targeting dynamics of nanocarriers in living animals which is of significance for the development of anti-cancer nanomedicine. In this work, luminescent nanoparticles Eu(tta)3bpt@SMA (dav = 15 nm), which exhibited good water dispersion stability and high yields of red Eu-luminescence under near-infrared two-photon excitation, were prepared by a modified microfluidic mixing method in the absence of surfactants. Tumor-targeting agents, Arg-Gly-Asp-D-Phe-Lys (cRGD) polypeptide or transferrin (Tf), were then anchored on the nanoparticle surfaces to form the desired nanocarriers Eu@SMA-RGD or Eu@SMA-Tf.

Dependence of Excited-State Properties of a Low-Bandgap Photovoltaic Copolymer on Side-Chain Substitution and Solvent.

The excited-state properties and chain conformations of a new low-bandgap copolymer based on benzo[1,2-b:4,5-b']dithiophene (BDT) and thieno[3,4-b]thiophene with meta-alkoxyphenyl-substituted side chains in solution were investigated comprehensively. Time-resolved spectroscopy suggested that the excited-state properties were sensitive to the conformations of the copolymer in solution. In addition, excited-state dynamics analyses revealed the photogeneration of triplet excited states by intersystem crossing (ISC) at a rate constant of ∼0.