Solar overall water-splitting by a spin-hybrid all-organic semiconductor.

Direct solar-to-hydrogen conversion from pure water using all-organic heterogeneous catalysts remains elusive. The challenges are twofold: (i) full-band low-frequent photons in the solar spectrum cannot be harnessed into a unified S1 excited state for water-splitting based on the common Kasha-allowed S0 → S1 excitation; (ii) the H+ → H2 evolution suffers the high overpotential on pristine organic surfaces. Here, we report an organic molecular crystal nanobelt through the self-assembly of spin-one open-shell perylene diimide diradical anions (:PDI2-) and their tautomeric spin-zero closed-shell quinoid isomers (PDI2-). The self-assembled :PDI2-/PDI2- crystal nanobelt alters the spin-dependent excitation evolution, leading to spin-allowed S0S1 → 1(TT) → T1 + T1 singlet fission under visible-light (420 nm~700 nm) and a spin-forbidden S0 → T1 transition under near-infrared (700 nm~1100 nm) within spin-hybrid chromophores. With a triplet-triplet annihilation upconversion, a newly formed S1 excited state on the diradical-quinoid hybrid induces the H+ reduction through a favorable hydrophilic diradical-mediated electron transfer, which enables simultaneous H2 and O2 production from pure water with an average apparent quantum yield over 1.5% under the visible to near-infrared solar spectrum.

Nanochannel-Induced Efficient Water Splitting at the Superhydrophobic Interface.

Constructing a favorable reaction configuration at the water/catalyst interface is crucial for high-efficiency semiconductor-based water splitting. For a long time, a hydrophilic surface of semiconductor catalysts has been considered necessary for efficient mass transfer and adequate contact with water. In this work, by constructing a superhydrophobic PDMS-Ti3+/TiO2 interface (denoted P-TTO) with nanochannels arranged by nonpolar silane chains, we observe overall water splitting efficiencies improved by an order of magnitude under both the white light and simulated AM1.5G solar irradiation compared to the hydrophilic Ti3+/TiO2 interface. The electrochemical overall water splitting potential on the P-TTO electrode also decreased from 1.62 to 1.27 V, which is close to the thermodynamic limit of 1.23 V. Through the in situ diffuse reflection infrared Fourier transform spectroscopy, a nanochannel-induced water configuration transition is directly detected. The density functional theory calculation further verifies the lower reaction energy of water decomposition at the water/PDMS-TiO2 interface. Our work achieves efficient overall water splitting through nanochannel-induced water configurations without changing the bulk of semiconductor catalyst, which reveals the significant role of water status at the interface in the efficiency of the water splitting reaction over the properties of catalyst materials.

Target delivering paclitaxel by ferritin heavy chain nanocages for glioma treatment.

Glioma is one of the most common aggressive brain malignancies, but the treatment of glioma is still far from satisfying. The efficiency of chemotherapy - the major choice of glioma treatment - is severely limited by low chemotherapeutic agents delivery across blood-brain barrier (BBB) and low tumor retention. Therefore, a safe and effective drug delivery system to help chemotherapy agents traverse the BBB and accumulate at tumor sites is urgently needed. Paclitaxel (PTX) is one of the most common and effective chemotherapy agent, however, it suffers from extremely low solubility and BBB penetration ability. Herein, we developed endogenous human ferritin heavy chain nanocage (HFn) as PTX carrier, which could specifically bind to widely overexpressed transferrin receptor 1 (TfR1) on BBB and glioma cells. We propose that this binding may help PTX cross the BBB and enhance its tumor accumulation. PTX-loaded HFn (HFn-PTX) was prepared and exhibited satisfactory targeting effect in Bend.3 and C6 cells in vitro. In vivo tissue biodistribution assay also demonstrated that HFn-PTX could indeed promote the accumulation of PTX in the brain. HFn-PTX exhibited the best anti-tumor effect with median survival time of 30 days, significantly longer than that of free PTX (14 days) and physiological saline group (13 days). In summary, we have designed and fabricated an effective delivery system for PTX to treat glioma. We also provided evidences that Transferrin (Tf) could not prevent the binding of HFn to TfR1 nor consequent TfR1-mediated HFn uptake, providing a clue for future research.

Numerical investigation of cavity self-oscillation and noise radiation induced by turbulent flow at non-zero inclination angle.

A hybrid numerical approach was used on a three-dimensional cavity at a non-zero inclination angle of the upstream section to reveal the mechanism of self-oscillation and the characteristics of far-field sound field. In this hybrid approach, the unsteady flow physics was captured by a compressible large eddy simulation, and the far-field sound field was calculated by the FW-H integral equation, with the noise source provided by near-field calculation. The mechanism of self-oscillation was revealed based on the instantaneous flow field structure and the pressure inside the cavity. The effects of the position of opening, inclination angle and neck thickness on the frequency and amplitude of the fluctuation pressure inside the cavity were examined. Results showed that the frequency and the amplitude were sensitive to the inclination angle but not to the position of the opening. Under varying neck thicknesses, the fundamental frequencies changed, but the amplitude remained almost constant. The influences of the boundary layer thickness on the amplitude of the fluctuation pressure was also investigated. Results revealed that the oscillation was suppressed once the boundary layer thickness reached a critical value. The findings could provide a reference for a quiet car with a low sunroof buffeting noise.