Fine modulation of the energy band strategy to control the carrier confinement capability of digital alloys.

In this paper, a strategy to finely modulate the energy band structure to control the carrier confinement capability of digital alloys (DA) is proposed. Strain analysis shows that As and Sb atoms are exchanged within the AlAsSb DA. The bottom of the corrected potential well is low on the left and high on the right in the growth direction, resulting in a higher band offset of the AlSb potential barrier layer on the left side of the potential well than on the right side. The modulation of the band leads to a higher probability of electron tunneling in DA under the action of an electric field opposite to the growth direction. Conversely, it is difficult for the electrons to tunnel into the lower energy level potential wells. TheI-Vcurve of DA shows that the current value under positive bias is significantly smaller than the value under negative bias when the voltage is higher. The measured results correspond perfectly with the modified energy band model, which verifies the feasibility of energy band modulation. This is important for the structural design of DA and the reduction of dark current in optoelectronic devices.

Visible light triggered controlled formation of rapidly self-healing hydrogels based on thiol-disulfide exchange.

The properties of stimuli-responsive hydrogels can be tailored under various external stimuli, but it is difficult to realize the customized adjustment of hydrogel properties since the crosslinking degree in the gelation process is intractable. Here, a visible light triggered thiol-disulfide exchange reaction was applied for constructing disulfide-crosslinked hydrogels from P(EMA-SS-PEG), a poly(ethylene glycol) grafted poly(ethyl methacrylate) derivative with a disulfide linkage as the grafting point. This photochemical method provides mild gelation conditions to handily regulate the morphology, mechanical properties, swelling ratio, and degradation rate of hydrogels by simply varying the irradiation time. Based on this strategy, these disulfide-crosslinked hydrogel coatings showed rapid self-healing in 10 min under ambient conditions, which was dependent on the width of the scratch, temperature, and humidity. Notably, spraying water on these coatings could significantly accelerate the self-healing process of large scratches (360 µm) at room temperature with a self-healing time of 1 hour, enabling the practical application of hydrogel coatings in a natural environment.

Room-Temperature Response Performance of Coupled Doped-Well Quantum Cascade Detectors with Array Structure.

Energy level interaction and electron concentration are crucial aspects that affect the response performance of quantum cascade detectors (QCDs). In this work, two different-structured array QCDs are prepared, and the detectivity reaches 109 cm·Hz1/2/W at room temperature. The overlap integral (OI) and oscillator strength (OS) between different energy levels under a series of applied biases are fitted and reveal the influence of energy level interaction on the response performance. The redistribution of electrons in the cascade structure at room temperatures is established. The coupled doped-well structure shows a higher electron concentration at room temperature, which represents a high absorption efficiency in the active region. Even better responsivity and detectivity are exhibited in the coupled doped-well QCD. These results offer a novel strategy to understand the mechanisms that affect response performance and expand the application range of QCDs for long-wave infrared (LWIR) detection.

Bioinspired self-degradable hydrogels towards wound sealing.

Inspired by the autolysis of shaggy mane, we developed a self-degradable hydrogel as a medical adhesive for skin wounds. The rapid gelation and self-degradation of the hydrogel were achieved via the Michael addition and subsequent hydrolysis of the addition product. In vivo experiments further showed that the hydrogel adhesive was efficiently applied for skin wound repair.

POSS-based supramolecular amphiphilic zwitterionic complexes for drug delivery.

Zwitterionic complexes in aqueous solutions have been extensively explored as the most promising candidate in drug delivery systems for targeted cancer chemotherapy. A POSS-based supramolecular AD-POSS-(sulfobetaine)7/CD-PLLA zwitterionic complex has been fabricated via a combination of efficient click chemistry and host-guest interaction. The well-defined POSS-based zwitterionic polymer could self-assemble into spherical nanoparticles that encapsulated a model cancer drug (DOX) and exhibited drug release in a controlled manner in a faintly acidic environment. On account of the hydrophilic block with cationic and anionic groups in the microscopic range that can form a hydration layer via electrostatic interactions, these drug-loaded nanoparticles exhibited excellent stability in a tumor intracellular microenvironment or under other pH conditions as revealed by dynamic light scattering (DLS) and zeta potential measurements. In vitro experiments demonstrated that these POSS-based nanoparticles had high resistance to non-specific protein absorption and low cytotoxicity against normal cells. Moreover, these DOX-loaded aggregates could be accumulated and effectively internalized by HeLa and MCF-7 tumor cells, exhibiting effective cellular proliferation inhibition via the release of anticancer agents. Therefore, these POSS-based supramolecular amphiphilic zwitterionic complexes, relying on the simple supramolecular interaction and efficient click reaction, could further emerge as a potential universal anticancer drug nanocarrier system for multifunctional cancer chemotherapy.

Foscarnet calcium microcrystals as the intravitreal drug depot.

Foscarnet sodium is an antiviral drug for the treatment of CMV retinitis, currently in the form of twice-weekly intravitreal injection. Here we developed foscarnet calcium microcrystals as the drug depot, and using the rabbit model we demonstrated that the injected microcrystals maintained a therapeutically relevant drug concentration in the vitreous for more than 3 months.

[Bioindicating function of sulfur in Haplocladium under heavy metals pollution by SRXRF and XANES].

Haplocladium was cultivated in a special prepared nutrient medium containing different concentrations of Pb, Fe and Cr in laboratory. The sulfur content in moss was measured by synchrotron radiation X-ray fluorescence (SRXRF), and the percentage of various oxidation states of sulfur was analyzed by X-ray absorption near-edge structure (XANES) spectrum. The results show that the sulfur absorption increases under exposure to heavy metal ions of Pb and Fe, but it decreases under exposure to 400 mg/L Pb and 200 mg/L Fe. When Haplocladium was cultivated for 15 days, under the stress of 100 mg/L Pb, the relative content of low oxidation states sulfur increases from 17.8% to 23.6% and the sulfate sulfur decreases from 56.3% to 51.2%. Under the stress of 400 mg/L Pb, the relative content of low oxidation state sulfur increases from 17.8% to 24.8%, and the sulfate sulfur decreases from 56.3% to 48.4%. Under heavy metal exposure, the total relative content of low oxidation states sulfur such as cystine, cysteine, methionine and glutathione increases, and the relative content of sulfate sulfur apparently decreases. All these results indicate that the changing characteristics of sulfur content and oxidation states percentage in sulfur assimilation process under heavy metal exposure can be used as a bioindicator of heavy metal pollution.