The mechanisms of triplet energy transfer across the inorganic nanocrystal/organic molecule interface remain poorly understood. Many seemingly contradictory results have been reported, mainly because of the complicated trap states characteristic of inorganic semiconductors and the ill-defined relative energetics between semiconductors and molecules used in these studies. Here we clarify the transfer mechanisms by performing combined transient absorption and photoluminescence measurements, both with sub-picosecond time resolution, on model systems comprising lead halide perovskite nanocrystals with very low surface trap densities as the triplet donor and polyacenes which either favour or prohibit charge transfer as the triplet acceptors. Hole transfer from nanocrystals to tetracene is energetically favoured, and hence triplet transfer proceeds via a charge separated state. In contrast, charge transfer to naphthalene is energetically unfavourable and spectroscopy shows direct triplet transfer from nanocrystals to naphthalene; nonetheless, this "direct" process could also be mediated by a high-energy, virtual charge-transfer state.

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Novel biodegradable star poly(ester-urethanes) containing three-arm poly(ε-caprolactone) (PCL) as switching segment were prepared as shape-memory polymers (SMPs) with switching temperature (T s ) around body temperature. PCL-triols with molecular weight (M n ) of 2700-4200 g/mol and T m of 45-47 °C were synthesized in 55-67% yield by Novozym 435-catalyzed ring-opening polymerization of ε-caprolactone with glycerol as initiator, and their three-arm structures were confirmed by 1 H and 13 C NMR analysis. Reaction of the PCL-triols with methylene diphenyl 4,4′-diisocyanate isocynate and 1,6-hexanediol gave three-arm PCL-based poly(ester-urethane)s (tPCL-PUs) in 83-92% yield, with 65-75% soft segment. The structure of tPCL-PUs was confirmed by 1 H NMR analysis, and the thermal properties were analyzed by DSC with T s of 36-39 °C. tPCL-PUs showed excellent shape-memory effects at 38 °C during cyclic thermomechanical tensile tests: shape recovery within 10 s, shape fixity rate of 92%, and shape recovery rate of 99%. The novel biodegradable star SMPs are potentially useful in biomedical applications.

We have fabricated a mixed-shell polymeric micelle (MSPM) that closely mimics the natural molecular chaperone GroEL-GroES complex in terms of structure and functionality. This MSPM, which possesses a shared PLA core and a homogeneously mixed PEG and PNIAPM shell, is constructed through the co-assembly of block copolymers poly(lactide-b-poly(ethylene oxide) (PLA-b-PEG) and poly(lactide)-b-poly(N-isopropylacryamide) (PLA-b-PNIPAM). Above the lower critical solution temperature (LCST) of PNIPAM, the MSPM evolves into a core-shell-corona micelle (CSCM), as a functional state with hydrophobic PNIPAM domains on its surface. Light scattering (LS), TEM, and fluorescence and circular dichroism (CD) spectroscopy were performed to investigate the working mechanism of the chaperone-like behavior of this system. Unfolded protein intermediates are captured by the hydrophobic PNIPAM domains of the CSCM, which prevent harmful protein aggregation. During cooling, PNIPAM reverts into its hydrophilic state, thereby inducing the release of the bound unfolded proteins. The refolding process of the released proteins is spontaneously accomplished by the presence of PEG in the mixed shell. Carbonic anhydrase B (CAB) was chosen as a model to investigate the refolding efficiency of the released proteins. In the presence of MSPM, almost 93 % CAB activity was recovered during cooling after complete denaturation at 70 °C. Further results reveal that this MSPM also works with a wide spectrum of proteins with more-complicated structures, including some multimeric proteins. Given the convenience and generality in preventing the thermal aggregation of proteins, this MSPM-based chaperone might be useful for preventing the toxic aggregation of misfolded proteins in some diseases.

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Zn–Ni–Co ternary hydroxide nanoarrays with a controlled morphology are used as the cathode material for supercapacitors for the first time.

Ionic liquids (ILs) have been employed as solvents for dissolving wool keratin which can be further regenerated and applied in high-value and biocompatible keratin-based materials. It is urgent to determine the changes in disulfide bonds and keratin microstructures in the dissolution process for designing efficient ILs. Herein, the breakage of disulfide bonds by ILs was verified for the first time using a model compound, oxidized glutathione. Furthermore, at least 65% of disulfide bonds in keratin should be cleaved in order to be dissolved in ILs. The keratin regenerated in a series of ILs, and variable conditions were also characterized by a combination of S-linked techniques. The results indicated that changing both anions and cations can lead to a dramatically different ability to cleave disulfide bonds, while the side chains of the cations have little effect on it. Also, the dissolution variables, such as temperature and time, led to different amounts of disulfide bonds remaining in the regenerated keratin. Finally, molecular dynamics (MD) simulation found that the distribution of ILs around cystine was linked with the ILs’ disulfide bond cleaving ability.

Two-dimensional (2D) van der Waals heterostructures have attracted enormous research interests due to their emergent electrical and optical properties. The comprehensive understanding and efficient control of interlayer couplings in such devices are crucial for realizing their functionalities, as well as improving their performance. Here, we report a successful manipulation of interlayer charge transfer between 2D materials by varying different stacking layers consisting of graphene, hexagonal boron nitride, and tungsten disulfide. Under visible light excitation, despite being separated by few-layer boron nitride, the graphene and tungsten disulfide exhibit clear modulation of their doping level, i.e., a change of the Fermi level in graphene as large as 120 meV and a net electron accumulation in WS2. By using a combination of micro Raman and photoluminescence spectroscopy, we demonstrate that the modulation is originated from simultaneous manipulation of charge and/or energy transfer between each two adjacent layers.