Multifunctional Core–Shell Upconverting Nanoparticles for Imaging and Photodynamic Therapy of Liver Cancer Cells

Lanthanide‐doped upconversion nanoparticles (UCNPs) have attracted considerable attention for their application in biomedicine. Here, silica‐coated NaGdF₄:Yb,Er/NaGdF₄ nanoparticles with a tetrasubstituted carboxy aluminum phthalocyanine (AlC₄Pc) photosensitizer covalently incorporated inside the silica shells were prepared and applied in the photodynamic therapy (PDT) and magnetic resonance imaging (MRI) of cancer cells. These UCNP@SiO₂(AlC₄Pc) nanoparticles were uniform in size, stable against photosensitizer leaching, and highly efficient in photogenerating cytotoxic singlet oxygen under near‐infrared (NIR) light. In vitro studies indicated that these nanoparticles could effectively kill cancer cells upon NIR irradiation. Moreover, the nanoparticles also demonstrated good MR contrast, both in aqueous solution and inside cells. This is the first time that NaGdF₄:Yb,Er/NaGdF₄ upconversion‐nanocrystal‐based multifunctional nanomaterials have been synthesized and applied in PDT. Our results show that these multifunctional nanoparticles are very promising for applications in versatile imaging diagnosis and as a therapy tool in biomedical engineering.     

Preparation of Polylactide/Poly(ether)urethane Blends with Excellent Electro-actuated Shape Memory <Emphasis Type="Italic">via</Emphasis> Incorporating Carbon Black and Carbon Nanotubes Hybrids Fillers

In this work, hybrid conductive fillers of carbon black (CB) and carbon nanotubes (CNTs) were introduced into polylactide (PLA)/thermoplastic poly(ether)urethane (TPU) blend (70/30 by weight) to tune the phase morphology and realize rapid electrically actuated shape memory effect (SME). Particularly, the dispersion of conductive fillers, the phase morphology, the electrical conductivities and the shape memory properties of the composites containing CB or CB/CNTs were comparatively investigated. The results suggested that both CB and CNTs were selectively localized in TPU phase, and induced the morphological change from the sea-island structure to the co-continuous structure. The presence of CNTs resulted in a denser CB/CNTs network, which enhanced the continuity of TPU phase. Because the formed continuous TPU phase provided stronger recovery driving force, the PLA/TPU/CB/CNTs composites showed better shape recovery properties compared with the PLA/TPU/CB composites at the same CB content. Moreover, the CB and CNTs exerted a synergistic effect on enhancing the electrical conductivities of the composites. As a result, the prepared composites exhibited excellent electrically actuated SME and the shape recovery speed was also greatly enhanced. This work demonstrated a promising strategy to achieve rapid electrically actuated SME via the addition of hybrid nanoparticles with self-networking ability in binary PLA/TPU blends over a much larger composition range.     

The influence of nanoparticle shape on bilateral exocytosis from Caco-2 cells

Nanoparticles are able to be excreted from both apical and basolateral sides after taken up by cells. Compared to nanospheres, nanorods preferred basolateral exocytosis to apical exocytosis.     

Recent advances in the preparation of Fmoc-SPPS-based peptide thioester and its surrogates for NCL-type reactions

Solid phase peptide synthesis (SPPS) based on Fmoc chemistry has become a commonly used technique in peptide chemistry, as it can be easily conducted using automated machine, and not requiring highly toxic HF in comparison to Boc-SPPS. With the fast development in the emerging field of protein chemical synthesis, many efforts have been endeavored aiming to find more efficient methods for preparing peptide fragments required in ligation reactions. This review briefly summarizes recent advances in the engineering and modification of Fmoc-SPPS-derived peptides, which can be used as the N-terminal fragments in a native chemical ligation (NCL) or NCL-type ligation reactions.     

Neoengleromycin,a Novel Compound from Engleromyces goetzii

A novel N‐containing compound, neoengleromycin ( 1 ) was isolated from the fruiting bodies of the ascomycete Engleromyces goetzii together with two known cytochalasins: cytochalasin D ( 2 ) and 19,20‐epoxycytochalasin D ( 3 ). Structures were established by spectroscopic (including 2D‐NMR) and chemical means. Neoengleromycin ( 1 ) possesses the rare structure of an N‐substituted hydroxamic acid and represents a new type of natural products.     

Selective fast pyrolysis of biomass impregnated with ZnCl2: Furfural production together with acetic acid and activated carbon as by-products

Fast pyrolysis of biomass materials impregnated with ZnCl₂ offered a promising way to obtain a liquid product rich in furfural (FF) and acetic acid (AA), and the pyrolytic solids could be used as the precursors to prepare activated carbons (ACs). In this study, a lab-scale fast pyrolysis set was designed and used for the quantitative production of the three chemicals. The maximum FF was produced from the corncob impregnated with at least 15 wt% ZnCl₂ and at the pyrolysis temperature around 340 °C, with the yield of more than 8 wt% compared with only 0.49 wt% from the raw corncob. Meanwhile, AA of around 4 wt% could be obtained. The content of the FF and AA was over 50 wt% and 25 wt% on the water-free basis of the pyrolytic liquids. In addition, ACs were prepared from the pyrolytic solids, and they exhibited similar properties as those prepared from direct activation of ZnCl₂-impregnated biomass materials.     

Catalytic Asymmetric Functionalization of Aromatic CH Bonds by Electrophilic Trapping of Metal‐Carbene‐Induced Zwitterionic Intermediates

Asymmetric functionalization of aromatic C? H bonds of N,N‐disubstituted anilines with diazo compounds and imines is reported for the efficient construction of α,α‐diaryl benzylic quaternary stereocenters in good yields with high diastereoselectivities and excellent enantioselectivities. This Rh^II/chiral phosphoric acid cocatalyzed transformation is proposed to proceed through a metal‐carbene‐induced zwitterionic intermediate which undergoes electrophilic trapping. To the best of our knowledge, this is the first asymmetric example of metal carbene‐induced intermolecular functionalization of aryl C? H bonds.     

Gold(I)‐Catalyzed Diazo Coupling: Strategy towards Alkene Formation and Tandem Benzannulation

A gold(I)‐catalyzed cross‐coupling of diazo compounds to afford tetrasubstituted alkenes has been developed by taking advantage of a trivial electronic difference between two diazo substrates. A N‐heterocyclic‐carbene‐derived gold complex is the most effective catalyst for this transformation. Based on this new strategy, a gold(I)‐initiated benzannulation has been achieved through a tandem reaction involving a diazo cross‐coupling, 6π electrocyclization, and oxidative aromatization.     

Theoretical studies on N-loss predissociation mechanisms of N2O+ (A?2Σ+) in Cs symmetry

The N-loss predissociation mechanisms of the A ²Σ⁺ (2 ² A′) state of N₂O⁺ to the first and second dissociation limits were studied in the C _s symmetry. The potential energy curves (PECs) and minimum energy crossing points (MECPs) for the C _s states of N₂O⁺ were calculated at the CAS levels. On the basis of our CAS calculation results (CASPT2 energetic results and CASSCF spin orbit couplings), we suggest two processes for N-loss predissociation mechanisms of A ²Σ⁺ (2 ² A′) to the first and second limits. The first two steps in the two processes are the same: A ²Σ⁺ passes through the 2 ² A′/1 ⁴ A″ MECP and then reaches the 1 ⁴ A″ (1 ⁴Σ⁻) PEC. The 2 ² A′/1 ⁴ A″ MECP has a bent geometry and is slightly higher in energy than the transition state along the 1 ⁴ A″ PEC. Our mechanisms are different from the previously suggested mechanisms (via 1 ⁴Π).