Ribbon of DNA Lattice on Gold Nanoparticles for Selective Drug Delivery to Cancer Cells

Herein, we report on the design of a programmable DNA ribbon using long‐chain DNA molecules with a user‐defined repetitive padlock sequence. The DNA ribbon can be further combined with gold nanoparticles (AuNPs) to create a composite nanomaterial that contains an AuNP core and a high‐density DNA crown carrying a cancer‐cell‐targeting DNA aptamer, a fluorescent tag for location tracking, and a cell‐killing drug. This composite material can be efficiently internalized by cancer cells and its cellular location can be tracked by fluorescence imaging. The system offers several attractive characteristics, including simple design, tunable DNA crown, high drug‐loading capacity, selective cell targeting, and pH‐sensitive drug release. These features make such a material a promising therapeutic agent.     

Photoinduced Copper‐Catalyzed Asymmetric Decarboxylative Alkynylation with Terminal Alkynes

We describe a photoinduced copper‐catalyzed asymmetric radical decarboxylative alkynylation of bench‐stable N‐hydroxyphthalimide(NHP)‐type esters of racemic alkyl carboxylic acids with terminal alkynes, which provides a flexible platform for the construction of chiral C(sp³)?C(sp) bonds. Critical to the success of this process are not only the use of the copper catalyst as a dual photo‐ and cross‐coupling catalyst but also tuning of the NHP‐type esters to inhibit the facile homodimerization of the alkyl radical and terminal alkyne, respectively. Owing to the use of stable and easily available NHP‐type esters, the reaction features a broader substrate scope compared with reactions using the alkyl halide counterparts, covering (hetero)benzyl‐, allyl‐, and aminocarbonyl‐substituted carboxylic acid derivatives, and (hetero)aryl and alkyl as well as silyl alkynes, thus providing a vital complementary approach to the previously reported method.     

High‐Tc Enantiomeric Ferroelectrics Based on Homochiral Dabco‐derivatives (Dabco=1,4‐Diazabicyclo[2.2.2]octane)

1,4‐Diazabicyclo[2.2.2]octane (dabco) and its derivatives have been extensively utilized as building units of excellent molecular ferroelectrics for decades. However, the homochiral dabco‐based ferroelectric remains a blank. Herein, by adding a methyl (Me) group accompanied by the introduction of homochirality to the [H₂dabco]²⁺ in the non‐ferroelectric [H₂dabco][TFSA]₂ (TFSA=bis(trifluoromethylsulfonyl)ammonium), we successfully designed enantiomeric ferroelectrics [R and S‐2‐Me‐H₂dabco][TFSA]₂. The two enantiomers show two sequential phase transitions with transition temperature (T_c) as high as 405.8 K and 415.8 K, which is outstanding in both dabco‐based ferroelectrics and homochiral ferroelectrics. To our knowledge, [R and S‐2‐Me‐H₂dabco][TFSA]₂ are the first examples of dabco‐based homochiral ferroelectrics. This finding opens an avenue to construct dabco‐based homochiral ferroelectrics and will inspire the exploration of more eminent enantiomeric molecular ferroelectrics.     

Engineering Sensitized Photon Upconversion Efficiency via Nanocrystal Wavefunction and Molecular Geometry

Triplet energy transfer from inorganic nanocrystals to molecular acceptors has attracted strong attention for high‐efficiency photon upconversion. Here we study this problem using CsPbBr₃ and CdSe nanocrystals as triplet donors and carboxylated anthracene isomers as acceptors. We find that the position of the carboxyl anchoring group on the molecule dictates the donor‐acceptor coupling to be either through‐bond or through‐space, while the relative strength of the two coupling pathways is controlled by the wavefunction leakage of nanocrystals that can be quantitatively tuned by nanocrystal sizes or shell thicknesses. By simultaneously engineering molecular geometry and nanocrystal wavefunction, energy transfer and photon upconversion efficiencies of a nanocrystal/molecule system can be improved by orders of magnitude.     

Centerband-Only Detection of Exchange NMR with Natural-Abundance Correction Reveals an Expanded Unit Cell in Phenylalanine Crystals

The NMR pulse sequence CODEX (centerband-only detection of exchange) is a widely used method to report on the number of magnetically inequivalent spins that exchange magnetization via spin diffusion. For crystals, this rules out certain symmetries, and the rate of equilibration is sensitive to distances. Here we show that for ¹³C CODEX, consideration of natural abundance spins is necessary for crystals of high complexity, demonstrated here with the amino acid phenylalanine. The NMR data rule out the C₂ space group that was originally reported for phenylalanine, and are only consistent with a larger unit cell containing eight magnetically inequivalent molecules. Such an expanded cell was recently described based on single crystal data. The large unit cell dictates the use of long spin diffusion times of more than 200 seconds, in order to equilibrate over the entire unit cell volume of 1622 ų.     

Chemical constituents isolated from stems of Schisandra chinensis and their antifeedant activity against Tribolium castaneum

Abstract

One new sesquiterpene (α-iso-cubebenol acetate, 8), together with 9 known compounds (1-7, 9, 10) were isolated from the stems of Schisandra chinensis (Turcz.) Baill. by repeated silica gel column chromatography. Based on the results of MS, NMR spectra and comparing with literature data, the six dibenzocyclooctadiene lignans were identified as schizandrin A to C (1-3), schizandrin (4), schisantherin A (5) and gomisin J (6), the two sesquiterpenes were identified as α-iso-cubebenol (7) and α-iso-cubebenol acetate (8), while the two triterpenic acids were identified as ganwuweizic acid (9) and kadsuric acid (10). The antifeedant activity of the 10 compounds against Tribolium castaneum adults was tested. Gomisin J (6) exhibited activity at 1500?ppm concentration with 40.3% antifeeding index percentages. As for the dibenzocyclooctene lignans (compounds 1–3, 6), the number of methylenedioxies and the position of hydroxyl groups were the main factors to affect their antifeedant activities.     

Chemical profiling and marker characterization of Huangqin decoction prepared with three types of peony root by liquid chromatography with electrospray ionization mass spectrometry

Clarification of the quality and biological effect equivalence of traditional Chinese medicines containing multi‐origin species is essential to improve their current quality standards, and also is the core problem to clarify the origins of single herbs with multi‐species in Chinese formulas that will guarantee their clinical application. Huangqin decoction is the typical one of multi‐origin formulas frequently used in traditional Chinese medicine and Kampo medicine. An ultra high performance liquid chromatography with electrospray ionization–tandem mass spectrometry was developed for chemical profiling and marker quantification of Huangqin decoction prepared with two different original types of peony root, white and red peony root. Forty‐seven main peaks in chemical profiling of Huangqin decoction prepared with white and red peony root were identified: nine were from peony root, 20 from baical skullcap root, 17 from licorice root, and one from jujubae fruit. The markers characteristics of the respective types of peony root in Huangqin decoction differ from that in single herbs, especially in terms of monoterpenoids and hydrolysable tannins. Subsequently, 17 representative markers in Huangqin decoction prepared with three types of peony root and their chemical characteristics and content distribution were carried out.     

Biosurfactant trehalose lipid‐enhanced ultrasound‐assisted micellar extraction and determination of the main antioxidant compounds from functional plant tea

Hydrosoluble trehalose lipid (a biosurfactant) was employed for the first time as a green extraction solution to extract the main antioxidant compounds (geniposidic acid, chlorogenic acid, caffeic acid, and rutin) from functional plant tea (Eucommia ulmoides leaves). Single‐factor tests and response surface methodology were employed to optimize the extraction conditions for ultrasound‐assisted micellar extraction combined with ultra‐high‐performance liquid chromatography in succession. A Box‐Behnken design (three‐level, three‐factorial) was used to determine the effects of extraction solvent concentration (1–5 mg/mL), extraction solvent volume (5–15 mL), and extraction time (20–40 min) at a uniform ultrasonic power and temperature. In consequence, the best analyte extraction yields could be attained when the trehalose lipid solution concentration was prepared at 3 mg/mL, the trehalose lipid solution volume was 10 mL and the extraction time was set to 35 min. In addition, the recoveries of the antioxidants from Eucommia ulmoides leaves analyzed by this analytical method ranged from 98.2 to 102%. These results indicated that biosurfactant‐enhanced ultrasound‐assisted micellar extraction coupled with a simple ultra‐high‐performance liquid chromatography method could be effectively applied in the extraction and analysis of antioxidants from Eucommia ulmoides leaf samples.     

Untargeted metabolomic study on the insomnia effect of Suan‐Zao‐Ren decoction in the rat serum and brain using ultra‐high‐performance liquid chromatography quadrupole time‐of‐flight mass spectrometry combined with data processing analysis

Insomnia is a common clinical disease that can seriously damage the normal lives of sufferers. Suan‐Zao‐Ren decoction has been used to treat insomnia for a long time. However, the underlying molecular mechanism of Suan‐Zao‐Ren decoction is still not clear. In this study, the nontargeted metabolomics based on high‐resolution mass spectrometry and multiple statistical approaches were initially used to investigate the changes of potential serum and brain biomarkers and metabolic pathways in the insomnia model rat. Principal component analysis‐discriminate analysis indicated that the Suan‐Zao‐Ren decoction treatment improved the metabolic phenotype insomnia. Moreover, the heatmap analysis identified the most important biomarkers involved in insomnia. According to the pathway analysis, phenylalanine metabolism, tryptophan metabolism, and so on were recognized as the most affected metabolic pathways associated with insomnia disease. These findings provided a comprehensive understanding of the regulative effects of Suan‐Zao‐Ren decoction on the host metabolic phenotype of the insomnia rats. Our work demonstrated that the metabolomics approach is a promising tool that could help us to conduct the exploration of the therapeutic effects and mechanism of traditional Chinese medicines.     

Recent advances of ambient ionization mass spectrometry imaging in clinical research

The structural information and spatial distribution of molecules in biological tissues are closely related to the potential molecular mechanisms of disease origin, transfer, and classification. Ambient ionization mass spectrometry imaging is an effective tool that provides molecular images while describing in situ information of biomolecules in complex samples, in which ionization occurs at atmospheric pressure with the samples being analyzed in the native state. Ambient ionization mass spectrometry imaging can directly analyze tissue samples at a fairly high resolution to obtain molecules in situ information on the tissue surface to identify pathological features associated with a disease, resulting in the wide applications in pharmacy, food science, botanical research, and especially clinical research. Herein, novel ambient ionization techniques, such as techniques based on spray and solid‐liquid extraction, techniques based on plasma desorption, techniques based on laser desorption ablation, and techniques based on acoustic desorption were introduced, and the data processing of ambient ionization mass spectrometry imaging was briefly reviewed. Besides, we also highlight recent applications of this imaging technology in clinical researches and discuss the challenges in this imaging technology and the perspectives on the future of the clinical research.