Preparation of chitin twisted fiber and its functional applications.

Chitin has garnered significant attention due to its renewable, biocompatibility and biodegradability, while its practical application seriously hindered as the functionality of chitin itself can no longer meet people's increasing requirements for materials. Here, an effective method is successfully built for high-performance chitin fibers fabrication through a multi-step strategy that involved chemical pre-crosslinking, followed by wet-twisting and wet-stretching techniques, combined with physical cross-linking. The as-prepared chitin fiber exhibited a smooth surface, adjustable diameter, and mechanical strong properties (144.6 MPa). More importantly, functional chitin fiber with magnetic or conductive abilities can be easily obtained by spraying Fe3O4 particles or Ag nanowire on the chemical pre-crosslinking chitin gel film before stretching and twisting. The doped functional inorganic particles exist in a continuous ribbon structure in the fiber reduced the decrease in material strength caused by uneven particles dispersion, resulting 88.4 % of stress and 91.6 % of strain retention. This work not only bestow invaluable insights into the fabrication of functional chitin fibers but also provide a novel approach to solve the problem of poor compatibility between organic and inorganic composite materials.

Rational Engineering of a Multifunctional DNA Assembly for Enhanced Antibacterial Efficacy and Accelerated Wound Healing.

DNA-based assemblies hold immense prospects for antibacterial application, yet are constrained by their poor specificity and deficient antibacterial delivery. Herein, the fabrication of a versatile rolling circle amplification (RCA)-sustained DNA assembly is reported, encoding simultaneously with multivalent aptamers and tandem antibacterial agents, for target-specific and efficient antibacterial application. In the compact RCA-sustained antibacterial platform, the facilely organized multivalent aptamers guarantee the target bacteria-specific delivery of sufficient antibacterial agents which is assembled through DNA-stabilizing silver nanostructures. It is shown that the biocompatible DNA system could enhance bacteria elimination and simultaneously facilitate wound healing in vivo. By virtue of the programmable RCA assembly, the present RCA-sustained system provides a highly modular and scalable approach to design versatile multifunctional therapeutic systems.

Preparation and properties of chitin/silk fibroin biocompatible composite fibers.

In the present world chitin is used enormously in various fields, such as biopharmaceuticals, medical and clinical bioproducts, food packaging, etc. However, its development has been curbed by the impaired performance and cumbersome dissolution process when chitin materials are dissolved and regenerated by physical or chemical methods. To further obtain the regenerated chitin fiber material with improved performance, silk fibroin was introduced into the chitin matrix material, and chitin/silk fibroin biocompatible composite fibers were obtained by formic acid/calcium chloride/ethanol ternary system and top-down wet spinning technology. The produced composite fibers outperformed previously reported chitin-silk composites in terms of the tensile strength (160 MPa) and failure strain (25%). The fibers also performed good cell compatibility and strong cellular affinity for non-toxicity. The cell viabilities of the fibers were about 20% greater than those of silk fiber after three days of co-culture with NIH-3T3. Furthermore, no hemolysis occurs in the presence of chitin/silk fibers, demonstrating their superior hemocompatibility. The fibers had a hemolysis index as low as 1%, which is far lower than the acceptable level of 5%. The material offers prospective opportunities for biomaterial applications in anticoagulation, absorbable surgical sutures, etc.

[Effects of Tripterine on Adhesion Molecules and Cell Cycle in Human Acute Promyelocytic Leukemia Model Mice].

OBJECTIVE: To observe the effects of tripterine on adhesion molecules and cell biological characteristics in mice with acute promyelocytic leukemia (APL) tumor. METHODS: Eighteen SCID beige mice were caudal vein injected with NB4 cell lines (5×106/only) to construct a human APL tumor-bearing model, then the mice were divided into tumor-bearing model group, arsenic trioxide group and tripterine group randomly, and another 6 mice which didn't construct model were set up as control group; after 3 weeks, the control group and the tumor-bearing model were intraperitoneally injected with normal saline as compared, arsenic trioxide was intraperitoneally injected according to 100 µg/kg, and tripterine was intraperitoneally injected according to 3 mg/kg. Four groups were all injected for 3 weeks. The biological characteristics of NB4 cells and the expression of adhesion molecules in venous blood of mice after treatment were observed. RESULTS: The neutrophil decrased and promyelocytes, NB4 cells, B lymphocytes and white blood cells increased in tumor-bearing group as compared with control group (P<0.05), and the expressions of serum P-selectin (P-selectin), soluble vascular adhesion molecule-1 (soluble vascular adhesion molecule-1, sVCAM-1) and soluble intercellular adhesion molecule-1 (soluble intercellular adhesion molecule-1, sICAM-1) all increased (P<0.05). The cell cycle showed that the proportion of G0 and G1 increased, but S, G2-M phases obviously decreased (P<0.05). Compared with the tumor-bearing group, the neutrophils increased in the tripterine group, and the expression of early promyelocyte, NB4 cell, B lymphocyte, leukocyte, P-selectin, sVCAM-1 and sICAM-1 protein decreased (P<0.05), moreover, the ratio of G0 and G1 decreased, the G2-M and S phases increased (P<0.05). Among which sVCAM-1 and sICAM-1 of leucocyte, NB4 cell, P-selectin and adhesion molecules in tripterine group showed significant difference as compared with arsenic trioxide group (P<0.05). CONCLUSION: Tripterine may not only inhibit the expression of sVCAM-1 and sICAM-1 proteins in APL tumor-bearing mice and reduce the adhesion of tumor cells, but also block tumor cells at G2-M and S phases, thereby exerting therapeutic effect on APL.

(3 + 2)-Annulation of p-Quinamine and Aryne: A Strategy To Construct the Multisubstituted Hydrocarbazoles.

A strategy for the synthesis of multisubstituted hydrocarbazoles has been developed through (3 + 2)-annulation of p-quinamines and arynes. In this way, new analogs of hydrocarbazoles with quaternary carbon center can be synthesized in satisfactory yield under mild conditions. Furthermore, this (3 + 2)-annulation can be easily scaled-up, and the products can be modified through simple transformation.

Visible-light-mediated radical insertion/cyclization cascade reaction: synthesis of phenanthridines and isoquinolines from isocyanides.

A visible-light promoted single electron oxidation of ether enabled by photoredox catalysis has been accomplished. This procedure initiates a novel radical insertion/cyclization cascade reaction to generate phenanthridines and isoquinolines from easily available isocyanides under mild reaction conditions.

Protecting-Group-Free Total Synthesis of (-)-Lycopodine via Phosphoric Acid Promoted Alkyne Aza-Prins Cyclization.

A protecting-group-free route for the total synthesis of (-)-lycopodine was demonstrated in only 8 steps from Wade's fawcettimine enone (12 steps from commercial availiable (R)-(+)-pulegone). The key core of this alkaloid was constructed through a phosphoric acid promoted and highly stereocontrolled alkyne aza-Prins cyclization reaction, synchronously establishing the bridged B-ring and the C13 quaternary stereocenter. Importantly, the synthesis further features a new efficient approach for the preparation of other lycopodine-type alkaloids.

Bioinspired Total Syntheses of Isospongian-type Diterpenoids (-)-Kravanhins†A and C.

The first bioinspired total syntheses of (-) kravanhins A and C were accomplished from a labdane diterpenoid derivative. The key reactions involve a photooxidation and a one-pot sequential aldol cyclization and lactonization, which provide a new plausible biosynthetic pathway for the kravanhins and other symbiotic members.

Short and Scalable Total Synthesis of Myrioneuron Alkaloids (±)-α,ß-Myrifabral A and B.

The first total synthesis of the Myrioneuron alkaloids (±)-α,ß-myrifabral A and B has been accomplished in only four steps from conveniently available starting materials. This short synthesis relied on the use of a key tandem Mannich/amidation reaction to rapidly construct the core framework and two carbon stereocenters. The synthetic route allows for large scale preparation of these promising natural products against the hepatitis C virus (HCV).

Biomimetic Total Syntheses of (+)-Dihydrolyfoline and (-)-5-epi-Dihydrolyfoline.

The first asymmetric total syntheses of (+)-dihydrolyfoline and (-)-5-epi-dihydrolyfoline have been achieved in five and six steps with 4.6% and 14% overall yields, respectively, in which the chiral biaryl axes were constructed in a highly regioselective and stereoselective manner via a biogenetic enzymatic oxidative couplings of phenols, and the requisite quinolizidinone cores were prepared by an enzymatic Mannich reaction.

[Identification on three kinds of Diphylleia sinensis (I)].

OBJECTIVE: In order to provide reference for the development of quality standards and distinction of authenticity, some sources of Diphylleia sinensis Li. in the market were identified by sampling. METHODS: To identify the traits and microscopic features of six batches of Diphylleia sinensis Li. in the market. RESULTS: They were the dried rhizome of Diphylleia sinensis Li., Dysosma versipellis (Hance) M. Cheng and D. pleiantha (Hance) Woods. CONCLUSION: The differences in traits and microscopic features of them are obvious.

[Identification on three kinds of Diphylleia sinensis (II)].

OBJECTIVE: In order to provide reference for the development of quality standards and distinction of authenticity, some sources of Diphylleia sinensis Li. in the maket were identified by sampling. METHODS: The TLC of six batches of Diphylleia sinensis Li. in the market were identified. RESULTS: They were the dried rhizome of Diphylleia sinensis Li., Dysosma versipellis (Hance.) M. Cheng and D. pleiantha (Hance) Woods. According to the pharmaceutical characteristics, retrieval tables of identification on plants, traits, microscopic and TLC were established. CONCLUSION: It is simple and reliable to use TLC and retrieval table to identify three sources of Diphylleia sinensis Li.