Preserving Structurally Labile Peptide Nanosheets After Molecular Functionalization of the Self-Assembling Peptides.

A significant challenge in creating supramolecular materials is that conjugating molecular functionalities to building blocks often results in dissociation or undesired morphological transformation of their assemblies. Here we present a facile strategy to preserve structurally labile peptide assemblies after molecular modification of the self-assembling peptides. Sheet-forming peptides are designed to afford a staggered alignment with the segments bearing chemical modification sites protruding from the sheet surfaces. The staggered assembly allows for simultaneous separation of attached molecules from each other and from the underlying assembly motifs. Strikingly, using PEGs as the external molecules, PEG400 - and PEG700 -peptide conjugates directly self-associate into nanosheets with the PEG chains localized on the sheet surfaces. In contrast, the sheet formation based on in-register lateral packing of peptides does not recur upon the peptide PEGylation. This strategy allows for fabrication of densely modified assemblies with a variety of molecules, as demonstrated using biotin (hydrophobic molecule), c(RGDfK) (cyclic pentapeptide), and nucleic acid aptamer (negatively charged ssDNA). The staggered co-assembly also enables extended tunability of the amount/density of surface molecules, as exemplified by screening ligand-appended assemblies for cell targeting. This study paves the way for functionalization of historically challenging fragile assemblies while maintaining their overall morphology.

Design of high-avidity multivalent ligand structures that target cells with high ligand economy.

Novel cell-targeting ligand structures are constructed with a spikey core scaffold, where multiple copies of coiled-coil peptide nanorods are conjugated on the surface of a peptide nanosheet. Clustering of carbohydrate and aptamer ligands at the end of the coiled coils optimizes ligand accessibility to cell-surface receptors. Display of the ligand-coil conjugates on the nanosheet generates a patchy ligand pattern bearing two levels of multivalency. With the ligand-scaffold system, high-avidity cell targeting is realized using fewer ligands than ever, which facilitates future applications in cell detection and drug delivery.

Anti-Interference Detection of Vibrio parahaemolyticus from Aquatic Food Based on Target-Cyclized RCA with Dynamic Adapter Followed by LAMP.

Vibrio parahaemolyticus (V. parahaemolyticus) is considered the most concerning pathogen for seafood. Like other pathogens in food samples, its gene detection suffers from a problem of background interference when isothermal detection methods are used. The sensitivity and specificity greatly decrease due to large amounts of background genome. Here we describe a novel isothermal detection technology based on target-cyclized rolling circle amplification combined with loop-mediated isothermal amplification (tRCA-lamp). By avoiding unexpected ligation, a short dynamic adapter is employed to increase the sensitivity of target cyclization in the presence of the background genome. At the amplification step, highly specific detection is obtained by linear RCA and simplified LAMP (only two primers are used). Furthermore, visual detection is easily realized with hydroxynaphthol blue (HNB). In the oyster samples, the tRCA-lamp approach can detect V. parahaemolyticus with a detection limit of 22 cfu/g with none necessary to enrich the bacteria and remove the host DNA. This method gets rid of the complicated primer design process and can be extended to the detection of other pathogens in food samples.

[Characteristics of maxillary anterior teeth of 191 individuals living in Fujian Province].

PURPOSE: To investigate the anatomical characteristics of upper anterior teeth of residents in Fujian province using cone-beam CT (CBCT). METHODS: The length and width of 1146 maxillary anterior teeth (central incisors, lateral incisors, and canines) from 191 patients were measured. SPSS 19.0 software package was used to analyze the data. RESULTS: The width and length of males' maxillary central incisors and canine were significantly greater than those of females(P<0.05). No significant difference was found in the width and length of maxillary lateral incisors between genders (P>0.05). No significant difference was found in the width-length ratio of maxillary anterior teeth between genders(P>0.05). Significant difference was found in the width-width ratio of maxillary anterior teeth between genders(P<0.05). CONCLUSIONS: Varied anatomical characteristics of the maxillary anterior teeth of residents in Fujian Province should be observed between genders.

Thermus thermophilus DNA Ligase Connects Two Fragments Having Exceptionally Short Complementary Termini at High Temperatures.

Thermus thermophilus DNA ligase (Tth DNA ligase) is widely employed for cloning, enzymatic synthesis, and molecular diagnostics at high temperatures (e.g., 65 °C). It has been long believed that the complementary ends must be very long (e.g., >30 bp) to place two DNA fragments nearby for the ligation. In the current study, the length of the complementary portion was systematically varied, and the ligation efficiency was evaluated using the high resolution melting (HRM) method. Unexpectedly, very short oligonucleotides (7-10 nt) were successfully ligated on the complementary overhang attached to a dsDNA at 70 °C. Furthermore, sticky ends with the overhang of only 4 nt long, available after scission with many restriction enzymes, were also efficiently ligated at 45-70 °C. The ligation yield for the 6-nt-long sticky ends was as high as 80%. It was concluded that Tth DNA ligase can be used as a unique tool for DNA manipulation that cannot be otherwise easily accomplished.

Design, synthesis, biological evaluation of benzoyl amide derivatives containing nitrogen heterocyclic ring as potential VEGFR-2 inhibitors.

For the purpose of synthesizing drug candidates with desirable bioactivity, a class of benzoyl amide containing nitrogen heterocyclic ring derivatives targeting VEGFR-2 was designed and screened out using Discovery Studio. Eighteen target compounds were synthesized and then selected by some biological trials sequentially including inhibition of VEGFR-2, anti-proliferation in vitro, flow cytometry. Among them, compound 8h showed the best inhibitory activity (IC50 = 0.34 ±â€¯0.02 µM against VEGFR-2, IC50 = 1.08 ±â€¯0.06 µM and 2.44 ±â€¯0.15 µM against MCF-7 and HepG-2, respectively, which were at the same inhibitory level with the commercially antitumor drug: vandetanib). In addition, flow cytometry demonstrated that compound 8h induced MCF-7 cell apoptosis through a cell membrane-mediated pathway. This research highlights the therapeutic potential of novel VEGFR-2 inhibitors in treating cancers and provides a promising strategy for drug discovery.

Design, synthesis, and biological evaluation of pyrazole derivatives containing acetamide bond as potential BRAFV600E inhibitors.

With the increasingly acquired resistance, relapse and side effects of known marketed BRAFV600E inhibitors, it's significant to design the more effective and novel drugs. In this study, a series of novel pyrazole derivatives containing acetamide bond had been designed and synthesized on the basis of analysis of the endogenous ligands extracted from the known B-Raf co-crystals in the PDB database. Then, the compounds were evaluated for biological activities as potential BRAFV600E inhibitors. The bioassay results in vitro against three human tumor cell lines revealed that some of the compounds showed very impressed antiproliferative property. Among them, the compound 5r with IC50 values of 0.10 ±â€¯0.01 µM against BRAFV600E and 0.96 ±â€¯0.10 µM against A375 cell line, showed the most potent inhibitory effect, compared with the positive-controlled agents vemurafenib (IC50 = 0.04 ±â€¯0.004 µM for BRAFV600E, IC50 = 1.05 ±â€¯0.10 µM against A375). Further investigation confirmed that the compound 5r could induce A375 cell apoptosis, induce A375 cell death through changing mitochondrial membrane potential, and result in A375 cell arrest at the G1 phase of the cell cycle. Docking simulations results indicated that the compound 5r could bind tightly at the BRAFV600E active site. Meanwhile, 3D-QSAR model suggested that these compounds may be potential anticancer inhibitors. Overall, the article provided some new molecular scaffolds for the further BRAFV600E inhibitors.