An unconventionally secreted effector from the root knot nematode Meloidogyne incognita, Mi-ISC-1, promotes parasitism by disrupting salicylic acid biosynthesis in host plants.

Plant-parasitic nematodes need to deliver effectors that suppress host immunity for successful parasitism. We have characterized a novel isochorismatase effector from the root-knot nematode Meloidogyne incognita, named Mi-ISC-1. The Mi-isc-1 gene is expressed in the subventral oesophageal glands and is up-regulated in parasitic-stage juveniles. Tobacco rattle virus-induced gene silencing targeting Mi-isc-1 attenuated M. incognita parasitism. Enzyme activity assays confirmed that Mi-ISC-1 can catalyse hydrolysis of isochorismate into 2,3-dihydro-2,3-dihydroxybenzoate in vitro. Although Mi-ISC-1 lacks a classical signal peptide for secretion at its N-terminus, a yeast invertase secretion assay showed that this protein can be secreted from eukaryotic cells. However, the subcellular localization and plasmolysis assay revealed that the unconventional secretory signal present on the Mi-ISC-1 is not recognized by the plant secretory pathway and that the effector was localized within the cytoplasm of plant cells, but not apoplast, when transiently expressed in Nicotiana benthamiana leaves by agroinfiltration. Ectopic expression of Mi-ISC-1 in N. benthamiana reduced expression of the PR1 gene and levels of salicylic acid (SA), and promoted infection by Phytophthora capsici. The cytoplasmic localization of Mi-ISC-1 is required for its function. Moreover, Mi-ISC-1 suppresses the production of SA following the reconstitution of the de novo SA biosynthesis via the isochorismate pathway in the cytoplasm of N. benthamiana leaves. These results demonstrate that M. incognita deploys a functional isochorismatase that suppresses SA-mediated plant defences by disrupting the isochorismate synthase pathway for SA biosynthesis to promote parasitism.

The critical size of gold nanoparticles for overcoming P-gp mediated multidrug resistance.

Multidrug resistance (MDR) remains a huge obstacle during cancer treatment. One of the most studied MDR mechanisms is P-glycoprotein (P-gp) mediated drug efflux. Based on the three-dimensional structural characteristics of P-gp, gold nanoparticles (AuNPs) with average sizes of 4.1 nm and 5.4 nm were designed for the construction of nanodrug delivery systems (NanoDDSs), with the anticancer molecules 2-(9-anthracenylmethylene)-hydrazinecarbothioamide (ANS) and 6-mercaptopurine (6-MP) modified on the AuNP surfaces through the thiol group. In vitro cytotoxicity results suggested that the larger sized AuNPs can effectively decrease the drug resistance index of MCF-7/ADR cells to ∼2. Verapamil and P-gp antibody competitive experiments, combined with the cellular uptake of AuNPs, indicated that larger NanoDDSs were more conducive to intracellular drug accumulation and thus had improved anticancer activities, due to a size mismatch between the nanoparticles and the active site of P-gp, and, therefore, reduced drug efflux was seen. Measurements of ATPase activity and intracellular ATP levels indicated that the larger nanoparticles do not bind well to P-gp, thus avoiding effective recognition by P-gp. This was further evidenced by the observation that 4.1 nm and 5.4 nm NanoDDS-treated MCF-7/ADR cells showed remarkable differences in energy-related metabolic pathways. Therefore, the critical size of AuNPs for overcoming MDR was identified to be between 4.1 nm and 5.4 nm. This provides a more accurate description of the composite dimension requirements for NanoDDSs that are designed to overcome MDR.

Gold Nanorods Functionalized with Cathepsin B Targeting Peptide and Doxorubicin for Combinatorial Therapy against Multidrug Resistance.

Multidrug resistance (MDR) and adverse effects of chemotherapeutic agents are severe issues in clinical cancer treatment. Due to the dysregulation of enzymes in the cancer cells, enzyme-responsive drug delivery systems (DDSs) have been considered as a viable technology for cancer chemotherapy. In the present work, doxorubicin (DOX) is visible after leaving from AuNR-LAX. After treatment with AuNR-LAX, the drug resistance index of DOX-resistant MCF-7/ADR cells was reduced from extremely high 955.0 to 1.7, implying high potential of AuNR-LAX in the MDR phenotype cancer treatment. In addition, the cellular viability of both MCF-7 and MCF-7/ADR cells decreased from 50% to 80% after treatment with AuNR-LAX along (equivalent DOX concentration = 2.3 µg/mL, Au concentration = 30 µg/mL) to below 10% after AuNR-LAX treatment plus radiation of 808 nm, due to the NIR photothermal effect of AuNRs. Human bronchial epithelial cell line 16HBE was chosen to evaluate the adverse effect of AuNR-LAX on the normal cells. At the low concentration, the cytotoxicity of LAX and AuNR-LAX is comparable for breast cancer cell MCF-7 and normal cell 16HBE. It is noted that, at high concentration (with equivalent DOX concentration = 13.1 µg/mL, Au concentration = 167.7 µg/mL), the cellular viability of 16HBE cells is over 50%, whereas that of MCF-7 cancer cells is close to 0, implying the potential of AuNR-LAX in reducing the adverse effects of DOX against normal cells/tissues. Overall, AuNR-LAX showed high potential in overcoming MDR and alleviating adverse effect on normal cells.

Synthesis of a Novel Fluorescent Ruthenium Complex with an Appended Ac4GlcNAc Moiety by Click Reaction.

The O-linked ß-N-acetylglucosamine (O-GlcNAc) modification is an abundant post-translational modification in eukaryotic cells, which plays a fundamental role in the activity of many cells and is associated with pathologies like type II diabetes, Alzheimer's disease or some cancers. However, the precise connexion between O-GlcNAc-modified proteins and their function in cells is largely undefined for most cases. Confocal microscopy is a powerful and effective tool for in-cell elucidation of the function of biological molecules. Chemical labeling of non-ultraviolet or non-fluorescent carbohydrates with fluorescent tag is an essential step that makes intra-cellular microscopic inspection possible. Here we report a strategy based on the 1,3-dipolar cycloaddition, called click chemistry, between unnatural N-acetylglucosamine (GlcNAc) analogues Ac4GlcNAc (substituted with an azido group) and the corresponding fluorescent tag Ru(bpy)2(Phen-alkyne)Cl2 (4) to synthesize the fluorescent dye Ru(bpy)2(Phen-Ac4GlcNAc)Cl2 (5) under mild and neutral reaction conditions. Moreover, 5 showed good stability, desirable fluorescence characteristics, and exhibited rather low levels of cytotoxicity against sensitive MCF-7 cells. Additionally, we have achieved successful fluorescent imaging of 5 transported in living MCF-7 cells. Cell images displayed that proteins are potentially labelled with 5 in the cytoplasm.

Constraining the conformation of peptides with Au nanorods to construct multifunctional therapeutic agents with targeting, imaging, and photothermal abilities.

We demonstrated an easy-to-use strategy, instead of the tedious cyclization of the peptide backbone, to constrain the freedom of an RGD (arginine, glycine, aspartic acid) sequence with gold nanorods. We further constructed a multifunctional therapeutic agent which showed targeting, application in two-photon photoluminescence imaging, and near-infrared photothermal ability, suggesting the potential of this novel strategy in the development of RGD-containing drugs for biomedical applications.

Schiff base derived from thiosemicarbazone and anthracene showed high potential in overcoming multidrug resistance in vitro with low drug resistance index.

Multidrug resistance (MDR) is a huge obstacle in cancer chemotherapeutics. Overcoming MDR is a great challenge for anticancer drug discovery. Here, DNA binding and cytotoxicity of Schiff base L1 and L2 were explored to assess their efficiency in fighting cancer and overcoming the MDR. L1 and L2 could treat extremely chemoresistant MCF-7/ADR cell as drug-sensitive cell, with drug resistance index (DRI) <2.13, showing high potential in overcoming the MDR. The apoptotic ratio induced by L1 and L2 was low for both MCF-7 and MCF-7/ADR cells. L1 and L2 induced an impairment of cell cycle progression of MCF-7 and MCF-7/ADR cell lines and suppressed cell growth by perturbing progress through the G0/G1 phase, with L2 causing more profound effect, which might account for lower drug resistance after L2 treatment. The molecular docking revealed weak interaction between L1/L2 and P-glycoprotein (P-gp), the most important drug efflux pump and intracellular Rhodamine 123 accumulation indicated that the activity of P-gp was not inhibited by L1 and L2. Combined with the cellular uptake results, it implied that L1 and L2 could bypass P-gp efflux to exert anticancer activity.

TAT-Modified Gold Nanoparticle Carrier with Enhanced Anticancer Activity and Size Effect on Overcoming Multidrug Resistance.

Highly efficient targeted delivery is crucial for successful anticancer chemotherapy. In this study, we developed a drug delivery system ANS-TAT-AuNP that loads anticancer molecule 2-(9-anthracenylmethylene)-hydrazinecarbothioamide (ANS) via conjugation with cell-penetrating peptide TAT modified AuNPs. The in vitro study showed that the IC50 value of ANS-TAT-AuNPs3.8 nm reduced by 11.28- (24 h) and 12.64-fold (48 h) after incubation with liver hepatocellular carcinoma HepG2 cells compared to that of free ANS, suggesting that TAT modified AuNPs could enhance the antiproliferative activity of ANS. Also, ANS-TAT-AuNPs showed a size effect on overcoming multidrug resistance (MDR). The potential of ANS-TAT-AuNPs in overcoming MDR was assessed with MCF-7/ADR drug-resistant cell line, the drug resistance index (DRI) of which was extremely high (>190). The DRI of ANS-TAT-AuNPs22.1 nm decreased dramatically to 1.48 (24 h) and 2.20 (48 h), while that of ANS-TAT-AuNPs3.8 nm decreased to 7.64 (24 h) and 7.77 (48 h), indicating that ANS-TAT-AuNPs22.1 nm could treat extremely resistant MCF-7/ADR cancer cells as drug sensitive ones. The data suggest that the larger AuNPs had more profound effect on overcoming MDR, which could effectively prevent drug efflux due to their size being much larger than that of the p-glycoprotein channel (9-25 Å).

Evaluating p97 inhibitor analogues for their domain selectivity and potency against the p97-p47 complex.

We previously found that p97 ATPase inhibitors 2-(2-amino-1H-benzo[d]imidazol-1-yl)-N-benzyl-8-methoxyquinazolin-4-amine (ML240) and 2-(2H-benzo[b][1,4]oxazin-4(3H)-yl)-N-benzyl-5,6,7,8-tetrahydroquinazolin-4-amine (ML241) specifically target the D2 domain of wild-type p97. In addition, one of the major p97 cofactors, p47, decreases their potencies by ∼50-fold. In contrast, N(2) ,N(4) -dibenzylquinazoline-2,4-diamine (DBeQ) targets both the D1 and D2 domains and shows only a four- to sixfold decrease in potency against the p97-p47 complex. To elucidate structure-activity relationships for the inhibitors, we screened 200 p97 inhibitor analogues for their ability to inhibit the ATPase activity of either or both of the D1 or D2 domains, as well for their effects on p47 potency. The selectivity of 29 of these compounds was further examined by eight-dose titrations. Four compounds showed modest selectivity for inhibiting the ATPase activity of D1. Eleven compounds inhibited D2 with greater potencies, and four showed similar potencies against D1 and D2. p47 decreased the potencies of the majority of the compounds and increased the potencies of five compounds. These results highlight the possibility of developing domain-selective and complex-specific p97 inhibitors in order to further elucidate the physiological roles of p97 and its cofactors.

An efficient ruthenium tris(bipyridine)-based luminescent chemosensor for recognition of Cu(II) and sulfide anion in water.

A novel efficient luminescent chemosensor based on a 1,4,7,10-tetraazacyclododecane (cyclen)-tethered Ru(bpy)3(2+) derivative (Ru-cyclen) has been synthesized and characterized. It displays an ON-OFF-type luminescence change with excellent selectivity towards Cu(II) amongst 16 metal ions in 100% aqueous solution. The binding stoichiometry of Ru-cyclen with Cu(2+) was established by Job plot analysis and mass spectral evidence. Furthermore, the in situ generated Ru-cyclen-Cu ensemble recovered luminescence in the presence of S(2-), indicating an 'OFF-ON'-type sensing process. Similar phenomena were not observed with other common anions and biothiols, making it a high selective sulfide probe. Finally, the sensing mechanism is confirmed to be displacement approach by NMR, mass and emission spectrometry.

Modifying mesoporous silica nanoparticles to avoid the metabolic deactivation of 6-mercaptopurine and methotrexate in combinatorial chemotherapy.

Mesoporous silica nanoparticles with amino and thiol groups (MSNSN) were prepared and covalently modified with methotrexate and 6-mercaptopurine to form 6-MP-MSNSN-MTX. In the presence of DTT, 6-MP-MSNSN-MTX gradually releases 6-MP. In rat plasma, 6-MP-MSNSN-MTX effectively inhibits the metabolic deactivation of 6-MP and MTX. 6-MP-MSNSN-MTX could be an agent for long-acting chemotherapy.

Chelating Schiff base assisted azide-bridged Mn(II), Ni(II) and Cu(II) magnetic coordination polymers.

Four new Mn(II), Ni(II) and Cu(II) coordination polymers [Mn2(L1)(µ(1,1)-N3)2(µ(1,3)-N3)2]n (1), [Ni(L2)2(µ(1,3)-N3)]n(ClO4)n (2), [Cu(L3)(µ(1,1)-N3)(N3)]n (3) and [Cu(L4)(µ(1,1)-N3)2]n (4) (L1 = N,N'-bis(2-pyridylmethylene)ethane-1,2-diamine, L2 = N-(2-pyridylmethylene)methylamine, L3 = N-(2-pyridylmethylene)-3-pyridylamine, L4 = N-(2-pyridylmethylene)-tbutylamine) have been synthesized and characterized by single-crystal X-ray analysis and magnetic measurements. Complex 1 indicates a stoichiometry-dependent structural change (based on Mn:L1:N3 = 2:1:4 molar ratio) and consists of two-dimensional (2-D) (4,4) net layers, in which Mn(II) centers are co-bridged by single end-to-end (EE), double end-on (EO) azide and chelate-bridging L1 ligands. Complex 2 shows a single EE azide-bridged one-dimensional (1-D) Ni(II) chain. Complexes 3 and 4 indicate single EO and double EO azide-bridged 1-D Cu(II) chains, respectively. Complex 1 exhibits weak ferromagnetism due to its intra-layer spin-canting with T(c) = 20 K. Complex 2 shows an unusual intra-chain ferromagnetic coupling and spin-canting behaviour. Both complexes 3 and 4 exhibit intra-chain antiferromagnetic interactions. Magneto-structural parameters for these related complexes were also discussed.

2:1 multiplexing function in a simple molecular system.

1-[(Anthracen-9-yl)methylene] thiosemicarbazide shows weak fluorescence due to a photo-induced electron transfer (PET) process from the thiosemicarbazide moiety to the excited anthracene. The anthracene emission can be recovered via protonation of the amine as the protonated aminomethylene as an electron-withdrawing group that suppresses the PET process. Similarly, chelation between the ligand and the metal ions can also suppress the PET process and results in a fluorescence enhancement (CHEF). When solvents are introduced as the third control, a molecular 2:1 multiplexer is constructed to report selectively the inputs. Therefore, a molecular 2:1 multiplexer is realized in a simple molecular system.

The intracellular controlled release from bioresponsive mesoporous silica with folate as both targeting and capping agent.

A smart mesoporous silica nanocarrier with intracellular controlled release is fabricated, with folic acid as dual-functional targeting and capping agent. The folate not only improves the efficiency of the nanocarrier internalized by the cancer cells, but also blocks the pores of the mesoporous silica to eliminate premature leakage of the drug. With disulfide bonds as linkers to attach the dual-functional folate within the surface of mesoporous silica, the controlled release can be triggered in the presence of reductant dithiothreitol (DTT) or glutathione (GSH). The cellular internalization via folate-receptor-mediated endocytosis and the intracellular controlled release of highly toxic anticancer drug DOX were demonstrated with an in vitro HeLa cell culture, indicating an efficient cancer-targeted drug delivery.

Logic information communication in a fluorescent molecular switch.

Based on the chemical-sensitive fluorescence emission behaviors of the molecular switch 4-bromo-5-methoxy-2-(2-pyridyl)thiazole (2-BMPT), the communication of logic information between two functional units has been realized. With the rational control of the protonation and coordination reaction of 2-BMPT, an upstream switching unit (a 1:2 demultiplexer) and two downstream data-processing units are involved and interconnected in the communication. The two output states of the 1:2 demultiplexer serve as the initial input states of the two parallel downstream data-processing units, which execute the information communication between the two circuit layers. Furthermore, in the parallel data-processing layer, the logic gates of INHIBIT and YES accomplish their specific logic functions. Therefore, a molecular cascade circuit composed of an upstream switch and two downstream processing units has been constructed based on the chemical-modulated fluorescence properties of 2-BMPT.

Intramolecular charge transfer in 5-methoxy-2-(2-pyridyl)thiazole-derived fluorescent molecules with different acceptor or donor substituents.

On the basis of the rational derivation of 5-methoxy-2-(2-pyridyl)thiazole (2-MPT), we synthesized a new series of charge-transfer-based fluorescent molecules bearing different electronic donors or acceptors. The substituents range from strong electronic donors (e.g., amino and hydroxyl groups) to weak donating groups (e.g., proton and methyl groups) and electronic acceptors (e.g., pyridine ring). Through systematic investigation on the substituent-/polarity-dependent spectra (including room-temperature absorption, room-/low-temperature steady-state fluorescence spectra, and transient fluorescence lifetime characterization) and theoretical calculations, the emission properties of MPT derivatives are found to be governed by the rotation of the substituent around the triple bond axis, which produces distinct intramolecular charge transfer processes in either the twisted or planar excited states. The interconversion of excited-state geometry triggered by local interactions in polar solvents may produce a bathochromic shift of approximately 100 nm in fluorescence spectra. The solution state may also affect the ground- and excited-state conformation and hence results in the solvent-frozen-point sensitive fluorescence for some of the as-prepared molecules.

Orientational organization of organic semiconductors within periodic nanoscale silica channels: modification of fluorophore photophysics through hierarchical self-assembly.

Smart nanomaterials: The orientational organization of small organic semiconductors (anthracene, in this case) within periodic nanoscale silica channels (see figure) is achieved through a novel hierarchical self-assembly approach. This elicits interesting optical effects and improved mechanical properties that could be of potential importance for functional materials.A novel hierarchical organic-inorganic self-assembly approach is proposed in driving the orientational organization of small organic semiconductors (anthracene, in this case). A cationic surfactant with the special organic semiconductor anthracene at the hydrophobic tail was synthesized and used as both the structure-directing agent and as functional nanobuilding blocks. The self-assembly procedure was rapid and allowed for the uniform and molecular-level controllable organization of the organic semiconductors within periodic nanoscale silica channels. A range of techniques were used to demonstrate that the photophysical and photochemical nature of anthracene is significantly altered in the inorganic host, consistent with orientational packing of the organic semiconductors and excimer formation within the channels, from which energy migration and significant emission occur. The nanocomposite has also been demonstrated to show an interesting selective sensor function with respect to small solvent molecules. We suggest that this method could be used to drive the assembly of a wide range of organic semiconductor guests, offering the development of a variety of useful, smart nanomaterials that are able to self-assemble in a controllable and robust fashion.

A fluorescent-switch-based computing platform in defending information risk.

A molecular computing platform to defend against illegal information theft and invasion is obtained by the rational control of chemical reaction sequences in a newly prepared multiswitchable fluorophore 2-(4-aminophenylethylyl)-5-methoxy-2-(2-pyridyl)thiazole. Some of the fluorescent states with distinct recognition features are only activated through input-sequence-sensitive conversions. Chemically encoded user identity information can then be transmitted from a sequential logic unit to a combinational logic circuit, and hence, result in user-specific digital functionalities. The user's password entry is authorized prior to each computing step to check not only the user's identity, but also to reconfigure the molecular platform from the standby state to the corresponding operational state. Illegal accesses to the molecular computing platform are unable to activate the operation of the trusted users due to the incorrect activation processes, thereby ensuring the information is secured against information invasions.

Supramolecular engineering of a 2D Kagomé lattice: synthesis, structures, and magnetic properties.

Two 2D Mn (II) complexes, [Mn3(TzDC)2(phen)3] x 2 H2O (1; H3TzDC = 1,2,3-triazole-4,5-dicarboxylic acid, phen = 1,10-phenanthroline) and [Mn3(TzDC)2(bipy)3] x 4 H2O (2; bipy = 2,2'-bipyridine), were synthesized by hydrothermal reactions and characterized magnetically, and complex 1 was the first example of the chiral complex with a Kagomé lattice connectivity obtained through spontaneous resolution.