Ultrasound-Assisted miR-122-Loaded Polymeric Nanodroplets for Hepatocellular Carcinoma Gene Therapy.

Ultrasound-induced microbubble sonoporation has been shown to effectively improve drug/gene delivery efficiency by enhancing tissue and cell permeability. However, the microscale size and short duration of ultrasound contrast agents limit their accumulation in target areas. Here, a kind of ultrasound-triggered phase-transitioning and size-changing cationic nanodroplet, perfluoropentane/C9F17-PAsp(DET)/miR-122/poly(glutamic acid)-g-MeO-poly(ethylene glycol) (PGA-g-mPEG) ternary nanodroplets (PFP-TNDs/miR-122), was developed to deliver microRNA-122 (miR-122) for hepatocellular carcinoma (HCC) treatment. PFP served as an ultrasound-sensitive core for ultrasound-triggered phase transition and size change from the nanoscale to the microscale. Positively charged C9F17-PAsp(DET) ensured adequate miRNA loading. PGA-g-mPEG, which served as the shell of the nanodroplet, modified the nanodroplets, enhanced their stability in serum, and protected miR-122 from degradation in vivo. The results exhibited that PFP-TNDs/miR-122 has a nanosize diameter (362 ± 15 nm) and remained stable for 24 h. After treatment with PFP-TNDs/miR-122 combined with ultrasound irradiation, the miR-122 expression level was significantly increased by approximately 600-fold in HepG2 cells, 500-fold in SMMC-7721 cells, and 30-fold in human HCC xenografts. Moreover, PFP-TNDs/miR-122 combined with ultrasound radiation effectively suppressed the growth, migration, and invasion of HCC cells, and inhibited tumor proliferation in mice. This study revealed that the biodegradable PFP-TNDs is a promising therapeutic gene carrier with functions of gene protection and effective gene delivery for clinical applications. Furthermore, PFP-TNDs/miR-122 associated with ultrasound irradiation may pave a new way to improve the prognosis of patients with HCC.

Noncovalent Spin-Labeling of DNA and RNA Triplexes.

Studying nucleic acids often requires labeling. Many labeling approaches require covalent bonds between the nucleic acid and the label, which complicates experimental procedures. Noncovalent labeling avoids the need for highly specific reagents and reaction conditions, and the effort of purifying bioconjugates. Among the least invasive techniques for studying biomacromolecules are NMR and EPR. Here, we report noncovalent labeling of DNA and RNA triplexes with spin labels that are nucleobase derivatives. Spectroscopic signals indicating strong binding were detected in EPR experiments in the cold, and filtration assays showed micromolar dissociation constants for complexes between a guanine-derived label and triplex motifs containing a single-nucleotide gap in the oligopurine strand. The advantages and challenges of noncovalent labeling via this approach that complements techniques relying on covalent links are discussed.

One Step e-Beam Radiation Cross-Linking of Quaternary Hydrogels Dressings Based on Chitosan-Poly(Vinyl-Pyrrolidone)-Poly(Ethylene Glycol)-Poly(Acrylic Acid).

We report on the successful preparation of wet dressings hydrogels based on Chitosan-Poly(N-Vinyl-Pyrrolidone)-Poly(ethylene glycol)-Poly(acrylic acid) and Poly(ethylene oxide) by e-beam cross-linking in weakly acidic media, to be used for rapid healing and pain release of infected skin wounds. The structure and compositions of hydrogels investigated according to sol-gel and swelling studies, network parameters, as well as FTIR and XPS analyses showed the efficient interaction of the hydrogel components upon irradiation, maintaining the bonding environment while the cross-linking degree increasing with the irradiation dose and the formation of a structure with the mesh size in the range 11-67 nm. Hydrogels with gel fraction above 85% and the best swelling properties in different pH solutions were obtained for hydrogels produced with 15 kGy. The hydrogels are stable in the simulated physiological condition of an infected wound and show appropriate moisture retention capability and the water vapor transmission rate up to 272.67 g m-2 day-1, to ensure fast healing. The hydrogels proved to have a significant loading capacity of ibuprofen (IBU), being able to incorporate a therapeutic dose for the treatment of severe pains. Simultaneously, IBU was released up to 25% in the first 2h, having a release maximum after 8 h.

Electron microscopy analysis of the thermal phase transition from hydroxyapatita to ß-TCP observed in human teeth.

Samples of enamel and dentin from human molar teeth were heated in air from room temperature (25°C) up to 1200°C and the phase transition from hydroxyapatite (HAP) to tricalcium phosphate (ß-TCP) was recorded. The changes produced in morphology and chemical composition in the tooth during heating were analysed by light microscopy, scanning electron microscopy (SEM), characteristic x-ray energy dispersion spectroscopy (EDS), x-ray diffraction (XRD), electron diffraction, transmission electron microscopy (TEM) and high-resolution electron microscopy (HRTEM). The results indicated a high correlation relationship among Ca content, P content, O content and Na content, and the existence of the Kirkendall effect during the HAP- ß-TCP phase transition. LAY DESCRIPTION: This work is related with tooth materials. Samples of enamel and dentine from human molar teeth were heated in air from 25°C up to 1200°C and the phase transition from hydroxyapatite (HAP) to tricalcium phosphate (ß-TCP) was recorded. The ß-TCP phase is also known as whitlockite. The changes produced in morphology and chemical composition in the tooth during heating were analysed by electron microscopy and X-ray diffraction. The results indicated a high correlation relationship among Ca, P, O and Na contents, and the existence of the Kirkendall effect, the atomic diffusion producing voids, during the HAP- ß-TCP phase transition.

Photomodulated Morphologies in Halogen Bond-Driven Assembly during Gel-Sol Transition.

Photoresponsive supramolecular gels with various applications are being constantly pursued; however, achieving well-defined morphology changes of gels via light irradiation remains a formidable challenge. In this study, a gel is prepared through halogen bond between azopyridine-containing Azopy-C10 and 1,4-tetrafluorodiiodobenzene. The gel exhibits gel-sol transition due to trans-cis isomerization of the azopyridine moiety upon UV irradiation. During this transition, the morphologies vary from flake to fluffy bobble-like and finally to peony-like with increasing exposure time, which is difficult to achieve in traditional assembly systems. The microstructure change is attributed to the variations of cis-isomer content and halogen-bonding strength. The supramolecular gel provides a novel method to achieve photomodulated morphologies and broadens the applications of such kind of materials, ranging from information storage to high-tech anticounterfeit.

Excellent Temperature-Control Based on Reversible Thermochromic Materials for Light-Driven Phase Change Materials System.

Light-driven phase change materials (PCMs) have received significant attention due to their capacity to convert visible light into thermal energy, storing it as latent heat. However, continuous photo-thermal conversion can cause the PCMs to reach high thermal equilibrium temperatures after phase transition. In our study, a novel light-driven phase change material system with temperature-control properties was constructed using a thermochromic compound. Thermochromic phase change materials (TC-PCMs) were prepared by introducing 2-anilino-6-dibutylamino-3-methylfluoran (ODB-2) and bisphenol A (BPA) into 1-hexadecanol (1-HD) in various proportions. Photo-thermal conversion performance was investigated with solar radiation (low power of 0.09 W/cm2) and a xenon lamp (at a high power of 0.14 W/cm2). The TC-PCMs showed a low equilibrium temperature due to variations in absorbance. Specifically, the temperature of TC-PCM180 (ODB-2, bisphenol A and 1-HD ratio 1:2:180) could stabilize at 54 °C approximately. TC-PCMs exhibited reversibility and repeatability after 20 irradiation and cooling cycles.

Exploring the impact of the side-chain length on peptide/RNA binding events.

The impact of the amino-acid side-chain length on peptide-RNA binding events has been investigated using HIV-1 Tat derived peptides as ligands and the HIV-1 TAR RNA element as an RNA model. Our studies demonstrate that increasing the length of all peptide side-chains improves unexpectedly the binding affinity (KD) but reduces the degree of compactness of the peptide-RNA complex. Overall, the side-chain length appears to modulate in an unpredictable way the ability of the peptide to compete with the cognate TAR RNA partner. Beyond the establishment of non-intuitive fundamental relationships, our results open up new perspectives in the design of effective RNA ligand competitors, since a large number of them have already been identified but few studies report on the modulation of the biological activity by modifying in the same way the length of all chains connecting RNA recognition motives to the central scaffold of a ligand.

Alternative route to charge density wave formation in multiband systems.

Charge and spin density waves, periodic modulations of the electron, and magnetization densities, respectively, are among the most abundant and nontrivial low-temperature ordered phases in condensed matter. The ordering direction is widely believed to result from the Fermi surface topology. However, several recent studies indicate that this common view needs to be supplemented. Here, we show how an enhanced electron-lattice interaction can contribute to or even determine the selection of the ordering vector in the model charge density wave system ErTe(3). Our joint experimental and theoretical study allows us to establish a relation between the selection rules of the electronic light scattering spectra and the enhanced electron-phonon coupling in the vicinity of band degeneracy points. This alternative proposal for charge density wave formation may be of general relevance for driving phase transitions into other broken-symmetry ground states, particularly in multiband systems, such as the iron-based superconductors.

Photo-induced reversible structural transition of cationic diphenylalanine peptide self-assembly.

The photo-induced self-assembly of a cationic diphenylalanine peptide (CDP) is investigated using a photoswitchable sulfonic azobenzene as the manipulating unit. A reversible structural transition between a branched structure and a vesicle-like structure is observed by alternating between UV and visible light irradiation.

Contribution of synchrotron radiation to photoactivation studies of biomolecular ions in the gas phase.

Photon activation of ions in the visible and ultraviolet range attracts a growing interest, partly for its promising applications in tandem mass spectrometry. However, this task is not trivial, as it requires notably high brilliance photon sources. Hence, most of the work in that field has been performed using lasers. Synchrotron radiation is a source continuously tunable over a wide photon energy range and which possesses the necessary characteristics for ion activation. This review focuses on the array of applications of synchrotron radiation in photon activation of ions ranging from near UV to soft X-rays.

Lipid Liquid-Crystal Phase Change Induced through near-Infrared Irradiation of Entrained Graphene Particles.

Lipid packing is intimately related to the geometry of the lipids and the forces that drive self-assembly. Here, the photothermal response of a cubic liquid-crystalline phase formed using phytantriol in the presence of low concentrations of pristine graphene was evaluated. Small-angle X-ray scattering showed the reversible phase changes from cubic to hexagonal to micellar due to localized heating through irradiation with near-infrared (NIR) light and back to cubic after cooling.

Photoinduced intermolecular cross-linking of gas phase triacylglycerol lipid ions.

Complex mixtures of plant derived triglycerol (TG) lipids are commonly used as feedstock components for the production of industrial polymers. However, there remains a need for the development of analytical strategies to investigate the intrinsic intermolecular cross-linking reactivity of individual TG molecules within these mixtures as a function of their structures and physicochemical properties, and for the characterization of the resultant products. Here, to address this need, we describe a novel multistage tandem mass spectrometry based method for intermolecular cross-linking and subsequent structural characterization of TG lipid ions in the gas phase. Cross-linking reactions were initiated using 266 nm ultraviolet photodissociation tandem mass spectrometry (UVPD-MS/MS) of saturated or unsaturated TG dimers introduced via electrospray ionization into a linear ion trap mass spectrometer as noncovalent complexes with protonated 3,4-, 2,4- or 3,5- diiodoaniline (diIA). UVPD resulted in the initial formation of an anilinyl biradical via the sequential loss of two iodine radicals, which underwent further reaction to yield multiple cross-linked TG products along with competing noncross-linking processes. These chemistries are proposed to occur via sequential combinations of hydrogen abstraction (H-abstraction), radical addition and radical recombination. Multistage collision induced dissociation tandem mass spectrometry (CID-MS(n)) was used to obtain evidence for the structures and mechanisms of formation for these products, as a function of both the TG lipid and diIA ion structures. The efficiency of the UVPD reaction was shown to be dependent on the number of unsaturation sites present within the TG lipids. However, when unsaturation sites were present, formation of the cross-linked and noncross-linked product ions via H-abstraction and radical addition mechanisms was found to be competitive. Finally, the identity of the anilinyl biradical (e.g., 3,4- versus 2,4-substituted) was found to significantly affect the distribution of these two types of product ions. Importantly, owing to the observed propensity for cross-linking to occur via H-abstraction-initiated processes, this novel gas-phase cross-linking reaction provides a convenient method to link two molecules covalently without the requirement of any specific functional group, and therefore could be applied to examine the gas-phase intermolecular interactions and cross-linking of a wide range of biomolecular classes.

Phase transformation of VO2 nanoparticles assisted by microwave heating.

The microwave assisted synthesis nowadays attracts a great deal of attention. Monoclinic phase VO2 (M) was prepared from NH4VO3 and H2C2O4 · 2H2O by a rapid microwave assisted technique. The synthesis parameters, microwave irradiation time, microwave power, and calcinations temperature were systematically varied and their influences on the structure and morphology were evaluated. The microwave power level has been carried out in range 180-600 W. TEM analysis demonstrated nanosized samples. The structural and morphological properties were measured using XRD, TEM, and thermal analyses. The variations of vanadium phase led to thermochromic properties.

Photo-activated phase separation in giant vesicles made from different lipid mixtures.

Using giant unilamellar vesicles (GUVs) made from POPC, DPPC, cholesterol and a small amount of a porphyrin-based photosensitizer that we name PE-porph, we investigated the response of the lipid bilayer under visible light, focusing in the formation of domains during the lipid oxidation induced by singlet oxygen. This reactive species is generated by light excitation of PE-porf in the vicinity of the membrane, and thus promotes formation of hydroperoxides when unsaturated lipids and cholesterol are present. Using optical microscopy we determined the lipid compositions under which GUVs initially in the homogeneous phase displayed Lo-Ld phase separation following irradiation. Such an effect is attributed to the in situ formation of both hydroperoxized POPC and cholesterol. The boundary line separating homogeneous Lo phase and phase coexistence regions in the phase diagram is displaced vertically towards the higher cholesterol content in respect to ternary diagram of POPC:DPPC:cholesterol mixtures in the absence of oxidized species. Phase separated domains emerge from sub-micrometer initial sizes to evolve over hours into large Lo-Ld domains completely separated in the lipid membrane. This study provides not only a new tool to explore the kinetics of domain formation in mixtures of lipid membranes, but may also have implications in biological signaling of redox misbalance.

Speeding up liquid crystal SLMs using overdrive with phase change reduction.

Nematic liquid crystal spatial light modulators (SLMs) with fast switching times and high diffraction efficiency are important to various applications ranging from optical beam steering and adaptive optics to optical tweezers. Here we demonstrate the great benefits that can be derived in terms of speed enhancement without loss of diffraction efficiency from two mutually compatible approaches. The first technique involves the idea of overdrive, that is the calculation of intermediate patterns to speed up the transition to the target phase pattern. The second concerns optimization of the target pattern to reduce the required phase change applied to each pixel, which in addition leads to a substantial reduction of variations in the intensity of the diffracted light during the transition. When these methods are applied together, we observe transition times for the diffracted light fields of about 1 ms, which represents up to a tenfold improvement over current approaches. We experimentally demonstrate the improvements of the approach for applications such as holographic image projection, beam steering and switching, and real-time control loops.

Measurement of a photoinduced transition from a nonordered phase to a transient ordered phase in the organic quantum-paraelectric compound dimethyltetrathiafulvalene-dibromodichloro-p-benzoquinone using femtosecond laser irradiation.

We report a new photoinduced transition from a nonordered phase to a transient ordered phase with symmetry breaking in an organic charge-transfer compound, dimethyltetrathiafulvalene (DMTTF)-dibromodichloro-p-benzoquinone (2,6QBr(2)Cl(2)), which is a neutral compound located near the neutral-ionic phase boundary and shows quantum paraelectricity at low temperatures. By an irradiation of a femtosecond laser pulse, an ionic domain consisting of ~40 molecules is introduced into the neutral lattice per photon, giving rise to coherent molecular oscillations with fractional charge modulations over ~400 molecules. This response is due to the recovery of ferroelectric nature from the quantum paraelectricity by a photoinjection of an ionic domain with a large dipole moment.

Bacteria-directed construction of hollow TiO2 micro/nanostructures with enhanced photocatalytic hydrogen evolution activity.

A general method has been developed for the synthesis of various hollow TiO2 micro/nanostructures with bacteria as templates to further study the structural effect on photocatalytic hydrogen evolution properties. TiO2 hollow spheres and hollow tubes, served as prototypes, are obtained via a surface sol-gel process using cocci and bacillus as biotemplates, respectively. The formation mechanisms are based on absorption of metal-alkoxide molecules from solution onto functional cell wall surfaces and subsequent hydrolysis to give nanometer-thick oxide layers. The UV-Vis absorption spectrum shows that the porous TiO2 hollow spheres have enhanced light harvesting property compared with the corresponding solid counterpart. This could be attributed to their unique hollow porous micro/nanostructures with microsized hollow cavities and nanovoids which could bring about multiple scattering and rayleigh scattering of light, respectively. The hollow TiO2 structures exhibit superior photocatalytic hydrogen evolution activities under UV and visible light irradiation in the presence of sacrificial reagents. The hydrogen evolution rate of hollow structures is about 3.6 times higher than the solid counterpart and 1.5 times higher than P25-TiO2. This work demonstrates the structural effect on enhancing the photocatalytic hydrogen evolution performance which would pave a new pathway to tailor and improve catalytic properties over a broad range.

Microwave assisted sintering of Al-Cu-Mg-Si-Sn alloy.

Microwave sintering has been a well-established technique to consolidate metal powders due to its instantaneous volumetric and rapid heating as compared to conventional heating. Al-3.8Cu-1Mg-0.8Si-0.3Sn (2712) alloy powders were compacted (200 and 400 MPa) and microwave sintered at different temperatures (570 to 630 degrees C) under different atmospheres (vacuum, N2, Ar and H2). Increasing sintering temperature enhanced sintered density from 91% to 98%. Sintering under vacuum at 590 degrees C was more efficient with a densification parameter of 0.36 followed by N2, Ar and H2. Regardless of the sintering condition, phase analysis via XRD revealed the presence of only alpha-Al peak attributed to lesser time available for diffusion of alloying elements. In addition, microstructural inhomogeneity leading to more intergranular melt formation was observed for all sintered compacts. Contrasting to densification, sintering in N2 resulted in better corrosion resistance.

Measurement of evaporation rates of different kind of aqueous solutions under microwave irradiation.

The evaporation rate of water is, of course, different under the same heating conditions of different aqueous solutions. Under conventional heating conditions, the evaporation rate of water is much higher than the evaporation rate of water of aqueous solutions of different kinds of solute materials, which is well accordance with the classical Raoult's law. The results obtained in this study have clearly shown that the chemical characteristics of dissolved materials in water very seriously affect the evaporation rates of water under the microwave heating. This generally causes contradictory results to Raoult's law and this can be explained with the additional microwave energy absorption by the ionic or molecular solute materials found in the solutions other than the microwave energy absorption by water molecules themselves.

Structural and electrical properties of microwave processed Ag modified KNN-LS ceramics.

Microwave processing steps of 0.95[(K0.5Na0.5)0.94Ag0.06NbO3]-0.05[LiSbO3]/(KNAN-LS) lead free ferroelectric ceramics were optimized for better densification and electrical properties. Calcination temperature and time for single perovskite phase formation were optimized and found to be 850 degrees C for 60 min., respectively. Crystal structural study revealed the presence of mixed structure in the microwave processed (MWP) KNAN-LS ceramics. The sintering of the KNAN-LS ceramics was carried out at 1080 degrees C for 10 min, 20 min and 30 min, respectively, and the sample sintered for 20 min exhibited best properties.