Fabrication of silver seeds and nanoparticle on core-shell Ag@SiO2 nanohybrids for combined photothermal therapy and bioimaging.

In this study, two core-shell nanohybrids of different morphologies, namely SiO2-coated silver (Ag) with surface-exposed silver seeds (Ag@SiO2@Agseed) and SiO2-coated Ag with surface-exposed Ag nanoparticles (Ag@SiO2@AgNPs), were fabricated using the Stober method. Potential applications in bioimaging and photothermal therapy (PTT) of the two fabricated nanohybrids were also explored. Upon exposure to visible light (400 nm), Ag@SiO2@Agseed with surface-exposed Ag seeds exhibited greater photothermal conversion efficiency than Ag@SiO2@AgNPs. In vitro MTT assays in the dark and subsequent bioimaging using HeLa cells proved the potential biocompatibility of the fabricated core-shell nanohybrids. PTT applications of the two fabricated core-shell nanohybrids were studied by incubating HeLa cells with the nanohybrids, exposure to 400 nm laser, and subsequent staining with annexin V and propidium iodide (PI), and the two core-shell nanohybrids gave distinctively different PI staining results. Interestingly, Ag@SiO2@Agseed caused higher cell death upon light exposure compared to Ag@SiO2@AgNPs as the former generated more heat within the cells. These results demonstrated potential bioimaging and PPT applications of the fabricated core-shell nanohybrids and offer a novel candidate for phototherapy-based biomedical applications.

Fabrication of an artificial nanosucker device with a large area nanotube array of metallic glass.

The concurrent attachment and detachment movements of geckos on virtually any type of surface via their foot pads have inspired us to develop a thermal device with numerous arrangements of a multi-layer thin film together with electrodes that can help modify the temperature of the surface via application of a voltage. A sequential fabrication process was employed on a large-scale integration to generate well-defined contact hole arrays of photoresist for use as templates on the electrode-based device. The photoresist templates were then subjected to sputter deposition of the metallic glass Zr55Cu30Al10Ni5. Consequently, a metallic glass nanotube (MGNT) array having a nominal wall thickness of 100 nm was obtained after removal of the photoresist template. When a water droplet was placed on the MGNT array, close nanochambers of metallic glass were formed. By applying voltage, the surface was heated to increase the pressure inside the nanochambers; this generated an expanding force that raised the droplet; thus, the static water contact angle (SWCA) was increased. In contrast, a sucking force was generated during surface cooling, which decreased the SWCA. Our fabrication strategy exploits the MGNT array surface as nanosuckers, which can mimic the climbing aptitude of geckos as they attach to (>10 N m-2) and detach from (0.26 N m-2) surfaces at 0.5 and 3 V of applied voltage, respectively. Thus, the climbing aptitude of geckos can be mimicked by employing the processing strategy presented herein for the development of artificial foot pads.

Real-Time Packing Behavior of Core-Shell Silica@Poly(N-isopropylacrylamide) Microspheres as Photonic Crystals for Visualizing in Thermal Sensing.

We grafted thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) brushes from monodisperse SiO2 microspheres through surface-initiated atom transfer radical polymerization (SI ATRP) to generate core-shell structured SiO2@PNIPAM microspheres (SPMs). Regular-sized SPMs dispersed in aqueous solution and packed as photonic crystals (PCs) in dry state. Because of the microscale of the SPMs, the packing behavior of the PCs in water can be observed by optical microscopy. By increasing the temperature above the lower critical solution temperature (LCST) of PNIPAM, the reversible swelling and shrinking of the PNIPAM shell resulted in dispersion and precipitation (three-dimensional aggregation) of the SPM in aqueous solution. The SPMs were microdispersed in a water layer to accommodate the aggregation along two dimensions. In the microdispersion, the SPMs are packed as PCs with microscale spacing between SPMs below the LCST. When the temperature is increased above the LCST, the microdispersed PCs exhibited a close-packed arrangement along two dimensions with decreased spacing between SPMs. The change in spacing with increasing temperature above the LCST resulted in a color change from red to blue, which could be observed by the naked eye at an incident angle. Thus, the SPM array could be applied as a visual temperature sensor.

Methyl 2-(5-chloro-1-methyl-2-oxo-2,3-di-hydro-1H-indol-3-ylidene)acetate.

The title compound, C12H10ClNO3, the indoline ring system is essentially planar, with a maximum deviation of 0.009 Šfor the N atom. The indoline ring and acetate group are essentially coplanar, with a maximum deviation of 0.086 Šfor the O atom. The mean plane through the methoxy-carbonyl-methyl group forms a dihedral angle of 3.68 (5)° with the plane of the indoline ring system. The mol-ecular structure is stabilized by an intra-molecular C-H⋯O hydrogen-bond inter-action. In the crystal, π-π stacking inter-actions [centroid-centroid distance = 3.7677 (8) Å] occur between benzene rings, forming a chain running along the c-axis direction.

Methyl 5''-chloro-1',1''-dimethyl-2,2''-dioxodi-spiro-[indoline-3,2'-pyrrolidine-3',3''-indoline]-4'-carboxyl-ate.

In the title compound, C22H20ClN3O4, the central pyrrolidine ring adopts an envelope conformation on the N atom. The indolinone systems are individually roughly planar, with maximum deviations from their mean planes of 0.130 Šfor the spiro C atom of the indolinone unit and 0.172 Šfor the carbonyl C atom of the 5-chloro-1-methyl-indolinone unit. They make dihedral angles of 77.7 (8) and 86.1 (8)° with the mean plane through the central pyrrolidine ring. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds supported by C-H⋯O contacts into chains along the ab diagonal. The structure also features C-H⋯O hydrogen bonds, forming R 2 (2)(8) and R 2 (2)(16) rings and generating a three-dimensional array.