Photoresponsive Bridged Polysilsesquioxanes for Protein Immobilization/Controlled Release and Micropatterns.

Protein micropatterning on microfabricated surfaces is a promising technology in applications for biochip microarrays, cell attachment, and biosensors. In the present work, a novel photoresponsive polymer based on light-triggered charge shifting bridged polysilsesquioxane (CBPS) is designed and prepared. The organic bridged units containing a photocleavable group of diethylaminocoumarin-4-yl in CBPS could be cleaved rapidly upon irradiation at 410 nm, resulting in the polymer surface switching from a positive charge to a negative charge property. The photoresponsive behavior of CBPS is studied using FTIR, UV-vis, SEM, fluorescence microscopy, and zeta potential analysis. Proteins are easily immobilized on the polymer surface via electrostatic interactions and released after irradiation as required. Combined with photopatterning techniques, accurate protein micropatterns are fabricated by covering a photomask upon irradiation. A gradient protein pattern is also spatially and temporally controlled by regulating irradiation parameters. This smart photoresponsive polymer surface provides a gentle and straightforward strategy to micropattern charged proteins. Moreover, the photoresponsive polymer holds permitting potential in biomedical applications such as conjugating biomolecules, guiding cell arrays, and resisting bacteria.

68Ga-Labeled Magnetic-NIR Persistent Luminescent Hybrid Mesoporous Nanoparticles for Multimodal Imaging-Guided Chemotherapy and Photodynamic Therapy.

Featured with a zero-autofluorescence background, superior signal-to-noise ratio, high sensitivity, and deep penetration ability, near-infrared persistent luminescence nanoparticle (NIR-PLNP)-based multimodal nanoprobes show great potential for full-scale noninvasive cancer diagnosis. However, direct synthesis of NIR-PLNP-based multimodal nanoprobes with high drug loading capacity to meet growing cancer theranostic demands remains a challenge. In this work, multifunctional hybrid mesoporous nanoparticles (HMNPs) that integrate NIR-PLNPs (Ga2O3:Cr3+, Nd3+), magnetic nanoparticles (Gd2O3), and radionuclides (68Ga) are designed and constructed via a large-pore (mesoporous silica nanoparticle) MSN-templated strategy. The ingenious composition design endows HMNPs with rechargeable NIR-PL, superior longitudinal relaxivity, and excellent radioactivity, making these versatile nanoparticles available for long-term in vivo NIR-PL imaging, magnetic resonance imaging (MRI), and positron emission tomography (PET) imaging. More importantly, the application of large-pore MSN templates maintains the mesoporous structure of HMNPs, promising excellent drug loading capacity of these nanoparticles. As a proof-of-concept, HMNPs loaded with a high dose of DOX (chemotherapy agent) and Si-Pc (photosensitizer) are rationally designed for chemotherapy and NIR-PL-sensitized photodynamic therapy (PDT), respectively. Studies with mice tumor models demonstrate that the DOX/Si-Pc-loaded HMNPs possess excellent cancer cell killing ability and an outstanding tumor suppression effect without systemic toxicity. This work shows the great potential of HMNPs as an "all-in-one" nanotheranostic tool for multimodal NIR-PL/MR/PET imaging-guided chemotherapy and NIR-PL-sensitized photodynamic cancer therapy and provides an innovative paradigm for the development of NIR-PLNP-based nanoplatforms in cancer theranostic.

A Molecular Logic Gate Enables Single-Molecule Imaging and Tracking of Lipids in Intracellular Domains.

Photoactivatable dyes enable single-molecule imaging and tracking in biology. Despite progress in the development of new fluorophores and labeling strategies, many intracellular compartments remain difficult to image beyond the limit of diffraction in living cells. For example, lipid domains, e.g., membranes and droplets, remain difficult to image with nanometric resolution. To visualize these challenging subcellular targets, it is necessary to develop new fluorescent molecular devices beyond simple on/off switches. Here, we report a fluorogenic molecular logic gate that can be used to image single molecules associated with lipid domains, most notably droplets, with excellent specificity. This probe requires the subsequent action of light, a lipophilic environment, and a competent nucleophile to produce a fluorescent product. The combination of these inputs results in a probe that can be used to image the boundary of lipid droplets in three dimensions with resolution beyond the limit of diffraction. Moreover, this probe enables single-molecule tracking of lipid trafficking between droplets and the endoplasmic reticulum.

Abiotic and biotic degradation of five aromatic organosilicon compounds in aqueous media-Structure degradability relationships.

Silicones have many applications and are produced in large quantities. Despite their potential toxicity, information on their environmental mineralisation is scarce. Therefore, we investigated a group of five organosilicon compounds (o-MeOC6H4SiMe3 (1), p-MeOC6H4SiMe3 (2), (p-MeOC6H4)2SiMe2 (3), o-Me2NC6H4SiMe3 (4) and p-Me2NC6H4SiMe3 (5)), recently developed to be 'benign by design' based on their readily degradable core structure. Five different degradability tests were performed, one assessing hydrolytic and two analysing biological and photolytic stability, respectively. All substances, except (p-MeOC6H4)2SiMe2 (3), hydrolysed within 24 h to 50% indicating that this is one of the major pathways of their primary elimination. In agreement with previous research, none of the substances was readily biodegradable. In contrast, 100% of p-Me2NC6H4SiMe3 (5) was primarily eliminated by photolytic and hydrolytic processes. The elimination rates of the other substances ranged from 7% to 64%. Irradiation at shorter wavelengths increased both the extent and speed of photodegradation. Eleven transformation products of p-Me2NC6H4SiMe3 (5) were detected, all of which were completely eliminated within 64 min of irradiation with a Hg lamp (200-400 nm). The insertion of an electron-donating group on the benzene ring like in p-Me2NC6H4SiMe3 (5) clearly enhanced photolytic degradability but further research is necessary to achieve truly biodegradable silicones.

Donor-acceptor conjugated polymer-based nanoparticles for highly effective photoacoustic imaging and photothermal therapy in the NIR-II window.

We prepared novel conjugated polymer based NIR-II nanoparticles, which display extremely high photothermal conversion efficiency (65%). Both in vitro and in vivo investigations revealed that the as-prepared nanoparticles exhibit excellent theranostic properties including an extremely high cancer cell killing ability, admirable tumor elimination efficiency (100%) and a remarkable photoacoustic imaging contrast enhancing ability.

Design and Synthesis of an Activatable Photoacoustic Probe for Hypochlorous Acid.

Photoacoustic (PA) imaging is a novel imaging modality that combines the high contrast of optical imaging and the deep tissue penetration of ultrasound. PA imaging contrast agents targeting various biological phenomena have been reported, but the development of activatable PA probes, which show a PA signal only in the presence of target molecules, remains challenging in spite of their potential usefulness for real-time PA imaging of specific biomolecules in vivo. To establish a simple design strategy for activatable PA probes, we first designed and synthesized a silicon-rhodamine based near-infrared nonfluorescent dye, wsSiNQ660 (water-soluble SiNQ660), as a scaffold and demonstrated that it offers a high conversion efficiency from light to ultrasound compared to typical near-infrared fluorescent dyes. Importantly, absorption off/on strategies previously established for rhodamine-based fluorescent probes are also applicable to this nonfluorescent dye scaffold. We validated this approach by synthesizing an activatable PA probe for hypochlorous acid (HOCl) and confirmed that it enables three-dimensional imaging of HOCl in mouse subcutis.

Gamma-Irradiation Induced Functionalization of Graphene Oxide with Organosilanes.

Gamma-ray radiation was used as a clean and easy method for turning the physicochemical properties of graphene oxide (GO) in this study. Silane functionalized-GO were synthesized by chemically grafting 3-aminopropyltriethoxysilane (APTES) and 3-glycidyloxypropyltrimethoxysilane (GPTES) onto GO surface using gamma-ray irradiation. This established non-contact process is used to create a reductive medium which is deemed simpler, purer and less harmful compared conventional chemical reduction. The resulting functionalized-GO were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), and Raman spectroscopy. The chemical interaction of silane with the GO surface was confirmed by FT-IR. X-ray diffraction reveals the change in the crystalline phases was due to surface functionalization. Surface defects of the GO due to the introduction of silane mioties was revealed by Raman spectroscopy. Thermogravimetric analysis of the functionalized-GO exhibits a multiple peaks in the temperature range of 200-650 °C which corresponds to the degradation of chemically grafted silane on the GO surface.

Widely Applicable AIE Chemosensor for On-Site Fast Detection of Drugs Based on the POSS-Core Dendrimer with the Controlled Self-Assembly Mechanism.

A novel fluorescence chemosensor that can quickly on-site detect synthetic drugs and undergo prescreening is first reported. An eight tetraphenylethene (TPE)-modified polyhedral oligomeric silsesquioxane (POSS) dendrimer is designed and synthesized as an aggregation-induced emission (AIE) chemosensor, which exhibits great enhancement of unique monomer emission in pure tetrahydrofuran (THF) and AIE emission in THF/water, thanks to forming different self-assembly morphologies. In addition, POSS-TPE can sensitively detect methamphetamine and ketamine even in artificial saliva by noncovalent interaction forces. It has great potential to be a new widely applicable AIE chemosensor for aromatic molecules.

Two-Color 810 nm STED Nanoscopy of Living Cells with Endogenous SNAP-Tagged Fusion Proteins.

A 810 nm STED nanoscopy setup and an appropriate combination of two fluorescent dyes (Si-rhodamine 680SiR and carbopyronine 610CP) have been developed for near-IR live-cell super-resolution imaging. Vimentin endogenously tagged using the CRISPR/Cas9 approach with the SNAP tag, together with a noncovalent tubulin label, provided reliable and cell-to-cell reproducible dual-color confocal and STED imaging of the cytoskeleton in living cells.

Investigation of Ultraviolet Light Curable Polysilsesquioxane Gate Dielectric Layers for Pentacene Thin Film Transistors.

Polysilsesquioxane (PSQ) comprising 3-methacryloxypropyl groups was investigated as an ultraviolet (UV)-light curable gate dielectric-material for pentacene thin film transistors (TFTs). The surface of UV-light cured PSQ films was smoother than that of thermally cured ones, and the pentacene layers deposited on the UV-Iight cured PSQ films consisted of larger grains. However, carrier mobility of the TFTs using the UV-light cured PSQ films was lower than that of the TFTs using the thermally cured ones. It was shown that the cross-linker molecules, which were only added to the UV-light cured PSQ films, worked as a major mobility-limiting factor for the TFTs.

Thiol-ene photocrosslinked hybrid vesicles from co-assembly of POSS and poly(ether amine) (PEA).

We demonstrated here the thiol-ene photocrosslinked hybrid vesicles from co-assembly of POSS and poly(ether amine) (PEA), which are amphiphilic and responsive to temperature in water, and can be used to control the dispersion of both hydrophilic and hydrophobic dyes in water.

Laser emission from mirrorless waveguides based on photosensitized polymers incorporating POSS.

Laser emission from leaky waveguides based in dye-doped organic gain media incorporating Polyhedral Oligomeric Silsesquioxanes (POSS) nanoparticles is reported. The samples consist of thin film gain media deposited onto glass substrate defining a planar asymmetric slab waveguide, which does not incorporate any resonant substructure. The presence of POSS results in additional amplified spontaneous emission (ASE) spectral narrowing, and conditions have been found for which directional multimode laser emission is achieved. The spectral narrowing is ascribed to the photon path enlargement caused by a non-resonant feedback mechanism provided by individual scatterers, which enhances incoherently the magnitude of the amplification process. On the contrary, the appearance of multimode lasing is attributed to coherent random lasing from a many scatterers collective effect.

Selective protein patterning based on the micro-structured organosilane self-assembled monolayer by vacuum ultraviolet light lithography.

We have succeeded to immobilize fluorescent proteins selectively using a micro-structured organosilane self-assembled monolayer as a template. An organosilane layer with amino terminal group was formed on a thermally oxidized Si wafer by liquid-phase method and then was pattern-etched by vacuum ultraviolet light (VUV). The second organosilane layer with thiol terminal group was deposited on the etched area by chemical vapor surface modification method (CVSM). These micro-structured organosilane layer containing two reactive terminal groups were chemically modified using bi-functional linkers. Two kinds of fluorescent protein, Enhanced Cyan Fluorescent Protein (ECFP) and R-phycoerythrin were selectively immobilized on the chemically modified surface.

Hydrophobicity, topography in membranes and photosensitization of silicon phthalocyanines with axial ligands of varying lengths.

Six amphiphilic silicon phthalocyanines (SiPc's) axially linked to a dimethylated amino alkyl group of varying length have been examined for their potential suitability as photosensitizers for photodynamic therapy (PDT). This group of molecules was chosen because the length of the axial ligand might place the chromophoric part of the molecule at different vertical depths in the membrane and possibly affect the extent of membrane localized damage caused by singlet oxygen. We tested the relative penetration depth of the SiPc groups in the membrane by the extent to which their fluorescence was quenched by external iodide ions. We also measured singlet oxygen quantum yields of the SiPc's in a liposome membrane, using the fluorescent target for singlet oxygen, 9,10-dimethylanthracene. The hydrophobicity parameters, LogP, were calculated and were also measured. Some correlation was found between them and Kb's, the binding constants for liposomes. The effect of the axial ligand's length is less striking than in similar cases with hematoporphyrins and protoporphyrins. We link this smaller effect with a bending of the linker chain that enables, sterically, a better positioning of the sensitizer molecules within the ordered lipid layer structure.

A simple polysilsesquioxane sealing of nanofluidic channels below 10 nm at room temperature.

We present a simple sealing method to fabricate nanofluidic channels, where plasma treated polysilsesquioxane (PSQ) thin film on a rigid support is used to bond to a hydrophilic glass surface permanently at room temperature. This method shows precise dimension control below 10 nm with easy experimental setup. Using this method, one dimensional confined shallow nanochannels with a depth as small as 8 nm and an aspect ratio of <4 x 10(-5), two dimensional confined nanochannel arrays, and integrated nano/microchannel devices with a micro-to-nano interface have been demonstrated. Smooth transfer of DNA fragments from microchannel to nanochannel through the interface area was observed.

UV/ozone degradation of gaseous hexamethyldisilazane (HMDS).

As a carcinogen, hexamethyldisilazane (HMDS) is extensively adopted in life science microscopy, materials science and nanotechnology. However, no appropriate technology has been devised for treating HMDS in gas streams. This investigation evaluated the feasibility and effectiveness of the UV (185+254nm) and UV (254nm)/O(3) processes for degradation of gaseous HMDS. Tests were performed in two batch reactors with initial HMDS concentrations of 32-41mgm(-3) under various initial ozone dosages (O(3) (mg)/HMDS (mg)=1-5), atmospheres (N(2), O(2), and air), temperatures (28, 46, 65 and 80 degrees C), relative humilities (20%, 50%, 65%, 99%) and volumetric UV power inputs (0.87, 1.74, 4.07 and 8.16Wl(-1)) to assess their effects on the HMDS degradation rate. Results indicate that for all conditions, the decomposition rates for the UV (185+254nm) irradiation exceeded those for the UV (254nm)/O(3) process. UV (185+254nm) decompositions of HMDS displayed an apparent first-order kinetics. A process with irradiation of UV (185+254nm) to HMDS in air saturated with water at temperatures of 46-80 degrees C favors the HMDS degradation. With the condition as above and a P/V of around 8Wl(-1), k was approximately 0.20s(-1) and a reaction time of just 12s was required to degrade over 90% of the initial HMDS. The main mechanisms for the HMDS in wet air streams irradiated with UV (185+254nm) were found to be caused by OH free-radical oxidation produced from photolysis of water or O((1)D) produced from photolysis of oxygen. The economic evaluation factors of UV (185+254nm) and UV (254nm)/O(3) processes at different UV power inputs were also estimated.

Assembling a mixed phthalocyanine-porphyrin array in aqueous media through host-guest interactions.

A stable 1:1 host-guest complex is formed between a silicon(IV) phthalocyanine conjugated axially with two permethylated beta-cyclodextrin units and a tetrasulfonated porphyrin. The complex exhibits a light-harvesting property and works as an efficient photosensitizing system, killing HT29 human colon adenocarcinoma cells with an IC50 value of 0.09 microM. [structure: see text].

Tetrapyrrole singlet excited state quenching by carotenoids in an artificial photosynthetic antenna.

Two artificial photosynthetic antenna models consisting of a Si phthalocyanine (Pc) bearing two axially attached carotenoid moieties having either 9 or 10 conjugated double bonds are used to illustrate some of the function of carotenoids in photosynthetic membranes. Both models studied in toluene, methyltetrahydrofuran, and benzonitrile exhibited charge separated states of the type C*+-Pc*- confirming that the quenching of the Pc S1 state is due to photoinduced electron transfer. In hexane, the Pc S1 state of the 10 double bond carotenoid-Pc model was slightly quenched but the C*+-Pc*- transient was not spectroscopically detected. A semiclassical analysis of the data in hexane at temperatures ranging from 180 to 320 K was used to demonstrate that photoinduced electron transfer could occur. The model bearing the 10 double bond carotenoids exhibits biexponential fluorescence decay in toluene and in hexane, which is interpreted in terms of an equilibrium mixture of two isomers comprising s-cis and s-trans conformers of the carotenoid. The shorter fluorescence lifetime is associated with an s-cis carotenoid conformer where the close approach between the donor and acceptor moieties provides through-space electronic coupling in addition to the through-bond component.

Photophysical and photochemical processes of 9,10-dihydro-9-silaphenanthrene derivatives: photochemical formation and electronic structure of 9-silaphenanthrenes.

Photophysical and photochemical processes of 9-methyl- and 9-phenyl-9,10-dihydro-9-silaphenanthrene derivatives have been studied at room temperature and 77 K in comparison with the carbon analogue, 9,10-dihydrophenanthrene. These 9,10-dihydro-9-silaphenanthrene derivatives show smaller fluorescence quantum yield and remarkably larger Stokes shifts than those of the carbon analogue. In contrast, their phosphorescence quantum yields are two times larger than those of the carbon analogue, although the absolute value is not so large (approximately 0.1). Reaction products and intermediates produced by the 266 nm light photolysis have been studied, and it has been confirmed that 9-methyl- and 9-phenyl-9-silaphenanthrenes have been photochemically formed in methylcyclohexane at 77 K, in addition to the formation of radical cations of 9,10-dihydro-9-silaphenanthrene derivatives and the carbon-centered radical: 9-hydro-9-silaphenanthrenyl radical.

Absorption and Raman study for POSS-oligophenylene nanohybrid molecules.

Photoluminescence excitation and Raman measurements have been conducted for hybrid materials in which the oligophenylene derivatives are attached to the corners of a cubic inorganic cage of Polyhedral Oligosilsesquioxane (POSS). The theoretical study for energy levels and probable transitions between occupied orbital to un-occupied orbital and corresponding intensity for the hybrid molecule has been performed using density functional theory electronic structure program-DMol. The comparison between the theoretical and experimental results leads to a possible assignment for the excitation peaks in the PLE spectra. Moreover, the Raman bands of the conjugated chains in these materials are red-shifted and broadened with respect to their bulk counterparts. This systematic peak shift and broadening of the Raman bands provided additional confirmation that the conjugated chains in hybrid materials of bulk state are isolated without obvious pi-pi stacking and therefore the excitons in the organic arms are confined in the system.