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CaP coated mesoporous polydopamine nanoparticles with responsive membrane permeation ability for combined photothermal and siRNA therapy
摘要： Combined photothermal and gene therapy provides a promising modality toward cancer treatment, yet facile integration and controlled codelivery of gene payloads and photothermal conversion agents (PTCAs) remains a great challenge. Inspired by the robust wet adhesion of marine mussels, we present a rationally designed nanosystem constructed by using hybrid mesoporous polydopamine nanoparticles (MPDA) with sub-100 nm sizes and a high photothermal conversion efficiency of 37%. The surface of the particles were modified with tertiary amines by the facile Michael addition/Schiff base reactions of PDA to realize high siRNA loading capacity (10 wt%). Moreover, a successful calcium phosphate (CaP) coating via biomineralization was constructed on the cationic nanoparticle to prohibit premature release of siRNA. The CaP coating underwent biodegradation in weakly-acidic subcellular conditions (lysosomes). The synergistic integration of tertiary amines and catechol moieties on the subsequently exposed surfaces was demonstrated to feature the destabilization/disruption ability toward model cellular membranes via the greatly enhanced interfacial adhesion and interactions. Consequently, sufficient permeability of lysosomal membranes, and in turn, a high lysosomal escape efficiency, was realized, which then resulted in high gene silencing efficiencies via sufficient cytosolic delivery of siRNA. When an efficient knocking down (65%) of survivin (an inhibitor of apoptosis proteins) was combined with a subsequent photothermal ablation, remarkably higher therapeutic efficiencies were observed both in vitro and in vivo, as compared with monotherapy. The system may help to pave a new avenue on the utilization of bio-adhesive surfaces for handling the obstacles of combined photothermal and gene therapy.
关键词： porous polydopamine nanocarriers,bioadhesion,lysosomal escape,siRNA delivery,photothermal therapy
更新于2025-09-23 15:22:29
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Selective Gas Sensor Using Porous Silicon
摘要： The effect of polar and non-polar vapors, like ethanol, methanol, acetonitrile, chloroform and toluene vapors on porous silicon gas sensor was studied. We demonstrated that the selectivity of a single sensor can be achieved by the impedance measurements within the frequency range 103–105 Hz. It is shown that the capacitance of the structure and its frequency dispersion are different under influence of different gases providing an unique signature of an agent. A set of parameters is proposed in order to numerically characterize the response to different gases. The characteristic time of response to different vapors gives an additional parameter to sense gases selectively.
关键词： Organic Vapors,Gas Sensor,Porous Silicon,Selectivity
更新于2025-09-23 15:22:29
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Properties of Porous Silicon Precipitated with Nickel for Gas Sensors
摘要： The preparation and properties of modified porous silicon is discussed and a proposal of a sensitive layer for a gas detector is presented. The modification is done by precipitation and electrochemical deposition of nickel. The morphology of sample surfaces is examined by atomic force microscopy and scanning electron microscopy (SEM). SEM-coupled energy dispersive spectroscopy is used to analyse the chemical composition of the samples. Magnetic response is measured with a SQUID magnetometer. Electrochemical impedance spectroscopy is used to study the sensitivity of the samples to isopropanol vapour in the presence of alternating electric current. A series of samples prepared with a higher anodic current density show higher sensitivity to isopropanol vapours in comparison to a lower anodic current.
关键词： Electrochemical Impedance Spectroscopy,Porous Silicon,Gas Sensors,SQUID,Electroless Nickel Deposition,Atomic Force Microscopy
更新于2025-09-23 15:22:29
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Bulk Photodriven CO <sub/>2</sub> Conversion through TiO <sub/>2</sub> @Si(HIPE) Monolithic Macrocellular Foams
摘要： Operating photo-induced reactions exclusively on catalyst surfaces while not exploiting the full catalyst volume generates a major footprint penalty for the photocatalytic reactor and leads to an inefficient use of the catalytic material. Photonic investigations clearly show that the solid foams have a strongly multi-diffusive character, with photons being significantly trapped within the sample cores while addressing a photon mean free path lt = 20.1 ± 1.3 μm. This 3D process both greatly limits back-reactions and promotes outstanding selectivity toward methane (around 80%) generation, and even ethane (around 18%) through C-C coupling reaction, with residual carbon monoxide and dihydrogen contents (around 2%). Silica–titania TiO2@Si(HIPE) self-standing macrocellular catalysts lead to optimal efficient thicknesses up to 20 times those of powders, thereby enhancing the way for real 3D-photodriven catalytic processes above the millimeter scale and up to a 6 mm thickness. A rather simple Langmuir–Hinshelwood based kinetic model is proposed which highlights the strong dependence of photocatalytic reaction rates on light scattering and the crucial role on oxidation back-reactions. In addition, a strong correlation between light attenuation coefficient and photon mean free path and median pore aperture diameter is demonstrated, offering thus a tool for photocatalytic behavior prediction.
关键词： heterogeneous catalysis,CO2 photoreduction,sol–gel process,porous materials,integrative chemistry
更新于2025-09-23 15:22:29
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GeO <sub/>2</sub> Encapsulated Ge Nanostructure with Enhanced Lithium-Storage Properties
摘要： Germanium (Ge)-based nanostructures, especially those with germanium dioxide (GeO2), have drawn great interest for applications in lithium (Li)-ion batteries due to their ultrahigh theoretical Li+ storage capability (8.4 Li/Ge). However, GeO2 in conventional Ge(s)/GeO2(c) (where (c) means the core and (s) means the shell) composite anodes with Ge shell outside GeO2 undergoes an irreversible conversion reaction, which restricts the maximum capacity of such batteries to 1126 mAhg?1 (the equivalent of storing 4.4 Li+). In this work, a porous GeO2(s)/Ge(c) nanostructure with GeO2 shell outside Ge cores are successfully fabricated utilizing the Kirkendall effect and used as a lithium-ion battery anode, giving a substantially improved capacity of 1333.5 mAhg?1 at a current density of 0.1 Ag?1 after 30 cycles and a stable long-time cycle performance after 100 cycles at a current density of 0.5 A g?1. The enhanced battery performance is attributed to the improved reversibility of GeO2 lithiation/delithiation processes catalyzed by Ge in the properly structured porous GeO2(s)/Ge(c) nanostructure.
关键词： porous,Kirkendall effect,nanostructures,lithium ion batteries,GeO2(s)/Ge(c)
更新于2025-09-23 15:22:29
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Multisegmented Metallic Nanorods: Sub-10 nm Growth, Nanoscale Manipulation, and Subwavelength Imaging
摘要： Multisegmented metallic nanorods (MS-M-NRs) have attracted increasing attention thanks to their integrated structures and complex functions. The integration of nanoscale segments in 1D enables maximum exposure of each segment and enhanced interaction between adjacent segments. Such structural integration will induce functional complexity in the nanorods, leading to superior properties for the individual components. Herein, recent progress on the development of MS-M-NRs is reviewed. Their precise fabrication, nanoscale manipulation, and subwavelength imaging, as well as simultaneous manipulation and imaging are discussed, respectively. Specifically, precise fabrication of MS-M-NRs focuses on porous anodic alumina (PAA) templated electrodeposition, which enables sub-10 nm growth of the segments and their interfaces/fronts. Nanoscale manipulation of MS-M-NRs introduces the fundamental methods that are employed for delicate movement control on the nanorods through internal or external stimulations. Subwavelength imaging of MS-M-NRs highlights the achievements on identification and location of constituent nanoscale segments/gaps based on their differences and interactions. Simultaneous manipulation and imaging of MS-M-NRs addresses the significance and potential applications of the nanorods with magnetic–plasmonic dual modulation. The development of MS-M-NRs will greatly contribute to materials science and nanoscience/nanotechnology.
关键词： metallic nanorods,porous anodic alumina (PAA),electrodeposition,imaging,manipulation
更新于2025-09-23 15:22:29
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Hierarchical porous TiO2 single crystals templated from partly glassified polystyrene
摘要： Hierarchical macro-mesoporous anatase TiO2 single crystal is one-pot synthesized in an EtOH-H2O system using polystyrene (PS) as the single porogen both for macropore and mesopore and TiF4 as the titanium precursor. The key to the simultaneous growth of single crystal and the introduction of hierarchical pores is the assembly of PS and titania at the glassification temperature of PS (100 °C). During the hydrolytic polymerization of TiF4, PS is encapsulated inside titania and gradually glassified. The interference from elastic PS on the oriental growth of TiO2 crystallite is thus minimized and the final removal of PS through calcination leaves interconnected macropore and mesopore inside the single crystal. According to XPS, EPR and fluorescence analyses, abundant oxygen vacancies are formed on the hierarchical porous single crystal, which presents extraordinary photocatalytic activity and stability in degrading organic pollutants under simulated sunlight irradiation using Rhodamine B as the model. The improved photocatalytic activity is a synergistic effect of improved separation of charge carrier and facilitated interfacial charge transfer benefitting from highly accessible porous single crystal structure.
关键词： Oxygen vacancy,Photocatalysis,Single crystal,Charge transfer,Hierarchical porous TiO2
更新于2025-09-23 15:22:29
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Hyperspectral and Color Imaging of Solvent Vapor Sorption Into Porous Silicon
摘要： A porous silicon thin film photonic crystal (rugate) sample with both a radial gradient in the rugate reflectance band wavelength and two spatially separated pore-wall surface chemistries (methylated and oxidized) was monitored by hyperspectral and color imaging while it was dosed with vapors of acetone, ethanol, heptane, 2-propanol, and toluene at concentrations ranging from 100 to 3,000 mg m?3. The shift in the wavelength of the rugate reflectance band maximum at each position along a transect across the two surface chemistries, as derived from the hyperspectral imaging, could discriminate between the different solvents and concentrations of solvents, while the change in hue derived from the color camera data along an analogous transect did not provide discrimination. The discrimination between solvents was mainly due to the two different surface chemistries, and the gradient associated with the change in the rugate reflectance band wavelength did not affect the selectivity significantly. There was spatial variability in the spectral and color responses along the transect independent of the overall rugate reflectance band wavelength gradient and pore-wall surface chemistries, and this was attributed to factors such as the presence of striations in the silicon wafer from which the porous silicon was prepared.
关键词： sensor,porous silicon,hyperspectral imaging,surface modification,vapor sensing
更新于2025-09-23 15:22:29
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Processing and Characterization of ZrO<sub>2</sub>-TiO<sub>2</sub> Porous Films by Dip Coating for Application as Environmental Sensors
摘要： The main objective of this work is to study and characterize porous ZrO2-TiO2 films on alumina substrates that will be used for the production of porous ceramic sensors for the monitoring of air humidity in environments subject to the incidence of solar radiation. For the production of the films the dip coating technique was adopted. A viscosity study was performed to obtain stable suspensions of ZrO2-TiO2 in isopropyl alcohol with the para-aminobenzoic acid deflocculant (PABA), at concentrations of 10, 12.5 and 15% by weight of solids. X-ray diffraction (XRD) characterizations were performed for the identification of crystalline phases, morphological analyzes by scanning electron microscopy (SEM) and chemical analyzes by energy dispersive X-ray spectroscopy (EDS). The results allowed to determine the minimum value of viscosity and amount of deflocculant to stabilize the suspension. The sensor elements in the form of 1:1 (weight) ZrO2 - TiO2 porous films showed great potential to be used as sensors for the measurement of relative humidity the size and distribution of desirable pores in the porous film for application as moisture sensors was obtained with 12.5 and 15 % by weight ZrO2-TiO2
关键词： deflocculant,sensors,porous ceramic films,viscosity
更新于2025-09-23 15:22:29
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Novel Porous Boron Nitride Nanosheet with Carbon Doping: Potential Metal-Free Photocatalyst for Visible-Light-Driven Overall Water Splitting
摘要： The band gap of hexagonal boron nitride (h-BN) is far too wide for efficiently utilizing visible light, limiting its application in photocatalysis. The present study employs first principles calculations to demonstrate that the band gap energies of porous h-BN (p-BN) can be tuned by carbon doping to levels appropriate for the absorption of visible-light, and that the conduction band and valence band match well with the potentials of both hydrogen and oxygen evolution reactions. Importantly, a strategy of carbon doping to improve the energy level of valence band maximum is also proposed. Moreover, the carbon-doped p-BN exhibits good separation between photogenerated electrons/holes and structural stability at high temperatures. The DFT results help the design of high-performance two-dimensional photocatalysts that avoid the use of metals.
关键词： metal-free catalysts,photocatalyst,porous boron nitride nanosheets,overall water splitting,band structure engineering
更新于2025-09-23 15:22:29