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Development of titania-integrated silica cell walls of the titanium-resistant diatom, <i>Fistulifera solaris</i>
摘要： We report the biological synthesis of titania that is integrated into the silica-based cell walls of a titanium-resistant diatom, Fistulifera solaris. Titania is deposited across the diatom cell walls by simply incubating F. solaris in a culture medium containing a high concentration (2 mM) of a water-soluble organo-titanium compound, titanium(IV) bis(ammonium lactato) dihydroxide (TiBALDH) that would otherwise inhibit the growth of other diatom species. Furthermore, we genetically engineered the interfaces of the diatom cell walls with a titanium-associated peptide, which subsequently increased the Ti/Si atomic ratio by more than 50% (i.e., from 6.2 ± 0.2 % to 9.7 ± 0.5 %, as identified by inductively coupled plasma-atomic emission spectrometry). The titanium content on the F. solaris silica cell walls is one of the highest reported to date, and comparable to that of chemically synthesized TiO2-silica composites. Subsequent thermal annealing at 500°C in air converted the wall-bound titania to nanocrystalline anatase TiO2, a highly photocatalytically active phase. We propose that incubation of the titanium-resistant F. solaris with TiBALDH as demonstrated in this study could be a promising bioprocess towards the scalable synthesis of TiO2. In addition, the genetic engineering we used to modulate the surface properties of diatom silica cell walls could be extended to synthesize controlled nanomaterials for multiple applications including bioremediation, water purification, and energy conversion/storage.
关键词： Genetic engineering,silica cell wall,TiO2,Fistulifera solaris,diatom
更新于2025-09-23 15:21:21
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Controlling Fano resonances in multilayer dielectric gratings towards optical bistable devices
摘要： The spectral properties of Fano resonance generated in multilayer dielectric gratings (MDGs) are reported and numerically investigated in this paper. We examine the MDG consisting of numerous identically alternative chalcogenide glass (As2S3) and silica (SiO2) multilayers with several grating widths inscribed through the structure, emphasizing quality (Q) and asymmetric (q) factors. Manipulation of Fano lineshape and its linear characteristics can be achieved by tailoring the layers’ amount and grating widths so that the proposed structure can be applicable for several optical applications. Moreover, we demonstrate the switching/bistability behaviors of the MDG at Fano resonance which provide a significant switching intensity reduction compared to the established Lorentzian resonant structures.
关键词： Fano resonance,silica,optical bistable devices,chalcogenide glass,multilayer dielectric gratings
更新于2025-09-23 15:21:21
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Luminescent silica mesoparticles for protein transduction
摘要： Unlike silica nanoparticles, the potential of silica mesoparticles (SMPs) (i.e. particles of submicron size) for biological applications in particular the in vitro (let alone in vivo) cellular delivery of biological cargo has so far not been sufficiently studied. Here we examine the potential of luminescent (namely, octahedral molybdenum cluster doped) SMPs synthesised by a simple one-pot reaction for the labelling of cells and for protein transduction into larynx carcinoma (Hep-2) cells using GFP as a model protein. Our data demonstrates that the SMPs internalise into the cells within half an hour. This results in cells that detectably luminesce via conventional methods. In addition, the particles are non-toxic both in darkness and upon photo-irradiation. The SMPs were modified to allow their functionalisation by a protein, which then delivered the protein (GFP) efficiently into the cells. Thus, the luminescent SMPs offer a cheap and trackable alternative to existing materials for cellular internalisation of proteins, such as the HIV TAT protein and commercial protein delivery agents (e.g. Pierce?).
关键词： protein transduction,cytotoxicity,silica,Octahedral molybdenum cluster,cellular uptake
更新于2025-09-23 15:21:21
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Sol-gel coating of colloidal particles deposited glass surface pertinent to self-cleaning applications
摘要： A sol-gel coating using colloidal silica on a glass surface is carried out towards improving the self-cleaning properties. The optical transmittance and hydrophobic characteristics of the resulting coating are analyzed using analytical tools. Since the sol-gel coating reduces the optical transmittance of the glass samples, due to scattering and diffusion of the incident optical radiation at the coating surface, silicon oil (Sigma-Aldrich, 10 cSt) impregnation method is introduced to improve the optical transmittance. Silicon oil has good heat transfer characteristics, stable properties over range of temperatures, and optically transparent characteristics with refractive index of 1.4034. The resulting coated surface is tested in outdoor environments to examine the dust effect on the optical transmittance of the sol-gel coated and oil impregnated glass samples. It is found that deposition of 75 nm size silica particles on the glass surface modifies the texture height of the sol-gel coating, which in turn, improves the surface hydrophobicity. Sol-gel coating results in a web-type fully connected porous structures; in which case, agglomeration of the synthesized particles is responsible for the fully connected porous texture at the coating surface. The optical transmittance remains low for the sol-gel coated glass samples because of scattering and diffusion of the incident optical radiation at the coating surface. Silicon oil impregnation improves the optical transmittance of the sol-gel coated samples. The dust particles immerse into the oil film and reduce the optical transmittance of the oil impregnated samples in outdoor environments.
关键词： Sol-gel coating,Hydrophobicity,Silicon oil impregnation,Silica,Outdoor testing
更新于2025-09-23 15:21:21
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Vibrational electron energy loss spectroscopy in truncated dielectric slabs
摘要： Specially designed instrumentation for electron energy loss spectroscopy (EELS) in a scanning transmission electron microscope makes it possible to probe very low-loss excitations in matter with a focused electron beam. Here we study the nanoscale interaction of fast electrons with optical phonon modes in silica. In particular, we analyze the spatial dependence of EEL spectra in two geometrical arrangements: a free-standing truncated slab of silica and a slab with a junction between silica and silicon. In both cases, we identify different loss channels, involving polaritonic and nonpolaritonic contributions to the total electron energy loss, and we obtain the corresponding energy-filtered maps. Furthermore, we present a comparison of the theoretical simulations for a silica-silicon junction with experimental results, and we discuss the spatial resolution attainable from the energy-filtered map considering optical phonon excitations in a conventional experimental arrangement.
关键词： optical phonon modes,nonpolaritonic,polaritonic,silica,electron energy loss spectroscopy,EELS,silicon
更新于2025-09-23 15:21:21
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A dosimetric study on the use of 3D-printed customized boluses in photon therapy: A hydrogel and silica gel study
摘要： Purpose: The aim of the study was to compare the dose differences between two kinds of materials (silica gel and hydrogel) used to prepare boluses based on three‐dimensional (3D) printing technologies and commercial bolus in head phantoms simulating nose, ear, and parotid gland radiotherapy. Methods and materials: We used 3D printing technology to make silica gel and hydrogel boluses. To evaluate the clinical feasibility, intensity modulated radiation therapy (IMRT) plans were created for head phantoms that were bolus‐free or had a commercial bolus, a silica gel bolus, or a hydrogel bolus. Dosimetry differences were compared in simulating nose, ear, and parotid gland radiotherapy separately. Results: The air gaps were smaller in the silica gel and hydrogel bolus than the commercial one. In nose plans, it was shown that the V95% (relative volume that is covered by at least 95% of the prescription dose) of the silica gel (99.86%) and hydrogel (99.95%) bolus were better than the commercial one (98.39%) and bolus‐free (87.52%). Similarly, the homogeneity index (HI) and conformity index (CI) of the silica gel (0.06; 0.79) and hydrogel (0.058; 0.80) bolus were better than the commercial one (0.094; 0.72) and bolus‐free (0.59; 0.53). The parameters of results (HI, CI, V95%) were also better in 3D printing boluses than in the commercial bolus or without bolus in ear and parotid plans. Conclusions: Silica gel and hydrogel boluses were not only good for fit and a high level of comfort and repeatability, but also had better parameters in IMRT plans. They could replace the commercial bolus for clinical use.
关键词： hydrogel,silica gel,radiotherapy,tissue compensator,3D printing
更新于2025-09-23 15:21:21
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Functionalized Holmium-Doped Hollow Silica Nanospheres for Combined Sonodynamic and Hypoxia-Activated Therapy
摘要： The oxygen concentration dependence of sonodynamic therapy (SDT) and bioreductive therapy can be utilized to design the strategy of synergistic therapy. Herein, holmium-doped hollow silica nanospheres are synthesized and then sequentially modified with chlorin e6, carboxyl poly(ethylene glycol) silane, and prostate stem cell antigen (PSCA) monoclonal antibody. The resultant nanocomposite designated as HHSN-C/P-mAb has good biocompatibility and can specifically target cancer cells overexpressing PSCA. Due to the inner cavity structure and Ho doping, HHSN-C/P-mAb shows high ultrasound (US) imaging contrast capability and excellent high-field magnetic resonance contrast performance. HHSN-C/P-mAb can act as a nanocarrier for loading the bioreductive prodrug tirapazamine (TPZ), and the degradation of the hollow nanospheres under the trigger of acidic microenvironment favors the pH responsive release of TPZ from the material. Upon US irradiation, HHSN-C/P-mAb produces reactive oxygen species to kill the cancer cells, and importantly, the oxygen consumption during SDT induces an intratumoral hypoxic environment to activate the therapeutic function of codelivered TPZ, resulting in a high-effective synergistic therapy. The findings of this study highlight that HHSN-C/P-mAb is a versatile theranostic nanoplatform for efficient cancer treatment.
关键词： magnetic resonance imaging,sonodynamic therapy,ultrasound imaging,holmium-doped hollow silica nanosphere,bioreductive therapy
更新于2025-09-23 15:21:21
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Light driven PVDF fibers based on photochromic nanosilica@naphthopyran fabricated by wet spinning
摘要： Photoresponsive polyvinylidene fluoride (PVDF) fibers doped with naphthopyran-functionalized silica nanoparticles (SiO2@NPT) were successfully prepared by dry–jet wet spinning. The incorporated photochromic nanomaterials, SiO2@S1 and SiO2@S2, were previously prepared by covalent post-grafting of the silylated NPTs – 2H-naphtho[1,2-b]pyran derivatives, S1 and S2 – onto nano-sized SiO2 (15 ± 3 nm). The morphological and chemical characterization of the resulting doped fibers PVDF@SiO2@S1 and PVDF@SiO2@S2 was evaluated by scanning electron microscopy with energy dispersive spectroscopy and Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR). Both PVDF@SiO2@S1 and PVDF@SiO2@S2 fibers presented average diameters of 133 ± 8 μm and 98 ± 7 μm, respectively, and a porous outer surface. The presence of the SiO2@NPT within the fibers was confirmed through the observation of dense clusters embedded within the polymeric matrix. Furthermore, the FTIR-ATR spectra of the fibers revealed that the PVDF matrix was composed of α and β crystalline and amorphous phases. The PVDF@SiO2@S1 and PVDF@SiO2@S2 fibers showed photoresponsive properties under UV and sunlight irradiation, exhibiting fast coloration kinetics and good optical contrast (ΔE*ab = 7.2 and 15.1, respectively), and changing from a pale orange and an off-white color to a more intense yellow-orange and purple coloration, respectively, in less than 1 min. Moreover, they showed an initial fast bleaching, losing half of their color in less than 30 min (t1/2 = 28 and 20 min for PVDF@SiO2@S1 and PVDF@SiO2@S2 fibers, respectively), but displaying a residual coloration that took 1 and 2 h to return to the initial uncolored state (t3/4 = 95 and 49 min, respectively). The PVDF@SiO2@S2 fibers presented the best photochromic performance.
关键词： Photochromism,Silica nanoparticles,PVDF fibers,Naphthopyrans,Wet spinning
更新于2025-09-23 15:21:21
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Manufacture of Magnesium Oxide Nanoparticles Coated with Silica Shells
摘要： MgO@SiO 2 core–shell nanoparticles were manufactured, and a synthetic protocol was developed to prepare MgO nanoparticles where the SiO2 shell thickness was less than 10 nm. The influence of synthesis parameters on the formation of MgO@SiO2 nanoparticles was studied. The fact of a SiO2 shell being formed on the MgO surface was established and the sizes of the thus-prepared MgO@SiO2 nanoparticles were determined by TEM and Fourier-transform IR spectroscopy.
关键词： metal oxide nanoparticles,magnesium oxide,silica shell,core–shell nanoparticles,tetraethoxysilane
更新于2025-09-23 15:21:21
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GNRs/PPy/m-SiO2 Core/Shell Hybrids as Drug Nanocarriers for Efficient Chemo-Photothermal Therapy
摘要： Combination therapy as a novel strategy with the combination of photothermal therapy and chemotherapy (photothermal-chemotherapy) has aroused the tremendously increasing interest owing to the synergistic therapeutic effect on destroying cancer cells since that the hyperthermia generated from photothermal therapy can promote drug delivery into tumors, which would highly increase therapeutic efficacy as compared to those sole treatments. Herein, we fabricated a novel nanomaterial-based carrier composed of GNRs, polypyrrole (PPy) and mesoporous silica to form GNRs/PPy/m-SiO2 core/shell hybrids. After loading the anticancer drug of doxorubicin (DOX), the photothermal effect and the drug-release behavior of GNRs/PPy@m-SiO2-DOX hybrids were investigated. The in vitro and in vivo near-infrared (NIR) photothermal-chemotherapy were also revealed. The results indicated the NIR-induced photothermal effect was beneficial to promote the release of the drug. In addition, combination therapy demonstrated the enhanced synergistic efficacy and excellent treatment efficacy for cancer therapy.
关键词： drug-controlled release,gold nanorod,mesoporous silica,combination therapy,photothermal,conducting polymer
更新于2025-09-23 15:21:21