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A turn-on fluorescent probe for vitamin C based on the use of a silicon/CoOOH nanoparticle system
摘要： The authors describe a fluorometric method for the turn-on determination of vitamin C (ascorbic acid). The blue fluorescence of silicon nanoparticles (SiNPs; with excitation/emission maxima at 350/450 nm) is found to be quenched by CoOOH nanoparticles (NPs). In the presence of vitamin C, the CoOOH NPs are decomposed by a redox reaction between the diol group of vitamin C and CoOOH NPs. As a result, fluorescence recovers. On the basis of this finding, a fluorometric method was designed for the turn-on detection of vitamin C. Under optimal conditions, the method has a low detection limit (0.47 μM) and a linear response in the 0.5 μM to 20 μM a concentration range. It was successfully applied to the determination of vitamin C in spiked red grape and orange juice, and in vitamin C tablets.
关键词： Fluorescence Bturn-on^ strategy,Cobalt oxyhydroxide nanoparticles,Fluorometry,Stern-Volmer plot,Surface energy transfer,Redox reaction,Inner filter effect,Quenching,Silicon nanoparticles
更新于2025-09-23 15:23:52
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NIR light-triggered gelling <i>in situ</i> of porous silicon nanoparticles/PEGDA hybrid hydrogels for localized combinatorial therapy of cancer cells
摘要： Porous silicon-based nanocomposite hydrogels were readily constructed with the gelation of poly(ethylene glycol) double acrylates (PEGDA) macromers, due to the initiation of singlet oxygen photosensitized with porous silicon nanoparticles (PSiNPs) under near-infrared (NIR) light irradiation. Multifunctional PSiNPs/PEGDA nanocomposite hydrogels showed strong ?uorescence, excellent biodegradability, signi?cant photothermal effect, and sustained drug release with high ef?ciency (>80%). Finally, in situ growth of PSiNPs/PEGDA hybrid hydrogels on cancer cells was also achieved by NIR light, and then their biodegradation, drug release and synergistic chemo-phototherapeutic ef?cacy were further demonstrated, which could provide a signi?cant localized inhibition for the viability, adherence, and migration of cancer cells in vitro. Thus, we suggested that these resultant hybrid hydrogels would have important potential on local cancer therapy in future clinical practice.
关键词： porous silicon nanoparticles,hybrid hydrogels,therapy,insitu gelation,localized cancer
更新于2025-09-23 15:23:52
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Fluorometric determination of glucose based on a redox reaction between glucose and aminopropyltriethoxysilane and in-situ formation of blue-green emitting silicon nanodots
摘要： A method is described for fluorometric detection of glucose. It is based on the finding that silicon nanodots (SNDs) are formed from glucose and aminopropyltriethoxysilane (APTES) under mild experimental conditions. The SNDs thus formed have an average diameter of ～2 nm, exhibit good water dispersibility, blue fluorescence (with excitation/emission maxima at 410/475 nm), broad pH tolerance, and are photostable. The assay was applied to the quantification of glucose with high sensitivity, good specificity, and over a wide detection range (from 10 μM to 0.9 mM). It was applied to the determination of glucose in spiked serum samples and gave satisfactory results and recoveries.
关键词： Fluorescence detection,Enzyme-free analysis,Diabetes,Silicon nanoparticles
更新于2025-09-23 15:23:52
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High-throughput laser generation of Si-nanoparticle based surface coatings for antibacterial applications
摘要： High-productivity regime of nanosecond IR-laser ablative generation of silicon colloidal solutions in water for anti-bacterial applications was found in terms of GW/cm2-level laser intensity and scanning velocity by measuring multi-shot ablative mass loss and extinction coefficients of the colloids as sub-linear and third-power intensity functions, respectively. This advantageous regime implies sub-linear mass loss versus laser intensity at the simultaneous third-power yield of nanoparticles, resulting from the subcritical-density, opaque ablative plasma regulating the sample ablation rate and the related plasma-mediated dissociation (dispergation) of the ablation products. In contrast, at higher intensities, there is a drastic increase in mass loss with the corresponding increased yield of (sub) micrometer-sized particles owing to intense plasma-driven expulsion of micro-scale melt droplets and the corresponding saturation of the extinction coefficient of the colloidal solutions because of their dynamic local “self-limiting” effect during the high-rate ablation. The optimal low-intensity regime for Si nanoparticle production demonstrates the monotonous correlated increase of mass loss and extinction coefficient in terms of increasing laser scanning velocity, indicating the diminished cumulative effects. Surface coatings prepared from the generated Si nanoparticles exhibit minor surface oxidation, as acquired as their elemental composition via energy-dispersive X-ray spectroscopy, making their contact angle for water droplets (≈51°) close to that of bare Si wafer (≈58°) with its nanometer-thick native oxide layer. Owing to good wetting, the nanoparticle-based surface coatings show strong antibacterial response regarding Gram-negative Pseudomonas auereginosa bacteria even despite their minor oxidative passivation.
关键词： Silicon nanoparticles,Colloids,Surface oxidation,Extinction coefficient,Wetting,Antibacterial tests,Gram-negative bacteria Pseudomonas auereginosa,Sub-critical ablative plasma,Nanosecond laser ablation,Mass loss
更新于2025-09-23 15:21:21
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Highly selective and sensitive detection of catechol by one step synthesized highly fluorescent and water-soluble silicon nanoparticles
摘要： Because the chemical properties and structures of catechol and its analogues (hydroquinone and resorcinol) are similar, it still is a great challenge to detect catechol from other hydroxybenzene isomers with high accuracy and reliability. Herein, a selective and sensitive method based on the water soluble silicon nanoparticles (Si NPs) was established for catechol detection, and to the best of our knowledge, this is the first time using Si NPs for catechol measurement. The synthesis of Si NPs was very cheap and simple, no time-consuming, and no need for high temperature processing, or special instrument. The as-synthesized Si NPs, with high salt and temperature stabilities emitted yellow-green fluorescence (540 nm). A good linear relationship was observed from 0.06 to 40 μM and the limit of detection (based on 3s/k) was calculated as 20 nM, and the sensor displayed a significant selectivity toward catechol over other dihydroxybenzene isomers. Moreover, the Si NPs were applied in tap water, human serum samples and Yellow River water for catechol measurement.
关键词： Silicon nanoparticles,Catechol,Fluorescence
更新于2025-09-23 15:21:01
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Structural Analysis of Nanoparticles Formed via Laser Ablation of Porous Silicon and Silicon Microparticles in Water
摘要： Silicon nanoparticles with sizes of 50–300 nm have been formed via picosecond laser ablation of porous silicon and silicon microparticles in water using various targets. Raman spectroscopy has revealed the presence of a low amount of the amorphous phase in the obtained particles (10–12%) prepared from micro- and mesoporous silicon layers and almost a zero degree of crystallinity in the case of laser fragmentation of silicon micropowders in water. The results are promising for further application of the nanoparticles in photonics and biomedicine.
关键词： silicon nanoparticles,laser ablation,Raman scattering
更新于2025-09-23 15:19:57
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Tailoring Photoluminescence from Si-Based Nanocrystals Prepared by Pulsed Laser Ablation in He-N2 Gas Mixtures
摘要： Using methods of pulsed laser ablation from a silicon target in helium (He)-nitrogen (N2) gas mixtures maintained at reduced pressures (0.5–5 Torr), we fabricated substrate-supported silicon (Si) nanocrystal-based ?lms exhibiting a strong photoluminescence (PL) emission, which depended on the He/N2 ratio. We show that, in the case of ablation in pure He gas, Si nanocrystals exhibit PL bands centered in the “red - near infrared” (maximum at 760 nm) and “green” (centered at 550 nm) spectral regions, which can be attributed to quantum-con?ned excitonic states in small Si nanocrystals and to local electronic states in amorphous silicon suboxide (a-SiOx) coating, respectively, while the addition of N2 leads to the generation of an intense “green-yellow” PL band centered at 580 nm. The origin of the latter band is attributed to a radiative recombination in amorphous oxynitride (a-SiNxOy) coating of Si nanocrystals. PL transients of Si nanocrystals with SiOx and a-SiNxOy coatings demonstrate nonexponential decays in the micro- and submicrosecond time scales with rates depending on nitrogen content in the mixture. After milling by ultrasound and dispersing in water, Si nanocrystals can be used as e?cient non-toxic markers for bioimaging, while the observed spectral tailoring e?ect makes possible an adjustment of the PL emission of such markers to a concrete bioimaging task.
关键词： pulsed laser ablation in gases,pulsed laser deposition,silicon quantum dots,bioimaging,silicon nanoparticles,quantum con?nement,photoluminescence,silicon oxynitride
更新于2025-09-19 17:13:59
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Resonant Metagratings for Spectral and Angular Control of Light for Colored Rooftop Photovoltaics
摘要： We design semi-transparent metagrating supercells that enable control over the spectrum and directivity of incident light for applications in photovoltaics with tailored angular appearance. The building block of the supercells is a 110-120 nm wide and 175 nm tall silicon nanowire that shows a strong Mie resonance around λ= 650 nm. By arranging the resonant Mie scatterers into metagratings of increasing pitch (675-1300 nm) we create a Lambertian-like scattering distribution over an angular range of choice. The millimeter-sized metasurfaces were fabricated using electron beam lithography and reactive ion etching. The fabricated metasurface nearly fully suppress specular reflection on resonance while 10% of the incoming light around the resonance is scattered into the angular range between 30-75°, creating a bright red appearance over this specific range of angles. Off-resonant light in the blue, green and near-infrared is efficiently transmitted through the metasurface and absorbed in the underlying photovoltaic cell. The implemented silicon heterojunction solar cells with integrated metagrating supercells show a reduction in external quantum efficiency matching the resonant scattering spectral range. The short circuit current is reduced by 13% due to the combined effects of resonant scattering, reflection from the high-index substrate and absorption in the Si nanowires. In addition, to efficient colorful photovoltaics with tailored angular appearance, the metagrating concept can find application in many other light management designs for photovoltaics and other opto-electronic devices.
关键词： light management,metasurface,Mie resonators,BIPV,silicon nanoparticles,colored photovoltaics,transparent metagratings,solar cells
更新于2025-09-19 17:13:59
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Structural and optical properties of nanoparticles formed by laser ablation of porous silicon in liquids: Perspectives in biophotonics
摘要： The paper discusses the possibility of manufacturing silicon nanoparticles, which are suitable for contrasting biological tissues imaged by optical coherence tomography, by femtosecond laser ablation of porous silicon in various liquids. The manufactured nanoparticles are characterised by average sizes of 87, 112, and 102 nm for cases of ablation in water, ethanol, and liquid nitrogen, respectively, as well as a relatively narrow size distribution, which provides additional advantages for subsequent delivery into biological tissues. Electro chemical etching, which results in the formation of layers of porous silicon, allows the yield of ablation products to be increased several-fold by lowering the ablation threshold, thereby increasing the light scattering efficiency of the prepared suspensions compared with the case of using crystalline silicon as targets. The possibility of obtaining high-contrast images of a biotissue phantom based on an agar gel with embedded nanoparticles is shown. The magnitude of the contrast depends on the liquid used for ablation and correlates with the values of the reduced scattering coefficient of the studied suspensions.
关键词： silicon nanoparticles,laser ablation in liquids,atomic force microscopy,light scattering,optical coherence tomography,spectrophotometry
更新于2025-09-19 17:13:59
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Engineering the Charge Transport Properties of Resonant Silicon Nanoparticles in Perovskite Solar Cells
摘要： Resonant semiconductor nanoparticles (NPs) that improve both light trapping and scattering have recently emerged as an additional tool for enhancing the efficiency of perovskite solar cells. Among the various types of nanostructures, silicon NPs, which support Mie modes and have lower losses compared with metallic particles with plasmon resonances, exhibit the best improvement for standard methyl-ammonium lead iodide (MAPbI3)-based solar cells. Herein, not only the optical problem of solar cell optimization with silicon nanoantennas is studied, but also the effects related to charge carrier transport in the presence of NPs are considered. In particular, it is theoretically shown that the silicon nanoantennas can be further optimized by p-doping. The experimental verification is conducted for MAPbI3-based solar cells by p-doped silicon NPs in a hole transport layer (Spiro-OMeTAD). The improved generation rate of charge carriers and hole transport through the doped silicon NPs leads to improved efficiency of the device.
关键词： numerical modeling,perovskite solar cells,Mie resonances,silicon nanoparticles
更新于2025-09-11 14:15:04