As-prepared Silicon Nanoparticles Research Articles

One-pot synthesis of highly fluorescent silicon nanoparticles for sensitive and selective detection of hemoglobin.

In this work, a simple, selective, and sensitive probe for hemoglobin based on the quenched fluorescence of silicon nanoparticles (SiNPs) was fabricated. The SiNPs were synthesized by a simple hydrothermal treatment from N-[3-(trimethoxysilyl)propyl]ethylenediamine and sodium citrate. The as-prepared SiNPs exhibited good water-solubility and high fluorescence with the quantum yield of 70%. The fluorescence of the SiNPs could be remarkably quenched by hemoglobin. A wide linear range was obtained from 50 nM to 4000 nM with a LOD of 40 nM. The quenching mechanism was investigated by UV-Vis absorption spectrometry and time-resolved fluorescence spectrometry.

The Role of Solvent Environment on the Optical Behavior of Chemically Synthesized Silicon Nanoparticles

Silicon nanoparticles (Si-NPs) were prepared by solution-based chemical etching method. Optical characteristics of the as-prepared Si-NPs were investigated in different polar and nonpolar organic solvents. The emission and absorption properties of Si-NPs were tuned by altering the environment (solvents). The variation in absorption coefficient was observed because of the solvent interaction nature of Si-NPs. Si-NPs in polar aprotic and nonpolar solvents manifested good luminescence under UV excitation. PL intensities were observed to be depending on etched cross-section area on wafer surface. The results show a linear dependence of the refractive index (n) on wavelength (λ). The nature of solvents altered the luminescence efficiency of Si-NPs when examining under UV lamp. The emission and absorption properties of Si-NPs were tuned by altering the environment (solvents) through electrostatic interaction of various organic solvents with the Si-NPs. The band shapes of the Si-NPs show remarkable changes in passing from noncoordinating solvent (chloroform) to various coordinating solvents, which was the result of change in the environment around Si-NPs in various solutions.

One-Pot Microwave Synthesis of Water-Dispersible, High Fluorescence Silicon Nanoparticles and Their Imaging Applications in Vitro and in Vivo.

Silicon nanoparticles (SiNPs) have been reported to be synthesized by microwave-assisted methods under high pressure. However, there is still a lack of knowledge about the synthesis of SiNPs via microwave-assisted methods under normal pressure. Here we developed a new, facile, one-pot microwave-assisted method for the synthesis SiNPs (∼4.2 nm) with excellent water solubility under normal pressure by employing glycerol as the solvent. Furthermore, glycerol might be responsible for the photoluminescence quantum yield (PLQY) value up to 47% for the resultant SiNPs. The use of organic solvent could afford less nanoparticle surface defects compared with those prepared in aqueous solution, thus improving the fluorescent efficiency. The as-prepared SiNPs simultaneously featured bright blue-green fluorescence, long lifetime (∼12.8 ns), obvious up-conversion luminescence originating from two-photon absorption, superbly strong photostability, and favorable low toxicity. As a satisfactory probe, the as-synthesized SiNPs were successfully applied in fluorescence imaging of human cervical carcinoma cell lines (HeLa) and zebrafish.

Biomimetic Preparation and Dual-Color Bioimaging of Fluorescent Silicon Nanoparticles.

Fluorescent silicon nanoparticles (SiNPs), as the most important zero-dimensional silicon nanostructures, hold high promise for long-awaited silicon-based optic applications. There currently remain major challenges for the green, inexpensive, and mass production of fluorescent SiNPs, resulting in difficulties in sufficiently exploiting the properties of these remarkable materials. Here, we show that fluorescent small-sized (∼3.8 nm) SiNPs can be produced through biomimetic synthesis in rapid (10 min), low-cost, and environmentally benign manners. The as-prepared SiNPs simultaneously feature bright fluorescence (quantum yield (QY), ∼15-20%), narrow emission spectral width (full width at half-maximum (fwhm), ∼30 nm), and nontoxicity, making them as high-quality fluorescent probes for biological imaging in vitro and in vivo.

Facile, Large-Quantity Synthesis of Stable, Tunable-Color Silicon Nanoparticles and Their Application for Long-Term Cellular Imaging.

We herein introduce a facile, low-cost photochemical method capable of rapid (<40 min) and large-quantity (∼10 g) production of highly fluorescent (quantum yield: 25%) silicon nanoparticles (SiNPs) of tunable optical properties (peak emission wavelength in the range of 470-560 nm) under ambient air conditions, by introducing 1,8-naphthalimide as a reducing agent and surface ligands. The as-prepared SiNPs feature robust storage stability and photostability preserving strong and stable fluorescent during long-term (>3 h) high-power UV irradiation, in contrast to the rapid fluorescence quenching within 2 h of conventional organic dyes and II-VI quantum dots under the same conditions. The as-prepared SiNPs serving as photostable nanoprobes are workable for cellular imaging in long-term manners. Our findings provide a powerful method for mild-condition and low-cost, large-quantity production of highly fluorescent and photostable SiNPs for various promising applications.

Large-Scale Aqueous Synthesis of Fluorescent and Biocompatible Silicon Nanoparticles and Their Use as Highly Photostable Biological Probes

A large-scale synthetic strategy is developed for facile one-pot aqueous synthesis of silicon nanoparticles (SiNPs) yielding ∼0.1 g SiNPs of small sizes (∼2.2 nm) in 10 min. The as-prepared SiNPs feature strong fluorescence (photoluminescence quantum yield of 20-25%), favorable biocompatibility, and robust photo- and pH-stability. Moreover, the SiNPs are naturally water dispersible, requiring no additional post-treatment. Such SiNPs can serve as highly photostable bioprobes and are superbly suitable for long-term immunofluorescent cellular imaging.

Electrical Properties of Thin Layers Consisting of Surface Functionalized Silicon Nanoparticles

ABSTRACTThe present study investigates systematically, how the electrical properties of thin films consisting of silicon nanoparticles are affected by an organic monolayer coating the particles. Therefore, films of as-prepared silicon nanoparticles with a size of about 23 nm as well as freshly etched ones, both terminated with hydrogen, are compared with films of silicon nanoparticles functionalized with different 1-alkenes. It is found that the activation energy of the electron transport through the nanoparticle films scales with the thickness and permittivity of the respective organic monolayer.

Electroluminescence from silicon nanoparticles fabricated from the gas phase

Electroluminescence from as-prepared silicon nanoparticles, fabricated by gasphase synthesis, is demonstrated. The particles are embedded between an n-dopedGaAs substrate and a semitransparent indium tin oxide top electrode. The totalelectroluminescence intensity of the Si nanoparticles is more than a factor of three higherthan the corresponding signal from the epitaxial III–V semiconductor. This, together withthe low threshold voltage for electroluminescence, shows the good optical properties ofthese untreated particles and the efficient electrical injection into the device. Impactionization by electrons emitted from the top electrode is identified as the origin of theelectrically driven light emission.