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Silicon Nanoparticles: Synthesis and Application

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Advanced Nanomaterials and Nanotechnology".

Deadline for manuscript submissions: closed (31 March 2021) | Viewed by 21855

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Special Issue Editor

Dr. Yimin Chao

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Guest Editor

School of Chemistry, University of East Anglia, Norwich NR4 7TJ, UK
Interests: quantum dots; porous silicon; electrochemical etching; surface functionalization; energy conversion; thermoelectrics; energy storage; battery anode; energetic bridge; biosensor; drug delivery; bioimaging; cancer targeting and diagnosis
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Dear Colleagues,

Since the novel optical properties of porous silicon were discovered by Leigh Canham in the early 1990s, the research community has been carrying out intensive research on developing silicon quantum dots (SiQDs) and silicon nanoparticles (SiNPs) from classical porous silicon and from nanotechnology-based synthesis methods. For example, inverse micelle template formation, laser plasma synthesis, and lithography template methods are among typical bottom–up and top–down routes. During synthesis procedures, a critical issue is to prevent oxidation, which can be done by conjugation with functional groups on the surface.

The quantum confined optical and electronic properties render wide applications of SiQDs in biomedical imaging, drug delivery, and cancer targeting. The key step for such applications is to modify the surface with various functional ligands. Alkyl group capped SiQDs are among the earliest versions, but the surfaces are well protected from oxidation, which is still the best choice in terms of stability and the reliability of emission intensity. Amine-terminated SiQDs are acting as a platform for further functionalization. Recently-developed thiourea-functionalized SiQDs possess a strong ability to target epidermal growth factor receptors (EGFR) that are overexpressed in cancer cells. Other complex designs, such as encapsulations with drugs, provide vehicles for drug delivery and monitoring.

Silicon is the foundation for modern electronics and is still unreplaceable in the semiconductor industry, such as in information technology, artificial intelligence, and energy conversion and storage. Silicon nanostructures have been playing extraordinary roles in memory devices, thermoelectrics, solar energy conversion, and have been acting as powerful anodes in batteries and supercapacitors.

Nanotoxicity, reliability, stability, and reactivity of nanoparticles are important topics for environmentally-friendly synthesis and sustainable applications. The research field is advancing to new areas very rapidly.

It is my great pleasure to invite you to submit your manuscripts to this Special Issue. Research articles, communications, and reviews are all welcome.

Dr. Yimin Chao
Guest Editor

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Keywords

Porous silicon
silicon quantum dots
synthesis and functionalization
energy and environment
biomedical imaging
biosensor
drug delivery
cancer targeting and diagnosis

Published Papers (5 papers)

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Research

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11 pages, 2453 KiB

Open AccessArticle

Research into Two Photonic-Integrated Waveguides Based on SiGe Material

by Song Feng and Bin Xue

Materials 2020, 13(8), 1877; https://doi.org/10.3390/ma13081877 - 16 Apr 2020

Cited by 1 | Viewed by 1825

Abstract

SiGe (Silicon Germanium) is a common semiconductor material with many excellent properties, and many photonic-integrated devices are designed and fabricated with SiGe material. In this paper, two photonic-integrated SiGe waveguides are researched, namely the SiGe-SOI (Silicon Germanium-Silicon-On-Insulator) waveguide and the SiGe-OI (Silicon Germanium-On-Insulator) waveguide. In order to verify which structure has the better waveguide performance, two waveguide structures are built, and the effective refractive indexes and the loss characteristics of the two waveguides are analyzed and compared. By simulation, the SiGe-OI optical waveguide has better losses characteristics at a wavelength of 1.55 μm. Finally, SiGe-OI and SiGe-SOI waveguides are fabricated and tested to verify the correctness of theoretical analysis, and the experimental results show that the transmission losses of the SiGe-OI waveguide are respectively decreased by 36.6% and 28.3% at 400 nm and 600 nm waveguide width in comparison with the SiGe-SOI waveguide. The results also show that the SiGe-OI waveguide has better loss characteristics than those of the SiGe-SOI waveguide at the low Ge content. Full article

(This article belongs to the Special Issue Silicon Nanoparticles: Synthesis and Application)

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20 pages, 1703 KiB

Open AccessFeature PaperArticle

Endocytosis and Lack of Cytotoxicity of Alkyl-Capped Silicon Quantum Dots Prepared from Porous Silicon

by Wipaporn Phatvej, Harish K. Datta, Simon C. Wilkinson, Elaine Mutch, Ann K. Daly and Benjamin R. Horrocks

Materials 2019, 12(10), 1702; https://doi.org/10.3390/ma12101702 - 25 May 2019

Cited by 7 | Viewed by 3095

Abstract

Freely-dissolved silicon quantum dots were prepared by thermal hydrosilation of 1-undecene at high-porosity porous silicon under reflux in toluene. This reaction produces a suspension of alkyl-capped silicon quantum dots (alkyl SiQDs) with bright orange luminescence, a core Si nanocrystal diameter of about 2.5 nm and a total particle diameter of about 5 nm. Previous work has shown that these particles are rapidly endocytosed by malignant cell lines and have little or no acute toxicity as judged by the standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for viability and the Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay for apoptosis. We have extended this work to the CACO-2 cell line, an established model for the human small intestinal mucosa, and demonstrate that neither acute nor chronic (14 days) toxicity is observed as judged by cell morphology, viability, ATP production, ROS production and DNA damage (single cell gel electrophoresis) at doses of 50–200

μ

g mL

^{- 1}

. Quantitative assessment of the extent of uptake of alkyl SiQDs by CACO-2, HeLa, HepG2, and Huh7 cell lines by flow cytometry showed a wide variation. The liver cell lines (HepG2 and Huh7) were the most active and HeLa and CACO-2 showed comparable activity. Previous work has reported a cholesterol-sensitivity of the endocytosis (HeLa), which suggests a caveolin-mediated pathway. However, gene expression analysis by quantitative real–time polymerase chain reaction (RT-PCR) indicates very low levels of caveolins 1 and 2 in HepG2 and much higher levels in HeLa. The data suggest that the mechanism of endocytosis of the alkyl SiQDs is cell-line dependent. Full article

(This article belongs to the Special Issue Silicon Nanoparticles: Synthesis and Application)

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11 pages, 5847 KiB

Open AccessArticle

Microstructure and Thermal Insulation Property of Silica Composite Aerogel

by Lei Shang, Yang Lyu and Wenbo Han

Materials 2019, 12(6), 993; https://doi.org/10.3390/ma12060993 - 26 Mar 2019

Cited by 25 | Viewed by 5778

Abstract

Tetraethyl orthosilicate was selected as a matrix of heat insulating materials among three silanes, and an anti-infrared radiation fiber was chosen as a reinforcement for silica aerogel insulation composite. The silica aerogel was combined well and evenly distributed in the anti-infrared radiation fiber. The heat insulation effect was improved with the increase in thickness of the aerogel insulation material, as determined by the self-made aerospace insulation material insulation performance test equipment. The 15 mm and 30 mm thick thermal insulation material heated at 250 °C for 3 h, the temperatures at the cold surface were about 80 °C and 60 °C, respectively, and the temperatures at 150 mm above the cold surface were less than 60 °C and 50 °C, respectively. The silica aerogel composites with various thicknesses showed good thermal insulation stability. The silica insulation composite with a thickness of 15 mm exhibited good heat insulation performance, meets the thermal insulation requirements of general equipment compartments under low-temperature and long-term environmental conditions. The thermal conductivity of prepared silica aerogel composite was 0.0191 W·m⁻¹·k⁻¹ at room temperature and 0.0489 W·m⁻¹·k⁻¹ at 500 °C. Full article

(This article belongs to the Special Issue Silicon Nanoparticles: Synthesis and Application)

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Review

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33 pages, 7990 KiB

Open AccessFeature PaperReview

Mesoporous Silica Nanoparticles in Bioimaging

by Daohe Yuan, Connor M. Ellis and Jason J. Davis

Materials 2020, 13(17), 3795; https://doi.org/10.3390/ma13173795 - 27 Aug 2020

Cited by 33 | Viewed by 6646

Abstract

A biomedical contrast agent serves to enhance the visualisation of a specific (potentially targeted) physiological region. In recent years, mesoporous silica nanoparticles (MSNs) have developed as a flexible imaging platform of tuneable size/morphology, abundant surface chemistry, biocompatibility and otherwise useful physiochemical properties. This review discusses MSN structural types and synthetic strategies, as well as methods for surface functionalisation. Recent applications in biomedical imaging are then discussed, with a specific emphasis on magnetic resonance and optical modes together with utility in multimodal imaging. Full article

(This article belongs to the Special Issue Silicon Nanoparticles: Synthesis and Application)

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21 pages, 4577 KiB

Open AccessReview

Si-QD Synthesis for Visible Light Emission, Color Conversion, and Optical Switching

by Chih-Hsien Cheng and Gong-Ru Lin

Materials 2020, 13(16), 3635; https://doi.org/10.3390/ma13163635 - 17 Aug 2020

Cited by 3 | Viewed by 3090

Abstract

This paper reviews the developing progress on the synthesis of the silicon quantum dots (Si-QDs) via the different methods including electrochemical porous Si, Si ion implantation, and plasma enhanced chemical vapor deposition (PECVD), and exploring their featured applications for light emitting diode (LED), color-converted phosphors, and waveguide switching devices. The characteristic parameters of Si-QD LED via different syntheses are summarized for discussion. At first, the photoluminescence spectra of Si-QD and accompanied defects are analyzed to distinguish from each other. Next, the synthesis of porous Si and the performances of porous Si LED reported from different previous works are compared in detail. Later on, the Si-QD implantation in silicide (SiX) dielectric films developed to solve the instability of porous Si and their electroluminescent performances are also summarized for realizing the effect of host matrix to increase the emission quantum efficiency. As the Si-ion implantation still generates numerous defects in host matrix owing to physical bombardment, the PECVD method has emerged as the main-stream methodology for synthesizing Si-QD in SiX semiconductor or dielectric layer. This method effectively suppresses the structural matrix imperfection so as to enhance the external quantum efficiency of the Si-QD LED. With mature synthesis technology, Si-QD has been comprehensively utilized not only for visible light emission but also for color conversion and optical switching applications in future academia and industry. Full article

(This article belongs to the Special Issue Silicon Nanoparticles: Synthesis and Application)

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