Nanomaterials

Editorial

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4 pages, 220 KiB

Open AccessEditorial

Synthesis and Applications of Optical Materials

by Seung-Min Park and Bong-Hyun Jun

Nanomaterials 2023, 13(2), 297; https://doi.org/10.3390/nano13020297 - 11 Jan 2023

Cited by 1 | Viewed by 1673

Abstract

As optical materials have shown outstanding physical and chemical characteristics in the bio, medical, electronics, energy and related fields of studies, the potential benefits of using these materials have been widely recognized [...] Full article

(This article belongs to the Special Issue Synthesis and Application of Optical Materials)

Research

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11 pages, 3590 KiB

Open AccessFeature PaperArticle

Large Area Patterning of Highly Reproducible and Sensitive SERS Sensors Based on 10-nm Annular Gap Arrays

by Sihai Luo, Andrea Mancini, Enkui Lian, Wenqi Xu, Rodrigo Berté and Yi Li

Nanomaterials 2022, 12(21), 3842; https://doi.org/10.3390/nano12213842 - 31 Oct 2022

Cited by 8 | Viewed by 2157

Abstract

Applicable surface-enhanced Raman scattering (SERS) active substrates typically require low-cost patterning methodology, high reproducibility, and a high enhancement factor (EF) over a large area. However, the lack of reproducible, reliable fabrication for large area SERS substrates in a low-cost manner remains a challenge. [...] Read more.

Applicable surface-enhanced Raman scattering (SERS) active substrates typically require low-cost patterning methodology, high reproducibility, and a high enhancement factor (EF) over a large area. However, the lack of reproducible, reliable fabrication for large area SERS substrates in a low-cost manner remains a challenge. Here, a patterning method based on nanosphere lithography and adhesion lithography is reported that allows massively parallel fabrication of 10-nm annular gap arrays on large areas. The arrays exhibit excellent reproducibility and high SERS performance, with an EF of up to 10⁷. An effective wearable SERS contact lens for glucose detection is further demonstrated. The technique described here extends the range of SERS-active substrates that can be fabricated over large areas, and holds exciting potential for SERS-based chemical and biomedical detection. Full article

(This article belongs to the Special Issue Synthesis and Application of Optical Materials)

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13 pages, 917 KiB

Open AccessArticle

Size Effects in Single- and Few-Layer MoS₂ Nanoflakes: Impact on Raman Phonons and Photoluminescence

by Sandra Cortijo-Campos, Carlos Prieto and Alicia De Andrés

Nanomaterials 2022, 12(8), 1330; https://doi.org/10.3390/nano12081330 - 12 Apr 2022

Cited by 12 | Viewed by 2199

Abstract

The high optical absorption and emission of bidimensional MoS₂ are fundamental properties for optoelectronic and biodetection applications and the opportunity to retain these properties in high quality nano-sized flakes would bring further possibilities. Here, a large set of single-layer and few-layer (2–3 [...] Read more.

The high optical absorption and emission of bidimensional MoS₂ are fundamental properties for optoelectronic and biodetection applications and the opportunity to retain these properties in high quality nano-sized flakes would bring further possibilities. Here, a large set of single-layer and few-layer (2–3 layers) MoS₂ flakes with size in the range from 10 nm to 20 μm are obtained on sapphire by vapor deposition techniques and evaluated combining the information from the Raman phonons with photoluminescence (PL) and absorption bands. The flakes have triangular shape and are found to be progressively relaxed from the tensile strain imposed by the sapphire substrate as their size is reduced. An increasing hole doping as size decreases is deduced from the blue shift of the A_1g phonon, related to charge transfer from adsorbed oxygen. No clear correlation is observed between defects density and size, therefore, doping would be favored by the preferential adsorption of oxygen at the edges of the flakes, being progressively more important as the edge/surface ratio is incremented. This hole doping also produces a shift of the PL band to higher energies, up to 60 meV. The PL intensity is not found to be correlated to the size but to the presence of defects. The trends with size for single-layer and for 2–3 layer samples are found to be similar and the synthesis method does not influence PL efficiency which remains high down to 40 nm being thus promising for nanoscale photonics. Full article

(This article belongs to the Special Issue Synthesis and Application of Optical Materials)

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12 pages, 25533 KiB

Open AccessArticle

Improved Characteristics of CdSe/CdS/ZnS Core-Shell Quantum Dots Using an Oleylamine-Modified Process

by Kai-Ping Chang, Yu-Cheng Yeh, Chung-Jui Wu, Chao-Chun Yen and Dong-Sing Wuu

Nanomaterials 2022, 12(6), 909; https://doi.org/10.3390/nano12060909 - 9 Mar 2022

Cited by 9 | Viewed by 3907

Abstract

CdSe/CdS with ZnS/ZnO shell quantum dots (QDs) are synthesized by a one-pot method with various oleylamine (OLA) contents. The crystal structures of the QDs were analyzed by X-ray diffractometry, which showed ZnS diffraction peaks. It was represented that the ZnS shell was formed [...] Read more.

CdSe/CdS with ZnS/ZnO shell quantum dots (QDs) are synthesized by a one-pot method with various oleylamine (OLA) contents. The crystal structures of the QDs were analyzed by X-ray diffractometry, which showed ZnS diffraction peaks. It was represented that the ZnS shell was formed on the surface of the CdSe/CdS core. Interestingly, QDs with a high OLA concentration exhibit diffraction peaks of ZnS/ZnO. As a result, the thermal stability of QDs with ZnS/ZnO shells exhibits better performance than those with ZnS shells. In addition, the photoluminescence intensity of QDs with ZnS/ZnO shells shows a relatively slow decay of 7.1% compared with ZnS shells at 85 °C/85% relative humidity aging test for 500 h. These indicate that QDs with different OLA modifications can form ZnS/ZnO shells and have good stability in a harsh environment. The emission wavelength of QDs can be tuned from 505 to 610 nm, suitable for micro-LED display applications. Full article

(This article belongs to the Special Issue Synthesis and Application of Optical Materials)

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11 pages, 1946 KiB

Open AccessArticle

Movable Layer Device for Rapid Detection of Influenza a H1N1 Virus Using Highly Bright Multi-Quantum Dot-Embedded Particles and Magnetic Beads

by Islam Seder, Ahla Jo, Bong-Hyun Jun and Sung-Jin Kim

Nanomaterials 2022, 12(2), 284; https://doi.org/10.3390/nano12020284 - 17 Jan 2022

Cited by 2 | Viewed by 2183

Abstract

Preventing the rapid spread of viral infectious diseases has become a major concern for global health. In this study, we present a microfluidic platform that performs an immunoassay of viral antigens in a simple, automated, yet highly sensitive manner. The device uses silica [...] Read more.

Preventing the rapid spread of viral infectious diseases has become a major concern for global health. In this study, we present a microfluidic platform that performs an immunoassay of viral antigens in a simple, automated, yet highly sensitive manner. The device uses silica particles embedded with highly bright quantum dots (QD²) and performs the immunoassay with a vertically movable top layer and a rotating bottom layer. Through the motion of the layers and the surface tension in the liquids, reagents move from top chambers to bottom chambers and mix homogeneously. A tip in the top layer with a mobile permanent magnet moves the immune complexes comprising the magnetic beads, virus particles, and QD² between the bottom chambers. In this way, our automated device achieves a highly sensitive magnetic bead-based sandwich immunoassay for the influenza A H1N1 virus within 32.5 min. The detection limit of our method is 5.1 × 10⁻⁴ hemagglutination units, which is 2 × 10³ times more sensitive than that of the conventional hemagglutination method and is comparable to PCR. Our device is useful for the rapid and sensitive detection of infectious diseases in point-of-care applications and resource-limited environments. Full article

(This article belongs to the Special Issue Synthesis and Application of Optical Materials)

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11 pages, 2512 KiB

Open AccessArticle

Lateral Flow Immunoassay with Quantum-Dot-Embedded Silica Nanoparticles for Prostate-Specific Antigen Detection

by Sungje Bock, Hyung-Mo Kim, Jaehi Kim, Jaehyun An, Yun-Sik Choi, Xuan-Hung Pham, Ahla Jo, Kyeong-min Ham, Hobeom Song, Jung-Won Kim, Eunil Hahm, Won-Yeop Rho, Sang Hun Lee, Seung-min Park, Sangchul Lee, Dae Hong Jeong, Ho-Young Lee and Bong-Hyun Jun

Nanomaterials 2022, 12(1), 33; https://doi.org/10.3390/nano12010033 - 23 Dec 2021

Cited by 27 | Viewed by 5139

Abstract

Prostate cancer can be detected early by testing the presence of prostate-specific antigen (PSA) in the blood. Lateral flow immunoassay (LFIA) has been used because it is cost effective and easy to use and also has a rapid sample-to-answer process. Quantum dots (QDs) [...] Read more.

Prostate cancer can be detected early by testing the presence of prostate-specific antigen (PSA) in the blood. Lateral flow immunoassay (LFIA) has been used because it is cost effective and easy to use and also has a rapid sample-to-answer process. Quantum dots (QDs) with very bright fluorescence have been previously used to improve the detection sensitivity of LFIAs. In the current study, a highly sensitive LFIA kit was devised using QD-embedded silica nanoparticles. In the present study, only a smartphone and a computer software program, ImageJ, were used, because the developed system had high sensitivity by using very bright nanoprobes. The limit of PSA detection of the developed LFIA system was 0.138 ng/mL. The area under the curve of this system was calculated as 0.852. The system did not show any false-negative result when 47 human serum samples were analyzed; it only detected PSA and did not detect alpha-fetoprotein and newborn calf serum in the samples. Additionally, fluorescence was maintained on the strip for 10 d after the test. With its high sensitivity and convenience, the devised LFIA kit can be used for the diagnosis of prostate cancer. Full article

(This article belongs to the Special Issue Synthesis and Application of Optical Materials)

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15 pages, 2988 KiB

Open AccessArticle

Nonenzymatic Hydrogen Peroxide Detection Using Surface-Enhanced Raman Scattering of Gold–Silver Core–Shell-Assembled Silica Nanostructures

by Xuan-Hung Pham, Bomi Seong, Sungje Bock, Eunil Hahm, Kim-Hung Huynh, Yoon-Hee Kim, Wooyeon Kim, Jaehi Kim, Dong-Eun Kim and Bong-Hyun Jun

Nanomaterials 2021, 11(10), 2748; https://doi.org/10.3390/nano11102748 - 17 Oct 2021

Cited by 14 | Viewed by 3413

Abstract

Hydrogen peroxide (H₂O₂) plays important roles in cellular signaling and in industry. Thus, the accurate detection of H₂O₂ is critical for its application. Unfortunately, the direct detection of H₂O₂ by surface-enhanced Raman spectroscopy [...] Read more.

Hydrogen peroxide (H₂O₂) plays important roles in cellular signaling and in industry. Thus, the accurate detection of H₂O₂ is critical for its application. Unfortunately, the direct detection of H₂O₂ by surface-enhanced Raman spectroscopy (SERS) is not possible because of its low Raman cross section. Therefore, the detection of H₂O₂ via the presence of an intermediary such as 3,3,5,5-tetramethylbenzidine (TMB) has recently been developed. In this study, the peroxidase-mimicking activity of gold–silver core–shell-assembled silica nanostructures (SiO₂@Au@Ag alloy NPs) in the presence of TMB was investigated using SERS for detecting H₂O₂. In the presence of H₂O₂, the SiO₂@Au@Ag alloy catalyzed the conversion of TMB to oxidized TMB, which was absorbed onto the surface of the SiO₂@Au@Ag alloy. The SERS characteristics of the alloy in the TMB–H₂O₂ mixture were investigated. The evaluation of the SERS band to determine the H₂O₂ level utilized the SERS intensity of oxidized TMB bands. Moreover, the optimal conditions for H₂O₂ detection using SiO₂@Au@Ag alloy included incubating 20 µg/mL SiO₂@Au@Ag alloy NPs with 0.8 mM TMB for 15 min and measuring the Raman signal at 400 µg/mL SiO₂@Au@Ag alloy NPs. Full article

(This article belongs to the Special Issue Synthesis and Application of Optical Materials)

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14 pages, 4075 KiB

Open AccessArticle

Top-Down N-Doped Carbon Quantum Dots for Multiple Purposes: Heavy Metal Detection and Intracellular Fluorescence

by Francesca Limosani, Elvira Maria Bauer, Daniele Cecchetti, Stefano Biagioni, Viviana Orlando, Roberto Pizzoferrato, Paolo Prosposito and Marilena Carbone

Nanomaterials 2021, 11(9), 2249; https://doi.org/10.3390/nano11092249 - 31 Aug 2021

Cited by 41 | Viewed by 4382

Abstract

In the present study, we successfully synthesized N-doped carbon quantum dots (N-CQDs) using a top-down approach, i.e., hydroxyl radical opening of fullerene with hydrogen peroxide, in basic ambient using ammonia for two different reaction times. The ensuing characterization via dynamic light scattering, SEM, [...] Read more.

In the present study, we successfully synthesized N-doped carbon quantum dots (N-CQDs) using a top-down approach, i.e., hydroxyl radical opening of fullerene with hydrogen peroxide, in basic ambient using ammonia for two different reaction times. The ensuing characterization via dynamic light scattering, SEM, and IR spectroscopy revealed a size control that was dependent on the reaction time, as well as a more pronounced -NH₂ functionalization. The N-CQDs were probed for metal ion detection in aqueous solutions and during bioimaging and displayed a Cr³⁺ and Cu²⁺ selectivity shift at a higher degree of -NH₂ functionalization, as well as HEK-293 cell nuclei marking. Full article

(This article belongs to the Special Issue Synthesis and Application of Optical Materials)

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10 pages, 3652 KiB

Open AccessArticle

Multi-Quantum Dots-Embedded Silica-Encapsulated Nanoparticle-Based Lateral Flow Assay for Highly Sensitive Exosome Detection

by Hyung-Mo Kim, Chiwoo Oh, Jaehyun An, Seungki Baek, Sungje Bock, Jaehi Kim, Heung-Su Jung, Hobeom Song, Jung-Won Kim, Ahla Jo, Dong-Eun Kim, Won-Yeop Rho, Jin-Young Jang, Gi Jeong Cheon, Hyung-Jun Im and Bong-Hyun Jun

Nanomaterials 2021, 11(3), 768; https://doi.org/10.3390/nano11030768 - 18 Mar 2021

Cited by 31 | Viewed by 5013

Abstract

Exosomes are attracting attention as new biomarkers for monitoring the diagnosis and prognosis of certain diseases. Colorimetric-based lateral-flow assays have been previously used to detect exosomes, but these have the disadvantage of a high limit of detection. Here, we introduce a new technique [...] Read more.

Exosomes are attracting attention as new biomarkers for monitoring the diagnosis and prognosis of certain diseases. Colorimetric-based lateral-flow assays have been previously used to detect exosomes, but these have the disadvantage of a high limit of detection. Here, we introduce a new technique to improve exosome detection. In our approach, highly bright multi-quantum dots embedded in silica-encapsulated nanoparticles (M–QD–SNs), which have uniform size and are brighter than single quantum dots, were applied to the lateral flow immunoassay method to sensitively detect exosomes. Anti-CD63 antibodies were introduced on the surface of the M–QD–SNs, and a lateral flow immunoassay with the M–QD–SNs was conducted to detect human foreskin fibroblast (HFF) exosomes. Exosome samples included a wide range of concentrations from 100 to 1000 exosomes/µL, and the detection limit of our newly designed system was 117.94 exosome/μL, which was 11 times lower than the previously reported limits. Additionally, exosomes were selectively detected relative to the negative controls, liposomes, and newborn calf serum, confirming that this method prevented non-specific binding. Thus, our study demonstrates that highly sensitive and quantitative exosome detection can be conducted quickly and accurately by using lateral immunochromatographic analysis with M–QD–SNs. Full article

(This article belongs to the Special Issue Synthesis and Application of Optical Materials)

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12 pages, 3691 KiB

Open AccessArticle

Effect of Au Nanoparticles and Scattering Layer in Dye-Sensitized Solar Cells Based on Freestanding TiO₂ Nanotube Arrays

by Kang-Hun Lee, Seung-Hee Han, Ana Chuquer, Hwa-Young Yang, Jaehi Kim, Xuan-Hung Pham, Won-Ju Yun, Bong-Hyun Jun and Won-Yeop Rho

Nanomaterials 2021, 11(2), 328; https://doi.org/10.3390/nano11020328 - 27 Jan 2021

Cited by 6 | Viewed by 3085

Abstract

The development of high efficiency dye-sensitized solar cells (DSSCs) has received tremendous attention. Many researchers have introduced new materials for use in DSSCs to achieve high efficiency. In this study, the change in power conversion efficiency (PCE) of DSSCs was investigated by introducing [...] Read more.

The development of high efficiency dye-sensitized solar cells (DSSCs) has received tremendous attention. Many researchers have introduced new materials for use in DSSCs to achieve high efficiency. In this study, the change in power conversion efficiency (PCE) of DSSCs was investigated by introducing two types of materials—Au nanoparticles (Au NPs) and a scattering layer. A DSSC fabricated without neither Au NPs nor a scattering layer achieved a PCE of 5.85%. The PCE of a DSSC based on freestanding TiO₂ nanotube arrays (f-TNTAs) with Au NPs was 6.50% due to better electron generation because the plasmonic absorption band of Au NPs is 530 nm, which matches the dye absorbance. Thus, more electrons were generated at 530 nm, which affected the PCE of the DSSC. The PCE of DSSCs based on f-TNTAs with a scattering layer was 6.61% due to better light harvesting by scattering. The scattering layer reflects all wavelengths of light that improve the light harvesting in the active layer in DSSCs. Finally, the PCE of DSSCs based on the f-TNTAs with Au NPs and a scattering layer was 7.12% due to the synergy of better electron generation and light harvesting by plasmonics and scattering. The application of Au NPs and a scattering layer is a promising research area for DSSCs as they can increase the electron generation and light harvesting ability. Full article

(This article belongs to the Special Issue Synthesis and Application of Optical Materials)

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Review

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18 pages, 4085 KiB

Open AccessReview

Recent Insights into NIR-Light-Responsive Materials for Photothermal Cell Treatments

by Md Imran Hossain, Sitansu Sekhar Nanda, Subramanian Tamil Selvan and Dong Kee Yi

Nanomaterials 2022, 12(19), 3318; https://doi.org/10.3390/nano12193318 - 23 Sep 2022

Cited by 9 | Viewed by 3102

Abstract

Controlling cells using photo-responsive materials is highly indispensable in the current biomedical sector. Considering the potential side effects of nanoparticles, it has become a challenge to control cells with photo-responsive materials. Recent studies have described several methods for controlling cell behavior using nanoparticles [...] Read more.

Controlling cells using photo-responsive materials is highly indispensable in the current biomedical sector. Considering the potential side effects of nanoparticles, it has become a challenge to control cells with photo-responsive materials. Recent studies have described several methods for controlling cell behavior using nanoparticles subjected to the near-infrared (NIR) laser light operating at the wavelength of 808 nm to 980 nm and at the power densities of 0.33 to 0.72 W·cm⁻². The challenge here is the preparation of biocompatible nanoparticles for both in vivo and in vitro studies and understanding cell behavior with an external light source recommended for biological application. Earlier studies have well documented many approaches and associated mechanisms for controlling cell behavior and the interaction between nanoparticles, cells, and appropriate external light sources. In this review, various nanomaterials such as metal nanomaterials and carbon-based nanomaterials are compared systematically regarding the effects of controlling cell behavior and inflammation by studying their mechanisms, route of administration, dose, and adverse effects such as toxicity and the interaction of nanoparticles with a specific wavelength of the light. Future directions should focus on stable and efficient light-responsive materials with minimal cytotoxicity. Full article

(This article belongs to the Special Issue Synthesis and Application of Optical Materials)

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26 pages, 7471 KiB

Open AccessReview

Nano-Physical Characterization of Chemical Vapor Deposition-Grown Monolayer Graphene for High Performance Electrode: Raman, Surface-Enhanced Raman Spectroscopy, and Electrostatic Force Microscopy Studies

by Won-Hwa Park

Nanomaterials 2021, 11(11), 2839; https://doi.org/10.3390/nano11112839 - 25 Oct 2021

Cited by 6 | Viewed by 2659

Abstract

To achieve high-quality chemical vapor deposition of monolayer graphene electrodes (CVD-MG), appropriate characterization at each fabrication step is essential. In this article, (1) Raman spectroscopy/microscopy are employed to unravel the contact effect between the CVD-MG and Cu foil in suspended/supported formation. (2) The [...] Read more.

To achieve high-quality chemical vapor deposition of monolayer graphene electrodes (CVD-MG), appropriate characterization at each fabrication step is essential. In this article, (1) Raman spectroscopy/microscopy are employed to unravel the contact effect between the CVD-MG and Cu foil in suspended/supported formation. (2) The Surface-Enhanced Raman spectroscopy (SERS) system is described, unveiling the presence of a z-directional radial breathing-like mode (RBLM) around 150 cm⁻¹, which matches the Raman shift of the radial breathing mode (RBM) from single-walled carbon nanotubes (SWCNTs) around 150 cm⁻¹. This result indicates the CVD-MG located between the Au NPs and Au film is not flat but comprises heterogeneous protrusions of some domains along the z-axis. Consequently, the degree of carrier mobility can be influenced, as the protruding domains result in lower carrier mobility due to flexural phonon–electron scattering. A strongly enhanced G-peak domain, ascribed to the presence of scrolled graphene nanoribbons (sGNRs), was observed, and there remains the possibility for the fabrication of sGNRs as sources of open bandgap devices. (3) Electrostatic force microscopy (EFM) is used for the measurement of surface charge distribution of graphene at the nanoscale and is crucial in substantiating the electrical performance of CVD-MG, which was influenced by the surface structure of the Cu foil. The ripple (RP) structures were determined using EFM correlated with Raman spectroscopy, exhibiting a higher tapping amplitude which was observed with structurally stable and hydrophobic RPs with a threading type than surrounding RPs. (4) To reduce the RP density and height, a plausible fabrication could be developed that controls the electrical properties of the CVD-MG by tuning the cooling rate. Full article

(This article belongs to the Special Issue Synthesis and Application of Optical Materials)

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