Editorial

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Open AccessEditorial

Functional Optical Nano/Micromaterials

by

Won-Yeop Rho

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Bong-Hyun Jun

Int. J. Mol. Sci. 2023, 24(8), 7458; https://doi.org/10.3390/ijms24087458 - 18 Apr 2023

Viewed by 545

Abstract

The interaction between light and optical materials is central to science, as these materials possess remarkable physical, chemical, and photonical characteristics [...] Full article

(This article belongs to the Special Issue Functional Optical Nano/Micromaterials)

Research

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Open AccessCommunication

In Vitro Tracking of Human Umbilical Vein Endothelial Cells Using Ultra-Sensitive Quantum Dot-Embedded Silica Nanoparticles

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Mukhtar Anthony Safaa

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Yoon-Sik Lee

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Bong-Hyun Jun

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Hyun-Sook Park

Int. J. Mol. Sci. 2023, 24(6), 5794; https://doi.org/10.3390/ijms24065794 - 17 Mar 2023

Cited by 2 | Viewed by 1021

Abstract

The nanoscale spatiotemporal resolution of single-particle tracking (SPT) renders it a powerful method for exploring single-molecule dynamics in living cells or tissues, despite the disadvantages of using traditional organic fluorescence probes, such as the weak fluorescent signal against the strong cellular autofluorescence background [...] Read more.

The nanoscale spatiotemporal resolution of single-particle tracking (SPT) renders it a powerful method for exploring single-molecule dynamics in living cells or tissues, despite the disadvantages of using traditional organic fluorescence probes, such as the weak fluorescent signal against the strong cellular autofluorescence background coupled with a fast-photobleaching rate. Quantum dots (QDs), which enable tracking targets in multiple colors, have been proposed as an alternative to traditional organic fluorescence dyes; however, they are not ideally suitable for applying SPT due to their hydrophobicity, cytotoxicity, and blinking problems. This study reports an improved SPT method using silica-coated QD-embedded silica nanoparticles (QD²), which represent brighter fluorescence and are less toxic than single QDs. After treatment of QD² in 10 μg/mL, the label was retained for 96 h with 83.76% of labeling efficiency, without impaired cell function such as angiogenesis. The improved stability of QD² facilitates the visualization of in situ endothelial vessel formation without real-time staining. Cells retain QD² fluorescence signal for 15 days at 4 °C without significant photobleaching, indicating that QD² has overcome the limitations of SPT enabling long-term intracellular tracking. These results proved that QD² could be used for SPT as a substitute for traditional organic fluorophores or single quantum dots, with its photostability, biocompatibility, and superior brightness. Full article

(This article belongs to the Special Issue Functional Optical Nano/Micromaterials)

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Open AccessArticle

Copper(II) Etioporphyrinate as a Promising Photoluminescent and Electroluminescent Temperature Sensor

by

Andrey Yu. Chernyadyev

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Alexey E. Aleksandrov

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Dmitry A. Lypenko

and

Aslan Yu. Tsivadze

Int. J. Mol. Sci. 2022, 23(18), 10961; https://doi.org/10.3390/ijms231810961 - 19 Sep 2022

Cited by 3 | Viewed by 1033

Abstract

Luminescent temperature sensors are of great interest because they allow remote determination of temperature in transparent media, such as living tissues, as well as on scattering or transparent surfaces of materials. This study analyzes the luminescent properties of copper(II) etioporphyrinate (Cu-EtioP) in a [...] Read more.

Luminescent temperature sensors are of great interest because they allow remote determination of temperature in transparent media, such as living tissues, as well as on scattering or transparent surfaces of materials. This study analyzes the luminescent properties of copper(II) etioporphyrinate (Cu-EtioP) in a polystyrene film upon variation of temperature from −195 °C to +65 °C in a cryostat. It is shown that the ratio of intensities of phosphorescence transitions in the red spectral region of such a material varies significantly, that is, the material has thermosensory properties. The phosphorescence decay curves of copper(II) etioporphyrinate in a polystyrene film are analyzed. The quantum yield of phosphorescence of copper(II) etioporphyrinate determined by the absolute method was 3.15%. It was also found that the electroluminescence (EL) spectra of copper(II) etioporphyrinate in a poly(9-vinylcarbazole) (PVK) matrix demonstrated a similar change in the spectra in the temperature range −3 °C to +80 °C. That is, copper(II) etioporphyrinate can also be used as a luminescent temperature sensor as part of an active OLED layer. Full article

(This article belongs to the Special Issue Functional Optical Nano/Micromaterials)

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Open AccessCommunication

Silica Shell Thickness-Dependent Fluorescence Properties of SiO₂@Ag@SiO₂@QDs Nanocomposites

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Int. J. Mol. Sci. 2022, 23(17), 10041; https://doi.org/10.3390/ijms231710041 - 02 Sep 2022

Cited by 2 | Viewed by 1296

Abstract

Silica shell coatings, which constitute important technology for nanoparticle (NP) developments, are utilized in many applications. The silica shell’s thickness greatly affects distance-dependent optical properties, such as metal-enhanced fluorescence (MEF) and fluorescence quenching in plasmonic nanocomposites. However, the precise control of silica-shell thicknesses [...] Read more.

Silica shell coatings, which constitute important technology for nanoparticle (NP) developments, are utilized in many applications. The silica shell’s thickness greatly affects distance-dependent optical properties, such as metal-enhanced fluorescence (MEF) and fluorescence quenching in plasmonic nanocomposites. However, the precise control of silica-shell thicknesses has been mainly conducted on single metal NPs, and rarely on complex nanocomposites. In this study, silica shell-coated Ag nanoparticle-assembled silica nanoparticles (SiO₂@Ag@SiO₂), with finely controlled silica shell thicknesses (4 nm to 38 nm), were prepared, and quantum dots (QDs) were introduced onto SiO₂@Ag@SiO₂. The dominant effect between plasmonic quenching and MEF was defined depending on the thickness of the silica shell between Ag and QDs. When the distance between Ag NPs to QDs was less than ~10 nm, SiO₂@Ag@SiO₂@QDs showed weaker fluorescence intensities than SiO₂@QD (without metal) due to the quenching effect. On the other hand, when the distance between Ag NPs to QDs was from 10 nm to 14 nm, the fluorescence intensity of SiO₂@Ag@SiO₂@QD was stronger than SiO₂@QDs due to MEF. The results provide background knowledge for controlling the thickness of silica shells in metal-containing nanocomposites and facilitate the development of potential applications utilizing the optimal plasmonic phenomenon. Full article

(This article belongs to the Special Issue Functional Optical Nano/Micromaterials)

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Open AccessArticle

Optimizing the Aspect Ratio of Nanopatterned Mesoporous TiO₂ Thin-Film Layer to Improve Energy Conversion Efficiency of Perovskite Solar Cells

by

Hwa-Young Yang

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Ana Chuquer

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Seung-Hee Han

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Gangasagar Sharma Gaudel

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Int. J. Mol. Sci. 2021, 22(22), 12235; https://doi.org/10.3390/ijms222212235 - 12 Nov 2021

Cited by 5 | Viewed by 2151

Abstract

The energy conversion efficiency (ECE) (

η

), current density (J_sc), open-circuit voltage (V_oc), and fill factor (ff) of perovskite solar cells were studied by using the transmittance of a nanopatterned mesoporous TiO₂ (mp-TiO [...] Read more.

The energy conversion efficiency (ECE) (

η

), current density (J_sc), open-circuit voltage (V_oc), and fill factor (ff) of perovskite solar cells were studied by using the transmittance of a nanopatterned mesoporous TiO₂ (mp-TiO₂) thin-film layer. To improve the ECE of perovskite solar cells, a mp-TiO₂ thin-film layer was prepared to be used as an electron transport layer (ETL) via the nanoimprinting method for nanopatterning, which was controlled by the aspect ratio. The nanopatterned mp-TiO₂ thin-film layer had a uniform and well-designed structure, and the diameter of nanopatterning was 280 nm. The aspect ratio was controlled at the depths of 75, 97, 127, and 167 nm, and the perovskite solar cell was fabricated with different depths. The ECE of the perovskite solar cells with the nanopatterned mp-TiO₂ thin-film layer was 14.50%, 15.30%, 15.83%, or 14.24%, which is higher than that of a non-nanopatterned mp-TiO₂ thin-film layer (14.07%). The enhancement of ECE was attributed to the transmittance of the nanopatterned mp-TiO₂ thin-film layer that is due to the improvement of the electron generation. As a result, better electron generation affected the electron density, and J_sc increased the V_oc, and ff of perovskite solar cells. Full article

(This article belongs to the Special Issue Functional Optical Nano/Micromaterials)

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Open AccessArticle

Synthesis of Finely Controllable Sizes of Au Nanoparticles on a Silica Template and Their Nanozyme Properties

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Int. J. Mol. Sci. 2021, 22(19), 10382; https://doi.org/10.3390/ijms221910382 - 26 Sep 2021

Cited by 6 | Viewed by 2340

Abstract

The precise synthesis of fine-sized nanoparticles is critical for realizing the advantages of nanoparticles for various applications. We developed a technique for preparing finely controllable sizes of gold nanoparticles (Au NPs) on a silica template, using the seed-mediated growth and interval dropping methods. [...] Read more.

The precise synthesis of fine-sized nanoparticles is critical for realizing the advantages of nanoparticles for various applications. We developed a technique for preparing finely controllable sizes of gold nanoparticles (Au NPs) on a silica template, using the seed-mediated growth and interval dropping methods. These Au NPs, embedded on silica nanospheres (SiO₂@Au NPs), possess peroxidase-like activity as nanozymes and have several advantages over other nanoparticle-based nanozymes. We confirmed their peroxidase activity; in addition, factors affecting the activity were investigated by varying the reaction conditions, such as concentrations of tetramethyl benzidine and H₂O₂, pH, particle amount, reaction time, and termination time. We found that SiO₂@Au NPs are highly stable under long-term storage and reusable for five cycles. Our study, therefore, provides a novel method for controlling the properties of nanoparticles and for developing nanoparticle-based nanozymes. Full article

(This article belongs to the Special Issue Functional Optical Nano/Micromaterials)

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Review

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Open AccessReview

Recent Advances in Metallic Nanoparticle Assemblies for Surface-Enhanced Spectroscopy

by

Beata Tim

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Paulina Błaszkiewicz

and

Michał Kotkowiak

Int. J. Mol. Sci. 2022, 23(1), 291; https://doi.org/10.3390/ijms23010291 - 28 Dec 2021

Cited by 15 | Viewed by 2051

Abstract

Robust and versatile strategies for the development of functional nanostructured materials often focus on assemblies of metallic nanoparticles. Research interest in such assemblies arises due to their potential applications in the fields of photonics and sensing. Metallic nanoparticles have received considerable recent attention [...] Read more.

Robust and versatile strategies for the development of functional nanostructured materials often focus on assemblies of metallic nanoparticles. Research interest in such assemblies arises due to their potential applications in the fields of photonics and sensing. Metallic nanoparticles have received considerable recent attention due to their connection to the widely studied phenomenon of localized surface plasmon resonance. For instance, plasmonic hot spots can be observed within their assemblies. A useful form of spectroscopy is based on surface-enhanced Raman scattering (SERS). This phenomenon is a commonly used in sensing techniques, and it works using the principle that scattered inelastic light can be greatly enhanced at a surface. However, further research is required to enable improvements to the SERS techniques. For example, one question that remains open is how to design uniform, highly reproducible, and efficiently enhancing substrates of metallic nanoparticles with high structural precision. In this review, a general overview on nanoparticle functionalization and the impact on nanoparticle assembly is provided, alongside an examination of their applications in surface-enhanced Raman spectroscopy. Full article

(This article belongs to the Special Issue Functional Optical Nano/Micromaterials)

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Open AccessReview

Synthesis and Application of Silica-Coated Quantum Dots in Biomedicine

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Int. J. Mol. Sci. 2021, 22(18), 10116; https://doi.org/10.3390/ijms221810116 - 18 Sep 2021

Cited by 14 | Viewed by 4425

Abstract

Quantum dots (QDs) are semiconductor nanoparticles with outstanding optoelectronic properties. More specifically, QDs are highly bright and exhibit wide absorption spectra, narrow light bands, and excellent photovoltaic stability, which make them useful in bioscience and medicine, particularly for sensing, optical imaging, cell separation, [...] Read more.

Quantum dots (QDs) are semiconductor nanoparticles with outstanding optoelectronic properties. More specifically, QDs are highly bright and exhibit wide absorption spectra, narrow light bands, and excellent photovoltaic stability, which make them useful in bioscience and medicine, particularly for sensing, optical imaging, cell separation, and diagnosis. In general, QDs are stabilized using a hydrophobic ligand during synthesis, and thus their hydrophobic surfaces must undergo hydrophilic modification if the QDs are to be used in bioapplications. Silica-coating is one of the most effective methods for overcoming the disadvantages of QDs, owing to silica’s physicochemical stability, nontoxicity, and excellent bioavailability. This review highlights recent progress in the design, preparation, and application of silica-coated QDs and presents an overview of the major challenges and prospects of their application. Full article

(This article belongs to the Special Issue Functional Optical Nano/Micromaterials)

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