Research

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19 pages, 17285 KiB

Open AccessArticle

Fabrication of Anisotropic Cu Ferrite-Polymer Core-Shell Nanoparticles for Photodynamic Ablation of Cervical Cancer Cells

by Shuo-Hsiu Kuo, Po-Ting Wu, Jing-Yin Huang, Chin-Pao Chiu, Jiashing Yu and Mei-Yi Liao

Nanomaterials 2020, 10(12), 2429; https://doi.org/10.3390/nano10122429 - 04 Dec 2020

Cited by 11 | Viewed by 3510

Abstract

In this work we developed methylene blue-immobilized copper-iron nanoparticles (MB-CuFe NPs) through a facile one-step hydrothermal reaction to achieve a better phototherapeutic effect. The Fe/Cu ratio of the CuFe NPs was controllable by merely changing the loading amount of iron precursor concentration. The [...] Read more.

In this work we developed methylene blue-immobilized copper-iron nanoparticles (MB-CuFe NPs) through a facile one-step hydrothermal reaction to achieve a better phototherapeutic effect. The Fe/Cu ratio of the CuFe NPs was controllable by merely changing the loading amount of iron precursor concentration. The CuFe NPs could serve as a Fenton catalyst to convert hydrogen peroxide (H₂O₂) into reactive oxygen species (ROS), while the superparamagnetic properties also suggest magnetic resonance imaging (MRI) potential. Furthermore, the Food and Drug Administration (FDA)-approved MB photosensitizer could strongly adsorb onto the surface of CuFe NPs to facilitate the drug delivery into cells and improve the photodynamic therapy at 660 nm via significant generation of singlet oxygen species, leading to enhanced cancer cell-damaging efficacy. An MTT (thiazolyl blue tetrazolium bromide) assay proved the low cytotoxicity of the CuFe NPs to cervical cancer cells (HeLa cells), namely above 80% at 25 ppm of the sample dose. A slight dissolution of Cu and Fe ions from the CuFe NPs in an acidic environment was obtained, providing direct evidence for CuFe NPs being degradable without the risk of long-term retention in the body. Moreover, the tremendous photo-to-thermal conversion of CuFe NPs was examined, which might be combined with photodynamic therapy (PDT) for promising development in the depletion of cancer cells after a single pulse of deep-red light irradiation at high laser power. Full article

(This article belongs to the Special Issue Nanobiophotonics, Photomedicine, and Imaging)

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19 pages, 7024 KiB

Open AccessArticle

2D CTAB-MoSe₂ Nanosheets and 0D MoSe₂ Quantum Dots: Facile Top-Down Preparations and Their Peroxidase-Like Catalytic Activity for Colorimetric Detection of Hydrogen Peroxide

by Da-Ren Hang, Ya-Qi Pan, Krishna Hari Sharma, Mitch M. C. Chou, Sk Emdadul Islam, Hui-Fen Wu and Chi-Te Liang

Nanomaterials 2020, 10(10), 2045; https://doi.org/10.3390/nano10102045 - 16 Oct 2020

Cited by 22 | Viewed by 4264

Abstract

We report the facile and economic preparation of two-dimensional (2D) and 0D MoSe₂ nanostructures based on systematic and non-toxic top-down strategies. We demonstrate the intrinsic peroxidase-like activity of these MoSe₂ nanostructures. The catalytic processes begin with facilitated decomposition of H₂ [...] Read more.

We report the facile and economic preparation of two-dimensional (2D) and 0D MoSe₂ nanostructures based on systematic and non-toxic top-down strategies. We demonstrate the intrinsic peroxidase-like activity of these MoSe₂ nanostructures. The catalytic processes begin with facilitated decomposition of H₂O₂ by using MoSe₂ nanostructures as peroxidase mimetics. In turn, a large amount of generated radicals oxidizes 3,3,5,5-tetramethylbenzidine (TMB) to produce a visible color reaction. The enzymatic kinetics of our MoSe₂ nanostructures complies with typical Michaelis–Menten theory. Catalytic kinetics study reveals a ping–pong mechanism. Moreover, the primary radical responsible for the oxidation of TMB was identified to be Ȯ₂⁻ by active species-trapping experiments. Based on the peroxidase mimicking property, we developed a new colorimetric method for H₂O₂ detection by using 2D and 0D MoSe₂ nanostructures. It is shown that the colorimetric sensing capability of our MoSe₂ catalysts is comparable to other 2D materials-based colorimetric platforms. For instance, the linear range of H₂O₂ detection is between 10 and 250 μM by using 2D functionalized MoSe₂ nanosheets as an artificial enzyme. Our work develops a systematic approach to use 2D materials to construct novel enzyme-free mimetic for a visual assay of H₂O₂, which has promising prospects in medical diagnosis and food security monitoring. Full article

(This article belongs to the Special Issue Nanobiophotonics, Photomedicine, and Imaging)

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14 pages, 3754 KiB

Open AccessArticle

Enhancing Förster Resonance Energy Transfer (FRET) Efficiency of Titania–Lanthanide Hybrid Upconversion Nanomaterials by Shortening the Donor–Acceptor Distance

by Syue-Liang Lin, Han-Chun Chen and Cheng Allen Chang

Nanomaterials 2020, 10(10), 2035; https://doi.org/10.3390/nano10102035 - 15 Oct 2020

Cited by 5 | Viewed by 2211

Abstract

Several robust titania (TiO₂) coated core/multishell trivalent lanthanide (Ln) upconversion nanoparticles (UCNPs) hybrid architecture designs have been reported for use in photodynamic therapy (PDT) against cancer, utilizing the near-infrared (NIR) excited energy down-shifting and up-conversion chain of Nd³⁺ (λ_793-808 [...] Read more.

Several robust titania (TiO₂) coated core/multishell trivalent lanthanide (Ln) upconversion nanoparticles (UCNPs) hybrid architecture designs have been reported for use in photodynamic therapy (PDT) against cancer, utilizing the near-infrared (NIR) excited energy down-shifting and up-conversion chain of Nd³⁺ (λ_{793-808 nm}) → Yb³⁺ (λ_{980 nm}) → Tm³⁺(λ_{475 nm}) → TiO₂ to produce reactive oxygen species (ROS) for deep tissue-penetrating oxidative cytotoxicity, e.g., NaLnF₄:Yb,Tm (Ln = Y, Gd). Herein, we demonstrate that by doping the Tm³⁺ emitter ions in the outer shell and the Nd³⁺ sensitizer ions in the core, the newly designed NaYF₄:Nd,Yb@Yb@Yb,Tm@TiO₂ hybrid UCNPs exert more ROS production than the reference NaYF₄:Yb,Tm@Yb@Nd,Yb@ TiO₂ with the Tm³⁺ ions in the core and the Nd³⁺ ions in the outer shell, upon 793 nm laser irradiation, primarily due to the shortening of the Tm³⁺-TiO₂ distance of the former with greater Förster resonance energy transfer (FRET) efficiency. After coating with polyallylamine hydrochloride (PAH)/polyethylene glycol folate (PEG-FA), the resulting NaYF₄:Nd,Yb@Yb@Yb,Tm@TiO₂-PAH-PEG-FA hybrid nanocomposites could be internalized in MDA-MB-231 cancer cells, which also show low dark cytotoxicity and effective photocytotoxicity upon 793 nm excitation. These nanocomposites could be further optimized and are potentially good candidates as nanotheranostics, as well as for other light-conversion applications. Full article

(This article belongs to the Special Issue Nanobiophotonics, Photomedicine, and Imaging)

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17 pages, 2344 KiB

Open AccessArticle

Ultrawide Bandgap and High Sensitivity of a Plasmonic Metal-Insulator-Metal Waveguide Filter with Cavity and Baffles

by Yuan-Fong Chou Chau, Chung-Ting Chou Chao, Hung Ji Huang, Muhammad Raziq Rahimi Kooh, Narayana Thotagamuge Roshan Nilantha Kumara, Chee Ming Lim and Hai-Pang Chiang

Nanomaterials 2020, 10(10), 2030; https://doi.org/10.3390/nano10102030 - 15 Oct 2020

Cited by 61 | Viewed by 3071

Abstract

A plasmonic metal-insulator-metal waveguide filter consisting of one rectangular cavity and three silver baffles is numerically investigated using the finite element method and theoretically described by the cavity resonance mode theory. The proposed structure shows a simple shape with a small number of [...] Read more.

A plasmonic metal-insulator-metal waveguide filter consisting of one rectangular cavity and three silver baffles is numerically investigated using the finite element method and theoretically described by the cavity resonance mode theory. The proposed structure shows a simple shape with a small number of structural parameters that can function as a plasmonic sensor with a filter property, high sensitivity and figure of merit, and wide bandgap. Simulation results demonstrate that a cavity with three silver baffles could significantly affect the resonance condition and remarkably enhance the sensor performance compared to its counterpart without baffles. The calculated sensitivity (S) and figure of merit (FOM) in the first mode can reach 3300.00 nm/RIU and 170.00 RIU⁻¹. Besides, S and FOM values can simultaneously get above 2000.00 nm/RIU and 110.00 RIU⁻¹ in the first and second modes by varying a broad range of the structural parameters, which are not attainable in the reported literature. The proposed structure can realize multiple modes operating in a wide wavelength range, which may have potential applications in the on-chip plasmonic sensor, filter, and other optical integrated circuits. Full article

(This article belongs to the Special Issue Nanobiophotonics, Photomedicine, and Imaging)

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9 pages, 2705 KiB

Open AccessArticle

One-Pot Synthesis of Thiol-Modified Liquid Crystals Conjugated Fluorescent Gold Nanoclusters

by Po-Hsuan Hsu, Sibidou Yougbaré, Jui-Chi Kuo, Dyah Ika Krisnawati, Achmad Jazidie, Mohammad Nuh, Po-Ting Chou, Yu-Cheng Hsiao and Tsung-Rong Kuo

Nanomaterials 2020, 10(9), 1755; https://doi.org/10.3390/nano10091755 - 06 Sep 2020

Cited by 6 | Viewed by 2795

Abstract

Gold nanoclusters (AuNCs) and liquid crystals (LCs) have shown great potential in nanobiotechnology applications due to their unique optical and structural properties. Herein, the hardcore of the 4-cyano biphenyl group for commonly used LCs of 4-cyano-4′-pentylbiphenyl (5CB) was utilized to synthesize 4′-(2-mercaptoethyl)-(1,1′-biphenyl)-4-carbonitrile (TAT-12) [...] Read more.

Gold nanoclusters (AuNCs) and liquid crystals (LCs) have shown great potential in nanobiotechnology applications due to their unique optical and structural properties. Herein, the hardcore of the 4-cyano biphenyl group for commonly used LCs of 4-cyano-4′-pentylbiphenyl (5CB) was utilized to synthesize 4′-(2-mercaptoethyl)-(1,1′-biphenyl)-4-carbonitrile (TAT-12) based on Suzuki coupling and Appel reaction. The structural and optical properties of thiol-modified TAT-12 LCs were demonstrated by nuclear magnetic resonance (NMR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy and differential scanning calorimetry (DSC). By one-pot synthesis, thiol-modified TAT-12 LCs were used as the ligands to prepare fluorescent gold nanoclusters (AuNCs@TAT-12) according to the Au-S bond between AuNCs and TAT-12. The spectra of UV-vis absorption and X-ray photoelectron spectroscopy (XPS) of AuNCs@TAT-12 indicated that the core of gold of AuNCs@TAT-12 exhibited high gold oxidation states. The fluorescence of AuNCs@TAT-12 was observed with a maximum intensity at ~352 nm coming from TAT-12 on AuNCs@TAT-12 and the fluorescence quantum yield of AuNCs@TAT-12 was calculated to be 10.1%. Furthermore, the fluorescence with a maximum intensity at ~448 nm was attributed to a ligand–metal charge transfer between the ligands of TAT-12 LCs and the core of AuNCs. The image of transmission electron microscopy (TEM) further demonstrated an approximately spherical shape of AuNCs@TAT-12 with an average size of 2.3 nm. A combination of UV-vis absorption spectra, XPS spectra, fluorescence spectra and TEM image, fluorescent AuNCs@TAT-12 were successfully synthesized via one-pot synthesis. Our work provides a practical approach to the synthesis of LCs conjugated AuNCs for future applications in nanobiotechnology. Full article

(This article belongs to the Special Issue Nanobiophotonics, Photomedicine, and Imaging)

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14 pages, 2823 KiB

Open AccessArticle

Highly Sensitive and Tunable Plasmonic Sensor Based on a Nanoring Resonator with Silver Nanorods

by Chung-Ting Chou Chao, Yuan-Fong Chou Chau, Hung Ji Huang, N. T. R. N. Kumara, Muhammad Raziq Rahimi Kooh, Chee Ming Lim and Hai-Pang Chiang

Nanomaterials 2020, 10(7), 1399; https://doi.org/10.3390/nano10071399 - 18 Jul 2020

Cited by 73 | Viewed by 4005

Abstract

We numerically and theoretically investigate a highly sensitive and tunable plasmonic refractive index sensor that is composed of a metal-insulator-metal waveguide with a side-coupled nanoring, containing silver nanorods using the finite element method. Results reveal that the presence of silver nanorods in the [...] Read more.

We numerically and theoretically investigate a highly sensitive and tunable plasmonic refractive index sensor that is composed of a metal-insulator-metal waveguide with a side-coupled nanoring, containing silver nanorods using the finite element method. Results reveal that the presence of silver nanorods in the nanoring has a significant impact on sensitivity and tunability performance. It gives a flexible way to tune the system response in the proposed structure. Our designed sensor has a sensitivity of 2080 nm/RIU (RIU is the refractive index unit) along with a figure of merit and a quality factor of 29.92 and 29.67, respectively. The adequate refractive index sensitivity can increase by adding the silver nanorods in a nanoring, which can induce new surface plasmon polaritons (SPPs) modes that cannot be found by a regular nanoring. For a practical application, a valid introduction of silver nanorods in the nanoring can dramatically reduce the dimension of the proposed structure without sacrificing performance. Full article

(This article belongs to the Special Issue Nanobiophotonics, Photomedicine, and Imaging)

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13 pages, 2762 KiB

Open AccessArticle

Development of Folic Acid-Conjugated and Methylene Blue-Adsorbed Au@TNA Nanoparticles for Enhanced Photodynamic Therapy of Bladder Cancer Cells

by Che-Wei Hsu, Nai-Chi Cheng, Mei-Yi Liao, Ting-Yu Cheng and Yi-Chun Chiu

Nanomaterials 2020, 10(7), 1351; https://doi.org/10.3390/nano10071351 - 10 Jul 2020

Cited by 14 | Viewed by 3307 | Correction

Abstract

Photodynamic therapy (PDT) is a promising treatment for malignancy. However, the low molecular solubility of photosensitizers (PSs) with a low accumulation at borderline malignant potential lesions results in the tardy and ineffective management of recurrent urothelial carcinoma. Herein, we used tannic acid (TNA), [...] Read more.

Photodynamic therapy (PDT) is a promising treatment for malignancy. However, the low molecular solubility of photosensitizers (PSs) with a low accumulation at borderline malignant potential lesions results in the tardy and ineffective management of recurrent urothelial carcinoma. Herein, we used tannic acid (TNA), a green precursor, to reduce HAuCl₄ in order to generate Au@TNA core-shell nanoparticles. The photosensitizer methylene blue (MB) was subsequently adsorbed onto the surface of the Au@TNA nanoparticles, leading to the incorporation of a PS within the organic shell of the Au nanoparticle nanosupport, denoted as Au@TNA@MB nanoparticles (NPs). By modifying the surface of the Au@TNA@MB NPs with the ligand folate acid (FA) using NH₂-PEG-NH₂ as a linker, we demonstrated that the targeted delivery strategy achieved a high accumulation of PSs in cancer cells. The cell viability of T24 cells decreased to 87.1%, 57.1%, and 26.6% upon treatment with 10 ppm_[Au] Au@TNA/MB NPs after 45 min, 2 h, and 4 h of incubation, respectively. We also applied the same targeted PDT treatment to normal urothelial SV-HUC-1 cells and observed minor phototoxicity, indicating that this safe photomedicine shows promise for applications aiming to achieve the local depletion of cancer sites without side effects. Full article

(This article belongs to the Special Issue Nanobiophotonics, Photomedicine, and Imaging)

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14 pages, 3433 KiB

Open AccessArticle

Reusable TiN Substrate for Surface Plasmon Resonance Heterodyne Phase Interrogation Sensor

by Ru-Jing Sun, Hung Ji Huang, Chien-Nan Hsiao, Yu-Wei Lin, Bo-Huei Liao, Yuan-Fong Chou Chau and Hai-Pang Chiang

Nanomaterials 2020, 10(7), 1325; https://doi.org/10.3390/nano10071325 - 06 Jul 2020

Cited by 14 | Viewed by 2877

Abstract

A TiN-based substrate with high reusability presented high-sensitivity refractive index measurements in a home-built surface plasmon resonance (SPR) heterodyne phase interrogation system. TiN layers with and without additional inclined-deposited TiN (i-TiN) layers on glass substrates reached high bulk charge carrier densities of 1.28 [...] Read more.

A TiN-based substrate with high reusability presented high-sensitivity refractive index measurements in a home-built surface plasmon resonance (SPR) heterodyne phase interrogation system. TiN layers with and without additional inclined-deposited TiN (i-TiN) layers on glass substrates reached high bulk charge carrier densities of 1.28 × 10²² and 1.91 × 10²² cm⁻³, respectively. The additional 1.4 nm i-TiN layer of the nanorod array presented a detection limit of 6.1 × 10⁻⁷ RIU and was higher than that of the 46 nm TiN layer at 1.2 × 10⁻⁶ RIU when measuring the refractive index of a glucose solution. Furthermore, the long-term durability of the TiN-based substrate demonstrated by multiple processing experiments presented a high potential for various practical sensing applications. Full article

(This article belongs to the Special Issue Nanobiophotonics, Photomedicine, and Imaging)

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15 pages, 2769 KiB

Open AccessArticle

Perfect Dual-Band Absorber Based on Plasmonic Effect with the Cross-Hair/Nanorod Combination

by Yuan-Fong Chou Chau, Chung-Ting Chou Chao, Hung Ji Huang, Muhammad Raziq Rahimi Kooh, N. T. R. N. Kumara, Chee Ming Lim and Hai-Pang Chiang

Nanomaterials 2020, 10(3), 493; https://doi.org/10.3390/nano10030493 - 09 Mar 2020

Cited by 71 | Viewed by 4639

Abstract

Plasmonic effect using a cross-hair can convey strongly localized surface plasmon modes among the separated composite nanostructures. Compared to its counterpart without the cross-hair, this characteristic has the remarkable merit of enhancing absorptance at resonance and can make the structure carry out a [...] Read more.

Plasmonic effect using a cross-hair can convey strongly localized surface plasmon modes among the separated composite nanostructures. Compared to its counterpart without the cross-hair, this characteristic has the remarkable merit of enhancing absorptance at resonance and can make the structure carry out a dual-band plasmonic perfect absorber (PPA). In this paper, we propose and design a novel dual-band PPA with a gathering of four metal-shell nanorods using a cross-hair operating at visible and near-infrared regions. Two absorptance peaks at 1050 nm and 750 nm with maximal absorptance of 99.59% and 99.89% for modes 1 and 2, respectively, are detected. High sensitivity of 1200 nm refractive unit (1/RIU), figure of merit of 26.67 and Q factor of 23.33 are acquired, which are very remarkable compared with the other PPAs. In addition, the absorptance in mode 1 is about nine times compared to its counterpart without the cross-hair. The proposed structure gives a novel inspiration for the design of a tunable dual-band PPA, which can be exploited for plasmonic sensor and other nanophotonic devices. Full article

(This article belongs to the Special Issue Nanobiophotonics, Photomedicine, and Imaging)

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8 pages, 2834 KiB

Open AccessArticle

Optical Properties of Electrically Active Gold Nanoisland Films Enabled with Interfaced Liquid Crystals

by Hung-Chi Yen, Tsung-Rong Kuo, Chun-Ta Wang, Jia-De Lin, Chia-Chun Chen and Yu-Cheng Hsiao

Nanomaterials 2020, 10(2), 290; https://doi.org/10.3390/nano10020290 - 09 Feb 2020

Cited by 7 | Viewed by 2292

Abstract

A system comprising a gold nanoisland film (Au NIF) covered with a liquid crystal (LC) material is introduced. By applying a voltage across the LC bulk, we demonstrate that changes in the refractive-index and orientation significantly modified the hybrid plasmonic–photonic resonances of the [...] Read more.

A system comprising a gold nanoisland film (Au NIF) covered with a liquid crystal (LC) material is introduced. By applying a voltage across the LC bulk, we demonstrate that changes in the refractive-index and orientation significantly modified the hybrid plasmonic–photonic resonances of the Au NIF. The hybrid structure enabled active control of the spectrum of the resonance wavelength of the metallic nanoisland by means of an externally applied electric field. Our modeling supports the observed results in LC/Au NIF. In a combination of the nanostructured surface with birefringent LCs, nonpolarized wavelength tunability of ~15 nm and absorbance tunability of ~0.024 were achieved in the visible wavelength, opening the door to optical devices and nanoscale sensors. Full article

(This article belongs to the Special Issue Nanobiophotonics, Photomedicine, and Imaging)

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15 pages, 30721 KiB

Open AccessArticle

Fabrication and Characterization of a Metallic–Dielectric Nanorod Array by Nanosphere Lithography for Plasmonic Sensing Application

by Yuan-Fong Chou Chau, Kuan-Hung Chen, Hai-Pang Chiang, Chee Ming Lim, Hung Ji Huang, Chih-Hsien Lai and N. T. R. N. Kumara

Nanomaterials 2019, 9(12), 1691; https://doi.org/10.3390/nano9121691 - 26 Nov 2019

Cited by 77 | Viewed by 5205

Abstract

In this paper, a periodic metallic–dielectric nanorod array which consists of Si nanorods coated with 30 nm Ag thin film set in a hexagonal configuration is fabricated and characterized. The fabrication procedure is performed by using nanosphere lithography with reactive ion etching, followed [...] Read more.

In this paper, a periodic metallic–dielectric nanorod array which consists of Si nanorods coated with 30 nm Ag thin film set in a hexagonal configuration is fabricated and characterized. The fabrication procedure is performed by using nanosphere lithography with reactive ion etching, followed by Ag thin-film deposition. The mechanism of the surface and gap plasmon modes supported by the fabricated structure is numerically demonstrated by the three-dimensional finite element method. The measured and simulated absorptance spectra are observed to have a same trend and a qualitative fit. Our fabricated plasmonic sensor shows an average sensitivity of 340.0 nm/RIU when applied to a refractive index sensor ranging from 1.0 to 1.6. The proposed substrates provide a practical plasmonic nanorod-based sensing platform, and the fabrication methods used are technically effective and low-cost. Full article

(This article belongs to the Special Issue Nanobiophotonics, Photomedicine, and Imaging)

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11 pages, 1871 KiB

Open AccessArticle

A Diamond Temperature Sensor Based on the Energy Level Shift of Nitrogen-Vacancy Color Centers

by Mingyang Yang, Qilong Yuan, Jingyao Gao, Shengcheng Shu, Feiyue Chen, Huifang Sun, Kazuhito Nishimura, Shaolong Wang, Jian Yi, Cheng-Te Lin and Nan Jiang

Nanomaterials 2019, 9(11), 1576; https://doi.org/10.3390/nano9111576 - 07 Nov 2019

Cited by 27 | Viewed by 4546

Abstract

The nitrogen-vacancy (NV) color center in chemical vapor deposition (CVD) diamond has been widely investigated in quantum information and quantum biosensors due to its excellent photon emission stability and long spin coherence time. However, the temperature dependence of the energy level of NV [...] Read more.

The nitrogen-vacancy (NV) color center in chemical vapor deposition (CVD) diamond has been widely investigated in quantum information and quantum biosensors due to its excellent photon emission stability and long spin coherence time. However, the temperature dependence of the energy level of NV color centers in diamond is different from other semiconductors with the same diamond cubic structure for the high Debye temperature and very small thermal expansion coefficient of diamond. In this work, a diamond sensor for temperature measurement with high precision was fabricated based on the investigation of the energy level shifts of NV centers by Raman and photoluminescence (PL) spectra. The results show that the intensity and linewidth of the zero-phonon line of NV centers highly depend on the environmental temperature, and the energy level shifts of NV centers in diamond follow the modified Varshni model very well, a model which is better than the traditional version. Accordingly, the NV color center shows the ability in temperature measurement with a high accuracy of up to 98%. The high dependence of NV centers on environmental temperature shows the possibility of temperature monitoring of NV center-based quantum sensors in biosystems. Full article

(This article belongs to the Special Issue Nanobiophotonics, Photomedicine, and Imaging)

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14 pages, 3096 KiB

Open AccessArticle

Ultra-High Refractive Index Sensing Structure Based on a Metal-Insulator-Metal Waveguide-Coupled T-Shape Cavity with Metal Nanorod Defects

by Yuan-Fong Chou Chau, Chung-Ting Chou Chao, Hung Ji Huang, N. T. R. N. Kumara, Chee Ming Lim and Hai-Pang Chiang

Nanomaterials 2019, 9(10), 1433; https://doi.org/10.3390/nano9101433 - 10 Oct 2019

Cited by 66 | Viewed by 4223

Abstract

An ultra-high plasmonic refractive index sensing structure composed of a metal–insulator–metal (MIM) waveguide coupled to a T-shape cavity and several metal nanorod defects is proposed and investigated by using finite element method. The designed plasmonic MIM waveguide can constitute a cavity resonance zone [...] Read more.

An ultra-high plasmonic refractive index sensing structure composed of a metal–insulator–metal (MIM) waveguide coupled to a T-shape cavity and several metal nanorod defects is proposed and investigated by using finite element method. The designed plasmonic MIM waveguide can constitute a cavity resonance zone and the metal nanorod defects can effectively trap the light in the T-shape cavity. The results reveal that both the size of defects in wider rectangular cavity and the length of narrower rectangular cavity are primary factors increasing the sensitivity performance. The sensitivity can achieve as high as 8280 nm/RIU (RIU denotes the refractive index unit), which is the highest sensitivity reported in plasmonic MIM waveguide-based sensors to our knowledge. In addition, the proposed structure can also serve as a temperature sensor with temperature sensitivity as high as 3.30 nm/°C. The designed structure with simplicity and ease of fabrication can be applied in sensitivity nanometer scale refractive index sensor and may potentially be used in optical on-chip nanosensor. Full article

(This article belongs to the Special Issue Nanobiophotonics, Photomedicine, and Imaging)

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Review

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23 pages, 6112 KiB

Open AccessReview

Nanomaterials for the Photothermal Killing of Bacteria

by Sibidou Yougbaré, Chinmaya Mutalik, Dyah Ika Krisnawati, Heny Kristanto, Achmad Jazidie, Mohammad Nuh, Tsai-Mu Cheng and Tsung-Rong Kuo

Nanomaterials 2020, 10(6), 1123; https://doi.org/10.3390/nano10061123 - 06 Jun 2020

Cited by 99 | Viewed by 7508

Abstract

An upsurge in the multidrug-resistant (MDR) bacterial pestilence is a global cause for concern in terms of human health. Lately, nanomaterials with photothermal effects have assisted in the efficient killing of MDR bacteria, attributable to their uncommon plasmonic, photocatalytic, and structural properties. Examinations [...] Read more.

An upsurge in the multidrug-resistant (MDR) bacterial pestilence is a global cause for concern in terms of human health. Lately, nanomaterials with photothermal effects have assisted in the efficient killing of MDR bacteria, attributable to their uncommon plasmonic, photocatalytic, and structural properties. Examinations of substantial amounts of photothermally enabled nanomaterials have shown bactericidal effects in an optimized time under near-infrared (NIR) light irradiation. In this review, we have compiled recent advances in photothermally enabled nanomaterials for antibacterial activities and their mechanisms. Photothermally enabled nanomaterials are classified into three groups, including metal-, carbon-, and polymer-based nanomaterials. Based on substantial accomplishments with photothermally enabled nanomaterials, we have inferred current trends and their prospective clinical applications. Full article

(This article belongs to the Special Issue Nanobiophotonics, Photomedicine, and Imaging)

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16 pages, 4825 KiB

Open AccessReview

Light-Activated Heterostructured Nanomaterials for Antibacterial Applications

by Chinmaya Mutalik, Di-Yan Wang, Dyah Ika Krisnawati, Achmad Jazidie, Sibidou Yougbare and Tsung-Rong Kuo

Nanomaterials 2020, 10(4), 643; https://doi.org/10.3390/nano10040643 - 30 Mar 2020

Cited by 47 | Viewed by 4980

Abstract

An outbreak of a bacterial contagion is a critical threat for human health worldwide. Recently, light-activated heterostructured nanomaterials (LAHNs) have shown potential as antibacterial agents, owing to their unique structural and optical properties. Many investigations have revealed that heterostructured nanomaterials are potential antibacterial [...] Read more.

An outbreak of a bacterial contagion is a critical threat for human health worldwide. Recently, light-activated heterostructured nanomaterials (LAHNs) have shown potential as antibacterial agents, owing to their unique structural and optical properties. Many investigations have revealed that heterostructured nanomaterials are potential antibacterial agents under light irradiation. In this review, we summarize recent developments of light-activated antibacterial agents using heterostructured nanomaterials and specifically categorized those agents based on their various light harvesters. The detailed antibacterial mechanisms are also addressed. With the achievements of LAHNs as antibacterial agents, we further discuss the challenges and opportunities for their future clinical applications. Full article

(This article belongs to the Special Issue Nanobiophotonics, Photomedicine, and Imaging)

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