Nanomaterials

16 pages, 4579 KiB

Open AccessArticle

Synthesis, Characterizations, and 9.4 Tesla T₂ MR Images of Polyacrylic Acid-Coated Terbium(III) and Holmium(III) Oxide Nanoparticles

by Shanti Marasini, Huan Yue, Son Long Ho, Ji Ae Park, Soyeon Kim, Ki-Hye Jung, Hyunsil Cha, Shuwen Liu, Tirusew Tegafaw, Mohammad Yaseen Ahmad, Adibehalsadat Ghazanfari, Kwon-Seok Chae, Yongmin Chang and Gang Ho Lee

Nanomaterials 2021, 11(5), 1355; https://doi.org/10.3390/nano11051355 - 20 May 2021

Cited by 16 | Viewed by 3525

Abstract

Polyacrylic acid (PAA)-coated lanthanide oxide (Ln₂O₃) nanoparticles (NPs) (Ln = Tb and Ho) with high colloidal stability and good biocompatibility were synthesized, characterized, and investigated as a new class of negative (T₂) magnetic resonance imaging (MRI) contrast [...] Read more.

Polyacrylic acid (PAA)-coated lanthanide oxide (Ln₂O₃) nanoparticles (NPs) (Ln = Tb and Ho) with high colloidal stability and good biocompatibility were synthesized, characterized, and investigated as a new class of negative (T₂) magnetic resonance imaging (MRI) contrast agents at high MR fields. Their r₂ values were appreciable at a 3.0 T MR field and higher at a 9.4 T MR field, whereas their r₁ values were negligible at all MR fields, indicating their exclusive induction of T₂ relaxations with negligible induction of T₁ relaxations. Their effectiveness as T₂ MRI contrast agents at high MR fields was confirmed from strong negative contrast enhancements in in vivo T₂ MR images at a 9.4 T MR field after intravenous administration into mice tails. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Bioimaging)

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24 pages, 4445 KiB

Open AccessEditor’s ChoiceArticle

Hyaluronic Acid-Based Nanocapsules as Efficient Delivery Systems of Garlic Oil Active Components with Anticancer Activity

by Małgorzata Janik-Hazuka, Kamil Kamiński, Marta Kaczor-Kamińska, Joanna Szafraniec-Szczęsny, Aleksandra Kmak, Hassan Kassassir, Cezary Watała, Maria Wróbel and Szczepan Zapotoczny

Nanomaterials 2021, 11(5), 1354; https://doi.org/10.3390/nano11051354 - 20 May 2021

Cited by 15 | Viewed by 4224

Abstract

Diallyl disulfide (DADS) and diallyl trisulfide (DATS) are garlic oil compounds exhibiting beneficial healthy properties including anticancer action. However, these compounds are sparingly water-soluble with a limited stability that may imply damage to blood vessels or cells after administration. Thus, their encapsulation in [...] Read more.

Diallyl disulfide (DADS) and diallyl trisulfide (DATS) are garlic oil compounds exhibiting beneficial healthy properties including anticancer action. However, these compounds are sparingly water-soluble with a limited stability that may imply damage to blood vessels or cells after administration. Thus, their encapsulation in the oil-core nanocapsules based on a derivative of hyaluronic acid was investigated here as a way of protecting against oxidation and undesired interactions with blood and digestive track components. The nuclear magnetic resonance (¹H NMR) technique was used to follow the oxidation processes. It was proved that the shell of the capsule acts as a barrier limiting the sulfur oxidation, enhancing the stability of C=C bonds in DADS and DATS. Moreover, it was shown that the encapsulation inhibited the lysis of the red blood cell membrane (mainly for DADS) and interactions with serum or digestive track components. Importantly, the biological functions and anticancer activity of DADS and DATS were preserved after encapsulation. Additionally, the nanocapsule formulations affected the migration of neoplastic cells—a desirable preliminary observation concerning the inhibition of migration. The proposed route of administration of these garlic extract components would enable reaching their higher concentrations in blood, longer circulation in a bloodstream, and thus, imply a better therapeutic effect. Full article

(This article belongs to the Special Issue Nanoparticles from Natural Polymers: Synthesis and Applications)

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18 pages, 3430 KiB

Open AccessReview

Recent Progress on the Characterization of Cellulose Nanomaterials by Nanoscale Infrared Spectroscopy

by Qianqian Zhu, Rui Zhou, Jun Liu, Jianzhong Sun and Qianqian Wang

Nanomaterials 2021, 11(5), 1353; https://doi.org/10.3390/nano11051353 - 20 May 2021

Cited by 23 | Viewed by 4794

Abstract

Researches of cellulose nanomaterials have seen nearly exponential growth over the past several decades for versatile applications. The characterization of nanostructural arrangement and local chemical distribution is critical to understand their role when developing cellulose materials. However, with the development of current characterization [...] Read more.

Researches of cellulose nanomaterials have seen nearly exponential growth over the past several decades for versatile applications. The characterization of nanostructural arrangement and local chemical distribution is critical to understand their role when developing cellulose materials. However, with the development of current characterization methods, the simultaneous morphological and chemical characterization of cellulose materials at nanoscale resolution is still challenging. Two fundamentally different nanoscale infrared spectroscopic techniques, namely atomic force microscope based infrared spectroscopy (AFM-IR) and infrared scattering scanning near field optical microscopy (IR s-SNOM), have been established by the integration of AFM with IR spectroscopy to realize nanoscale spatially resolved imaging for both morphological and chemical information. This review aims to summarize and highlight the recent developments in the applications of current state-of-the-art nanoscale IR spectroscopy and imaging to cellulose materials. It briefly outlines the basic principles of AFM-IR and IR s-SNOM, as well as their advantages and limitations to characterize cellulose materials. The uses of AFM-IR and IR s-SNOM for the understanding and development of cellulose materials, including cellulose nanomaterials, cellulose nanocomposites, and plant cell walls, are extensively summarized and discussed. The prospects of future developments in cellulose materials characterization are provided in the final part. Full article

(This article belongs to the Special Issue Advanced Nanocellulose-Based Materials: Production, Properties and Applications)

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14 pages, 5228 KiB

Open AccessArticle

Photosensing and Characterizing of the Pristine and In-, Sn-Doped Bi₂Se₃ Nanoplatelets Fabricated by Thermal V–S Process

by Chih-Chiang Wang, Fuh-Sheng Shieu and Han C. Shih

Nanomaterials 2021, 11(5), 1352; https://doi.org/10.3390/nano11051352 - 20 May 2021

Cited by 19 | Viewed by 2902

Abstract

Pristine, and In-, Sn-, and (In, Sn)-doped Bi₂Se₃ nanoplatelets synthesized on Al₂O₃(100) substrate by a vapor–solid mechanism in thermal CVD process via at 600 °C under 2 × 10⁻² Torr. XRD and HRTEM reveal that [...] Read more.

Pristine, and In-, Sn-, and (In, Sn)-doped Bi₂Se₃ nanoplatelets synthesized on Al₂O₃(100) substrate by a vapor–solid mechanism in thermal CVD process via at 600 °C under 2 × 10⁻² Torr. XRD and HRTEM reveal that In or Sn dopants had no effect on the crystal structure of the synthesized rhombohedral-Bi₂Se₃. FPA–FTIR reveals that the optical bandgap of doped Bi₂Se₃ was 26.3%, 34.1%, and 43.7% lower than pristine Bi₂Se₃. XRD, FESEM–EDS, Raman spectroscopy, and XPS confirm defects (

I n^{3 +}_{B i^{3 +}}

), (

I n^{3 +}_{V^{0}}

), (

S n^{4 +}_{B i^{3 +}}

), (

V^{0}_{B i^{3 +}}

), and (

S n^{2 +}_{B i^{3 +}}

). Photocurrent that was generated in (In,Sn)-doped Bi₂Se₃ under UV(8 W) and red (5 W) light revealed stable photocurrents of 5.20 × 10⁻¹⁰ and 0.35 × 10⁻¹⁰ A and high I_photo/I_dark ratios of 30.7 and 52.2. The rise and fall times of the photocurrent under UV light were 4.1 × 10⁻² and 6.6 × 10⁻² s. Under UV light, (In,Sn)-dopedBi₂Se₃ had 15.3% longer photocurrent decay time and 22.6% shorter rise time than pristine Bi₂Se₃, indicating that (In,Sn)-doped Bi₂Se₃ exhibited good surface conduction and greater photosensitivity. These results suggest that In, Sn, or both dopants enhance photodetection of pristine Bi₂Se₃ under UV and red light. The findings also suggest that type of defect is a more important factor than optical bandgap in determining photo-detection sensitivity. (In,Sn)-doped Bi₂Se₃ has greater potential than undoped Bi₂Se₃ for use in UV and red-light photodetectors. Full article

(This article belongs to the Special Issue Optoelectronic Properties and Applications of Nanomaterials)

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64 pages, 15833 KiB

Open AccessReview

Behavior of Silicon Carbide Materials under Dry to Hydrothermal Conditions

by Nicolas Biscay, Lucile Henry, Tadafumi Adschiri, Masahiro Yoshimura and Cyril Aymonier

Nanomaterials 2021, 11(5), 1351; https://doi.org/10.3390/nano11051351 - 20 May 2021

Cited by 23 | Viewed by 5656

Abstract

Silicon carbide materials are excellent candidates for high-performance applications due to their outstanding thermomechanical properties and their strong corrosion resistance. SiC materials can be processed in various forms, from nanomaterials to continuous fibers. Common applications of SiC materials include the aerospace and nuclear [...] Read more.

Silicon carbide materials are excellent candidates for high-performance applications due to their outstanding thermomechanical properties and their strong corrosion resistance. SiC materials can be processed in various forms, from nanomaterials to continuous fibers. Common applications of SiC materials include the aerospace and nuclear fields, where the material is used in severely oxidative environments. Therefore, it is important to understand the kinetics of SiC oxidation and the parameters influencing them. The first part of this review focuses on the oxidation of SiC in dry air according to the Deal and Grove model showing that the oxidation behavior of SiC depends on the temperature and the time of oxidation. The oxidation rate can also be accelerated with the presence of H₂O in the system due to its diffusion through the oxide scales. Therefore, wet oxidation is studied in the second part. The third part details the effect of hydrothermal media on the SiC materials that has been explained by different models, namely Yoshimura (1986), Hirayama (1989) and Allongue (1992). The last part of this review focuses on the hydrothermal corrosion of SiC materials from an application point of view and determine whether it is beneficial (manufacturing of materials) or detrimental (use of SiC in latest nuclear reactors). Full article

(This article belongs to the Special Issue Hydrothermal Synthesis of Nanoparticles)

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11 pages, 4049 KiB

Open AccessArticle

Electromagnetically Induced Transparency-Like Effect by Dark-Dark Mode Coupling

by Qiao Wang, Kaili Kuang, Huixuan Gao, Shuwen Chu, Li Yu and Wei Peng

Nanomaterials 2021, 11(5), 1350; https://doi.org/10.3390/nano11051350 - 20 May 2021

Cited by 11 | Viewed by 2777

Abstract

Electromagnetically induced transparency-like (EIT-like) effect is a promising research area for applications of slow light, sensing and metamaterials. The EIT-like effect is generally formed by the destructive interference of bright-dark mode coupling and bright-bright mode coupling. There are seldom reports about EIT-like effect [...] Read more.

Electromagnetically induced transparency-like (EIT-like) effect is a promising research area for applications of slow light, sensing and metamaterials. The EIT-like effect is generally formed by the destructive interference of bright-dark mode coupling and bright-bright mode coupling. There are seldom reports about EIT-like effect realized by the coupling of two dark modes. In this paper, we numerically and theoretically demonstrated that the EIT-like effect is achieved through dark-dark mode coupling of two waveguide resonances in a compound nanosystem with metal grating and multilayer structure. If we introduce

| 1 ⟩

,

| 2 ⟩

and

| 3 ⟩

to represent the surface plasmon polaritons (SPPs) resonance, waveguide resonance in layer 2, and waveguide resonance in layer 4, the destructive interference occurs between two pathways of

| 0 ⟩ \to | 1 ⟩ \to | 2 ⟩

and

| 0 ⟩ \to | 1 ⟩ \to | 2 ⟩ \to | 3 ⟩ \to | 2 ⟩

, where

| 0 ⟩

is the ground state without excitation. Our work will stimulate more studies on EIT-like effect with dark-dark mode coupling in other systems. Full article

(This article belongs to the Special Issue Nonlinear and Quantum Optics with Nanostructures)

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11 pages, 2627 KiB

Open AccessArticle

Modified Camellia oleifera Shell Carbon with Enhanced Performance for the Adsorption of Cooking Fumes

by Dongliang Liao, Wen Shi, Jing Gao, Bin Deng and Ruijin Yu

Nanomaterials 2021, 11(5), 1349; https://doi.org/10.3390/nano11051349 - 20 May 2021

Cited by 5 | Viewed by 2496

Abstract

Using Camellia oleifera shell (COS) as a raw material and phosphoric acid as the activator, activated Camellia oleifera shell carbon (COSC-0) was prepared and then modified by Fenton’s reagent (named as COSC-1). SEM, GC-MS, FTIR, and specific surface area and pore analyzers were [...] Read more.

Using Camellia oleifera shell (COS) as a raw material and phosphoric acid as the activator, activated Camellia oleifera shell carbon (COSC-0) was prepared and then modified by Fenton’s reagent (named as COSC-1). SEM, GC-MS, FTIR, and specific surface area and pore analyzers were used to study the adsorption performance of COS, COSC-0, and COSC-1 on cooking fumes. Results showed that COSC-1 was the best adsorbent compared with COS and COSC-0. The adsorption quantity and penetrating time of COSC-1 were 44.04 mg/g and 4.1 h, respectively. Most aldehydes could be adsorbed by COSC-1, which was due to the large number of carbonyl and carboxyl groups generated on the surface of COSC-1 from the action of Fenton’s reagent. The adsorption effect of COSC-1 on different types of pollutants in cooking fumes was analyzed based on the similar compatibility principle. COSC-1 showed a much higher adsorption effect on the strong polarity functional groups than on weak polar groups. The results provide a theoretical basis for the application of Camellia oleifera shell carbon adsorption technology in the treatment of cooking fumes. Full article

(This article belongs to the Section Environmental Nanoscience and Nanotechnology)

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9 pages, 1469 KiB

Open AccessArticle

Deep-Ultraviolet Transparent Conductive MWCNT/SiO₂ Composite Thin Film Fabricated by UV Irradiation at Ambient Temperature onto Spin-Coated Molecular Precursor Film

by Hiroki Nagai, Naoki Ogawa and Mitsunobu Sato

Nanomaterials 2021, 11(5), 1348; https://doi.org/10.3390/nano11051348 - 20 May 2021

Cited by 3 | Viewed by 2643

Abstract

Deep-ultraviolet (DUV) light-transparent conductive composite thin films, consisting of dispersed multiwalled carbon nanotubes (MWCNTs) and SiO₂ matrix composites, were fabricated on a quartz glass substrate. Transparent and well-adhered amorphous thin films, with a thickness of 220 nm, were obtained by weak ultraviolet [...] Read more.

Deep-ultraviolet (DUV) light-transparent conductive composite thin films, consisting of dispersed multiwalled carbon nanotubes (MWCNTs) and SiO₂ matrix composites, were fabricated on a quartz glass substrate. Transparent and well-adhered amorphous thin films, with a thickness of 220 nm, were obtained by weak ultraviolet (UV) irradiation (4 mW cm⁻² at 254 nm) for more than 6 h at 20−40 °C onto the precursor films, which were obtained by spin coating with a mixed solution of MWCNT in water and Si(IV) complex in ethanol. The electrical resistivity of MWCNT/SiO₂ composite thin film is 0.7 Ω·cm, and transmittance in the wavelength region from DUV to visible light is higher than 80%. The MWCNT/SiO₂ composite thin film showed scratch resistance at pencil hardness of 8H. Importantly, the resistivity of the MWCNT/SiO₂ composite thin film was maintained at the original level even after heat treatment at 500 °C for 1 h. It was observed that the heat treatment of the composite thin film improved durability against both aqueous solutions involving a strong acid (HCl) and a strong base (NaOH). Full article

(This article belongs to the Special Issue Research of Carbon Nanomaterials and Nanocomposites)

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13 pages, 2740 KiB

Open AccessArticle

Controllable One-Step Synthesis of Mixed-Phase TiO₂ Nanocrystals with Equivalent Anatase/Rutile Ratio for Enhanced Photocatalytic Performance

by Yuchen Lei, Yun Yang, Peilin Zhang, Jiaojiao Zhou, Jing Wu, Kuang Li, Weiwei Wang and Luyang Chen

Nanomaterials 2021, 11(5), 1347; https://doi.org/10.3390/nano11051347 - 20 May 2021

Cited by 21 | Viewed by 2882

Abstract

In this study, the novel mixed-phase TiO₂ nanocrystals (s-TiO₂) with nearly equivalent anatase/rutile ratio were fabricated in the reagent of sec-butanol at the relatively low temperature of 80 °C by using a facile one-step condensing reflux method. The photocatalytic water [...] Read more.

In this study, the novel mixed-phase TiO₂ nanocrystals (s-TiO₂) with nearly equivalent anatase/rutile ratio were fabricated in the reagent of sec-butanol at the relatively low temperature of 80 °C by using a facile one-step condensing reflux method. The photocatalytic water splitting hydrogen production performance of s-TiO₂ nanocrystals is close to that of commercial TiO₂ (P25), and its photocatalytic degradation performance is about four times that of P25. The energy-level staggered interfaces and surface bridged hydroxyl groups significantly increased due to the anatase/rutile mixed-phase crystal structure and high specific surface area, which might generate the synergistic effect for the improvement of photocatalytic degradation. Full article

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11 pages, 2603 KiB

Open AccessArticle

A New Method for Dispersing Pristine Carbon Nanotubes Using Regularly Arranged S-Layer Proteins

by Andreas Breitwieser, Uwe B. Sleytr and Dietmar Pum

Nanomaterials 2021, 11(5), 1346; https://doi.org/10.3390/nano11051346 - 20 May 2021

Cited by 10 | Viewed by 2479

Abstract

Homogeneous and stable dispersions of functionalized carbon nanotubes (CNTs) in aqueous solutions are imperative for a wide range of applications, especially in life and medical sciences. Various covalent and non-covalent approaches were published to separate the bundles into individual tubes. In this context, [...] Read more.

Homogeneous and stable dispersions of functionalized carbon nanotubes (CNTs) in aqueous solutions are imperative for a wide range of applications, especially in life and medical sciences. Various covalent and non-covalent approaches were published to separate the bundles into individual tubes. In this context, this work demonstrates the non-covalent modification and dispersion of pristine multi-walled carbon nanotubes (MWNTs) using two S-layer proteins, namely, SbpA from Lysinibacillus sphaericus CCM2177 and SbsB from Geobacillus stearothermophilus PV72/p2. Both the S-layer proteins coated the MWNTs completely. Furthermore, it was shown that SbpA can form caps at the ends of MWNTs. Reassembly experiments involving a mixture of both S-layer proteins in the same solution showed that the MWNTs were primarily coated with SbsB, whereas SbpA formed self-assembled layers. The dispersibility of the pristine nanotubes coated with SbpA was determined by zeta potential measurements (−24.4 +/− 0.6 mV, pH = 7). Finally, the SbpA-coated MWNTs were silicified with tetramethoxysilane (TMOS) using a mild biogenic approach. As expected, the thickness of the silica layer could be controlled by the reaction time and was 6.3 +/− 1.25 nm after 5 min and 25.0 +/− 5.9 nm after 15 min. Since S-layer proteins have already demonstrated their capability to bind (bio)molecules in dense packing or to act as catalytic sites in biomineralization processes, the successful coating of pristine MWNTs has great potential in the development of new materials, such as biosensor architectures. Full article

(This article belongs to the Special Issue Growth, Characterization and Applications of Nanotubes)

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21 pages, 5179 KiB

Open AccessArticle

Calcium Alginate Beads with Entrapped Iron Oxide Magnetic Nanoparticles Functionalized with Methionine—A Versatile Adsorbent for Arsenic Removal

by Surbhi Lilhare, Sunitha B. Mathew, Ajaya K. Singh and Sónia A. C. Carabineiro

Nanomaterials 2021, 11(5), 1345; https://doi.org/10.3390/nano11051345 - 20 May 2021

Cited by 20 | Viewed by 4165

Abstract

A novel beads adsorbent, consisting of calcium alginate entrapped on magnetic nanoparticles functionalized with methionine (MFMNABs), was developed for effective elimination of arsenic from water. The material was characterized by FT-IR (Fourier Transform Infrared Spectroscopy), SEM (Scanning Electron Microscopic), XRD (X-ray Diffraction) and [...] Read more.

A novel beads adsorbent, consisting of calcium alginate entrapped on magnetic nanoparticles functionalized with methionine (MFMNABs), was developed for effective elimination of arsenic from water. The material was characterized by FT-IR (Fourier Transform Infrared Spectroscopy), SEM (Scanning Electron Microscopic), XRD (X-ray Diffraction) and TEM (Transmission Electron Microscopy). The arsenic removal capacity of the material was studied by altering variables such as pH of the solution, contact time, adsorbent dose and adsorbate concentration. The maximal removal of As(III) was 99.56% under optimal conditions with an equilibrium time of 110 min and pH 7.0–7.5. The adsorption followed a second order kinetics and data best fitted the Langmuir isotherm with a correlation coefficient of R² = 0.9890 and adsorption capacity (q_m) of 6.6533 mg/g. The thermodynamic study showed entropy change (∆S) and enthalpy change (∆H) to be 34.32 J mol⁻¹ K and 5.25 kJ mol⁻¹, respectively. This study proved that it was feasible to treat an As(III) solution with MFMNABs. The synthesized adsorbent was cost-effective, environmentally friendly and versatile, compared to other adsorbents. The adsorption study was carried by low cost spectrophotometric method using N- bromosuccinimide and rhodamine-B developed in our laboratory. Full article

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14 pages, 3649 KiB

Open AccessArticle

Molecular Dynamics Simulation for the Effect of Fluorinated Graphene Oxide Layer Spacing on the Thermal and Mechanical Properties of Fluorinated Epoxy Resin

by Qijun Duan, Jun Xie, Guowei Xia, Chaoxuan Xiao, Xinyu Yang, Qing Xie and Zhengyong Huang

Nanomaterials 2021, 11(5), 1344; https://doi.org/10.3390/nano11051344 - 20 May 2021

Cited by 7 | Viewed by 3116

Abstract

Traditional epoxy resin (EP) materials have difficulty to meet the performance requirements in the increasingly complex operating environment of the electrical and electronic industry. Therefore, it is necessary to study the design and development of new epoxy composites. At present, fluorinated epoxy resin [...] Read more.

Traditional epoxy resin (EP) materials have difficulty to meet the performance requirements in the increasingly complex operating environment of the electrical and electronic industry. Therefore, it is necessary to study the design and development of new epoxy composites. At present, fluorinated epoxy resin (F-EP) is widely used, but its thermal and mechanical properties cannot meet the demand. In this paper, fluorinated epoxy resin was modified by ordered filling of fluorinated graphene oxide (FGO). The effect of FGO interlayer spacing on the thermal and mechanical properties of the composite was studied by molecular dynamics (MD) simulation. It is found that FGO with ordered filling can significantly improve the thermal and mechanical properties of F-EP, and the modification effect is better than that of FGO with disordered filling. When the interlayer spacing of FGO is about 9 Å, the elastic modulus, glass transition temperature, thermal expansion coefficient, and thermal conductivity of FGO are improved with best effect. Furthermore, we calculated the micro parameters of different systems, and analyzed the influencing mechanism of ordered filling and FGO layer spacing on the properties of F-EP. It is considered that FGO can bind the F-EP molecules on both sides of the nanosheets, reducing the movement ability of the molecular segments of the materials, so as to achieve the enhancement effect. The results can provide new ideas for the development of high-performance epoxy nanocomposites. Full article

(This article belongs to the Special Issue Advanced Mechanical Modeling of Nanomaterials and Nanostructures)

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19 pages, 3081 KiB

Open AccessArticle

The Antimicrobial and Anti-Inflammatory Effects of Silver Nanoparticles Synthesised from Cotyledon orbiculata Aqueous Extract

by Caroline Tyavambiza, Abdulrahman Mohammed Elbagory, Abram Madimabe Madiehe, Mervin Meyer and Samantha Meyer

Nanomaterials 2021, 11(5), 1343; https://doi.org/10.3390/nano11051343 - 20 May 2021

Cited by 94 | Viewed by 6281

Abstract

Cotyledon orbiculata, commonly known as pig’s ear, is an important medicinal plant of South Africa. It is used in traditional medicine to treat many ailments, including skin eruptions, abscesses, inflammation, boils and acne. Many plants have been used to synthesize metallic nanoparticles, [...] Read more.

Cotyledon orbiculata, commonly known as pig’s ear, is an important medicinal plant of South Africa. It is used in traditional medicine to treat many ailments, including skin eruptions, abscesses, inflammation, boils and acne. Many plants have been used to synthesize metallic nanoparticles, particularly silver nanoparticles (AgNPs). However, the synthesis of AgNPs from C. orbiculata has never been reported before. The aim of this study was to synthesize AgNPs using C. orbiculata and evaluate their antimicrobial and immunomodulatory properties. AgNPs were synthesized and characterized using Ultraviolet-Visible Spectroscopy (UV-Vis), Dynamic Light Scattering (DLS) and High-Resolution Transmission Electron Microscopy (HR-TEM). The antimicrobial activities of the nanoparticles against skin pathogens (Staphylococcus aureus, Staphylococcus epidermidis, Methicillin Resistance Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans) as well as their effects on cytokine production in macrophages (differentiated from THP-1 cells) were evaluated. The AgNPs from C. orbiculata exhibited antimicrobial activity, with the highest activity observed against P. aeruginosa (5 µg/mL). The AgNPs also showed anti-inflammatory activity by inhibiting the secretion of pro-inflammatory cytokines (TNF-alpha, IL-6 and IL-1 beta) in lipopolysaccharide-treated macrophages. This concludes that the AgNPs produced from C. orbiculata possess antimicrobial and anti-inflammation properties. Full article

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9 pages, 5211 KiB

Open AccessArticle

Femtosecond Laser-Processing of Pre-Anodized Ti-Based Bone Implants for Cell-Repellent Functionalization

by Martina Muck, Benedikt Wolfsjäger, Karoline Seibert, Christian Maier, Shaukat Ali Lone, Achim Walter Hassel, Werner Baumgartner and Johannes Heitz

Nanomaterials 2021, 11(5), 1342; https://doi.org/10.3390/nano11051342 - 20 May 2021

Cited by 12 | Viewed by 3530

Abstract

Microstructures and nanostructures can be used to reduce the adhesion of the cells on the auxiliary material. Therefore, the aim of our work was to fabricate laser-induced hierarchical microstructures and nanostructures by femtosecond laser-treatment (wavelength 1040 nm, pulse length 350 fs, repetition rates [...] Read more.

Microstructures and nanostructures can be used to reduce the adhesion of the cells on the auxiliary material. Therefore, the aim of our work was to fabricate laser-induced hierarchical microstructures and nanostructures by femtosecond laser-treatment (wavelength 1040 nm, pulse length 350 fs, repetition rates in the kHz range) to reduce the cell adhesion. Additionally, surface chemistry modification by optimized electrochemical anodization was used to further reduce the cell adhesion. For testing, flat plates and bone screws made of Ti-6Al-4V were used. Bone-forming cells (human osteoblasts from the cell line SAOS-2) were grown on the bone implants and additional test samples for two to three weeks. After the growth period, the cells were characterized by scanning electron microscopy (SEM). While earlier experiments with fibroblasts had shown that femtosecond laser-processing followed by electrochemical anodization had a significant impact on cell adhesion reduction, for osteoblasts the same conditions resulted in an activation of the cells with increased production of extracellular matrix material. Significant reduction of cell adhesion for osteoblasts was only obtained at pre-anodized surfaces. It could be demonstrated that this functionalization by means of femtosecond laser-processing can result in bone screws that hinder the adhesion of osteoblasts. Full article

(This article belongs to the Special Issue Nanopatterning of Bionic Materials)

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13 pages, 3744 KiB

Open AccessArticle

Cold Plasma Preparation of Pd/Graphene Catalyst for Reduction of p-Nitrophenol

by Qian Zhao, Decai Bu, Zhihui Li, Xiuling Zhang and Lanbo Di

Nanomaterials 2021, 11(5), 1341; https://doi.org/10.3390/nano11051341 - 20 May 2021

Cited by 16 | Viewed by 2664

Abstract

Supported metal nanoparticles with small size and high dispersion can improve the performance of heterogeneous catalysts. To prepare graphene-supported Pd catalysts, graphene and PdCl₂ were used as support and Pd precursors, respectively. Pd/G-P and Pd/G-H catalysts were prepared by cold plasma and [...] Read more.

Supported metal nanoparticles with small size and high dispersion can improve the performance of heterogeneous catalysts. To prepare graphene-supported Pd catalysts, graphene and PdCl₂ were used as support and Pd precursors, respectively. Pd/G-P and Pd/G-H catalysts were prepared by cold plasma and conventional thermal reduction, respectively, for the catalytic reduction of p-nitrophenol (4-NP). The reaction followed quasi-first-order kinetics, and the apparent rate constant of Pd/G-P and Pd/G-H was 0.0111 and 0.0042 s⁻¹, respectively. The graphene support was exfoliated by thermal reduction and cold plasma, which benefits the 4-NP adsorption. Pd/G-P presented a higher performance because cold plasma promoted the migration of Pd species to the support outer surface. The Pd/C atomic ratio for Pd/G-P and Pd/G-H was 0.014 and 0.010, respectively. In addition, the Pd nanoparticles in Pd/G-P were smaller than those in Pd/G-H, which was beneficial for the catalytic reduction. The Pd/G-P sample presented abundant oxygen-containing functional groups, which anchored the metal nanoparticles and enhanced the metal-support interaction. This was further confirmed by the shift in the binding energy to a high value for Pd3d in Pd/G-P. The cold plasma method operated under atmospheric pressure is effective for the preparation of Pd/G catalysts with enhanced catalytic activity for 4-NP reduction. Full article

(This article belongs to the Special Issue Advances in Multifunctional Carbon-Based Nanocomposites: Synthesis, Characterization and Applications)

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15 pages, 5297 KiB

Open AccessEditor’s ChoiceArticle

Hydrous Hydrazine Decomposition for Hydrogen Production Using of Ir/CeO₂: Effect of Reaction Parameters on the Activity

by Davide Motta, Ilaria Barlocco, Silvio Bellomi, Alberto Villa and Nikolaos Dimitratos

Nanomaterials 2021, 11(5), 1340; https://doi.org/10.3390/nano11051340 - 19 May 2021

Cited by 21 | Viewed by 3257

Abstract

In the present work, an Ir/CeO₂ catalyst was prepared by the deposition–precipitation method and tested in the decomposition of hydrazine hydrate to hydrogen, which is very important in the development of hydrogen storage materials for fuel cells. The catalyst was characterised using [...] Read more.

In the present work, an Ir/CeO₂ catalyst was prepared by the deposition–precipitation method and tested in the decomposition of hydrazine hydrate to hydrogen, which is very important in the development of hydrogen storage materials for fuel cells. The catalyst was characterised using different techniques, i.e., X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) equipped with X-ray detector (EDX) and inductively coupled plasma—mass spectroscopy (ICP-MS). The effect of reaction conditions on the activity and selectivity of the material was evaluated in this study, modifying parameters such as temperature, the mass of the catalyst, stirring speed and concentration of base in order to find the optimal conditions of reaction, which allow performing the test in a kinetically limited regime. Full article

(This article belongs to the Section Energy and Catalysis)

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12 pages, 2673 KiB

Open AccessArticle

Cytotoxic Effect of Graphene Oxide Nanoribbons on Escherichia coli

by Shirong Qiang, Zhengbin Li, Li Zhang, Dongxia Luo, Rongyue Geng, Xueli Zeng, Jianjun Liang, Ping Li and Qiaohui Fan

Nanomaterials 2021, 11(5), 1339; https://doi.org/10.3390/nano11051339 - 19 May 2021

Cited by 7 | Viewed by 2934

Abstract

The biological and environmental toxicity of graphene and graphene derivatives have attracted great research interest due to their increasing applications. However, the cytotoxic mechanism is poorly understood. Here, we investigated the cytotoxic effect of graphene oxide nanoribbons (GORs) on Escherichia coli (E. [...] Read more.

The biological and environmental toxicity of graphene and graphene derivatives have attracted great research interest due to their increasing applications. However, the cytotoxic mechanism is poorly understood. Here, we investigated the cytotoxic effect of graphene oxide nanoribbons (GORs) on Escherichia coli (E. coli) in an in vitro method. The fabricated GORs formed long ribbons, 200 nm wide. Based on the results of the MTT assay and plate-culture experiments, GORs significantly inhibited the growth and reproduction of E. coli in a concentration-dependent manner. We found that GORs stimulated E. coli to secrete reactive oxygen species, which then oxidized and damaged the bacterial cell membrane. Moreover, interaction between GORs and E. coli cytomembrane resulted in polysaccharide adsorption by GORs and the release of lactic dehydrogenase. Furthermore, GORs effectively depleted the metal ions as nutrients in the culture medium by adsorption. Notably, mechanical cutting by GORs was not obvious, which is quite different from the case of graphene oxide sheets to E. coli. Full article

(This article belongs to the Special Issue Engineered Nanomaterials Exposure and Risk Assessment: Occupational Health and Safety)

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13 pages, 1328 KiB

Open AccessArticle

Synthesis of Mesoporous Silica Coated Gold Nanorods Loaded with Methylene Blue and Its Potentials in Antibacterial Applications

by Adrián Fernández-Lodeiro, Jamila Djafari, Javier Fernández-Lodeiro, Maria Paula Duarte, Elisabete Muchagato Mauricio, José Luis Capelo-Martínez and Carlos Lodeiro

Nanomaterials 2021, 11(5), 1338; https://doi.org/10.3390/nano11051338 - 19 May 2021

Cited by 23 | Viewed by 4169

Abstract

In this work, the successful preparation and characterization of gold nanorods (AuNRs) coated with a mesoporous silica shell (AuNRs@Simes) was achieved. Conjugation with methylene blue (MB) as a model drug using ultrasound-stimulated loading has been explored for further application in light-mediated antibacterial studies. [...] Read more.

In this work, the successful preparation and characterization of gold nanorods (AuNRs) coated with a mesoporous silica shell (AuNRs@Simes) was achieved. Conjugation with methylene blue (MB) as a model drug using ultrasound-stimulated loading has been explored for further application in light-mediated antibacterial studies. Lyophilization of this conjugated nanosystem was analyzed using trehalose (TRH) as a cryogenic protector. The obtained stable dry formulation shows potent antimicrobial activity against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria after a simple post-treatment irradiation method with a red laser during a short time period. Full article

(This article belongs to the Special Issue Design, Development, and Production of Nanocarriers and Nanovehicles)

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15 pages, 3941 KiB

Open AccessArticle

SERRS Detection on Silver Nanoparticles Supported on Acid-Treated Melamine-Resin Microspheres

by Chaofeng Duan, Lu Shen, Yuqing Guo, Xiaogang Wang, Xiaohua Wang and Zhixian Hao

Nanomaterials 2021, 11(5), 1337; https://doi.org/10.3390/nano11051337 - 19 May 2021

Cited by 1 | Viewed by 2365

Abstract

Melamine-resin microspheres were synthesized at a pH of 4.0 for 20 min and used as silver nanoparticle (AgNP) carriers for surface enhanced resonant Raman scattering (SERRS) detection. An acetic acid–treatment reaction was introduced into the fabrication of the final substrate. The SERRS performance [...] Read more.

Melamine-resin microspheres were synthesized at a pH of 4.0 for 20 min and used as silver nanoparticle (AgNP) carriers for surface enhanced resonant Raman scattering (SERRS) detection. An acetic acid–treatment reaction was introduced into the fabrication of the final substrate. The SERRS performance of the substrate was effectively optimized by regulating excess formaldehyde and experimental parameters, such as acidity, number of treatments and reaction temperature in the acid-treatment reaction. Based on the SERRS detection, it was declared that a trace amount of oligomers with a certain degree of polymerization is necessary for the construction of SERRS hotspots. In addition, it is important to remove excess oligomers with reference to the synthetic reaction of the polymer materials, given the special role of oligomers and the wide application of polymer materials in SERRS detection. Full article

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30 pages, 3468 KiB

Open AccessReview

Lignin Nanoparticles and Their Nanocomposites

by Zhao Zhang, Vincent Terrasson and Erwann Guénin

Nanomaterials 2021, 11(5), 1336; https://doi.org/10.3390/nano11051336 - 19 May 2021

Cited by 109 | Viewed by 12517

Abstract

Lignin nanomaterials have emerged as a promising alternative to fossil-based chemicals and products for some potential added-value applications, which benefits from their structural diversity and biodegradability. This review elucidates a perspective in recent research on nanolignins and their nanocomposites. It summarizes the different [...] Read more.

Lignin nanomaterials have emerged as a promising alternative to fossil-based chemicals and products for some potential added-value applications, which benefits from their structural diversity and biodegradability. This review elucidates a perspective in recent research on nanolignins and their nanocomposites. It summarizes the different nanolignin preparation methods, emphasizing anti-solvent precipitation, self-assembly and interfacial crosslinking. Also described are the preparation of various nanocomposites by the chemical modification of nanolignin and compounds with inorganic materials or polymers. Additionally, advances in numerous potential high-value applications, such as use in food packaging, biomedical, chemical engineering and biorefineries, are described. Full article

(This article belongs to the Special Issue Nanoparticles from Natural Polymers: Synthesis and Applications)

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11 pages, 2543 KiB

Open AccessArticle

Sieve-Like CNT Film Coupled with TiO₂ Nanowire for High-Performance Continuous-Flow Photodegradation of Rhodamine B under Visible Light Irradiation

by Zhengpeng Yang, Xiaoting Lv, Xuqing Liu, Shengmin Jia, Yongyi Zhang, Yingying Yu, Chunjing Zhang and Dandan Liu

Nanomaterials 2021, 11(5), 1335; https://doi.org/10.3390/nano11051335 - 19 May 2021

Cited by 4 | Viewed by 2611

Abstract

Continuous-flow photoreactors hold great promise for the highly efficient photodegradation of pollutants due to their continuity and sustainability. However, how to enable a continuous-flow photoreactor with the combined features of high photodegradation efficiency and durability as well as broad-wavelength light absorption and large-scale [...] Read more.

Continuous-flow photoreactors hold great promise for the highly efficient photodegradation of pollutants due to their continuity and sustainability. However, how to enable a continuous-flow photoreactor with the combined features of high photodegradation efficiency and durability as well as broad-wavelength light absorption and large-scale processing remains a significant challenge. Herein, we demonstrate a facile and effective strategy to construct a sieve-like carbon nanotube (CNT)/TiO₂ nanowire film (SCTF) with superior flexibility (180° bending), high tensile strength (75–82 MPa), good surface wettability, essential light penetration and convenient visible light absorption. Significantly, the unique architecture, featuring abundant, well-ordered and uniform mesopores with ca. 70 µm in diameter, as well as a homogenous distribution of TiO₂ nanowires with an average diameter of ca. 500 nm, could act as a “waterway” for efficient solution infiltration through the SCTF, thereby, enabling the photocatalytic degradation of polluted water in a continuous-flow mode. The optimized SCTF-2.5 displayed favorable photocatalytic behavior with 96% degradation of rhodamine B (RhB) within 80 min and a rate constant of 0.0394 min⁻¹. The continuous-flow photodegradation device made using SCTF-2.5 featured exceptional photocatalytic behavior for the continuous degradation of RhB under simulated solar irradiation with a high degradation ratio (99.6%) and long-term stability (99.2% retention after working continuously for 72 h). This work sheds light on new strategies for designing and fabricating high-performance continuous-flow photoreactors toward future uses. Full article

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20 pages, 5036 KiB

Open AccessArticle

Optimization Method of the Solvothermal Parameters Using Box–Behnken Experimental Design—The Case Study of ZnO Structural and Catalytic Tailoring

by Zoltán Kovács, Csanád Molnár, Urška Lavrenčič Štangar, Vasile-Mircea Cristea, Zsolt Pap, Klara Hernadi and Lucian Baia

Nanomaterials 2021, 11(5), 1334; https://doi.org/10.3390/nano11051334 - 19 May 2021

Cited by 11 | Viewed by 2991

Abstract

ZnO photocatalysts were synthesized via solvothermal method and a reduced experimental design (Box–Behnken) was applied to investigate the influence of four parameters (temperature, duration, composition of the reaction mixture) upon the photocatalytic activity and the crystal structure of ZnO. The four parameters were [...] Read more.

ZnO photocatalysts were synthesized via solvothermal method and a reduced experimental design (Box–Behnken) was applied to investigate the influence of four parameters (temperature, duration, composition of the reaction mixture) upon the photocatalytic activity and the crystal structure of ZnO. The four parameters were correlated with photocatalytic degradation of methyl orange and the ratio of two crystallographic facets ((002) and (100)) using a quadratic model. The quadratic model shows good fit for both responses. The optimization experimental results validated the models. The ratio of the crystal facets shows similar variation as the photocatalytic activity of the samples. The water content of the solvent is the primary factor, which predominantly influence both responses. An explanation was proposed for the effect of the parameters and how the ratio of (002) and (100) crystal facets is influenced and its relation to the photocatalytic activity. The present research laconically describes a case study for an original experimental work, in order to serve as guideline to deal with such complicated subjects as quantifying influence of synthesis parameters upon the catalytic activity of the obtained ZnO. Full article

(This article belongs to the Special Issue Latest Developments in Photocatalytic Materials and Processes)

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7 pages, 3034 KiB

Open AccessArticle

Directional Plasmonic Excitation by Helical Nanotips

by Leeju Singh, Nicolò Maccaferri, Denis Garoli and Yuri Gorodetski

Nanomaterials 2021, 11(5), 1333; https://doi.org/10.3390/nano11051333 - 19 May 2021

Cited by 14 | Viewed by 2460

Abstract

The phenomenon of coupling between light and surface plasmon polaritons requires specific momentum matching conditions. In the case of a single scattering object on a metallic surface, such as a nanoparticle or a nanohole, the coupling between a broadband effect, i.e., scattering, and [...] Read more.

The phenomenon of coupling between light and surface plasmon polaritons requires specific momentum matching conditions. In the case of a single scattering object on a metallic surface, such as a nanoparticle or a nanohole, the coupling between a broadband effect, i.e., scattering, and a discrete one, such as surface plasmon excitation, leads to Fano-like resonance lineshapes. The necessary phase matching requirements can be used to engineer the light–plasmon coupling and to achieve a directional plasmonic excitation. Here, we investigate this effect by using a chiral nanotip to excite surface plasmons with a strong spin-dependent azimuthal variation. This effect can be described by a Fano-like interference with a complex coupling factor that can be modified thanks to a symmetry breaking of the nanostructure. Full article

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15 pages, 4241 KiB

Open AccessReview

Strategies to Build Hybrid Protein–DNA Nanostructures

by Armando Hernandez-Garcia

Nanomaterials 2021, 11(5), 1332; https://doi.org/10.3390/nano11051332 - 18 May 2021

Cited by 9 | Viewed by 4216

Abstract

Proteins and DNA exhibit key physical chemical properties that make them advantageous for building nanostructures with outstanding features. Both DNA and protein nanotechnology have growth notably and proved to be fertile disciplines. The combination of both types of nanotechnologies is helpful to overcome [...] Read more.

Proteins and DNA exhibit key physical chemical properties that make them advantageous for building nanostructures with outstanding features. Both DNA and protein nanotechnology have growth notably and proved to be fertile disciplines. The combination of both types of nanotechnologies is helpful to overcome the individual weaknesses and limitations of each one, paving the way for the continuing diversification of structural nanotechnologies. Recent studies have implemented a synergistic combination of both biomolecules to assemble unique and sophisticate protein–DNA nanostructures. These hybrid nanostructures are highly programmable and display remarkable features that create new opportunities to build on the nanoscale. This review focuses on the strategies deployed to create hybrid protein–DNA nanostructures. Here, we discuss strategies such as polymerization, spatial directing and organizing, coating, and rigidizing or folding DNA into particular shapes or moving parts. The enrichment of structural DNA nanotechnology by incorporating protein nanotechnology has been clearly demonstrated and still shows a large potential to create useful and advanced materials with cell-like properties or dynamic systems. It can be expected that structural protein–DNA nanotechnology will open new avenues in the fabrication of nanoassemblies with unique functional applications and enrich the toolbox of bionanotechnology. Full article

(This article belongs to the Special Issue The Application of DNA Nanotechnology)

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34 pages, 2302 KiB

Open AccessReview

Recent Advances in the Development of Smart and Active Biodegradable Packaging Materials

by Mahmood Alizadeh Sani, Maryam Azizi-Lalabadi, Milad Tavassoli, Keyhan Mohammadi and David Julian McClements

Nanomaterials 2021, 11(5), 1331; https://doi.org/10.3390/nano11051331 - 18 May 2021

Cited by 97 | Viewed by 13681

Abstract

Interest in the development of smart and active biodegradable packaging materials is increasing as food manufacturers try to improve the sustainability and environmental impact of their products, while still maintaining their quality and safety. Active packaging materials contain components that enhance their functionality, [...] Read more.

Interest in the development of smart and active biodegradable packaging materials is increasing as food manufacturers try to improve the sustainability and environmental impact of their products, while still maintaining their quality and safety. Active packaging materials contain components that enhance their functionality, such as antimicrobials, antioxidants, light blockers, or oxygen barriers. Smart packaging materials contain sensing components that provide an indication of changes in food attributes, such as alterations in their quality, maturity, or safety. For instance, a smart sensor may give a measurable color change in response to a deterioration in food quality. This article reviews recent advances in the development of active and smart biodegradable packaging materials in the food industry. Moreover, studies on the application of these packaging materials to monitor the freshness and safety of food products are reviewed, including dairy, meat, fish, fruit and vegetable products. Finally, the potential challenges associated with the application of these eco-friendly packaging materials in the food industry are discussed, as well as potential future directions. Full article

(This article belongs to the Special Issue Food Packaging Bionanocomposites)

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21 pages, 2355 KiB

Open AccessArticle

Cytokine-Mediated Inflammation in the Oral Cavity and Its Effect on Lipid Nanocarriers

by Carolin Tetyczka, Sonja Hartl, Ramona Jeitler, Markus Absenger-Novak, Claudia Meindl, Eleonore Fröhlich, Sabrina Riedl, Dagmar Zweytick and Eva Roblegg

Nanomaterials 2021, 11(5), 1330; https://doi.org/10.3390/nano11051330 - 18 May 2021

Cited by 11 | Viewed by 3203

Abstract

Topical drug administration to the oral mucosa proves to be a promising treatment alternative for inflammatory diseases. However, disease-related changes in the cell barrier must be considered when developing such delivery systems. This study aimed at investigating the changes in the lining mucosa [...] Read more.

Topical drug administration to the oral mucosa proves to be a promising treatment alternative for inflammatory diseases. However, disease-related changes in the cell barrier must be considered when developing such delivery systems. This study aimed at investigating the changes in the lining mucosa caused by inflammation and evaluating the consequences on drug delivery systems such as nanostructured lipid carriers (NLC). For this, TR146 cells were treated with inflammatory cytokines and bacterial components. Cell viability and integrity, reactive oxygen species (ROS), and interleukin (IL)-8 release were used as endpoints to assess inflammation. Translocation of phosphatidylserine, cytoskeletal arrangement, opening of desmosomes, and cell proliferation were examined. Transport studies with NLC were performed considering active and passive pathways. The results showed that IL-1ß and tumor necrosis factor α induced inflammation by increasing IL-8 and ROS production (22-fold and 2-fold). Morphologically, loss of cell–cell connections and formation of stress fibers and hyperplasia were observed. The charge of the cell membrane shifted from neutral to negative, which increased the absorption of NLC due to the repulsive interactions between the hydrophobic negative particles and the cell membrane on the one hand, and interactions with lipophilic membrane proteins such as caveolin on the other. Full article

(This article belongs to the Special Issue Nanomedicine in Drug Delivery)

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14 pages, 5427 KiB

Open AccessArticle

Dimethylglyoxime Clathrate as Ligand Derived Nitrogen-Doped Carbon-Supported Nano-Metal Particles as Catalysts for Oxygen Reduction Reaction

by Luping Xu, Zhongqin Guo, Hanyu Jiang, Siyu Xu, Juanli Ma, Mi Hu, Jiemei Yu, Fengqi Zhao and Taizhong Huang

Nanomaterials 2021, 11(5), 1329; https://doi.org/10.3390/nano11051329 - 18 May 2021

Cited by 5 | Viewed by 3259

Abstract

Nitrogen-doped carbon-supported metal nano-particles show great promise as high-performance catalysts for novel energies, organic synthesis, environmental protection, and other fields. The synergistic effect between nitrogen-doped carbon and metal nano-particles enhances the catalytic properties. Thus, how to effectively combine nitrogen-doped carbon with metal nano-particles [...] Read more.

Nitrogen-doped carbon-supported metal nano-particles show great promise as high-performance catalysts for novel energies, organic synthesis, environmental protection, and other fields. The synergistic effect between nitrogen-doped carbon and metal nano-particles enhances the catalytic properties. Thus, how to effectively combine nitrogen-doped carbon with metal nano-particles is a crucial factor for the synthesis of novel catalysts. In this paper, we report on a facile method to prepare nitrogen-doped carbon-supported metal nano-particles by using dimethylgly-oxime as ligand. The nano-particles of Pd, Ni, Cu, and Fe were successfully prepared by the pyrolysis of the corresponding clathrate of ions and dimethylglyoxime. The ligand of dimethylglyoxime is adopted as the source for the nitrogen-doped carbon. The nano-structure of the prepared Pd, Ni, Cu, and Fe particles are confirmed by X-ray diffraction, scanning electron microscopy, and trans-mission electron microscopy tests. The catalytic performances of the obtained metal nano-particles for oxygen reduction reaction (ORR) are investigated by cyclic voltammetry, Tafel, linear sweeping voltammetry, rotating disc electrode, rotating ring disc electrode, and other technologies. Results show that the nitrogen-doped carbon-supported metal nano-particles can be highly efficient catalysts for ORR. The results of the paper exhibit a facile methodology to prepare nitrogen-doped carbon-supported metal nano-particles. Full article

(This article belongs to the Topic Nanomaterials for Sustainable Energy Applications)

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15 pages, 1613 KiB

Open AccessPerspective

Unveiling the Potential Role of Nanozymes in Combating the COVID-19 Outbreak

by Jafar Ali, Saira Naveed Elahi, Asghar Ali, Hassan Waseem, Rameesha Abid and Mohamed M. Mohamed

Nanomaterials 2021, 11(5), 1328; https://doi.org/10.3390/nano11051328 - 18 May 2021

Cited by 8 | Viewed by 4619

Abstract

The current coronavirus disease 2019 (COVID-19) outbreak is considered as one of the biggest public health challenges and medical emergencies of the century. A global health emergency demands an urgent development of rapid diagnostic tools and advanced therapeutics for the mitigation of COVID-19. [...] Read more.

The current coronavirus disease 2019 (COVID-19) outbreak is considered as one of the biggest public health challenges and medical emergencies of the century. A global health emergency demands an urgent development of rapid diagnostic tools and advanced therapeutics for the mitigation of COVID-19. To cope with the current crisis, nanotechnology offers a number of approaches based on abundance and versatile functioning. Despite major developments in early diagnostics and control of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), there is still a need to find effective nanomaterials with low cost, high stability and easy use. Nanozymes are nanomaterials with innate enzyme-like characteristics and exhibit great potential for various biomedical applications such as disease diagnosis and anti-viral agents. Overall the potential and contribution of nanozymes in the fight against SARS-CoV-2 infection i.e., rapid detection, inhibition of the virus at various stages, and effective vaccine development strategies, is not fully explored. This paper discusses the utility and potential of nanozymes from the perspective of COVID-19. Moreover, future research directions and potential applications of nanozymes are highlighted to overcome the challenges related to early diagnosis and therapeutics development for the SARS-CoV-2. We anticipate the current perspective will play an effective role in the existing response to the COVID-19 crisis. Full article

(This article belongs to the Special Issue Recent Advances in the Construction and Applications of Nanozymes)

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13 pages, 2725 KiB

Open AccessEditor’s ChoiceArticle

Spatiotemporal Visualization of Insecticides and Fungicides within Fruits and Vegetables Using Gold Nanoparticle-Immersed Paper Imprinting Mass Spectrometry Imaging

by Run Qin, Ping Li, Mingyi Du, Lianlian Ma, Yudi Huang, Zhibin Yin, Yue Zhang, Dong Chen, Hanhong Xu and Xinzhou Wu

Nanomaterials 2021, 11(5), 1327; https://doi.org/10.3390/nano11051327 - 18 May 2021

Cited by 19 | Viewed by 3738

Abstract

Food safety issues caused by pesticide residue have exerted far-reaching impacts on human daily life, yet the available detection methods normally focus on surface residue rather than pesticide penetration to the internal area of foods. Herein, we demonstrated gold nanoparticle (AuNP)-immersed paper imprinting [...] Read more.

Food safety issues caused by pesticide residue have exerted far-reaching impacts on human daily life, yet the available detection methods normally focus on surface residue rather than pesticide penetration to the internal area of foods. Herein, we demonstrated gold nanoparticle (AuNP)-immersed paper imprinting mass spectrometry imaging (MSI) for monitoring pesticide migration behaviors in various fruits and vegetables (i.e., apple, cucumber, pepper, plum, carrot, and strawberry). By manually stamping food tissues onto AuNP-immersed paper, this method affords the spatiotemporal visualization of insecticides and fungicides within fruits and vegetables, avoiding tedious and time-consuming sample preparation. Using the established MSI platform, we can track the migration of insecticides and fungicides into the inner region of foods. The results revealed that both the octanol-water partition coefficient of pesticides and water content of garden stuffs could influence the discrepancy in the migration speed of pesticides into food kernels. Taken together, this nanopaper imprinting MSI is poised to be a powerful tool because of its simplicity, rapidity, and easy operation, offering the potential to facilitate further applications in food analysis. Moreover, new perspectives are given to provide guidelines for the rational design of novel pesticide candidates, reducing the risk of food safety issues caused by pesticide residue. Full article

(This article belongs to the Special Issue Advances in Food Nanotechnology)

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18 pages, 3060 KiB

Open AccessArticle

Magneto-Plasmonic Nanoparticle Grid Biosensor with Enhanced Raman Scattering and Electrochemical Transduction for the Development of Nanocarriers for Targeted Delivery of Protected Anticancer Drugs

by Hoda Ilkhani, Chuan-Jian Zhong and Maria Hepel

Nanomaterials 2021, 11(5), 1326; https://doi.org/10.3390/nano11051326 - 18 May 2021

Cited by 9 | Viewed by 3166

Abstract

Safe administration of highly cytotoxic chemotherapeutic drugs is a challenging problem in cancer treatment due to the adverse side effects and collateral damage to non-tumorigenic cells. To mitigate these problems, promising new approaches, based on the paradigm of controlled targeted drug delivery (TDD), [...] Read more.

Safe administration of highly cytotoxic chemotherapeutic drugs is a challenging problem in cancer treatment due to the adverse side effects and collateral damage to non-tumorigenic cells. To mitigate these problems, promising new approaches, based on the paradigm of controlled targeted drug delivery (TDD), and utilizing drug nanocarriers with biorecognition ability to selectively target neoplastic cells, are being considered in cancer therapy. Herein, we report on the design and testing of a nanoparticle-grid based biosensing platform to aid in the development of new targeted drug nanocarriers. The proposed sensor grid consists of superparamagnetic gold-coated core–shell Fe₂Ni@Au nanoparticles, further functionalized with folic acid targeting ligand, model thiolated chemotherapeutic drug doxorubicin (DOX), and a biocompatibility agent, 3,6-dioxa-octanethiol (DOOT). The employed dual transduction method based on electrochemical and enhanced Raman scattering detection has enabled efficient monitoring of the drug loading onto the nanocarriers, attaching to the sensor surface, as well as the drug release under simulated intracellular conditions. The grid’s nanoparticles serve here as the model nanocarriers for new TDD systems under design and optimization. The superparamagnetic properties of the Fe₂Ni@Au NPs aid in nanoparticles’ handling and constructing a dense sensor grid with high plasmonic enhancement of the Raman signals due to the minimal interparticle distance. Full article

(This article belongs to the Special Issue Gold Nanoparticle-Based Biosensors)

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