Nanomaterials

171 KiB

Open AccessEditorial

Acknowledgement to Reviewers of Nanomaterials in 2015

by Nanomaterials Editorial Office

Nanomaterials 2016, 6(1), 23; https://doi.org/10.3390/nano6010023 - 21 Jan 2016

Viewed by 3696

The editors of Nanomaterials would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...] Full article

5191 KiB

Open AccessArticle

Coupling of Nanocrystalline Anatase TiO₂ to Porous Nanosized LaFeO₃ for Efficient Visible-Light Photocatalytic Degradation of Pollutants

by Muhammad Humayun, Zhijun Li, Liqun Sun, Xuliang Zhang, Fazal Raziq, Amir Zada, Yang Qu and Liqiang Jing

Nanomaterials 2016, 6(1), 22; https://doi.org/10.3390/nano6010022 - 20 Jan 2016

Cited by 37 | Viewed by 7293

Abstract

In this work we have successfully fabricated nanocrystalline anatase TiO₂/perovskite-type porous nanosized LaFeO₃ (T/P-LFO) nanocomposites using a simple wet chemical method. It is clearly demonstrated by means of atmosphere-controlled steady-state surface photovoltage spectroscopy (SPS) responses, photoluminescence spectra, and fluorescence spectra [...] Read more.

In this work we have successfully fabricated nanocrystalline anatase TiO₂/perovskite-type porous nanosized LaFeO₃ (T/P-LFO) nanocomposites using a simple wet chemical method. It is clearly demonstrated by means of atmosphere-controlled steady-state surface photovoltage spectroscopy (SPS) responses, photoluminescence spectra, and fluorescence spectra related to the formed OH⁻ radical amount that the photogenerated charge carriers in the resultant T/P-LFO nanocomposites with a proper mole ratio percentage of TiO₂ display much higher separation in comparison to the P-LFO alone. This is highly responsible for the improved visible-light activities of T/P-LFO nanocomposites for photocatalytic degradation of gas-phase acetaldehyde and liquid-phase phenol. This work will provide a feasible route to synthesize visible-light responsive nano-photocatalysts for efficient solar energy utilization. Full article

(This article belongs to the Special Issue Nanoparticles for Catalysis)

► Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
X-ray diffraction (XRD) patterns (A) and UV-vis diffuse reflectance (UV-vis DRS) spectra (B) of Porous-LaFeO3 (P-LFO) TiO2 (T) and TiO2/P-LFO (T/P-LFO) nanocomposites; Transmission electron microscopy (TEM) image of P-LFO with inset selected area electron diffraction (SAED) pattern (C); TEM image of 9T/P-LFO with inset high resolution transmission electron microscopy (HRTEM) image (D). Full article ">Figure 2
Scanning electron microscopy (SEM) micrograph of P-LFO (A) and 9T/P-LFO nanocomposite (B). Full article ">Figure 3
X-ray photoelectron spectroscopy (XPS) survey spectra of P-LFO and 9T/P-LFO nanocomposite (A); with high resolution images La3d (B); Fe2p (C); O1s (D); Ti2p (E). Full article ">Figure 4
N2 adsorption/desorption isotherms (A) and pore diameter (B) of P-LFO and 9T/P-LFO nanocomposite. Full article ">Figure 5
Surface photovoltage spectroscopy (SPS) responses of P-LFO (A) and 9T/P-LFO (B) in different atmospheres; SPS responses of P-LFO and T/P-LFO nanocomposites in air (C); Photoluminescence (PL) responses of P-LFO and T/P-LFO nanocomposites (D). Full article ">Figure 6
Visible-light photocatalytic activity for acetaldehyde and phenol degradation (A) and OH− radical amount related Fluorescence spectra (B) of P-LFO and T/P-LFO nanocomposites. Full article ">Figure 7
Scheme for energy band gaps and the mechanism for photogenerated charge separation and transfer in the fabricated T/P-LFO nanocomposite. Full article ">

2253 KiB

Open AccessArticle

Investigation of MnO₂ and Ordered Mesoporous Carbon Composites as Electrocatalysts for Li-O₂ Battery Applications

by Chih-Chun Chin, Hong-Kai Yang and Jenn-Shing Chen

Nanomaterials 2016, 6(1), 21; https://doi.org/10.3390/nano6010021 - 18 Jan 2016

Cited by 16 | Viewed by 8485

Abstract

The electrocatalytic activities of the MnO₂/C composites are examined in Li-O₂ cells as the cathode catalysts. Hierarchically mesoporous carbon-supported manganese oxide (MnO₂/C) composites are prepared using a combination of soft template and hydrothermal methods. The composites are characterized [...] Read more.

The electrocatalytic activities of the MnO₂/C composites are examined in Li-O₂ cells as the cathode catalysts. Hierarchically mesoporous carbon-supported manganese oxide (MnO₂/C) composites are prepared using a combination of soft template and hydrothermal methods. The composites are characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, small angle X-ray scattering, The Brunauer–Emmett–Teller (BET) measurements, galvanostatic charge-discharge methods, and rotating ring-disk electrode (RRDE) measurements. The electrochemical tests indicate that the MnO₂/C composites have excellent catalytic activity towards oxygen reduction reactions (ORRs) due to the larger surface area of ordered mesoporous carbon and higher catalytic activity of MnO₂. The O₂ solubility, diffusion rates of O₂ and O₂^•− coefficients (D_O₂andD_{_O⁻₂}), the rate constant (k_f) for producing O_₂^•−_, and the propylene carbonate (PC)-electrolyte

decomposition rate constant (k) of the MnO₂/C material were measured by RRDE experiments in the 0.1 M TBAPF₆/PC electrolyte. The values of k_f and k for MnO_₂/C are 4.29 × 10⁻² cm·s⁻¹ and 2.6 s⁻¹, respectively. The results indicate that the MnO₂/C cathode catalyst has higher electrocatalytic activity for the first step of ORR to produce O₂^•− and achieves a faster PC-electrolyte decomposition rate. Full article

(This article belongs to the Special Issue Nanoparticles for Catalysis)

► Show Figures

Figure 1

Figure 1
Schematic of a four-neck, jacketed glass cell with a rotating ring-disk electrode (RRDE) system. Full article ">Figure 2
(a) Wide-angle X-ray diffraction (XRD) patterns; (b) small angle X-ray scattering (SAXS) patterns of MnO2/C composites. Full article ">Figure 3
Scanning electron microscope (SEM) images (a) MnO2/C composites; (b) high magnification of the region marked with a square in (a); and transmission electron microscope (TEM) images (c,e) MnO2/C composites; (d) high magnification of the region marked with a square in (c); and (f) selected area electron diffraction (SAED) pattern of the region marked with a square in (e). Full article ">Figure 4
Nitrogen sorption isotherms of MnO2/C composites. The insert is the Barrett–Joyner–Halenda (BJH) desorption pore size distribution. Full article ">Figure 5
(a) CV curves were recorded at a scanning rate of 2 mV·s−1 for MnO2/C and Super-P carbon samples; (b) initial charge–discharge profiles for MnO2/C and Super P samples at a current density of 0.2 mA·cm−2. Full article ">Figure 6
(a) Example of determination of the superoxide radical (O2•−) transit-time (Ts) in O2-saturated solutions of 0.1 M TBAPF6 in propylene carbonate (PC) at ω = 100 rpm, Edisk = 1.85 V and Ering = 2.6 V. Transit time (Ts) values at different rotation rates for the diffusion of (b) O2 and (c) O2•−; (d) relation between the inverse of the rotation speed and the transient time for O2 and O2•−. Full article ">Figure 7
(a) Steady-state CV curves of a glassy carbon rotating disk electrode (RDE) in an O2-saturated 0.1 M TBAPF6/PC solution at a scan rate of 50 mV/s between 1.5 and 2.8 VLi with different rotation rates. The insert is the Koutecky–Levich plot derived from the disc current values at 1.50 VLi; (b) steady-state CV curves of a MnO2/C RDE in an O2-saturated 0.1 M TBAPF6/PC solution at a scan rate of 50 mV/s between 1.2 and 2.8 VLi with different rotation rates. Full article ">Figure 8
(a) RRDE profiles of MnO2/C recorded at 50 mV·s−1 in an O2-saturated 0.1 M TBAPF6/PC solution, at rotation rates between 300 and 2100 rpm with continuous holding of the Pt ring at 2.85 VLi; (b) evolution of the absolute ratio between the ring and disk current (Nk) and the electrode rotation speed (ω). Full article ">

1396 KiB

Open AccessCommunication

A Graphene Oxide-Based Fluorescent Platform for Probing of Phosphatase Activity

by Ting Sun, Ning Xia and Lin Liu

Nanomaterials 2016, 6(1), 20; https://doi.org/10.3390/nano6010020 - 18 Jan 2016

Cited by 13 | Viewed by 5872

Abstract

We presented a strategy for fabricating graphene oxide (GO)-based fluorescent biosensors to monitor the change of phosphorylation state and detect phosphatase activity. By regulating the interaction between the negatively charged phosphate group and the positively charged amino residue, we found that GO showed [...] Read more.

We presented a strategy for fabricating graphene oxide (GO)-based fluorescent biosensors to monitor the change of phosphorylation state and detect phosphatase activity. By regulating the interaction between the negatively charged phosphate group and the positively charged amino residue, we found that GO showed different quenching efficiency toward the phosphorylated and dephosphorylated dye-labeled peptides. To demonstrate the application of our method, alkaline phosphatase (ALP) was tested as a model enzyme with phosphorylated fluorescein isothiocyanate (FITC)-labeled short peptide FITC–Gly–Gly–Gly–Tyr(PO₃²⁻)–Arg as the probe. When the negatively charged phosphate group in the Tyr residue was removed from the peptide substrate by enzymatic hydrolysis, the resulting FITC–Gly–Gly–Gly–Tyr–Arg was readily adsorbed onto the GO surface through electrostatic interaction. As a result, fluorescence quenching was observed. Furthermore, the method was applied for the screening of phosphatase inhibitors. Full article

(This article belongs to the Special Issue Nanomaterials for Biosensing Applications)

► Show Figures

Figure 1

Figure 1
Schematic illustration of dephosphorylation process (A) and alkaline phosphatase (ALP) activity detection (B) using fluorescein isothiocyanate (FITC)–Gly–Gly–Gly–Tyr(PO32−)–Arg (GGGYpR) and graphene oxide (GO) as the probe and the quencher, respectively. Full article ">Figure 2
Quenching efficiency of different concentrations of GO toward phosphorylated peptide FITC–GGGYpR and dephosphorylated peptide FITC–Gly–Gly–Gly–Tyr–Arg (GGGYR). Full article ">Figure 3
(A) Fluorescence spectra of FITC–GGGYpR in the presence of GO and ALP; (B) Fluorescence intensity of FITC–GGGYpR/GO in the absence (bar 1) and presence of ALP (bar 2), bovine serum albumin (BSA) (bar 3), lysozyme (bar 4), myoglobin (bar 5), and ALP/BSA/lysozyme/myoglobin (bar 6). The final concentrations of FITC–GGGYpR, GO, ALP, BSA, lysozyme and myoglobin are 100 nM, 50 μg·mL−1, 10 nM, 0.5 μg·mL−1, 0.5 μg·mL−1 and 0.5 μg·mL−1, respectively. Full article ">Figure 4
(A) Fluorescence intensity of FITC–GGGYpR/GO after addition of different concentrations of ALP (from a to j: 0, 0.2, 0.5, 1, 2, 3, 4, 5, 7.5 and 10 nM). The final concentrations of GO and FITC–GGGYpR are 50 μg∙mL−1 and 100 nM, respectively; (B) Dependence of fluorescence intensity on the ALP concentration. Full article ">Figure 5
(A) Fluorescence spectra of 100 nM FITC–GGGYpR/GO in the presence of 10 nM ALP and different concentrations of levamisole (0, 5, 10, 20, 40, 60, 80, 100 and 120 nM); (B) Dependence of the fluorescence intensity on the concentration of levamisole. Full article ">

3324 KiB

Open AccessArticle

Synthesis of Nickel Nanowires with Tunable Characteristics

by Zengzilu Xia and Weijia Wen

Nanomaterials 2016, 6(1), 19; https://doi.org/10.3390/nano6010019 - 15 Jan 2016

Cited by 27 | Viewed by 8336

Abstract

A one-step synthesis of magnetic nickel nanowires (NiNWs) with tunable characteristics is reported. The method is simple and easy to be conducted, leading to high compatibility with scaling-up. It is discovered that the size and morphology of NiNWs can be adjusted by tuning [...] Read more.

A one-step synthesis of magnetic nickel nanowires (NiNWs) with tunable characteristics is reported. The method is simple and easy to be conducted, leading to high compatibility with scaling-up. It is discovered that the size and morphology of NiNWs can be adjusted by tuning the reaction temperature, time length, as well as surfactant concentration. It is found that the products have shown high purity which remained after being stored for several months. A remarkable enhanced saturation magnetization of the product was also observed, compared to that of bulk nickel. By providing both practical experimental details and in-depth mechanism, the work introduced in this paper may advance the mass production and further applications of NiNWs. Full article

(This article belongs to the Special Issue Nanoparticles in Bioimaging)

► Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
The photographs of nickel nanowires (NiNWs) (a) dispersed in ethanol (b) attracted by an external magnet, (c) X-ray diffraction (XRD) patterns, (d) low and (e) high magnification scanning electron microscopy (SEM) images of NiNWs; and the transmission electron microscopy (TEM) images of (f) the body and (g) the end of a NiNW. Full article ">Figure 1 Cont.
The photographs of nickel nanowires (NiNWs) (a) dispersed in ethanol (b) attracted by an external magnet, (c) X-ray diffraction (XRD) patterns, (d) low and (e) high magnification scanning electron microscopy (SEM) images of NiNWs; and the transmission electron microscopy (TEM) images of (f) the body and (g) the end of a NiNW. Full article ">Figure 2
SEM images with same magnification of NiNWs synthesized at (a) 70 °C, (b) 110 °C, and (c) 150 °C. The change of (d) length, (e) width, and (f) length-to-width ratio (LWR) of NiNWs with temperature. Full article ">Figure 3
Typical SEM images with same magnification of NiNWs synthesized with (a) 1 min, (b) 10 min, and (c) 90 min. The change of (d) length, (e) width, and (f) LWR of NiNWs with reaction time. Full article ">Figure 4
SEM images with same magnification of NiNWs synthesized with poly(vinylpyrrolidone) (PVP) concentration of (a) 0.03 w/v %, (b) 0.5 w/v %, and (c) 2 w/v %. The change of (d) length, (e) width, and (f) LWR of NiNWs with PVP concentration. Full article ">Figure 5
The typical energy-dispersive X-ray spectroscopy (EDS) spectrum. The inset is hysteretic loop at room temperature of typical NiNWs. These characterizations were conducted on the product synthesized with typical process. Full article ">Figure 6
The illustration of NiNW growth mechanism. The inset is the detailed illustration of Step 2 to 4. Full article ">

3758 KiB

Open AccessCommunication

Nitrogen-Doped Banana Peel–Derived Porous Carbon Foam as Binder-Free Electrode for Supercapacitors

by Bingzhi Liu, Lili Zhang, Peirong Qi, Mingyuan Zhu, Gang Wang, Yanqing Ma, Xuhong Guo, Hui Chen, Boya Zhang, Zhuangzhi Zhao, Bin Dai and Feng Yu

Nanomaterials 2016, 6(1), 18; https://doi.org/10.3390/nano6010018 - 15 Jan 2016

Cited by 63 | Viewed by 10746

Abstract

Nitrogen-doped banana peel–derived porous carbon foam (N-BPPCF) successfully prepared from banana peels is used as a binder-free electrode for supercapacitors. The N-BPPCF exhibits superior performance including high specific surface areas of 1357.6 m²/g, large pore volume of 0.77 cm³/g, [...] Read more.

Nitrogen-doped banana peel–derived porous carbon foam (N-BPPCF) successfully prepared from banana peels is used as a binder-free electrode for supercapacitors. The N-BPPCF exhibits superior performance including high specific surface areas of 1357.6 m²/g, large pore volume of 0.77 cm³/g, suitable mesopore size distributions around 3.9 nm, and super hydrophilicity with nitrogen-containing functional groups. It can easily be brought into contact with an electrolyte to facilitate electron and ion diffusion. A comparative analysis on the electrochemical properties of BPPCF electrodes is also conducted under similar conditions. The N-BPPCF electrode offers high specific capacitance of 185.8 F/g at 5 mV/s and 210.6 F/g at 0.5 A/g in 6 M KOH aqueous electrolyte versus 125.5 F/g at 5 mV/s and 173.1 F/g at 0.5 A/g for the BPPCF electrode. The results indicate that the N-BPPCF is a binder-free electrode that can be used for high performance supercapacitors. Full article

(This article belongs to the Special Issue Nanostructured Materials for Li-Ion Batteries and Beyond)

► Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
(a) Synthesis of porous carbon foam from banana peels. Scanning electron microscopy (SEM) images of (b) banana peel-derived porous carbon foam (BPPCF) and (c) nitrogen-doped BPPCF (N-BPPCF). Full article ">Figure 2
Transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) images at different magnifications of (a, c and e) BPPCF and (b, d and f) N-BPPCF. Full article ">Figure 3
Nitrogen sorption isotherms of (a) BPPCF and (b) N-BPPCF, and the corresponding pore size distribution (insets). Full article ">Figure 4
(a) X-ray diffraction (XRD) patterns for BPPCF and N-BPPCF samples. X-ray photoelectron spectroscopy (XPS) spectra of (b) C 1s, (c) O 1s and (d) N 1s for as-obtained BPPCF and N-BPPCF. Full article ">Figure 5
Cyclic voltammogram (CV) curves for (a) BPPCF and (b) N-BPPCF in 6 M KOH at different scan rates. (c) CV curves of the samples at a scan rate of 5 mV/s. (d) Specific capacitance calculated according to CVs. Full article ">Figure 6
Galvanostatic charge/discharge (GCD) curves for (a) BPPCF and (b) N-BPPCF in 6 M KOH at various current densities. (c) Specific capacitance and (d) the corresponding rate capacitance retention of BPPCF and N-BPPCF. Full article ">Figure 7
Cycle life of BPPCF and N-BPPCF at various currents: (a) 0.5 A/g for 500 cycles and (b) 2.5 A/g for 5000 cycles. Full article ">

2269 KiB

Open AccessReview

Excipient Nanoemulsions for Improving Oral Bioavailability of Bioactives

by Laura Salvia-Trujillo, Olga Martín-Belloso and David Julian McClements

Nanomaterials 2016, 6(1), 17; https://doi.org/10.3390/nano6010017 - 14 Jan 2016

Cited by 93 | Viewed by 12718

Abstract

The oral bioavailability of many hydrophobic bioactive compounds found in natural food products (such as vitamins and nutraceuticals in fruits and vegetables) is relatively low due to their low bioaccessibility, chemical instability, or poor absorption. Most previous research has therefore focused on the [...] Read more.

The oral bioavailability of many hydrophobic bioactive compounds found in natural food products (such as vitamins and nutraceuticals in fruits and vegetables) is relatively low due to their low bioaccessibility, chemical instability, or poor absorption. Most previous research has therefore focused on the design of delivery systems to incorporate isolated bioactive compounds into food products. However, a more sustainable and cost-effect approach to enhancing the functionality of bioactive compounds is to leave them within their natural environment, but specifically design excipient foods that enhance their bioavailability. Excipient foods typically do not have functionality themselves but they have the capacity to enhance the functionality of nutrients present in natural foods by altering their bioaccessibility, absorption, and/or chemical transformation. In this review article we present the use of excipient nanoemulsions for increasing the bioavailability of bioactive components from fruits and vegetables. Nanoemulsions present several advantages over other food systems for this application, such as the ability to incorporate hydrophilic, amphiphilic, and lipophilic excipient ingredients, high physical stability, and rapid gastrointestinal digestibility. The design, fabrication, and application of nanoemulsions as excipient foods will therefore be described in this article. Full article

(This article belongs to the Special Issue Nanoparticles Assisted Drug Delivery)

► Show Figures

Graphical abstract

3001 KiB

Open AccessArticle

Resistive Switching of Plasma–Treated Zinc Oxide Nanowires for Resistive Random Access Memory

by Yunfeng Lai, Wenbiao Qiu, Zecun Zeng, Shuying Cheng, Jinling Yu and Qiao Zheng

Nanomaterials 2016, 6(1), 16; https://doi.org/10.3390/nano6010016 - 13 Jan 2016

Cited by 23 | Viewed by 6850

Abstract

ZnO nanowires (NWs) were grown on Si(100) substrates at 975 °C by a vapor-liquid-solid method with ~2 nm and ~4 nm gold thin films as catalysts, followed by an argon plasma treatment for the as-grown ZnO NWs. A single ZnO NW–based memory cell [...] Read more.

ZnO nanowires (NWs) were grown on Si(100) substrates at 975 °C by a vapor-liquid-solid method with ~2 nm and ~4 nm gold thin films as catalysts, followed by an argon plasma treatment for the as-grown ZnO NWs. A single ZnO NW–based memory cell with a Ti/ZnO/Ti structure was then fabricated to investigate the effects of plasma treatment on the resistive switching. The plasma treatment improves the homogeneity and reproducibility of the resistive switching of the ZnO NWs, and it also reduces the switching (set and reset) voltages with less fluctuations, which would be associated with the increased density of oxygen vacancies to facilitate the resistive switching as well as to average out the stochastic movement of individual oxygen vacancies. Additionally, a single ZnO NW–based memory cell with self-rectification could also be obtained, if the inhomogeneous plasma treatment is applied to the two Ti/ZnO contacts. The plasma-induced oxygen vacancy disabling the rectification capability at one of the Ti/ZnO contacts is believed to be responsible for the self-rectification in the memory cell. Full article

(This article belongs to the Special Issue Plasma Nanoengineering and Nanofabrication)

► Show Figures

Figure 1

157 KiB

Open AccessEditorial

Frontiers in Mesoporous Nanomaterials

by Eva Pellicer and Jordi Sort

Nanomaterials 2016, 6(1), 15; https://doi.org/10.3390/nano6010015 - 11 Jan 2016

Cited by 3 | Viewed by 4254

Abstract

The Special Issue of Nanomaterials “Frontiers in Mesoporous Nanomaterials” gathers four reviews, one communication and eight regular papers. Full article

(This article belongs to the Special Issue Frontiers in Mesoporous Nanomaterials)

979 KiB

Open AccessArticle

X-ray Absorption Spectroscopy Characterization of a Li/S Cell

by Yifan Ye, Ayako Kawase, Min-Kyu Song, Bingmei Feng, Yi-Sheng Liu, Matthew A. Marcus, Jun Feng, Elton J. Cairns, Jinghua Guo and Junfa Zhu

Nanomaterials 2016, 6(1), 14; https://doi.org/10.3390/nano6010014 - 11 Jan 2016

Cited by 30 | Viewed by 9868

Abstract

The X-ray absorption spectroscopy technique has been applied to study different stages of the lithium/sulfur (Li/S) cell life cycle. We have investigated how speciation of S in Li/S cathodes changes upon the introduction of CTAB (cetyltrimethylammonium bromide, CH₃(CH₂)₁₅ [...] Read more.

The X-ray absorption spectroscopy technique has been applied to study different stages of the lithium/sulfur (Li/S) cell life cycle. We have investigated how speciation of S in Li/S cathodes changes upon the introduction of CTAB (cetyltrimethylammonium bromide, CH₃(CH₂)₁₅N⁺(CH₃)₃Br⁻) and with charge/discharge cycling. The introduction of CTAB changes the synthesis reaction pathway dramatically due to the interaction of CTAB with the terminal S atoms of the polysulfide ions in the Na₂S_x solution. For the cycled Li/S cell, the loss of electrochemically active sulfur and the accumulation of a compact blocking insulating layer of unexpected sulfur reaction products on the cathode surface during the charge/discharge processes make the capacity decay. A modified coin cell and a vacuum-compatible three-electrode electro-chemical cell have been introduced for further in-situ/in-operando studies. Full article

(This article belongs to the Special Issue Nanostructured Materials for Li-Ion Batteries and Beyond)

► Show Figures

Graphical abstract

1724 KiB

Open AccessArticle

White Light-Emitting Diodes Based on AgInS₂/ZnS Quantum Dots with Improved Bandwidth in Visible Light Communication

by Cheng Ruan, Yu Zhang, Min Lu, Changyin Ji, Chun Sun, Xiongbin Chen, Hongda Chen, Vicki L. Colvin and William W. Yu

Nanomaterials 2016, 6(1), 13; https://doi.org/10.3390/nano6010013 - 8 Jan 2016

Cited by 55 | Viewed by 10692

Abstract

Quantum dot white light-emitting diodes (QD-WLEDs) were fabricated from green- and red-emitting AgInS₂/ZnS core/shell QDs coated on GaN LEDs. Their electroluminescence (EL) spectra were measured at different currents, ranging from 50 mA to 400 mA, and showed good color stability. The [...] Read more.

Quantum dot white light-emitting diodes (QD-WLEDs) were fabricated from green- and red-emitting AgInS₂/ZnS core/shell QDs coated on GaN LEDs. Their electroluminescence (EL) spectra were measured at different currents, ranging from 50 mA to 400 mA, and showed good color stability. The modulation bandwidth of previously prepared QD-WLEDs was confirmed to be much wider than that of YAG:Ce phosphor-based WLEDs. These results indicate that the AgInS₂/ZnS core/shell QDs are good color-converting materials for WLEDs and they are capable in visible light communication (VLC). Full article

(This article belongs to the Special Issue Current Trends in Colloidal Nanocrystals)

► Show Figures

Figure 1

947 KiB

Open AccessArticle

The Coupled Photothermal Reaction and Transport in a Laser Additive Metal Nanolayer Simultaneous Synthesis and Pattering for Flexible Electronics

by Song-Ling Tsai, Yi-Kai Liu, Heng Pan, Chien-Hung Liu and Ming-Tsang Lee

Nanomaterials 2016, 6(1), 12; https://doi.org/10.3390/nano6010012 - 8 Jan 2016

Cited by 8 | Viewed by 6344

Abstract

The Laser Direct Synthesis and Patterning (LDSP) technology has advantages in terms of processing time and cost compared to nanomaterials-based laser additive microfabrication processes. In LDSP, a scanning laser on the substrate surface induces chemical reactions in the reactive liquid solution and selectively [...] Read more.

The Laser Direct Synthesis and Patterning (LDSP) technology has advantages in terms of processing time and cost compared to nanomaterials-based laser additive microfabrication processes. In LDSP, a scanning laser on the substrate surface induces chemical reactions in the reactive liquid solution and selectively deposits target material in a preselected pattern on the substrate. In this study, we experimentally investigated the effect of the processing parameters and type and concentration of the additive solvent on the properties and growth rate of the resulting metal film fabricated by this LDSP technology. It was shown that reactive metal ion solutions with substantial viscosity yield metal films with superior physical properties. A numerical analysis was also carried out the first time to investigate the coupled opto-thermo-fluidic transport phenomena and the effects on the metal film growth rate. To complete the simulation, the optical properties of the LDSP deposited metal film with a variety of thicknesses were measured. The characteristics of the temperature field and the thermally induced flow associated with the moving heat source are discussed. It was shown that the processing temperature range of the LDSP is from 330 to 390 K. A semi-empirical model for estimating the metal film growth rate using this process was developed based on these results. From the experimental and numerical results, it is seen that, owing to the increased reflectivity of the silver film as its thickness increases, the growth rate decreases gradually from about 40 nm at initial to 10 nm per laser scan after ten scans. This self-controlling effect of LDSP process controls the thickness and improves the uniformity of the fabricated metal film. The growth rate and resulting thickness of the metal film can also be regulated by adjustment of the processing parameters, and thus can be utilized for controllable additive nano/microfabrication. Full article

(This article belongs to the Special Issue Nanomaterials for Flexible and Stretchable Devices: Synthesis, Processes, and Applications)

► Show Figures

Figure 1

2611 KiB

Open AccessArticle

Repair of the Orbital Wall Fractures in Rabbit Animal Model Using Nanostructured Hydroxyapatite-Based Implant

by Sinziana Gradinaru, Laura Madalina Popescu, Roxana Mioara Piticescu, Sabina Zurac, Radu Ciuluvica, Alexandrina Burlacu, Raluca Tutuianu, Sorina-Nicoleta Valsan, Adrian Mihail Motoc and Liliana Mary Voinea

Nanomaterials 2016, 6(1), 11; https://doi.org/10.3390/nano6010011 - 7 Jan 2016

Cited by 9 | Viewed by 6130

Abstract

Cellular uptake and cytotoxicity of nanostructured hydroxyapatite (nanoHAp) are dependent on its physical parameters. Therefore, an understanding of both surface chemistry and morphology of nanoHAp is needed in order to be able to anticipate its in vivo behavior. The aim of this paper [...] Read more.

Cellular uptake and cytotoxicity of nanostructured hydroxyapatite (nanoHAp) are dependent on its physical parameters. Therefore, an understanding of both surface chemistry and morphology of nanoHAp is needed in order to be able to anticipate its in vivo behavior. The aim of this paper is to characterize an engineered nanoHAp in terms of physico-chemical properties, biocompatibility, and its capability to reconstitute the orbital wall fractures in rabbits. NanoHAp was synthesized using a high pressure hydrothermal method and characterized by physico-chemical, structural, morphological, and optical techniques. X-ray diffraction revealed HAp crystallites of 21 nm, while Scanning Electron Microscopy (SEM) images showed spherical shapes of HAp powder. Mean particle size of HAp measured by DLS technique was 146.3 nm. Biocompatibility was estimated by the effect of HAp powder on the adhesion and proliferation of mesenchymal stem cells (MSC) in culture. The results showed that cell proliferation on powder-coated slides was between 73.4% and 98.3% of control cells (cells grown in normal culture conditions). Computed tomography analysis of the preformed nanoHAp implanted in orbital wall fractures, performed at one and two months postoperative, demonstrated the integration of the implants in the bones. In conclusion, our engineered nanoHAp is stable, biocompatible, and may be safely considered for reconstruction of orbital wall fractures. Full article

(This article belongs to the Special Issue Nanoparticles Assisted Drug Delivery)

► Show Figures

Graphical abstract

1729 KiB

Open AccessFeature PaperArticle

The Influence of Carbonaceous Matrices and Electrocatalytic MnO₂ Nanopowders on Lithium-Air Battery Performances

by Alessandro Minguzzi, Gianluca Longoni, Giuseppe Cappelletti, Eleonora Pargoletti, Chiara Di Bari, Cristina Locatelli, Marcello Marelli, Sandra Rondinini and Alberto Vertova

Nanomaterials 2016, 6(1), 10; https://doi.org/10.3390/nano6010010 - 6 Jan 2016

Cited by 17 | Viewed by 5813

Abstract

Here, we report new gas diffusion electrodes (GDEs) prepared by mixing two different pore size carbonaceous matrices and pure and silver-doped manganese dioxide nanopowders, used as electrode supports and electrocatalytic materials, respectively. MnO₂ nanoparticles are finely characterized in terms of structural (X-ray [...] Read more.

Here, we report new gas diffusion electrodes (GDEs) prepared by mixing two different pore size carbonaceous matrices and pure and silver-doped manganese dioxide nanopowders, used as electrode supports and electrocatalytic materials, respectively. MnO₂ nanoparticles are finely characterized in terms of structural (X-ray powder diffraction (XRPD), energy dispersive X-ray (EDX)), morphological (SEM, high-angle annular dark field (HAADF)-scanning transmission electron microscopy (STEM)/TEM), surface (Brunauer Emmet Teller (BET)-Barrett Joyner Halenda (BJH) method) and electrochemical properties. Two mesoporous carbons, showing diverse surface areas and pore volume distributions, have been employed. The GDE performances are evaluated by chronopotentiometric measurements to highlight the effects induced by the adopted materials. The best combination, hollow core mesoporous shell carbon (HCMSC) with 1.0% Ag-doped hydrothermal MnO₂ (M_hydro_1.0%Ag) allows reaching very high specific capacity close to 1400 mAh·g⁻¹. Considerably high charge retention through cycles is also observed, due to the presence of silver as a dopant for the electrocatalytic MnO₂ nanoparticles. Full article

(This article belongs to the Special Issue Nanoparticles for Catalysis)

► Show Figures

Graphical abstract

3490 KiB

Open AccessArticle

Aqueous Dispersions of Silica Stabilized with Oleic Acid Obtained by Green Chemistry

by Cristina Lavinia Nistor, Raluca Ianchis, Marius Ghiurea, Cristian-Andi Nicolae, Catalin-Ilie Spataru, Daniela Cristina Culita, Jeanina Pandele Cusu, Victor Fruth, Florin Oancea and Dan Donescu

Nanomaterials 2016, 6(1), 9; https://doi.org/10.3390/nano6010009 - 5 Jan 2016

Cited by 12 | Viewed by 7854

Abstract

The present study describes for the first time the synthesis of silica nanoparticles starting from sodium silicate and oleic acid (OLA). The interactions between OLA and sodium silicate require an optimal OLA/OLANa molar ratio able to generate vesicles that can stabilize silica particles [...] Read more.

The present study describes for the first time the synthesis of silica nanoparticles starting from sodium silicate and oleic acid (OLA). The interactions between OLA and sodium silicate require an optimal OLA/OLANa molar ratio able to generate vesicles that can stabilize silica particles obtained by the sol-gel process of sodium silicate. The optimal molar ratio of OLA/OLANa can be ensured by a proper selection of OLA and respectively of sodium silicate concentration. The titration of sodium silicate with OLA revealed a stabilization phenomenon of silica/OLA vesicles and the dependence between their average size and reagent’s molar ratio. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) measurements emphasized the successful synthesis of silica nanoparticles starting from renewable materials, in mild condition of green chemistry. By grafting octadecyltrimethoxysilane on the initial silica particles, an increased interaction between silica particles and the OLA/OLANa complex was achieved. This interaction between the oleyl and octadecyl chains resulted in the formation of stable gel-like aqueous systems. Subsequently, olive oil and an oleophylic red dye were solubilized in these stable aqueous systems. This great dispersing capacity of oleosoluble compounds opens new perspectives for future green chemistry applications. After the removal of water and of the organic chains by thermal treatment, mesoporous silica was obtained. Full article

► Show Figures

Graphical abstract

4645 KiB

Open AccessFeature PaperArticle

Targeted Sterically Stabilized Phospholipid siRNA Nanomedicine for Hepatic and Renal Fibrosis

by Fatima Khaja, Dulari Jayawardena, Antonina Kuzmis and Hayat Önyüksel

Nanomaterials 2016, 6(1), 8; https://doi.org/10.3390/nano6010008 - 5 Jan 2016

Cited by 20 | Viewed by 6565

Abstract

Since its discovery, small interfering RNA (siRNA) has been considered a potent tool for modulating gene expression. It has the ability to specifically target proteins via selective degradation of messenger RNA (mRNA) not easily accessed by conventional drugs. Hence, RNA interference (RNAi) therapeutics [...] Read more.

Since its discovery, small interfering RNA (siRNA) has been considered a potent tool for modulating gene expression. It has the ability to specifically target proteins via selective degradation of messenger RNA (mRNA) not easily accessed by conventional drugs. Hence, RNA interference (RNAi) therapeutics have great potential in the treatment of many diseases caused by faulty protein expression such as fibrosis and cancer. However, for clinical application siRNA faces a number of obstacles, such as poor in vivo stability, and off-target effects. Here we developed a unique targeted nanomedicine to tackle current siRNA delivery issues by formulating a biocompatible, biodegradable and relatively inexpensive nanocarrier of sterically stabilized phospholipid nanoparticles (SSLNPs). This nanocarrier is capable of incorporating siRNA in its core through self-association with a novel cationic lipid composed of naturally occuring phospholipids and amino acids. This overall assembly protects and delivers sufficient amounts of siRNA to knockdown over-expressed protein in target cells. The siRNA used in this study, targets connective tissue growth factor (CTGF), an important regulator of fibrosis in both hepatic and renal cells. Furthermore, asialoglycoprotein receptors are targeted by attaching the galactosamine ligand to the nanocarries which enhances the uptake of nanoparticles by hepatocytes and renal tubular epithelial cells, the major producers of CTGF in fibrosis. On animals this innovative nanoconstruct, small interfering RNA in sterically stabilized phospholipid nanoparticles (siRNA-SSLNP), showed favorable pharmacokinetic properties and accumulated mostly in hepatic and renal tissues making siRNA-SSLNP a suitable system for targeting liver and kidney fibrotic diseases. Full article

(This article belongs to the Special Issue Nanoparticles Assisted Drug Delivery)

► Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
small interfering RNA in sterically stabilized phospholipid nanoparticles (siRNA-SSLNP) optimization in vitro: Representative particle size distribution of (A) Unimodal size distribution of empty SSMM (sterically stabilized mixed micelles); (B) Empty SSMM and siRNA-SSLNP with N/P ratio of 10; (C) Empty SSMM and siRNA-SSLNP with N/P ratio of 20; (D) Empty SSMM and siRNA-SSLNP with N/P ratio of 30; (E) siRNA lipofectamine (siRNA-Lipofectamine) complex; (F) Free siRNA molecules. Full article ">Figure 2
siRNA-SSLNP in vitro characterization: (A) Gel retardation assay of different formulations of siRNA, containing 200 nM siRNA per sample, on TBE-urea 15% gel , at a voltage of 180 V for 60 min, then stained with 1:500 SYBR Green-II in TBE with mild agitation for 30 min; (B) Fluorescence intensities measured by SYBR Green-II exclusion assay of SSMM and siRNA-SSLNP complexes at varying N/P ratios and siRNA with lipofectamine (LF) showing percent of un-incorporated siRNA (* p < 0.05 vs. free siRNA; mean ± SD; n = 3 replicates/group); (C) Gel retardation assay of different siRNA formulations after treatment with RNase; (D) Fluorescence intensities measured by SYBR Green-II fluorescence assay of different siRNA formulations after treatment with RNase (* p < 0.05 vs. free siRNA; † p < 0.05 vs. siRNA-lipofectamine; mean ± SD; n = 3 replicates/group). Full article ">Figure 3
Physicochemical characterization of siRNA-SSLNP-GalN: (A) Particle size distribution showing SSLNP-GalN peak at 91 ± 13 nm; (B) Transmission electron microscopy (TEM) image of siRNA-SSLNP-GalN, scale bar = 100 nm; (C) Results of SYBR Green-II exclusion assay. Bars represent percentage of siRNA before (un-incorporated) and after treatment with RNase enzyme (mean ± SD; n = 3 replicates/group). Full article ">Figure 4
Cell uptake and cytotoxicity assays: (A) Hepatic Hep-G2 cell uptake of FAM-labeled siRNA in various complexes. Changes in FACS histogram indicative of siRNA positive cells (upper), bars represent quantitative analysis of FACS histogram as a percentage siRNA-positive cells (lower). (* p < 0.05 vs. free siRNA and untreated control, † p > 0.05 meaning no statistical significance vs. siRNA-LF treated cells); (B) Cytotoxicity of siRNA in various complexes against primary hepatic stellate cells HSC at different siRNA concentration as determined by membrane integrity (LDH) assay; (C) Relative Hep-G2 cell viability expressed as a percentage of untreated control as a measure of cytotoxicity of siRNA complexes using MTS assay after 72 h incubation; (D) Cytotoxicity of different siRNA formulations after incubation with renal HK-2 cells for 72 h; (E) Cell proliferation kinetics of HK-2 cells after treatment with different formulations at siRNA concentration equivalent to 250 nM assessed at 24, 48, and 72 h time points (* p < 0.05 vs. siRNA-LF, data on B–D presented as mean ± SD; n = 3 replicates/group). Full article ">Figure 5
Protein downregulation: (A) Reduction of connective tissue growth factor (CTGF) expression in human hepatic Hep-G2 cells 24 h post transfection with anti CTGF-siRNA in different complexes; (B) Reduction of extracellular matrix (ECM) collagen expression in primary human hepatic stellate cells (HSC) 24 h post transfection with anti CTGF-siRNA in different complexes; (C) GTGF protein downregulation in renal tubular HK-2 cells, activated with transforming growth factor β1 (TGF-β1), 72 h post transfection with anti CTGF-siRNA in different complexes; (D) Reduction in ECM collagen expression by TGFβ activated HK-2 cells 72 h post transfection with anti CTFG-siRNA in different complexes. (Data are expressed as percent of the untreated control; mean ± SD; n = 3/treatment; * p < 0.05 vs. free siRNA at a corresponding siRNA dose; # p > 0.05 or statistically not significant vs. siRNA-lipofectamine (LF); ns—non significant among the groups indicated). The scrambled siRNA treatment showed no significance as compared to untreated controls and therefore control refers to untreated controls (Data not plotted). Full article ">Figure 6
Reversal of primary hepatic stellate cell (HSC) activation: (A) Down-regulation of collagen I; (B) Collagen III; and (C) α-smooth muscle actin (α-SMA) protein expression indicative of the reversal of activated myofibroblasts to quiescent stellate cells. Activated HSC were transfected with connective tissue growth factor (CTGF-siRNA) in various formulations. Standard immunocytochemistry performed 24 h post-transfection, cells were probed with primary antibodies followed by secondary Alexa-Fluor 488 (green) labeled antibody, then DAPI for nuclear staining (blue). Full article ">Figure 7
Biodistribution of different siRNA formulations compared to free Cy5 fluorophore over 24 h periods in (A) liver; (B) lung; (C) spleen; (D) heart; and (E) kidneys. Targeted formulation (siRNA-SSLNP-GalN) shows significant concentrations in liver and kidneys over observation period (n = 4 for each time point; * p < 0.05 vs. free siRNA treated animals, † p < 0.05 vs. free Cy5 treated animals); (F) Plasma concentration vs. time after single intravenous administration of various Cy-5 labeled formulations in Balb/c mice. (Data are presented as mean ± SD; n = 4 animals/each time point, MFI-Mean fluorescence intensity). Full article ">

2558 KiB

Open AccessFeature PaperArticle

Determination of Cd²⁺ and Pb²⁺ Based on Mesoporous Carbon Nitride/Self-Doped Polyaniline Nanofibers and Square Wave Anodic Stripping Voltammetry

by Chang Zhang, Yaoyu Zhou, Lin Tang, Guangming Zeng, Jiachao Zhang, Bo Peng, Xia Xie, Cui Lai, Beiqing Long and Jingjing Zhu

Nanomaterials 2016, 6(1), 7; https://doi.org/10.3390/nano6010007 - 4 Jan 2016

Cited by 39 | Viewed by 7621

Abstract

The fabrication and evaluation of a glassy carbon electrode (GCE) modified with self-doped polyaniline nanofibers (SPAN)/mesoporous carbon nitride (MCN) and bismuth for simultaneous determination of trace Cd²⁺ and Pb²⁺ by square wave anodic stripping voltammetry (SWASV) are presented here. The morphology [...] Read more.

The fabrication and evaluation of a glassy carbon electrode (GCE) modified with self-doped polyaniline nanofibers (SPAN)/mesoporous carbon nitride (MCN) and bismuth for simultaneous determination of trace Cd²⁺ and Pb²⁺ by square wave anodic stripping voltammetry (SWASV) are presented here. The morphology properties of SPAN and MCN were characterized by transmission electron microscopy (TEM), and the electrochemical properties of the fabricated electrode were characterized by cyclic voltammetry (CV). Experimental parameters, such as deposition time, pulse potential, step potential, bismuth concentration and NaCl concentration, were optimized. Under the optimum conditions, the fabricated electrode exhibited linear calibration curves ranging from 5 to 80 nM for Cd²⁺ and Pb²⁺. The limits of detection (LOD) were 0.7 nM for Cd²⁺ and 0.2 nM for Pb²⁺ (S/N = 3). Additionally, the repeatability, reproducibility, anti-interference ability and application were also investigated, and the proposed electrode exhibited excellent performance. The proposed method could be extended for other heavy metal determination. Full article

(This article belongs to the Special Issue Nanomaterials for Biosensing Applications)

► Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
Transmission electron microscopy (TEM) of the (A) self-doped polyaniline (SPAN) nanofiber and (B) mesoporous carbon nitride (MCN). Full article ">Figure 2
(A) Cyclic voltammetry diagrams of the glassy carbon electrode (GCE), GCE/SPAN and GCE/SPAN/MCN, using a 0.1 M KCl solution containing 5.0 mM ferro-/ferri-cyanide, with a potential range of −0.4–0.8 V and a scan rate of 100 mV·s−1; (B) electrochemical impedance spectra of GCE, GCE/SPAN and GCE/SPAN/MCN using a 0.1 M KCl solution containing 5.0 mM ferro-/ferri-cyanide, with a frequency range of 0.1–105 Hz, a bias potential of 0.19 V vs. a saturated calomel electrode (SCE) and an alternating current (AC) amplitude of 5 mV. Full article ">Figure 3
(A) Bi3+ concentration effect on peak height in a solution containing 200 mM NaCl, 10 μg·L−1 Pb2+ and Cd2+. Square wave anodic stripping voltammetry (SWASV) parameters: Ebegin = −1 V, Eend = −0.4 V, Estep = 0.010 V, Epulse = 0.02 V, Econdition = −0.4 V, Edeposition = −1 V, frequency = 50 Hz, deposition time = 300 s and equilibrium time = 20 s. (B) NaCl concentration effect on peak height in a solution containing 300 μg·L−1 Bi3+, 10 μg·L−1 Pb2+ and Cd2+. SWASV parameters: Ebegin = −1 V, Eend = −0.4 V, Estep = 0.010 V, Epulse = 0.02 V, Econdition = −0.4 V, Edeposition = −1 V, frequency = 50 Hz, deposition time = 300 s and equilibrium time = 20 s. Full article ">Figure 4
(A) Frequency effect on peak height in a solution containing 300 μg·L−1 Bi3+, 10 μg·L−1 Pb2+ and Cd2+ and 300 mM NaCl. SWASV parameters: Ebegin = −1 V, Eend = −0.4 V, Estep = 0.010 V, Epulse = 0.02 V, Econdition = −0.4 V, Edeposition = −1 V, frequency = 1–100 Hz, deposition time = 600 s and equilibrium time = 20 s. (B) Optimization of pulse potential (Epulse) using a solution containing 300 μg·L−1 Bi3+, 10 μg·L−1 Pb2+ and Cd2+ and 300 mM NaCl. SWV parameters: Ebegin = −1 V, Eend = −0.4 V, Estep = 0.010 V, Epulse = 0.005–0.05 V, Econdition = −0.4 V, Edeposition = −1 V, frequency = 100 Hz, deposition time = 600 s and equilibrium time = 20 s. Full article ">Figure 5
(A) SWASV curves at GCE/SPAN/MCN in 10 mM acetate buffer (pH 4.6) containing 300 mM NaCl, 300 μg·L−1 Bi3+, with different Cd2+ and Pb2+ concentrations (from a–i: 0, 1, 2, 5, 10, 20 , 40, 60, 80 μg·L−1). The SWASV parameters were Ebegin = −1 V, Eend = −0.4 V, Estep = 0.010 V, Epulse = 0.02 V, Econdition = −0.4 V, Edeposition = −1 V, frequency = 100 Hz, deposition time = 300 s and equilibrium time = 20 s. (B) and (C) show the plots of stripping peak current vs. the Cd(II) and Pb(II) concentration. Full article ">Figure 5 Cont.
(A) SWASV curves at GCE/SPAN/MCN in 10 mM acetate buffer (pH 4.6) containing 300 mM NaCl, 300 μg·L−1 Bi3+, with different Cd2+ and Pb2+ concentrations (from a–i: 0, 1, 2, 5, 10, 20 , 40, 60, 80 μg·L−1). The SWASV parameters were Ebegin = −1 V, Eend = −0.4 V, Estep = 0.010 V, Epulse = 0.02 V, Econdition = −0.4 V, Edeposition = −1 V, frequency = 100 Hz, deposition time = 300 s and equilibrium time = 20 s. (B) and (C) show the plots of stripping peak current vs. the Cd(II) and Pb(II) concentration. Full article ">Figure 5 Cont.
(A) SWASV curves at GCE/SPAN/MCN in 10 mM acetate buffer (pH 4.6) containing 300 mM NaCl, 300 μg·L−1 Bi3+, with different Cd2+ and Pb2+ concentrations (from a–i: 0, 1, 2, 5, 10, 20 , 40, 60, 80 μg·L−1). The SWASV parameters were Ebegin = −1 V, Eend = −0.4 V, Estep = 0.010 V, Epulse = 0.02 V, Econdition = −0.4 V, Edeposition = −1 V, frequency = 100 Hz, deposition time = 300 s and equilibrium time = 20 s. (B) and (C) show the plots of stripping peak current vs. the Cd(II) and Pb(II) concentration. Full article ">

6556 KiB

Open AccessArticle

Effects of Thickness and Amount of Carbon Nanofiber Coated Carbon Fiber on Improving the Mechanical Properties of Nanocomposites

by Ferial Ghaemi, Ali Ahmadian, Robiah Yunus, Fudziah Ismail and Saeed Rahmanian

Nanomaterials 2016, 6(1), 6; https://doi.org/10.3390/nano6010006 - 2 Jan 2016

Cited by 18 | Viewed by 5546

Abstract

In the current study, carbon nanofibers (CNFs) were grown on a carbon fiber (CF) surface by using the chemical vapor deposition method (CVD) and the influences of some parameters of the CVD method on improving the mechanical properties of a polypropylene (PP) composite [...] Read more.

In the current study, carbon nanofibers (CNFs) were grown on a carbon fiber (CF) surface by using the chemical vapor deposition method (CVD) and the influences of some parameters of the CVD method on improving the mechanical properties of a polypropylene (PP) composite were investigated. To obtain an optimum surface area, thickness, and yield of the CNFs, the parameters of the chemical vapor deposition (CVD) method, such as catalyst concentration, reaction temperature, reaction time, and hydrocarbon flow rate, were optimized. It was observed that the optimal surface area, thickness, and yield of the CNFs caused more adhesion of the fibers with the PP matrix, which enhanced the composite properties. Besides this, the effectiveness of reinforcement of fillers was fitted with a mathematical model obtaining good agreement between the experimental result and the theoretical prediction. By applying scanning electronic microscope (SEM), transmission electron microscope (TEM), and Raman spectroscopy, the surface morphology and structural information of the resultant CF-CNF were analyzed. Additionally, SEM images and a mechanical test of the composite with a proper layer of CNFs on the CF revealed not only a compactness effect but also the thickness and surface area roles of the CNF layers in improving the mechanical properties of the composites. Full article

► Show Figures

Figure 1

968 KiB

Open AccessFeature PaperReview

Biosensors Incorporating Bimetallic Nanoparticles

by John Rick, Meng-Che Tsai and Bing Joe Hwang

Nanomaterials 2016, 6(1), 5; https://doi.org/10.3390/nano6010005 - 31 Dec 2015

Cited by 56 | Viewed by 8797

Abstract

This article presents a review of electrochemical bio-sensing for target analytes based on the use of electrocatalytic bimetallic nanoparticles (NPs), which can improve both the sensitivity and selectivity of biosensors. The review moves quickly from an introduction to the field of bio-sensing, to [...] Read more.

This article presents a review of electrochemical bio-sensing for target analytes based on the use of electrocatalytic bimetallic nanoparticles (NPs), which can improve both the sensitivity and selectivity of biosensors. The review moves quickly from an introduction to the field of bio-sensing, to the importance of biosensors in today’s society, the nature of the electrochemical methods employed and the attendant problems encountered. The role of electrocatalysts is introduced with reference to the three generations of biosensors. The contributions made by previous workers using bimetallic constructs, grouped by target analyte, are then examined in detail; following which, the synthesis and characterization of the catalytic particles is examined prior to a summary of the current state of endeavor. Finally, some perspectives for the future of bimetallic NPs in biosensors are given. Full article

(This article belongs to the Special Issue Nanomaterials for Biosensing Applications)

► Show Figures

Graphical abstract

3433 KiB

Open AccessArticle

Dense Plasma Focus-Based Nanofabrication of III–V Semiconductors: Unique Features and Recent Advances

by Onkar Mangla, Savita Roy and Kostya (Ken) Ostrikov

Nanomaterials 2016, 6(1), 4; https://doi.org/10.3390/nano6010004 - 29 Dec 2015

Cited by 18 | Viewed by 7017

Abstract

The hot and dense plasma formed in modified dense plasma focus (DPF) device has been used worldwide for the nanofabrication of several materials. In this paper, we summarize the fabrication of III–V semiconductor nanostructures using the high fluence material ions produced by hot, [...] Read more.

The hot and dense plasma formed in modified dense plasma focus (DPF) device has been used worldwide for the nanofabrication of several materials. In this paper, we summarize the fabrication of III–V semiconductor nanostructures using the high fluence material ions produced by hot, dense and extremely non-equilibrium plasma generated in a modified DPF device. In addition, we present the recent results on the fabrication of porous nano-gallium arsenide (GaAs). The details of morphological, structural and optical properties of the fabricated nano-GaAs are provided. The effect of rapid thermal annealing on the above properties of porous nano-GaAs is studied. The study reveals that it is possible to tailor the size of pores with annealing temperature. The optical properties of these porous nano-GaAs also confirm the possibility to tailor the pore sizes upon annealing. Possible applications of the fabricated and subsequently annealed porous nano-GaAs in transmission-type photo-cathodes and visible optoelectronic devices are discussed. These results suggest that the modified DPF is an effective tool for nanofabrication of continuous and porous III–V semiconductor nanomaterials. Further opportunities for using the modified DPF device for the fabrication of novel nanostructures are discussed as well. Full article

(This article belongs to the Special Issue Plasma Nanoengineering and Nanofabrication)

► Show Figures

Figure 1

889 KiB

Open AccessReview

Receptor-Mediated Drug Delivery Systems Targeting to Glioma

by Shanshan Wang, Ying Meng, Chengyi Li, Min Qian and Rongqin Huang

Nanomaterials 2016, 6(1), 3; https://doi.org/10.3390/nano6010003 - 28 Dec 2015

Cited by 72 | Viewed by 11179

Abstract

Glioma has been considered to be the most frequent primary tumor within the central nervous system (CNS). The complexity of glioma, especially the existence of the blood-brain barrier (BBB), makes the survival and prognosis of glioma remain poor even after a standard treatment [...] Read more.

Glioma has been considered to be the most frequent primary tumor within the central nervous system (CNS). The complexity of glioma, especially the existence of the blood-brain barrier (BBB), makes the survival and prognosis of glioma remain poor even after a standard treatment based on surgery, radiotherapy, and chemotherapy. This provides a rationale for the development of some novel therapeutic strategies. Among them, receptor-mediated drug delivery is a specific pattern taking advantage of differential expression of receptors between tumors and normal tissues. The strategy can actively transport drugs, such as small molecular drugs, gene medicines, and therapeutic proteins to glioma while minimizing adverse reactions. This review will summarize recent progress on receptor-mediated drug delivery systems targeting to glioma, and conclude the challenges and prospects of receptor-mediated glioma-targeted therapy for future applications. Full article

(This article belongs to the Special Issue Nanoparticles in Theranostics)

► Show Figures

Graphical abstract

4545 KiB

Open AccessArticle

Effects of Particle Hydrophobicity, Surface Charge, Media pH Value and Complexation with Human Serum Albumin on Drug Release Behavior of Mitoxantrone-Loaded Pullulan Nanoparticles

by Xiaojun Tao, Shu Jin, Dehong Wu, Kai Ling, Liming Yuan, Pingfa Lin, Yongchao Xie and Xiaoping Yang

Nanomaterials 2016, 6(1), 2; https://doi.org/10.3390/nano6010002 - 25 Dec 2015

Cited by 34 | Viewed by 7896

Abstract

We prepared two types of cholesterol hydrophobically modified pullulan nanoparticles (CHP) and carboxyethyl hydrophobically modified pullulan nanoparticles (CHCP) substituted with various degrees of cholesterol, including 3.11, 6.03, 6.91 and 3.46 per polymer, and named CHP_−3.11, CHP_−6.03, CHP_−6.91 and [...] Read more.

We prepared two types of cholesterol hydrophobically modified pullulan nanoparticles (CHP) and carboxyethyl hydrophobically modified pullulan nanoparticles (CHCP) substituted with various degrees of cholesterol, including 3.11, 6.03, 6.91 and 3.46 per polymer, and named CHP_−3.11, CHP_−6.03, CHP_−6.91 and CHCP_−3.46. Dynamic laser light scattering (DLS) showed that the pullulan nanoparticles were 80–120 nm depending on the degree of cholesterol substitution. The mean size of CHCP nanoparticles was about 160 nm, with zeta potential −19.9 mV, larger than CHP because of the carboxyethyl group. A greater degree of cholesterol substitution conferred greater nanoparticle hydrophobicity. Drug-loading efficiency depended on nanoparticle hydrophobicity, that is, nanoparticles with the greatest degree of cholesterol substitution (6.91) showed the most drug encapsulation efficiency (90.2%). The amount of drug loading increased and that of drug release decreased with enhanced nanoparticle hydrophobicity. Nanoparticle surface-negative charge disturbed the amount of drug loading and drug release, for an opposite effect relative to nanoparticle hydrophobicity. The drug release in pullulan nanoparticles was higher pH 4.0 than pH 6.8 media. However, the changed drug release amount was not larger for negative-surface nanoparticles than CHP nanoparticles in the acid release media. Drug release of pullulan nanoparticles was further slowed with human serum albumin complexation and was little affected by nanoparticle hydrophobicity and surface negative charge. Full article

(This article belongs to the Special Issue Nanoparticles Assisted Drug Delivery)

► Show Figures

Figure 1

4446 KiB

Open AccessArticle

Synthesis and Application of Amine Functionalized Iron Oxide Nanoparticles on Menaquinone-7 Fermentation: A Step towards Process Intensification

by Alireza Ebrahiminezhad, Vikas Varma, Shuyi Yang, Younes Ghasemi and Aydin Berenjian

Nanomaterials 2016, 6(1), 1; https://doi.org/10.3390/nano6010001 - 25 Dec 2015

Cited by 60 | Viewed by 7256

Abstract

Industrial production of menaquione-7 by Bacillus subtilis natto is associated with major drawbacks. To address the current challenges in menaquione-7 fermentation, studying the effect of magnetic nanoparticles on the bacterial cells can open up a new domain for intensified menqainone-7 process. This article [...] Read more.

Industrial production of menaquione-7 by Bacillus subtilis natto is associated with major drawbacks. To address the current challenges in menaquione-7 fermentation, studying the effect of magnetic nanoparticles on the bacterial cells can open up a new domain for intensified menqainone-7 process. This article introduces the new concept of production and application of l-lysine coated iron oxide nanoparticles (l-Lys@IONs) as a novel tool for menaquinone-7 biosynthesis. l-Lys@IONs with the average size of 7 nm were successfully fabricated and were examined in a fermentation process of l-Lys@IONs decorated Bacillus subtilis natto. Based on the results, higher menaquinone-7 specific yield was observed for l-Lys@IONs decorated bacterial cells as compared to untreated bacteria. In addition, more than 92% removal efficacy was achieved by using integrated magnetic separation process. The present study demonstrates that l-Lys@IONs can be successfully applied during a fermentation of menaquinone-7 without any negative consequences on the culture conditions. This study provides a novel biotechnological application for IONs and their future role in bioprocess intensification. Full article

► Show Figures

Figure 1

Journal Menu

Journal Browser

Nanomaterials, Volume 6, Issue 1 (January 2016) – 23 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI