•ZnO and GeO2–ZnGeO4 nanowires were fabricated by thermal evaporation of Zn and Ge powder mixture.•Morphology of specimens were observed to have a nanowire structure to rod-like morphology.•Strong ...NBE emission band with suppressed visible green emission band were observed on the dominant ZnO nanowires.•Strong emission of ∼530nm were observed on the GeO2–Zn2GeO4 nanowires.
This paper reports the first attempt for fabrication of thermal evaporated Zn–Ge powder mixture to achieve near-band-edge (NBE) emission of ZnO and visible emission of GeO2–Zn2GeO4 nanowires with controllable intensities. The nanowires were fabricated by thermal evaporation of Zn and Ge powder mixture, particularly, by using different Zn:Ge ratio, temperature and evaporated times. The morphology of nanowires was depended on the Zn and Ge ratio that was observed to have a nanowire structure to rod-like morphology. The thermal evaporation of Zn:Ge powder mixture resulted in formation of dominant ZnO or GeO2–Zn2GeO4 nanowires as a function of evaporated parameters. These results suggest that the application of thermal evaporation of Zn and Ge mixture for potential application in synthesis of ZnO or GeO2–Zn2GeO4 nanowires for optoelectronic field.
A nanocomposite comprising cerium oxide nanoparticles (CeO2 NPs) and polypyrrole (PPy) was fabricated onto a microelectrode for cholesterol sensing application. The cholesterol oxidase (ChOx) was ...immobilized on the CeO2 NPs/PPy/electrode by the physical adsorption route. The structure and morphology of the CeO2 NPs/PPy nanocomposite were characterized by X-ray diffraction, field emission scanning electron microscopy, and energy dispersive X-ray spectroscopy. Results showed that the ChOx/CeO2 NPs/PPy/electrode was linearly related with cholesterol in the range of 50 to 500 mg/dL. The sensitivity of ChOx/CeO2 NPs/PPy/electrode was 5.7×10−6 mA/mg⋅dL−1. The optimal parameters, including pH value and temperature, and selectivity, storage stability, and reproducibility of ChOx/CeO2 NPs/PPy/electrode were investigated.
C-doped CeO
2
nanoparticles were synthesized by hydrothermal method using glucose as carbon source. The structure of the C-doped CeO
2
nanoparticles was controlled by the concentration of the glucose ...precursor. The structure and properties of the C-doped CeO
2
nanoparticles were characterized by X-ray diffraction and UV-Vis diffuse reflectance spectroscopy. Microscopic morphology of nanoparticles was characterized by transmission electron microscopy. Photocatalytic activity was assessed by considering the degradation of methylene blue under visible light irradiation. Results show that C-doping significantly improves the photocatalytic activity of CeO
2
nanoparticles because of the combination of extending radiation absorption in visible light and the efficient separation of electron–hole pairs. These findings suggest that the present method is useful for controlling the microstructure and dye degradation properties of C-doped CeO
2
nanoparticles, which is particularly important for catalyst engineering.
A facile label-free DNA sensor based on cerium oxide nanorods decorated with polypyrrole nanoparticles (CeO
2
-NRs/Ppy-NPs) matrix has been developed for detection of
Salmonella
. The sensor was ...fabricated by hydrothermal synthesis of CeO
2
-NRs on the microelectrode surface followed by
in situ
chemical oxidative polymerization of pyrrole on the CeO
2
-NRs to prepare a CeO
2
-NR/Ppy-NPs electrode. Single-stranded DNA (ssDNA) sequences were immobilized onto the modified microelectrode by covalent attachment. The properties of the material were explored by field-emission scanning electron microscopy, x-ray diffraction analysis, and Fourier-transform infrared spectroscopy techniques. The response of the DNA biosensor was investigated by electrochemical impedance spectroscopy with Fe(CN)
6
3−/4−
as redox probe. The results showed that the response of the DNA biosensor exhibited good linearity within the range of 1.0 × 10
−9
mol L
−1
to 1.0 × 10
−6
mol L
−1
with sensitivity of 14.7 × 10
6
Ω/mol L
−1
cm
−1
. The limit of detection and limit of quantification of the DNA biosensor were low, with values of 2.86.10
−7
mol L
−1
and 9.56.10
−7
mol L
−1
, respectively.
This paper reports a novel way of the fabrication of micro-/nano-anodic aluminum oxide containing electrochemical derived nanoporous Si (AAO–Si) to achieve strong co-emission of light with ...controllable intensities. The AAO–Si was fabricated by electrochemical anodizing of aluminum followed by spin coating of nanoporous Si particles onto AAO. The microstructure and its luminescence of micro-/nano-AAO were controlled by electrochemical anodizing times. The fabrication of micro-/nano-AAO containing nanoporous Si resulted in a light-emitting from both AAO and nanoporous Si emission under a single excitation source. These results suggest that the potential application of micro-/nano-AAO contains Si for potential application in optoelectronic and biocompatible substrates for tissue engineering.
•Micro-/nano-anodic aluminum oxide containing nanoporous Si (AAO–Si) was fabricated by electrochemical anodizing of aluminum followed by spin coating of electrochemical derived nanoporous Si particles onto AAO.•The microstructure and its luminescence of a micro-/nano-scale AAO were depended on anodizing times.•The fabrication of AAO–Si resulted in a light-emitting from both AAO and Si emission under a single excitation source.
One-step thermal treatment homogeneous blends of PVA, citric acid, and ethylenediamine results in composites that emit intensively under UV bumping. The origin of absorption, excitation and emission ...properties of composites was investigated by combining optical and chemical characterizations. It has been demonstrated that IPCA, being involved in diverse structures accounts for the optical properties of composites.
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•The synthesis of highly photoluminescent PVA composites is presented.•One step thermal annealing enables conversion of molecular precursors into fluorophores.•Chemical structure of fluorophores is identified.•IPCA involved in diverse structures dominates the optical properties of composites.
There is a strong demand for developing a simple, scalable, and transferable method to prepare homogeneous and highly photoluminescent composite for diverse applications. Herein, homogeneous composites were successfully synthesized by thermal annealing blends of polyvinyl alcohol, citric acid, and ethylenediamine. The composites exhibited intensive photoluminescence under excitation around 350 nm. Infrared, nuclear resonance, and optical characterizations suggest that diverse structures involving 5-oxo-1,2,3,5-tetrahydroimidazo-1,2-α-pyridine-7-carboxylic acid (IPCA) accounts for the high photoluminescence of the composites.
Gold nanoflowers (AuNF) were synthesized on a glassy carbon electrode via a one-step, eco-friendly protocol in deep eutectic solvent (DES) of choline choloride and urea, called reline, for label-free ...detection of DNA hybridization. DES is eco-friendly, low-cost, biocompatible, and nontoxic, and it can be used as an electrolyte to synthesize nanomaterials by using the electrochemical method. In this protocol, highly branched and stable AuNFs were obtained without using any surfactants for DNA sensor application. The electrochemical performance of the AuNF-modified electrode was studied by cyclic voltammetry and electrochemical impedance spectroscopy. Under optimal conditions, the AuNF-based DNA biosensor exhibited a sensitivity of 294.9 Ω nM−1cm−2 and 218 μA nM−1cm−2 and a limit of detection (LOD) of 10−9 M. The remarkable sensitivity and low LOD could be attributed to the good conductivity of AuNFs for accelerating electron transfer, resulting in obvious signal amplification. The DNA biosensor showed good reproducibility (RSD <3.65 %) and acceptable stability and selectivity. Its excellent performance in DNA detection suggested that the proposed electrochemical DNA sensor has great application potential in clinical diagnosis.
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•Gold nanoflowers (AuNF) were synthesized via a green protocol for label-free DNA hybridization detection.•AuNF-based DNA sensor exhibited a sensitivity of 294.9 Ω.nM−1cm−2 and 218 μA.nM−1cm−2, limit of detection of 10−9 M.•Proposed DNA sensor has great application potential in clinical diagnosis.
This study presents a cholesterol biosensor that uses cerium oxide nanorods (CeO
2
-NRs) as a platform for cholesterol oxidase (ChOx) attachment. The properties of the synthesized CeO
2
-NRs were ...characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The ChOx/CeO
2
-NR-modified electrode response displayed a high sensitivity of 85.8 μA mM
−1
cm
−2
over a linear detection range between 1 and 6.5 mM of cholesterol concentration and a limit of detection of approximately 0.68 mM. Optimal parameters, including pH value, temperature, and amount of ChOx, as well as the reproducibility, specificity, and stability of the ChOx/CeO
2
-NR-modified electrode, were also investigated.
This paper reports the visible-light photocatalysts and luminescence quenching of ZrO
2
/AgCl:Eu
3+
nanoparticles synthesized by the co-precipitation method as a function of AgCl concentration. XRD ...analysis indicated the presence of crystalline tetragonal ZrO
2
and an AgCl phase. The synthesized ZrO
2
/AgCl:Eu
3+
nanoparticles were observed to have a spherical morphology with diameters of ∼ 20 nm. The photocatalyst with 2.5% mole fractions of AgCl showed effective degradation of methylene blue under visible light with the decolorization percentage reaching ∼ 95% in 180 min. The red emission of Eu
3+
in the ZrO
2
/AgCl:Eu
3+
nanoparticles decreased with increasing AgCl mole fraction. Visible-light photocatalysts of ZrO
2
/AgCl:Eu
3+
nanoparticles can be attributed to the presence of AgCl resulting in higher photoexcited charges separation, which can be confirmed by lower luminescence intensity.
ZrO
2
·Al
2
O
3
:Er powder was synthesized by the conventional solid-state reaction method. All the synthesized materials were monoclinic structure of ZrO
2
(
m
-ZrO
2
) and Al
2
O
3
phases. Scanning ...electron microscope images showed the spherical particles with diameter of ∼ (30–200) nm. The down-conversion luminescence spectra excited by 380 nm shows near infrared emission band is centered at 1540 nm, corresponding to the transitions of
4
I
13/2
–
4
I
15/2
of Er
3+
ions. Under the excitation of a 976 nm laser diode, the up-conversion luminescence spectra of the samples show a red emission band at ∼ 680 nm and a green emission band at ∼ 565 nm, corresponding to the transitions of
4
F
9/2
–
4
I
15/2
,
4
S
3/2
–
4
I
15/2
, of Er
3+
ions, respectively. The dependence of up and down-conversion luminescence properties on dopant concentrations, annealing temperature and Al
2
O
3
concentrations are investigated. These results suggested that this phosphor is a very promising material for light emission and bioimaging.
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