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Current
Nanoscience
ISSN: 1573-4137
Current Nanoscience
Volume 6, Number 3, June 2010
Contents
Editor’s Choice
Enhanced Solubility and Covalent Functionalisation of Single
Walled Carbon Nanotubes via Atmospheric Pressure Microwave
Reflux and the Subsequent Spray Coating of Transparent Conducting
Thin Films Pp. 232-242
Mathew R. Waugh and Ivan P. Parkin
[Abstract] [Purchase
Article]
Dual-template Assisted Synthesis of Silica
Nanotubes Pp. 243-248
Qiulin Liao, Yexiang Wang, Yong Gao and Huaming
Li
[Abstract] [Purchase
Article]
Young’s Modulus of Nanowires Measured
by Electrostatic Attraction: Application to Multi- Walled
Carbon Nanotubes Pp. 249-255
Christophe Le Touze, Hsiu-Lun Yeh and Chuen-Horng
Tsai
[Abstract] [Purchase
Article]
Effect of TiO2
Nanotube Morphology on the Formation of Apatite Layer in Simulated
Body Fluid Pp. 256-261
Yanqin Liang, Xianjin Yang, Zhenduo Cui and Shengli
Zhu
[Abstract] [Purchase
Article]
Self-Assembled Superlattices from Colloidal
TiO2 Nanorods Pp.
262-268
Bo Ye, Guodong Qian, Xianping Fan and Zhiyu Wang
[Abstract] [Purchase
Article]
Characterization and Formation Process
of Highly Crystallized Single Crystalline TiO2
Nanorods for Dye-Sensitized Solar Cells Pp. 269-276
Takehiro Kurata, Yasushige Mori, Seiji Isoda, Jinting
Jiu, Katsumi Tsuchiya, Fumio Uchida and Motonari
Adachi
[Abstract] [Purchase
Article]
β–lactam
Functionalized Poly(Isoprene-B-Ethylene Oxide) Amphiphilic
Block Copolymer Micelles as a New Nanocarrier System for Curcumin
Pp. 277-284
Konstantinos Gardikis, Konstantinos Dimas, Aristidis
Georgopoulos, Eleni Kaditi, Stergios Pispas and Costas
Demetzos
[Abstract] [Purchase
Article]
A “Nano-dial” Molecular Computing
Model Based on Circular DNA Pp. 285-291
Cheng Zhang, Jing Yang, Jin Xu and Shudong Wang
[Abstract] [Purchase
Article]
Direct Imaging of Apoptosis Process of
Neural Stem Cells Exposed to Porous Silica Nanoparticles
Pp. 292-297
Yanli Wang, Shun Tan, Jia Wang, Qiuxia Wu, Xinxin
Chen, Xiongyong Deng, Qiong Lu and Minghong Wu
[Abstract] [Purchase
Article] [Supplementary
Material]
Self-aggregated Nanoparticles of Cholesterol-modified
Pullulan Conjugate as a Novel Carrier of Mitoxantrone
Pp. 298-306
Wen-zhi Yang, Hong-li Chen, Fu-ping Gao, Min-mao Chen,
Xue-min Li, Ming-ming Zhang, Qi-qing Zhang, Ling-rong Liu,
Qian Jiang and Yin-song Wang
[Abstract] [Purchase
Article]
Hydroxylated Dendrimer-Stabilized Gold
and Silver Nanoparticles: Spontaneous Formation, Characterization,
and Surface Properties Pp. 307-314
Mingwu Shen, Kai Sun and Xiangyang Shi
[Abstract] [Purchase
Article]
[Supplementary Material]
Angular Distribution of Cu Ions by Nd:YAG Laser Using
Faraday Cups Pp. 315-319
Rabia Qindeel, Noriah Bidin, Zuhairi Ibrahim, Yaacob Mat
Daud and Nur-Shahidah
[Abstract] [Purchase
Article]
Reflection on Existence of Neural and
Non-Neural Pathway for Nose- to- Brain using a Novel Formulation
of an Anticholinesterase Piperidine Derivative Pp.
320-323
Javed Ali, Mushir Ali, Sanjula Baboota, Rashid Ali, Gaurav
Mittal, Aseem Bhatnagar and Bhavna
[Abstract] [Purchase
Article]
Nanostructure Thin Films of Titanium
Dioxide Coated on Glass and its Anti UV Effect for Living
Organisms Pp. 324-329
Mohammad Hossein Habibi, Mojtaba Nasr-Esfahani, Giti Emtiazi
and Baharak Hosseinkhani
[Abstract] [Purchase
Article]
Abstracts
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Enhanced Solubility and Covalent Functionalisation of Single
Walled Carbon Nanotubes via Atmospheric Pressure Microwave
Reflux and the Subsequent Spray Coating of Transparent Conducting
Thin Films
Mathew R. Waugh and Ivan P. Parkin
High levels of covalently functionalised single walled
carbon nanotubes (SWCNT) have been produced using a rapid
atmospheric pressure microwave reflux in a 1:1 mix of concentrated
nitric and sulphuric acids. The resulting product shows high
solubility (0.74 mg/ml at pH 11) and also displays a maximum
solubility dependency based on the pH of the solution. The
presence of sulphone and sulphonate functional groups has
been shown using EDXA, TGA and IR analysis. The structural
and electronic characteristics of the nanotubes were monitored
using Raman spectroscopy and SEM imaging. Spray coating was
used to form transparent conducting thin films from the functionalised
nanotubes. The films demonstrated sheet resistances from 300
Ω/
and a 25-85% optical transmission at 800 nm. This method provides
a fast and effective route to the formation of conductive
nanotube thin-films without the need for surfactant stabilisation
of the solution. In addition the functionalisation was shown
to be a fully reversible process sensitive to thermal treatment.
Film formation removed the nanotube functionalisation and
restored the pristine nanotube structure.
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Dual-template Assisted Synthesis of Silica Nanotubes
Qiulin Liao, Yexiang Wang, Yong Gao and Huaming
Li
Silica nanotubes were synthesized via sol-gel
process using poly(ethylene glycol) functionalized multi-walled
carbon nanotubes (MWNT-PEG) as the dual templates. Through
the hydrolysis of tetraethoxysilane (TEOS), a continuous coating
of silica was deposited over the MWNT surfaces to form core-shell
structures. Hollow silica nanotubes were finally obtained
by removal of core carbon components through calcination.
The as-prepared hollow silica structures were characterized
by electron microscopy, energy dispersive X-ray spectrometry
and infrared spectroscopy. The synthesized silica nanotubes
might find potential applications in many fields such as encapsulation,
catalysis, biological separation, and sensing.
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Young’s Modulus of Nanowires Measured by Electrostatic
Attraction: Application to Multi- Walled Carbon Nanotubes
Christophe Le Touze, Hsiu-Lun Yeh and Chuen-Horng
Tsai
An electrostatic experiment, performed inside a Field-Emission
Scanning Electron Microscope equipped with two electrical
probes, is used for the accurate determination of the Young’s
modulus of as-grown nanowires. One electrode being in contact
with the substrate and the other one at close distance to
the nanowire’s tip, an electrical bias was slowly ramped
up to attract and eventually bring the nanowire into contact
with the attracting probe. While the SEM was shut down during
this procedure to avoid electrical perturbation, the threshold
bias that results in the eventual contact was determined from
an I-V curve recorded simultaneously. Despite the
impossibility of visualizing the nanowire’s motion during
this operation, a direct relationship can be established between
that threshold bias, the corresponding deflection and the
nanowire’s Young’s modulus. This technique, consisting
essentially of two SEM images and one I-V curve,
was applied to multi-walled carbon nanotubes of various lengths
and orientations and resulted in an accurate Young’s
modulus of 0.92 +/- 0.28 TPa.
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Effect of TiO2 Nanotube
Morphology on the Formation of Apatite Layer in Simulated
Body Fluid
Yanqin Liang, Xianjin Yang, Zhenduo Cui and Shengli
Zhu
The objective of this work is to discuss the microstructural
effect of TiO2 nanotubes
on formation mechanism and morphology of apatite layer. An
anodization method was employed to prepare self-organized
TiO2 nanotubes on the surface
of pure titanium, followed by these substrates being soaked
in simulated body fluid (SBF) to form a bioactive layer. By
manipulating the anodization time between 0.5 h and 3 h, nanotubes
could be grown of any desired length ranging from 662 ±
5 nm to 1291 ± 5 nm. The diameter of rod-like apatite
layer grown on the nanotubes decreased yet subsequently increased
with the variation of nanotubular surface morphology and length.
In addition, the nanotube length dependence of apatite formation
can be ascribed to the different dissolution rate of nanotubes
during the deposition of calcium phosphate (Ca-P) coatings,
as well as the different penetration rate of Ca and P ions
toward nanotube layer.
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Self-Assembled Superlattices from Colloidal
TiO2 Nanorods
Bo Ye, Guodong Qian, Xianping Fan and Zhiyu
Wang
The self-assembly of anatase TiO2
nanorods into 1D (ribbon), 2D (smectic, domino, honeycomb)
and 3D (lamellar) liquid-crystalline ordered superlattices
is a process that depends on the collaboration between evaporation
dynamics and directional interactions. Herein, the roles of
entropic depletion attractions and energetic dipole-dipole
couplings between TiO2 nanorods
in self-assembly process are particularly emphasized. Excess
oleic acid surfactants act as depletion agents to induce the
inter-rod depletion effect, and the origin of electric dipole
moment along the longitudinal axes of TiO2
rods is theoretically authenticated by applying the Accelrys
Materials Studio as a new strategy combined with Tasker’s
theory. These nanorod superlattices provided here may have
great importance for tailoring new promising structures for
photovoltaic application or exploring new inorganic liquid
crystal materials.
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Characterization and Formation Process of Highly Crystallized
Single Crystalline TiO2
Nanorods for Dye-Sensitized Solar Cells
Takehiro Kurata, Yasushige Mori, Seiji Isoda, Jinting
Jiu, Katsumi Tsuchiya, Fumio Uchida and Motonari
Adachi
Highly crystallized titania nanorods were prepared by
a hydrothermal method, and their formation processes were
investigated by characterizing reaction products in a series
of desired time intervals by X-ray diffraction (XRD), transmission
electron microscopy (TEM), high-resolution transmission electron
microscopy (HRTEM), selected-area electron diffraction (SAED),
and scanning electron microscopy (SEM). A complex electrode
of dye-sensitized solar cells was then fabricated using the
high-crystalline nanorods thus prepared. In the initial reaction
stage (0.5–3.5 h), film-like products with amorphous
or amorphous-like structure were observed. In the film with
amorphous phase, very tiny two-dimensional anatase crystals
were formed as nuclei, and the number and size of the nuclei
increased with time. The nuclei were identified to have plane-like
shape with the intensity ratio (004)/(200)—signifying
growth in the c-axis— being almost zero. When
the intensity ratio reached around 0.4, indicating slight
growth in the c-axis, a drastic change in the shape
and crystalline structure was observed to take place. This
change was found to occur in a very short period (3.5–4
h), resulting from the phase transition from film with amorphous-like
structure to titania nanorods with anatase crystalline structure.
It was at 6 h or later that the HRTEM images showed titanium
atoms aligning perfectly in titania anatase structure. This
series of findings evidenced the formation of highly crystallized
titania with various shapes and encouraged the fabrication
of high-efficiency dye-sensitized solar cells; high electronic
conductivity of the highly crystallized nanorods was found
to contribute to achieving a conversion efficiency as high
as 8.52 %.
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Article]
β–lactam
Functionalized Poly(Isoprene-B-Ethylene Oxide) Amphiphilic
Block Copolymer Micelles as a New Nanocarrier System for Curcumin
Konstantinos Gardikis, Konstantinos
Dimas, Aristidis Georgopoulos, Eleni Kaditi, Stergios Pispas
and Costas Demetzos
Curcumin is a natural compound with biological activities
and potent anticancer effects that has the drawback of poor
water solubility which leads to low bioavailability. In this
work curcumin was formulated in new physicochemically characterized
micellar carriers composed of new synthetic block copolymers.
The study of the in vitro release rate of curcumin
from the formulas, as well as the in vitro activity
of free curcumin and of curcumin-loaded into micelles, against
a panel of colorectal cancer cell lines was also part of this
study. New β–lactam
functionalized poly(isoprene-b-ethylene oxide) amphiphilic
block copolymers, were synthesized by the combination of anionic
polymerization and selective postpolymerization functionalization
of the polyisoprene block with chlorosulfonylisocyanate. Micelles
composed of the synthetic copolymers were formulated in order
to incorporate curcumin. As the results revealed, increase
in the percentage of the lipophilic block of micelles, led
to higher encapsulation efficiency and loading capacity while
the size was found to be smaller and the in vitro
release rate slower. In vitro cytotoxicity results
showed similar or slightly higher activity for curcuminloaded
into micelles than free curcumin, a fact that could be attributed
to the similar in vitro cellular uptake profiles
of curcumin and of curcumin-loaded into micelles.
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Article]
A “Nano-dial” Molecular Computing Model Based
on Circular DNA
Cheng Zhang, Jing Yang, Jin Xu and Shudong
Wang
A novel molecular computing model based on circular DNA
was developed to solve a 3-coloring graph problem. This computing
model uses circular DNA and works as to dial a number. The
method of selecting true solutions is similar to dialing on
a telephone. Moreover, the key methods in this model were
circularization of single single-strand DNA (ssDNA) molecules
and a backtracking deletion algorithm. In the course of computing,
the structure of the DNA molecule was transformed into linear
double-strand DNA (dsDNA), linear ssDNA, and circular ssDNA.
For a 3-coloring graph problem with n vertices, the algorithm
time complexity and the space complexity are both O(n2)
at most. The computing achievement by this model indicates
that circular DNA has extensive applications in molecular
computing research.
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Article]
Direct Imaging of Apoptosis Process of Neural Stem Cells Exposed
to Porous Silica Nanoparticles
Yanli Wang, Shun Tan, Jia Wang, Qiuxia Wu, Xinxin
Chen, Xiongyong Deng, Qiong Lu and Minghong
Wu
[Supplementary
Material]
The present study was designed to examine the uptake,
localization, and the cytotoxic effects of well-dispersed
fluorescent porous silica nanoparticles (FITC-SiO2
NPs) in mouse neural stem cells (C 17.2, NSCs). NSCs were
exposed to various concentrations of FITC-SiO2
NPs for different times and then the uptake and toxicity were
assessed. Apoptotic cells were observed and analyzed by confocal
microscopy and flow cytometry. Results of confocal microscopy
examination revealed that silica nanoparticles were taken
up into the cells. Cell viability decreased significantly
as a function of both nanoparticle dosage (12- 240 µg/ml)
and exposure time (12 h, 24 h 72 h). FITC-SiO2
NPs show marked toxicity at high concentration (240 µg/mL)
after co-incubation for 72 h. There were clear dose- and timedependent
silica-induced cytotoxicity and genotoxicity within the range
of experimental concentrations. Interestingly, we have caught
the whole process of NSCs apoptosis induced by FITC-SiO2
NPs. The understanding of such a mechanism may provide a scientific
basis for the possible application of porous silica in drug
delivery and controlled release.
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Self-aggregated Nanoparticles of Cholesterol-modified Pullulan
Conjugate as a Novel Carrier of Mitoxantrone
Wen-zhi Yang, Hong-li Chen, Fu-ping Gao, Min-mao Chen,
Xue-min Li, Ming-ming Zhang, Qi-qing Zhang, Ling-rong Liu,
Qian Jiang and Yin-song Wang
Cholesterol-modified pullulan (CHSP) conjugate with succinyl
linkages was synthesized and characterized by fourier transform
infrared (FT-IR), proton nuclear magnetic resonance (1H
NMR) and X-ray diffraction (XRD). The degree of substitution
(DS) of cholesterol moiety determined by 1H
NMR ranged from 3.87 to 5.70 cholesterol groups per hundred
glucose units. CHSP self-aggregated nanoparticles were prepared
by probe sonication in aqueous media and analyzed by dynamic
laser light-scattering (DLS), zeta potential, transmission
electron microscopy (TEM) and the fluorescence probe technologies.
These novel nanoparticles were almost spherical in shape,
and their size, ranging from 73.0 to 51.8 nm, could be controlled
by DS. The zeta potentials of CHSP self-aggregated nanoparticles
were near zero in aqueous media. The value of critical aggregation
concentration (cac) was dependent on the DS of cholesterol
moiety. Mitoxantrone (MTO), as a model anticancer drug, was
loaded into the CHSP nanoparticles by dialysis method. MTO-loaded
CHSP self-aggregated nanoparticles were almost spherical in
shape and their size increased from 153.1 to 174.2 nm with
the MTO-loading capacity increasing from 4.35% to 14.29%.
The encapsulation efficiency (EE) of the process and loading
capacity (LC) of the nanoparticles increased with increasing
cholesterol DS. XRD powder patterns showed that crystal peaks
of MTO disappeared when MTO was entrapped into CHSP nanoparticles.
The release behavior of MTO from CHSP self-aggregated nanoparticles
was studied in vitro. The results showed that the
release behavior of MTO from CHSP nanoparticles exhibited
a sustained release, and MTO release rate decreased with increasing
the pH value of media.
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Hydroxylated Dendrimer-Stabilized Gold and Silver Nanoparticles:
Spontaneous Formation, Characterization, and Surface Properties
Mingwu Shen, Kai Sun and Xiangyang Shi
[Supplementary
Material]
We present a general route to the facile and spontaneous
synthesis of gold (Au) and silver (Ag) nanoparticles (NPs)
through the use of hydroxylated poly(amidoamine) (PAMAM) dendrimers
as both stabilizers and reducing agents. The formation of
Au NPs can be achieved by simply mixing the generation 4 (G4)
and 5 (G5) glycidol-modified PAMAM dendrimers with HAuCl4
in either methanol or water at room temperature. The size
of the formed Au NPs can be varied through the change of dendrimer
generations and reaction solvents. We also show that 1,2-epoxyhexane-modified
G4 PAMAM dendrimers can be used as both stabilizers and reducing
agents to form Au NPs, providing a useful approach to tuning
the surface hydrophilicity of Au NPs. Furthermore, using the
same strategy of spontaneous formation of Au NPs, Ag NPs can
be readily formed through the use of glycidol hydroxyl-terminated
G5 PAMAM dendrimers as both stabilizers and reducing agents.
The facile synthesis of Au and Ag NPs using hydroxylated PAMAM
dendrimers may offer many opportunities for their uses in
a variety of applications.
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Angular Distribution of Cu Ions by Nd:YAG Laser Using Faraday
Cups
Rabia Qindeel, Noriah Bidin, Zuhairi Ibrahim, Yaacob Mat
Daud and Nur-Shahidah
The infrared radiation from Nd:YAG laser (1604 nm, 8ns,
125mJ, 15.6MW) is focused by IR lens (20cm) to irradiate Cu
(99.99%) target in air. The angular distribution and arrival
of ions are collected by Faraday Cups (FC). For anisotropic
investigation, the cups are arranged at different positions
(5cm and 10cm) from the target at different angles (5°,
30°, 45°, 60° and 90°) with respect to the
normal on target surface. Faraday Cups are biased at -100V
and the ion current signals are obtained on Tektronix TDS
3054B Digital Storage oscilloscope (500 MHz) through integrated
circuit. The debris that deposited on FC is also characterized
by SEM and EDX analysis. Metallurgical analysis of exposed
FC provides evidences of Cu material on Faraday’s cup.
Mass removal rate for copper target is also calculated. Maximum
arrival rate of ions is observed at angle 5° and minimum
ions flux is at angle 90° to normal on the target surface.
The results show the plume is peaked strongly in forward direction.
The laser matter interaction is good for the laser based ion
sources generation, which can produce a collimated beam of
ions because of forward peaking.
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Reflection on Existence of Neural and Non-Neural Pathway for
Nose- to- Brain using a Novel Formulation of an Anticholinesterase
Piperidine Derivative
Javed Ali, Mushir Ali, Sanjula Baboota, Rashid Ali, Gaurav
Mittal, Aseem Bhatnagar and Bhavna
Introduction: Intranasal drug administration is a non-invasive
method of bypassing the blood–brain barrier (BBB) to
deliver therapeutic agents to the brain and spinal cord. This
method also delivers those drugs that do not cross the BBB
to the central nervous system (CNS) thus eliminating the need
for systemic delivery, and subsequently reducing the unwanted
systemic side effects. Delivery from the nose- to-brain occurs
within minutes along both the olfactory and trigeminal neural
pathways. Materials and Methods: Rat model was developed
to determine existence of neural and non neural pathways after
nasal delivery in rats. For the study mucoadhesive nanoparticles
were prepared by ionic crosslinking method and the study was
investigated using intranasal administration of Tc99m
labeled chitosan nanoparticulate formulation in dead
and alive rats. Result: The result showed a significant
increase of 4.4 times radiolabeled drug concentration in the
brain of live rats as compared to the radiolabeled drug concentration
in the dead rats (p < 0.01). Conclusion This experimental
rat model provides a proof for existence of neural and non-neural
pathway for nose to brain using a novel formulation for crossing
BBB which is of importance in finding a solution for neurodegenerative
disorders.
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Nanostructure Thin Films of Titanium Dioxide Coated on Glass
and its Anti UV Effect for Living Organisms
Mohammad Hossein Habibi, Mojtaba Nasr-Esfahani, Giti Emtiazi
and Baharak Hosseinkhani
The increasing use of ultraviolet (UV) light in medicine,
industrial environments, for cosmetic use, and even in consumer
products necessitates that greater attention be paid to the
potential hazards of this type of electromagnetic radiation.
To avoid any adverse effects of exposure to this type of radiation,
suitable protection filters were produced to block UV bands.
Nanostructure composite and thin film of titanium dioxide
coatings on glass have been prepared by the sol–gel
method. TiO2 sol suspension
was prepared by first adding titanium tetra isopropoxide (Ti(OPr)4
or TTP) to a mixture of ethanol and HCl (molar ratio TTP:HCl:EtOH:H2O
= 1:1.1:10:10) and then adding a 2 wt.% solution of hydroxyl
ethyl cellulose (HEC) as dispersant followed by of stirring.
Precalcined TiO2 nanopowder
was mixed with a sol and heat treated. Thin and composite
films were deposited on the glass substrate (microscope glass
slide) by spincoating them at ambient conditions. After drying,
samples were heated to 500 ºC. The resulting films were
characterized by UV-Vis spectroscopy, X-ray diffraction (XRD)
and Atomic Force Microscopy (AFM). The purpose of our study
was to determine if thin and composite TiO2
films with ultraviolet light have any effect on the growth
of Escherichia coli (E. coli), Staphylococcus aureus (S.
aureus) and Bacillus species (Bacillus sp.) We have seen
unusual results in which TiO2
thin and composite films protect E. coli, S. aureus and
Bacillus sp from UV light. The survival of E. coli
with UV alone was 3.2 % while with UV and TiO2
composite film was 91%. The UVabsorbing coatings are transparent,
colorless, and exhibit high optical quality. The UV-protective
coatings offer an easy method to protect the living organisms
against UV.
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