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Bare laser-synthesized Au-based nanoparticles as nondisturbing surface-enhanced Raman scattering probes for bacteria identification
2018 г.
Аннотация The ability of noble
metal-based nanoparticles
(NPs) (Au, Ag)
to drastically enhance
Raman scattering from
molecules placed near
metal surface, termed
as surface-enhanced
Raman scattering
(SERS), is widely
used for identification of trace amounts of biological materials in biomedical, food
safety and security applications. However, conventional NPs synthesized by colloidal
chemistry are typically contaminated by nonbiocompatible by-products (surfactants,
anions), which can have negative impacts on many live objects under
examination (cells, bacteria) and thus decrease the precision of bioidentification. In
this article, we explore novel ultrapure laser-synthesized Au-based nanomaterials,
including Au NPs and AuSi hybrid nanostructures, as mobile SERS probes in tasks
of bacteria detection. We show that these Au-based nanomaterials can efficiently
enhance Raman signals from model R6G molecules, while the enhancement factor
depends on the content of Au in NP composition. Profiting from the observed
enhancement and purity of laser-synthesized nanomaterials, we demonstrate successful
identification of 2 types of bacteria (Listeria innocua and Escherichia coli).
The obtained results promise less disturbing studies of biological systems based on
good biocompatibility of contamination-free laser-synthesized nanomaterials.
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Recent Advances in Laser-Ablative Synthesis of Bare Au and Si Nanoparticles and Assessment of Their Prospects for Tissue Engineering Applications
2018 г.
Аннотация Driven by surface cleanness and unique physical, optical and chemical properties,
bare (ligand-free) laser-synthesized nanoparticles (NPs) are now in the focus of interest as promising
materials for the development of advanced biomedical platforms related to biosensing, bioimaging
and therapeutic drug delivery. We recently achieved significant progress in the synthesis of bare
gold (Au) and silicon (Si) NPs and their testing in biomedical tasks, including cancer imaging and
therapy, biofuel cells, etc. We also showed that these nanomaterials can be excellent candidates for
tissue engineering applications. This review is aimed at the description of our recent progress in laser
synthesis of bare Si and Au NPs and their testing as functional modules (additives) in innovative
scaffold platforms intended for tissue engineering tasks.
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Люминесцентные свойства композитных систем на основе поЛистироЛа и фтаЛоцианинатов эрбиЯ(III) в бЛижней ик обЛасти
И.А. Белогорохов, Л.И. Белогорохова, В.Е. Пушкарев
2018 г.
Аннотация Получены композитные материалы на основе полистирола и фталоцианинатов ErIII одно-, двух- и трёхпалубного
строения, изучены их спектральные люминесцентные характеристики в ближнем ИК (БИК) диапазоне.
Для всех исследованных комплексов в составе композитов характерна 4f фотолюминесценция (ФЛ), которая в случае
моно- и трис(фталоцианината) наблюдается при 1550 нм, в случае же бис(фталоцианината) максимум ФЛ смещён
в коротковолновую область и проявляется при 1440 нм. Проведен сравнительный анализ свойств композитов
и индивидуальных фталоцианиновых соединений в пленках и растворе. Так, например, в случае однопалубного
фталоцианина данную эмиссию удалось зафиксировать впервые именно в матрице полистирола – для индивидуальных
моно(фталоцианинатов) ErIII этот процесс ранее не наблюдался.
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Surface enhanced infrared absorption spectroscopy based on gold nanostars and spherical nanoparticles
2017 г.
Аннотация Plasmonic anisotropic nanoparticles possess a number of hot spots on their surface due to the presence
of sharp edges, tips or vertices, leading to a high electric field strength surrounding the nanostructures. In
this paper, we explore different plasmonic nanostructures, including anisotropic gold nanostars (AuNSts)
and spherical gold nanoparticles, in surface-enhanced infrared absorption spectroscopy (SEIRAS) in an
attenuated total reflection (ATR) configuration. In our experiments, we observed up to 10-times
enhancement of the infrared (IR) absorption of thioglycolic acid (TGA) and up to 2-times enhancement of signals for bovine serum albumin (BSA) protein on plasmonic nanostructure-based films
deposited on a silicon (Si) internal reflection element (IRE) compared to bare Si IRE. The dependence of
the observed enhancement on the amount of AuNSts present at the surface of the IRE has been
demonstrated. Quantitative studies with both, TGA and BSA were performed, observing that the SEIRA
signal can be correlated to the concentration of analyte molecules present within the evanescent field.
The calibration curves in the presence of the AuNSts showed enhanced sensitivity as compared with the
bare Si IRE.We finally compare efficiencies of anisotropic AuNSts and spherical citrate-capped and “bare”
laser-synthesized gold nanoparticles as SEIRAS substrates for the detection of TGA and BSA. The signal
obtained from AuNSts was at least 2 times higher for TGA molecules in comparison with spherical gold
nanoparticles, which was explained by a more efficient generation of hot spots on anisotropic surface
due to the presence of sharp edges, tips or vertices, leading to a high electric field strength surrounding
the AuNSts.
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Influence of oxidation state on water solubility of Si nanoparticles prepared by laser ablation in water
2017 г.
Аннотация Femtosecond laser fragmentation from preliminarily prepared water-dispersed Si microcolloids was used to synthesize
bare (ligand-free) spherical silicon nanoparticles (Si-NPs) with low size dispersion and controllable mean size from a few
nm to several tens of nm. In order to control the oxidation state of Si-NPs, the fragmentation was performed in normal
oxygen-saturated water (oxygen-rich conditions) or in water disoxygenated by pumping with noble gases (Ag, He) before
and during the experiment (oxygen-free conditions). XPS and TEM studies revealed that Si-NPs were composed of Si
nanocrystals with inclusions of silicon oxide species, covered by SiOx (1 x 2) shell, while the total oxide content
depended whether Si-NPs were prepared in oxygen-rich or oxygen-free conditions. When placed into a dialysis box, waterdispersed
Si-NPs rapidly dissolved, which was evidenced by TEM data. In this case, NPs prepared under oxygen-rich
conditions demonstrated much faster dissolution kinetics and their complete disappearance after 7-10 days, while the
dissolution process of less oxidized counterparts could last much longer (25-30 days). Much fast dissolution kinetics of
more oxidized Si-NPs was attributed to more friable structure of nanoparticle core due to the presence of numerous
oxidation-induced defects. Laser-synthesized Si-NPs are of paramount importance for biomedical applications.
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Surface-enhanced Raman spectroscopy for identification and discrimination of beverage spoilage yeasts using patterned substrates and gold nanoparticles
2017 г.
Аннотация In the beverage industry, the detection of spoilage yeasts such as Wickerhamomyces anomalus and
Brettanomyces bruxellensis can be labourious and time-consuming. In the present study, a simple and
repeatable technique was developed for rapid yeast detection using a combination of patterned goldcoated
surface-enhanced Raman spectroscopy (SERS) substrates and gold nanoparticles. W. anomalus
and B. bruxellensis showed several characteristic peaks, enabling the discrimination of these yeasts
without chemometric analysis. The control yeast used as an indicator yeast, Rhodotorula mucilaginosa,
showed 7 cell wall-related peaks originating from lipids and haemoproteins. AnalysingW. anomalus SERS
spectra with differently sized and shaped gold nanoparticles revealed the benefit of using either large,
spherical, chemically synthesised gold nanoparticles or small, laser-synthesised, gold-silicon nanoparticles
for yeast detection. Additionally, the spectra showed differences in SERS signal construction for
small molecules and biological cells, as the nanoparticles with best response in biological cell detection
did not excel in small molecule detection. The use of small composite gold-silicon nanoparticles in
combination with the SERS substrate gave distinctive spectra for all detected yeast species.
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Cavitation-Free Continuous-Wave Laser Ablation from a Solid Target to Synthesize Low-Size-Dispersed Gold Nanoparticles
2017 г.
Аннотация Continuous wave (CW) radiation from a Yb-fiber laser (central
wavelength 1064 nm, power 1–200 W) was used to initiate
ablation of a gold target in deionized water and to synthesize
bare (unprotected) gold nanoparticles. We show that the
formed nanoparticles present a single low-size-dispersed population
with a mean size of the order of 10 nm, which contrasts
with previously reported data on dual populations of nanoparticles
formed during pulsed laser ablation in liquids. The lack
of a second population of nanoparticles is explained by the absence
of cavitation-related mechanism of material ablation,
which typically takes place under pulsed laser action on a solid
target in liquid ambience, and this supposition is confirmed by
plume visualization tests. We also observe a gradual growth of
mean nanoparticle size from 8–10 nm to 20–25 nm under the
increase of laser power for 532 nm pumping wavelength,
whereas for 1064 nm pumping wavelength the mean size 8–
10 nm is independent of radiation power. The growth of the
nanoparticles observed for 532 nm wavelength is attributed to
the enhanced target melting and splashing followed by additional
heating due to an efficient excitation of plasmons over
gold nanoparticles. Bare, low-size-dispersed gold nanoparticles
are of importance for a variety of applications, including biomedicine,
catalysis, and photovoltaics. The use of CW radiation
for nanomaterial production promises to improve the cost efficiency
of this technology.
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Nonlinear Optical Properties of Silicon Carbide (SiC) Nanoparticles by Carbothermal Reduction
2016 г.
Аннотация SiC nanoparticles by carbothermal reduction show promising properties in terms of second harmonic and multiphoton
excited luminescence. In particular, we estimate a nonlinear eciency = 17 pm/V, as obtained
by Hyper Rayleigh Scattering. We also present results of cell labelling to demonstrate the potential use of SiC
nanoparticles for nonlinear bioimaging by simultaneous detection of second harmonic and luminescence.
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Ultrapure laser-synthesized Sibased nanomaterials for biomedical applications: in vivo assessment of safety and biodistribution
2016 г.
Аннотация Si/SiOx nanoparticles (NPs) produced by laser ablation in deionized water or aqueous biocompatible
solutions present a novel extremely promising object for biomedical applications, but the interaction
of these NPs with biological systems has not yet been systematically examined. Here, we present
the first comprehensive study of biodistribution, biodegradability and toxicity of laser-synthesized
Si-SiOx nanoparticles using a small animal model. Despite a relatively high dose of Si-NPs (20 mg/kg)
administered intravenously in mice, all controlled parameters (serum, enzymatic, histological etc.) were
found to be within safe limits 3 h, 24 h, 48 h and 7 days after the administration. We also determined
that the nanoparticles are rapidly sequestered by the liver and spleen, then further biodegraded
and directly eliminated in urine without any toxicity effects. Finally, we found that intracellular
accumulation of Si-NPs does not induce any oxidative stress damage. Our results evidence a huge
potential in using these safe and biodegradable NPs in biomedical applications, in particular as vectors,
contrast agents and sensitizers in cancer therapy and diagnostics (theranostics).
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Ultrapure laser-synthesized Si nanoparticles with variable oxidation states for biomedical applications
2016 г.
Аннотация We employ a method of femtosecond laser fragmentation of preliminarily prepared water-dispersed
microcolloids to fabricate aqueous solutions of ultrapure bare Si-based nanoparticles (Si-NPs) and assess
their potential for biomedical applications. The nanoparticles appear spherical in shape, with low size
dispersion and a controllable mean size, from a few nm to several tens of nm, while a negative surface
charge (35 mV 0.10 according to z-potential data) provides good electrostatic stabilization of
colloidal Si-NP solutions. Structural analysis shows that the Si-NPs are composed of Si nanocrystals with
inclusions of silicon oxide species, covered by a SiOx (1 o x o 2) shell, while the total oxide content
depends on whether the fragmentation is performed in normal oxygen-saturated water (oxygen-rich
conditions) or in water deoxygenated by pumping with noble gases (Ag or He) before and during the
experiment (oxygen-free conditions). Our dissolution tests show the excellent water-solubility of all the
NPs, while more oxidized NPs demonstrate much faster dissolution kinetics, which is explained by
oxidation-induced defects in the core of the Si-NPs. Finally, by examining the interaction of the NPs
with human cells after 72 h of incubation at different concentrations, we report the absence of any
adverse effects of the NPs up to high concentrations (50 mg mL1) and a good internalization of NPs via a
classical endocytosis mechanism. Possessing far superior purity compared to their chemically synthesized
counterparts and enabling a variety of imaging and therapeutic functionalities, the laser-synthesized
Si-NPs are promising for safe and efficient applications in nanomedicine.
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Si nanoparticles as sensitizers for radio frequency-induced cancer hyperthermia
2016 г.
Аннотация We review our recently obtained data on the employment of Si nanoparticles as sensitizers of radiofrequency (RF) -
induced hyperthermia for mild cancer therapy tasks. Such an approach makes possible the heating of aqueous
suspensions of Si nanoparticles by tens of degrees Celsius under relatively low intensities (1–5 W/cm2) of 27 MHz RF
radiation. The heating effect is demonstrated for nanoparticles synthesized by laser ablation in water and mechanical
grinding of porous silicon, while laser-ablated nanoparticles demonstrate a remarkably higher heating rate than porous
silicon-based ones for the whole range of the used concentrations. The observed RF heating effect can be explained in
the frame of a model considering the polarization of Si NPs and electrolyte in the external oscillating electromagnetic
field and the corresponding release of heat by electric currents around the nanoparticles. Our tests evidence relative
safety of Si nanostructures and their efficient dissolution in physiological solutions, suggesting potential clearance of
nanoparticles from a living organism without any side effects. Profiting from Si nanoparticle-based heating, we finally
demonstrate an efficient treatment of Lewis Lung carcinoma in vivo. The obtained data promise a breakthrough in the
development of mild, non-invasive methods for cancer therapy.
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Structural properties of gold-silicon nanohybrids formed by femtosecond laser ablation in water at different fluences
2016 г.
Аннотация A gold target was ablated by femtosecond laser radiation in aqueous solutions of preliminarily prepared Si nanoparticles.
The ablation process led to the formation of Au-based spherical colloids with the mean size around 5-10 nm and a weak
abundance of larger species. Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray (EDX) analysis
revealed the presence of Au and Si in colloid composition, while the stoichiometry of colloids did not depend on laser
fluence during the fabrication experiments. The formation of Au-Si nanohybrid structure was explained by an effect of
the interaction of laser-ablated Au nanoclusters with water-dispersed Si nanoparticles. The fabricated structures can be of
importance for biomedical, catalysis, and photovoltaics applications.
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Laser ablative nanostructuring of Au in liquid ambience in continuous wave illumination regime
2016 г.
Аннотация We study surface modifications and fabrication of nanoparticles under ablation of water-immerged Au target by a
moving beam of continuous wave Ytterbium fiber laser (532, 1064 nm). Our analysis of the target surface reveals the
presence of solidified nanoscale Au nanoparticles distributed over the crater of the laser beam, which is consistent with
the presence of metal melting and evaporation effects. Optical imaging of the hydrodynamic process shows the presence
of convective flows leading to a strong mixing of the liquid medium during the laser ablation process. The laser ablation
process results in the production of gold nanoparticle colloids with average particle sizes smaller than 10 nm under
relatively narrow size dispersion. Au nanoparticles prepared by CW laser ablation of Au in deionized water are of
importance for a variety of applications, including biomedical, catalysis and electrocatalysis, photovoltaics etc.
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Detection of Listeria innocua on roll-to-roll produced SERS substrates with gold nanoparticles
2016 г.
Аннотация The rapid and accurate detection of food pathogens plays a critical role in the early prevention of foodborne
epidemics. Current bacteria identification practices, including colony counting, polymerase chain reaction
(PCR) and immunological methods, are time consuming and labour intensive; they are not ideal for
achieving the required immediate diagnosis. Different SERS substrates have been studied for the
detection of foodborne microbes. The majority of the approaches are either based on costly patterning
techniques on silicon or glass wafers or on methods which have not been tested in large scale
fabrication. We demonstrate the feasibility of analyte specific sensing using mass-produced, polymerbased
low-cost SERS substrate in analysing the chosen model microbe with biological recognition. The
use of this novel roll-to-roll fabricated SERS substrate was combined with optimised gold nanoparticles
to increase the detection sensitivity. Distinctive SERS spectral bands were recorded for Listeria innocua
ATCC 33090 using an in-house build (785 nm) near infra red (NIR) Raman system. Results were
compared to both those found in the literature and the results obtained from a commercial time-gated
Raman system with a 532 nm wavelength laser excitation. The effect of the SERS enhancer metal and
the excitation wavelength on the detected spectra was found to be negligible. The hypothesis that
disagreements within the literature regarding bacterial spectra results from conditions present during the
detection process has not been supported. The sensitivity of our SERS detection was improved through
optimization of the concentration of the sample inside the hydrophobic polydimethylsiloxane (PDMS)
wells. Immunomagnetic separation (IMS) beads were used to assist the accumulation of bacteria into the
path of the beam of the excitation laser. With this combination we have detected Listeria with gold
enhanced SERS in a label free manner from such low sample concentrations as 104 CFU ml1.
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Enhanced Thermal Sensitivity of Silicon Nanoparticles Embedded in (Nano-Ag/)SiNx for Luminescent Thermometry
2014 г.
Аннотация Steady-state photoluminescence of silicon nanoparticles embedded
in solid-state (nano-Ag/)SiNx thin films at above room temperature is
studied and compared to silicon nanoparticles dispersed in low-polar liquids.
Roles of local surface plasmons as well as general mechanisms responsible for the
temperature-dependent photoluminescence are pointed out. Thermal sensitivities
of photoluminescence spectral shape, maximum position, and full width at halfmaximum
are estimated and application of the (nano-Ag/)SiNx layers as
photoluminescent thermal screens is proposed.
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Radio frequency radiation-induced hyperthermia using Si nanoparticle-based sensitizers for mild cancer therapy
2014 г.
Аннотация Offering mild, non-invasive and deep cancer therapy modality, radio frequency (RF) radiation-induced
hyperthermia lacks for efficient biodegradable RF sensitizers to selectively target cancer cells and thus avoid
side effects. Here, we assess crystalline silicon (Si) based nanomaterials as sensitizers for the RF-induced
therapy. Using nanoparticles produced by mechanical grinding of porous silicon and ultraclean
laser-ablative synthesis, we report efficient RF-induced heating of aqueous suspensions of the nanoparticles
to temperatures above 45-506C under relatively low nanoparticle concentrations (,1 mg/mL) and RF
radiation intensities (1–5 W/cm2). For both types of nanoparticles the heating rate was linearly dependent
on nanoparticle concentration, while laser-ablated nanoparticles demonstrated a remarkably higher heating
rate than porous silicon-based ones for the whole range of the used concentrations from 0.01 to 0.4 mg/mL.
The observed effect is explained by the Joule heating due to the generation of electrical currents at the
nanoparticle/water interface. Profiting from the nanoparticle-based hyperthermia, we demonstrate an
efficient treatment of Lewis lung carcinomain vivo. Combined with the possibility of involvement of parallel
imaging and treatment channels based on unique optical properties of Si-based nanomaterials, the proposed
method promises a new landmark in the development of new modalities for mild cancer therapy.
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Photoluminescence thermometry with alkyl-terminated silicon nanoparticles dispersed in low-polar liquids
2013 г.
Аннотация Steady-state and time-resolved photoluminescence of silicon
nanoparticles dispersed in low-polar liquids at above room
temperature is studied. The roles of low-polar liquids as well
as mechanisms responsible for their temperature-dependent
photoluminescence are discussed. The thermal sensitivity of
the photoluminescence is estimated and application of the
nanoparticles as nanothermometers is proposed.
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Design of microporous mixed zinc–nickel triazolate metal–organic frameworks with functional ligands
2013 г.
Аннотация We report two new microporous mixed-metal triazolate based
MOFs made from zinc and nickel salts combined with either
1,2,4-triazole or 3,5-diamino-1,2,4-triazole. Their structures,
refined from X-ray powder diffraction, their CO2 adsorption and
photoluminescent properties show a direct correlation with the
structure of their parent organic ligand.
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Photoluminescence of silicon nanoparticles chemically modified by alkyl groups and dispersed in low-polar liquids
2013 г.
Аннотация A detailed comparative analysis of photoluminescence
behavior of silicon nanoparticles in air
and dispersed in low-polar liquids is reported. Efficient
dispersion and excellent stability of the chemically
modified nanoparticles in low-polar liquids are
achieved. Influence of the chemical functionalization
and of the low-polar liquids on steady-state and timeresolved
photoluminescence of the silicon nanoparticles
is investigated. Role of low-polar liquids on
recombination mechanisms taking place in the nanoparticles
is discussed in terms of Fo¨rster resonant
energy transfer processes. Effect of exciting laser
power on photoluminescence spectra of the silicon
nanoparticles both in air and in low-polar liquids is
investigated and the electronic mechanisms involved
into the observed phenomena are discussed.
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Luminescence behavior of silicon and carbon nanoparticles dispersed in low-polar liquids
2012 г.
Аннотация A comparative photoluminescence analysis of as-prepared and chemically modified (by alkyl chains -C18H37) silicon
and carbon nanoparticles dispersed in low-polar liquids is reported. Influence of the low-polar liquid nature and
ambient temperature on photoluminescence of the nanoparticles has been investigated from the point of view of
their possible application as thermal nanoprobes.