nanoparticles

Presentation of the equipment for
processing and characterization of
nanoparticles, of the
magnetometer, and of their
possible applications
Darko Makovec
Department for Materials Synthesis
Jožef Stefan Institute
50 nm
Monodisperse nanoparticles of maghemite
Equipment
Laboratory for the processing and characterization of nanoparticles
equipped with fume hoods and with basic laboratory equipment.
• Autoclave (Parr 4641, volume 1 L ) for hydrothermal synthesis of
nanoparticles.
• Dynamic light-scattering granulometer (Fritsch ANALYSETTE 12
DynaSizer) for measurements of the particle size in suspensions.
Vibrating-sample magnetometer (LakeShore 7404VSM) for magnetic
measurements at room temperature.
The equipment of the Nanocenter supplements the equipment available in
the laboratory for the processing and characterization of nanoparticles at
the Department for Materials Synthesis, Jožef Stefan Institute.
Autoclave (Parr 4641)
Autoclave used for hydrothermal/sovothermal synthesis under high
pH.
Autoclave vessel (volume 1 L)
• used with bench-top furnace available at K8.
• Inconel 600 alloy resistant against high pH
(not for chlorides!).
• max. pressure 131 barr at 350 oC.
• equipped with manometer, two safety valves, and
set of valves for flushing the vessel with (inert) gas.
Hydrothermal synthesis
Hydrothermal: chemical reactions occur in aqueous solutions above 100 oC
under increased pressure, usually equilibrium water pressure.
Supercritical: at temperatures above critical point (374 oC, 218 barr)
Ravnotežni tlak
vodne
pare [barr]
Equilibrium
water
pressure
(barr)
3000
200
2500
150
2000
1500
100
1000
50
500
0
0
100
150
200
250
300
o
Temerature
(oC)
Temperatura
[ C]
350
400
Ravnotežni tlak
vodne
pare [psi]
Equilibrium
water
pressure
(psi)
3500
250
Max. pressure 131 barr
Max. temperature ≈ 330 oC
Dynamic light-scattering granulometer
(ANALYSETTE 12 DynaSizer)
Measurements of particle size (hydrodinamic) in suspensions.
Equipped with peristatic pump for sampling (on-line measurements).
Dynamic light-scattering
From Wikipedia, the free encyclopedia
Dynamic light scattering can be used to determine the size distribution profile of
small particles in suspensions.
Brownian motion is probed with scattering of monchromatic, cohetent laser light.
Brownian motion causes a time-dependent fluctuation in the scattering intensity,
because the distance between the scatterers in the suspension is constantly
changing with time. The scattered light undergoes either constructive or destructive
interference by the surrounding particles and within this intensity fluctuation.
Information is contained about the time scale of movement of the scatterers.
The dynamic information of the particles is derived from an autocorrelation of the
recorded intensity trace during the experiment.
Hypothetical Dynamic light scattering of two samples: Larger particles vs. smaller particles.
Dynamic light-scattering granulometer
(ANALYSETTE 12 DynaSizer)
Measurement Range:
Principle of Operation:
1 nm to 6000 nm
Dynamic Light Scattering in backward direction (135 o).
Measurement of diluted, concentrated, dark or black suspensions with monodisperse or
polydisperse suspension
Dynamic light-scattering granulometer
(ANALYSETTE 12 DynaSizer)
Concentration Range
Laser source:
0,001 to 40 wt%
Single Mode Laser with optical fibre
(wavelength 658 nm, Adjustment of Laser power from 1mW up to 75mW)
Optical Cell
cuvette).
Small volume:
Sample temperature
Integrated into the instrument (no consumables like
less then 50 μl
controlled by pettier element: 15°C up to 70°C
Patented design for concentrated or
opaque/dark samples.
High concentration sample are measured
using a very thin layer. Multi diffusion and
absorption of the laser beam intensity (local
warm up effect of the sample – gradient
index) are eliminated.
Using a ticker sample layer allows the
measurement of low concentrations down to
0,001wt/%
Dynamic light-scattering granulometer
(ANALYSETTE 12 DynaSizer)
Correlator:
Software:
Autocorrelation 1000 channels, 16 bits, 100ns pulse width
correlation
Different calculation algorithms included:CONTIN (Monomodal),
CUMULANT (Monodisperse / avarage size – polydispersity index),
PADÈ LAPLACE (unique proprietary algorithm developed for
polydisperse suspensions / high resolution)
Multi acquisition for statistical measurement possible . This yields
the possibility to determine complete size distributions.
Vibrating-sample magnetometer
(LakeShore 7404 VSM)
U ind = C ⋅ m
C- cal. constant
m- mag. moment
moment
M=
,
mass
sample holders
bulk
liquid
emu
mass magnetization
g
thin-film holders
side-mounted
bottom-mounted
Vibrating-sample magnetometer
(LakeShore 7404 VSM)
Moment range: 1x10-7 to 103 emu
Applied field strength:
Θ range: 00 to 3600
Field
16.2 mm air gap
2.17 T
3.6 mm sample access
23 mm air gap
10 mm sample access
29 mm air gap
16 mm sample access
H
1.81 T
N Θ
1.53 T
air gap
Equipment location:
Department for Materials Synthesis, Jožef Stefan Institute (Ground floor K800)
Equipment accessibility:
In agreement with
responsible person.
Responsible persons:
Laboratory:
Prof. Darko Makovec
([email protected])
Autoclave:
Bernarda Anželak
([email protected])
DLS:
Slavko Kralj
([email protected])
VSM magnetometer
Dr. Sašo Gyergyek
([email protected])
Department for Materials Synthesis
Magnetic materials:
Semiconducting materials:
Microwave materials:
Magnetic nanoparticles: PTCR ceramics,
photocatalytic nanoparticles:
Absorbers, nonreciprocal
devices (circulators)
Ferrofluids, nanoparticles for
biomedical applications
Semiconducting, ferroelectric
ceramics, photocatalytic
nanoparticles
Hexaferrites (BaFe12O19)
Spinel ferrites (Fe3O4,
CoFe2O4, …)
TiO2, ZnO, BaTiO3, high Tc
ferroelectrics, …
Ceramics, thick films
Nanoparticles, suspensions
Nanoparticles, ceramics
Multifunctional materials:
(Nano)composite materials combining different (coupled) functional properties,
magnetic photocatalysts, magnetodielectrics, multiferroics, etc.
Aggregates of magnetic (Fe2O3) and photocatalitic (TiO2) nanoparticles, solid materials
combining ferrites and ferroelectrics, ferrites and dielectrics, ...
Aggregation of different nanoparticles into nanocomposite particles in suspensions, sintering
into composite ceramics, dispersing nanoparticles into polymer, silica matrixes, …
Superparamagnetic nanoparticles
Syntheses of nanoparticles (spinel ferrites, hexaferrites, magnetic perovskites, alloys, …):
Coprecipitation, coprecipitation in microemulsions, hydrothermal synthesis, sonochemical
synthesis, sol-gel, ...
Ferrofluids (stable suspensions of superpramagnetic nanoparticles in a carrier liquid):
Nonpolar, polar (water) carrier liquids, different surfactantas
Stability of ferrofluids, magnetoreology, magnetic properties,....
Nanoparticles for biomedical applications:
Functionalization of magnetic nanoparticles (silika, silanes, polymers)
Nanoparticles for hyperthermia (perovskites with tuned Currie temperature, composite
nanoparticles spinel ferrite-hexaferrite )
Nanocomposites:
Homogeneously dispersed nanoparticles in matrixes of silica or polymer, nanocomposite
particles, multifunctional nanocomposites - magnetodielectrics, multiferroics, magnetic
photocatalysts…
Me
H
HO
O
O
Si
N
Si
H
+ HO
O
Me
Si
H
O
N
O
O
HO
Me
H
Si
Department for Materials Synthesis (and Characterization)
Synthesis of (magnetic) nanoparticles
Coprecipitation from aqueous solutions
Spinel ferrites (maghemite)
Coprecipitation in microemulsions
Spinel ferrites (maghemite)
Thermal decomposition of
organometallic complexes
Spinel ferrites (CoFe2O4)
Hydrothermal synthesis
Hexaferrite BaFe12O19
Superparamagnetic nanoparticles of
BaFe12O19 hexaferrite were
synthesized for the first time
Nanoparticles synthesis
Synthesis of superparamagnetic nanoparticles of hexaferrites,
preparation of ferrofluids.
BaFe12O19
SrFe12O19
Suspensions
Magnetic nanoparticles – ferrofluids …
Magneto-rheology
Application of magnetic nanoparticles in
biomedicine
Basic concept:
• Selective bonding of bioactive molecules (therapeutic agents, targeting
ligands, fluorescent dyes, ….) to the surface of magnetic nanoparticles (size
approx. 10 nm) via a functionalization layer.
• Manipulation and detection from distance.
Using external magnetic field, the nanoparticles can be concentrated in a desired
part of human body, they can be tracked through their magnetic properties, they can
be used to heat a tissue, …
Functionalization molekule
O
Si
Si
O
N
O
H
Si
Magnetic nanoparticle
Therapeutic agent, marker, dye, …
Applications of magnetic nanoparticles in
diagnostics
• Separation/detection of bioactive molecules (in vitro)
• Magnetorelaxometry (in vitro)
• Detection of nanoparticles marked with targeting ligands
(e.g. antibodies) using measurements of magnetic
properties (in vivo)
• NMR contrast enhancement (in vivo)
• ….
Detection using magnetic probe:
100 μg of nanoparticles at the distance of 30 cm
NMR image of magnetic nanoparticles
in a targeted part of mice brains
Endomagnetics
Piotr Walczak and Jeff Bulte
Department for Materials Synthesis
Magnetic nanoparticles – application in therapy
•
•
Magnetic hyperhermia
Targeted drug delivery
Nanoparticles
Siemens AG, Pictures of the future 01/2007
Magnetic nanoparticles internalized
into cells
Functionalization
Grafting functionalization molecules onto the
nanoparticles’ surfaces to provide specific functional
groups for further bonding of functional molecules.
Functionalization molecules:
Molecules with at least-two functional groups:
-
First functional group interacts with the nanoparticle’s surface,
Second functional group provides reactive site for further surface reactions
with “functional molecules needed in application”.
Functional molecules:
(Bio)molecules needed in application.
Nanoparticle
Functionalization molecule
Me
H
HO
O
O
Si
N
Si
H
+ HO
O
Me
Si
H
O
N
O
O
HO
Me
H
Si
Biocompatible layer
Fuctional molecule, therapeutic agent, marker, dye, …
Functionalized magnetic nanoparticles for
biomedical applications
Active sites for selective bonding of different (bio)molecules to the
nanoparticle’s surface:
• Biocompatible polymers (e.g. dextrane, PEG, to increase blood circulation times),
• Therapeutic agents, drugs,
• Targeting ligands (e.g. antibodies, for targeting tumour tissue),
• Fluorescent dyes (for tracking using optical methods),
• Permeation enhancers,
• …
Biocompatible layer
Magnetic core
Therapeutic agent
Abtibody
Coating magnetic nanoparticles with silica
Thin layer of silica provides surface silanol OH- groups for further
bonding of functionalization molecules. It also provides high negative
surface charge and thus ensures colloidal stability.
Hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) in stable aqueous
suspension of magnetic nanoparticles in presence of alkaline catalyst (ammonia,
KOH).
Layer of silica
Coating magnetic nanoparticles with silica
Control of suspension stability and thickness of silica layer using DLS.
Grafting of silane molecules onto
magnetic nanoparticles
Bonding amino- silane to surface OH groups of silica for amino
functionalization.
Control of the NH2 surface concentration:
Aminopropyl triethoxy silane
APS
(aminoethylamino)propyl
triethoxy silane
APMS
Grafting of silane molecules onto
magnetic nanoparticles
Agglomeration in the suspensions of APS-grafted maghemite
nanoparticles.
Aminopropyl triethoxy silane
APS
TEM size 13.7 ± 2.9 nm
R&D cooperation with Nanotesla Institute Ljubljana
Development of new methods for binding of bioactive molecules
(chromophores, therapeutic agents, monoclonal antibodies) onto
the functionalised nanoparticles.
Magnetic properties of nanoparticles:
Decrease in “saturation” magnetization
Zero corcivity = superparamagneticity
influence of large surface area
size effect
Coarse-grained maghemite powder
Maghemite nanoparticles, ~ 13 nm in size
Maghemite nanoparticles, ~ 3 nm in size
Magnetic properties
Magnetic nanoparticles are used in the form of stable colloidal
suspensions. The (magnetic) agglomeration should be
prevented.
Superparamagnetic nanoparticles
Paramagnetic
Ferromagnetic
Superparamagnetic
Without the influence of external
magnetic field, the superparamagnetic
nanoparticles do not show any
coercivity – no magnetic interactions.
Magnetic separation
Magnetic nanoparticles – magnetic separations, purifications, selection, …
Magnetic nanoparticle
Functionalization layer
Functionalization molecule
Magnetic separation
Force acting on the magnetic
particle in a mag. field gradient :
Fm = μ0 Vp Mp H
Δ
Magnetic-field gradient
Particle magnetization
Particle volume ∝ d3
The force acting on the
superparamagnetic
nanoparticle is too weak for
effective separation.
Stable suspension of the
superpramagnetic nanoparticles.
Suspension of the clusters of the
superpramagnetic nanoparticles.
Controlled clustering
Mixing the suspension of the nanoparticles coated with citric acid (0.005
%, pH = 9.0) in the suspension of the nanoparticles coated with APS (0.05
%, pH = 4.0) under agitation with ultrasound. pH after mixing = 5 – 7.
Nanoparticles coated
with APMS
Nanoparticles coated
with citric acid
R&D cooperation with Cinkarna Celje
Synthesis of superparamagnetic, photocatalytic particles for
decomposition of organic pollutants in water.
The immobilization of the photocatalysts on magnetic carriers, to
allow elimination of the photocatalyst from the water suspension
after cleaning using an external magnetic field
Hetero-agglomeration of anatase
nanoparticles and magnetic clusters in
aqueous suspensions
Direct precipitation of anatase nanoparticles
onto the magnetic clusters
R&D cooperation with Cinkarna Celje
Magnetic properties of superparamagnetic, photocatalytic
particles.
Superparamagnetic polymer
nanocomposites
Preparation of composite containing high content of dispersed magnetic
nanoparticles:
Dispersing hydrophobised
nanoparticles in decane,
addition of methyl methacrylate monomer,
precipitation polymerization.
oleic acid
50 nm
Dispersing hydrophobised nanoparticles
directly in methyl methacrylate monomer,
polymerization in miniemulsion.
ricinoleic acid
Bonding initiator onto the nanoparticles,
triggering polymerisation at the nanoparticles.
Cooperation with M. Huskić, National institute of chemistry
Department for Materials Synthesis
Asst. Prof. Darja Lisjak
Magnetic materials for applications at very high frequencies
Car collision-avoidance systems
Circulators
Absorbers
Thermal coating of absorber layers
Electrophoretic deposition
Electrophoretic deposition of hexaferrite
Electrophoretic deposition of thick films of hexaferrite
(nano)particles from suspensions for applications in mm-wave
nonreciprocal devices:
Thick film
Suspension of nanoparticles
Magnetophoretic deposition of hexaferrite
Deposition of structured layers of
magnetic particles using magnetic
field:
M
S. Kolev
Electrophoretic deposition of hexaferrite
Magnetic properties of oriented BaFe12O19 film measured in two
directions
Θ=00
Θ=900
Nanocenter Equipment at K8
Laboratory for the processing and characterization of nanoparticles equipped with fume
hoods and with basic laboratory equipment.
• Autoclave (Parr 4641, volume 1 L ) for hydrothermal synthesis of nanoparticles.
• Dynamic light-scattering granulometer (Fritsch ANALYSETTE 12
for measurements of the particle size in suspensions.
DynaSizer)
Vibrating-sample magnetometer (LakeShore 7404VSM) for magnetic measurements at
room temperature.
Prof. Darko Makovec
([email protected])
Bernarda Anželak
([email protected])
Slavko Kralj
([email protected])
Dr. Sašo Gyergyek
([email protected])