Contents: “Nanomaterials & Sensors”
Lecture I 01.06.2022:
a) PoC Bioanalytical immunoassays (some examples)
What does “PoC” stand for?
b) Benefits of gold nanoparticles (GNPs) for applications in PoC bioanalytical assays
What are the main benefits of using GNPs as labels in bioanalytical assays?
c) Mie theory and LSPR band of GNPs
What is the origin of the LSPR band?
: How do the absorption and scattering cross sections depend on the GNP size?
3) What happens to the LSPR when the dielectric constant of the surrounding medium is increased?
6)What are the simplifying assumptions in the dipolar (quasistatic) approximation of the Mie
theory?
5) Which precondition needs to be fulfilled for applying the dipolar approximation of Mie theory?
:
The calculation of the absorption spectrum of GNPs according to Mie theory requires the
imaginary and real parts of the dielectric function of bulk gold – how can those be obtained?
d) Turkevich Synthesis and advanced methods for the synthesis of citrate-stabilized GNPs
How does the Turkevich synthesis work? Which starting materials are used and what are their
main functions?
2) How is it possible to improve the size distribution and to adjust the size of citrate-stabilized
GNPs?
3) Over which approximate size range can citrate-stabilized GNPs be synthesized?
e) Structure and properties of antibodies (variable region, constant region, Fab fragments)
" How large is an antibody approximately in nm?
2) What is approximately the lower size limit of antigens that can be recognized by antibodies?
3) What is a Fab fragment?
,÷ Point-of-care (POC) testing involves performing a diagnostic test outside of a laboratory that produces a rapid and reliable result, aiding in
identifying or managing chronic diseases and acute infections.
e.g. blood glucose monitoring and home pregnancy tests
b)
c) a When a metal particle is exposed to light, the oscillating electromagnetic field of the light induces a collective coherent oscillation of the free electrons
.
(conduction band electrons) of the metal. This electron oscillation around the particle surface causes a charge separation with respect to the ionic
lattice, forming a dipole oscillation along the direction of the electric field of the light. The amplitude of the oscillation reaches maximum at a specific
frequency, called surface plasmon resonance (SPR). The SPR induces a strong absorption of the incident light and thus can be measured using a
UV–Vis absorption spectrometer. The SPR band is much stronger for plasmonc nanoparticles (noble metal, especially Au and Ag) than other metals.
The SPR band intensity and wavelength depends on the factors affecting the electron charge density on the particle surface such as the metal type,
particle size, shape, structure, composition and the dielectric constant of the surrounding medium, as theoretically described by Mie theory
2 .
of particles )
Gabs G) Rs ( The plasmon absorption Volume
✗
intensity of ✗
'
& sea
lil ✗ R
Imax Em When increased Imax
shift the larger wavelength and the the also
higher
Em to
intensity of peak
~
s .
area
4 .
For nanorods with any aspect ratios, discrete dipole approximation (DDA), a powerful electrodynamics and numerical methods to calculate
optical properties of targets with any arbitrary geometry and composition is generally used. In this numerical method, the target particle is
viewed as a cubic array of point dipoles. Each dipole interacts with the electric field of incident light and the induced field by other dipoles. From
the dipole moment with an initial guess, the extinction, absorption and scattering cross-sections can be derived from the optical theorem.
5 .
Condition
for
Mie theory : the
particles diameter must be much smaller than the WL
of
the incident
light .
(d) and the KCI ) the solid
6. From the values
of refractive
index n
absorption coefficient of gold ,
the both quantities calculated Maxwell relationships
are
using .
d)
7 .
,2. 3 -
→ less stabilizer
.
bigger particles
e)
1. 2)
3)
The fragment antigen-binding region (Fab region) is a region on an antibody that
binds to antigens. It is composed of one constant and one variable domain of each
of the heavy and the light chain. The variable domain contains the paratope (the
antigen-binding site), comprising a set of complementarity-determining regions, at
the amino terminal end of the monomer. Each arm of the Y thus binds an epitope
on the antigen.
Lecture I 01.06.2022:
a) PoC Bioanalytical immunoassays (some examples)
What does “PoC” stand for?
b) Benefits of gold nanoparticles (GNPs) for applications in PoC bioanalytical assays
What are the main benefits of using GNPs as labels in bioanalytical assays?
c) Mie theory and LSPR band of GNPs
What is the origin of the LSPR band?
: How do the absorption and scattering cross sections depend on the GNP size?
3) What happens to the LSPR when the dielectric constant of the surrounding medium is increased?
6)What are the simplifying assumptions in the dipolar (quasistatic) approximation of the Mie
theory?
5) Which precondition needs to be fulfilled for applying the dipolar approximation of Mie theory?
:
The calculation of the absorption spectrum of GNPs according to Mie theory requires the
imaginary and real parts of the dielectric function of bulk gold – how can those be obtained?
d) Turkevich Synthesis and advanced methods for the synthesis of citrate-stabilized GNPs
How does the Turkevich synthesis work? Which starting materials are used and what are their
main functions?
2) How is it possible to improve the size distribution and to adjust the size of citrate-stabilized
GNPs?
3) Over which approximate size range can citrate-stabilized GNPs be synthesized?
e) Structure and properties of antibodies (variable region, constant region, Fab fragments)
" How large is an antibody approximately in nm?
2) What is approximately the lower size limit of antigens that can be recognized by antibodies?
3) What is a Fab fragment?
,÷ Point-of-care (POC) testing involves performing a diagnostic test outside of a laboratory that produces a rapid and reliable result, aiding in
identifying or managing chronic diseases and acute infections.
e.g. blood glucose monitoring and home pregnancy tests
b)
c) a When a metal particle is exposed to light, the oscillating electromagnetic field of the light induces a collective coherent oscillation of the free electrons
.
(conduction band electrons) of the metal. This electron oscillation around the particle surface causes a charge separation with respect to the ionic
lattice, forming a dipole oscillation along the direction of the electric field of the light. The amplitude of the oscillation reaches maximum at a specific
frequency, called surface plasmon resonance (SPR). The SPR induces a strong absorption of the incident light and thus can be measured using a
UV–Vis absorption spectrometer. The SPR band is much stronger for plasmonc nanoparticles (noble metal, especially Au and Ag) than other metals.
The SPR band intensity and wavelength depends on the factors affecting the electron charge density on the particle surface such as the metal type,
particle size, shape, structure, composition and the dielectric constant of the surrounding medium, as theoretically described by Mie theory
2 .
of particles )
Gabs G) Rs ( The plasmon absorption Volume
✗
intensity of ✗
'
& sea
lil ✗ R
Imax Em When increased Imax
shift the larger wavelength and the the also
higher
Em to
intensity of peak
~
s .
area
4 .
For nanorods with any aspect ratios, discrete dipole approximation (DDA), a powerful electrodynamics and numerical methods to calculate
optical properties of targets with any arbitrary geometry and composition is generally used. In this numerical method, the target particle is
viewed as a cubic array of point dipoles. Each dipole interacts with the electric field of incident light and the induced field by other dipoles. From
the dipole moment with an initial guess, the extinction, absorption and scattering cross-sections can be derived from the optical theorem.
5 .
Condition
for
Mie theory : the
particles diameter must be much smaller than the WL
of
the incident
light .
(d) and the KCI ) the solid
6. From the values
of refractive
index n
absorption coefficient of gold ,
the both quantities calculated Maxwell relationships
are
using .
d)
7 .
,2. 3 -
→ less stabilizer
.
bigger particles
e)
1. 2)
3)
The fragment antigen-binding region (Fab region) is a region on an antibody that
binds to antigens. It is composed of one constant and one variable domain of each
of the heavy and the light chain. The variable domain contains the paratope (the
antigen-binding site), comprising a set of complementarity-determining regions, at
the amino terminal end of the monomer. Each arm of the Y thus binds an epitope
on the antigen.
