Monday, June 20, 2016
From tradition SPR to MP-SPR:
From measurements to understanding
Surface Plasmon Resonance (SPR) is an established method for
biomolecular interaction analysis. It is popular due to its sensitivity
as well as its capability to measure label-free and in real-time.
Multi-Parametric Surface Plasmon Resonance (MP-SPR) is based on
SPR principle, however its advantageous optical setup measures
a full SPR curve which enables new insight into interactions.
For instance, PureKinetics™ feature provides measurements of
small molecules, lipids and biomaterials without bulk effect.
MP-SPR widens the application range of traditional SPR from small
molecules up to nanoparticles and even living cells. Measurements
can be performed also in complex media such as serum.
Additionaly, MP-SPR provides information about layer properties.
Thickness and refractive index (RI) data can be utilized in material
characterization from Ångström thick layers up to micrometers
or to ensure conformation of the molecules on the surface.
Premium quality kinetic data with
Bulk effect (sometimes called DMSO effect, salt or solvent artifact) is
the difference in liquid composition between samples and running
buffer. The composition difference is seen as a change in refractive
index, which in turn appears as a shift in measured SPR curve.
In traditional SPR, imaging SPR or localized SPR, only part of the SPR
curve can be seen and therefore, several steps have to be taken in
order to separate true molecular binding from the undesired bulk
The unique optical setup of MP-SPR instruments enables
cross-correlation of parameters provided by the MP-SPR method
and allows simple in-line elimination of interfering bulk signal
using PureKinetics™ feature. This feature is available in all
MP-SPR Navi™ instruments.
Gold nanoparticles were immobilized on a monolayer selfassembled
on gold. Functional groups on the chain ends of the
monolayer facilitated an anchoring of gold nanoparticles to the
layer. Multi-Parametric Surface Plasmon Resonance (MP-SPR)
enabled a real-time measurement of the binding of the gold
nanoparticles to the surface layer.
Gold nanoparticles (AuNPs) exhibits interesting optical and electronic
properties that find application in sensors, catalysis, electronics,
photonics, solar cells, cancer diagnosis and therapy. Controlled attachment
of Au nanoparticles at a solid interface is required for many of
these applications. Although many methods have been developed to
fabricate Au nanoparticle assemblies, developing simple and effective
routes is still very attractive. Usually, the immobilization can be
performed using a covalent or an electrostatic interaction between
the nanoparticles and the substrate. In this study functional molecules
are used for linking gold nanoparticles to a solid surface. Molecules
possessing functional groups can be attached to the solid surface in
a controlled manner and permits nanoparticle immobilization.
Monolayers with functional groups assembled on a gold surface
can be used for coupling of gold nanoparticles. In this study MP-SPR
turned out to be a unique method for determining the deposition of
metal nanoparticles to the surface layer in real-time. AuNPs exhibit
strong surface plasmon resonances and even a large response could
be observed by MP-SPR when nanoparticles were interacting with
the surface layer. Functional groups on the chains ends enable
an anchoring of gold nanoparticles or even embedding into the
chains. MP-SPR is a unique tool for studying metal nanoparticles for
applications in sensors, electronics, photonics, solar cells or cancer
diagnosis and therapy.
When is the PureKinetics™ useful?
• with Kinetic measurements of small molecules
• with Interaction measurements on lipid bilayers
• when there are Material interactions with biomolecules
• in case of Solvent interactions
• when using Crude samples (serum, growth medium, lysate, seawater)
IgG dissociation kinetics from immobilized Protein A was
studied using real-time Multi-Parametric Surface Plasmon
Resonance (MP-SPR). Various dissociation buffers were
tested to determine the most efficient solution. A unique
feature, PureKinetics™, allows differentiation of real binding
from interfering bulk signal artifacts, providing a pure
binding signal. The method can clear out even extremely
large bulk signals, such as high-ionic strength dissociation
buffers. In this study, the most efficient dissociation from
Protein A was achieved with buffers of pH below 4.0.
Surface Plasmon Resonance (SPR) is a well-established method for
molecule-molecule interaction studies. The SPR is a popular real-time
and label-free method measuring association and dissociation kinetic
constants in addition to the affinity constant. Multi-Parametric Surface
Plasmon Resonance (MP-SPR) is based on the SPR principle, but it utilizes
a unique optical setup which allows to solve challenges related to the
buffer composition changes during SPR measurements.
In non-labelled optical methods, changes in buffer composition
frequently cause a shift of the peak minimum angle value due to a
change in refractive index of the buffer (called bulk effect or solvent
effect). The usual method to counteract this is to subtract a reference
channel response from the measurement channel response. However,
the bulk effect is often not exactly the same in the different measurement
channels because ligands might prevent the liquid flow near the
surface. Sometimes suitable reference surface is hard to find, especially
in the case of interactions to a membrane protein or interactions to
coatings. Therefore, better methods than reference channel correction
to compensate for bulk artifacts are needed.
Many small molecule weight drugs have poor solubility in water-based
liquids, and solubility enhancers such as dimethyl-sulfoxide (DMSO) are
needed to obtain suitable solubility. As the organic solubility enhancers
create a large bulk signal in SPR, they also create huge challenges to
assays in terms of a protein stability and function. Traditionally the bulk
effect caused by DMSO is corrected using an empirical calibration curve
requiring multiple injections [Frostell-Karlsson et al. 2000].
The unique optical setup of the MP-SPR instruments enables
measurement of multiple optical parameters simultaneously and in
real-time. Cross-correlation of the parameters allows simple in line
characterization of the interfering bulk signal using the PureKinetics™
Friday, March 25, 2016
The superior QCM with Dissipation monitoring technology (QCM-D)
The Q-Sense Initiator is a QCM-D instrument with focus on the core functions. It produces data with superior accuracy, has a robust design with controlled liquid flow and enables a wide range of experimental conditions.The Q-Sense Initiator is a one-channel system with a fixed module in which the sensor is placed. The module is connected to the liquid handling system which ensures a controlled flow over the sensor surface. The instrument is compatible with all Q-Sensors
Next generation analysis software for QCM-D data
Q-Sense Dfind is the next generation analysis software from Q-Sense. It will help you to extract information such as mass, thickness, viscoelastic properties, adsorption rates etc and present it in a simple way. Q-Sense Dfind will be launched later this year but here we give you a quick introduction already now!
All data treatment and analysis tools in one unified program
Q-Sense™ Dfind covers all aspects needed in an analysis program. It assists you all the way from your raw data reviewing, through the modelling, to the information extraction and the final report. The graphical and intuitive interface efficiently helps you quantify, compile and compare your data, from start to end.Exploit the full potential of the information content in your data
Q-Sense™ Dfind helps you unveil and extract all the relevant information content embedded in your data. In addition to the software assisted modelling of mass and viscoelastic parameters, Q-Sense™ Dfind supports a range of qualitative and quantitative analysis methods.Analyze all your data in one go
Equipped with a powerful analysis engine, Q-Sense™ Dfind enables fast and efficient analysis of multiple data sets in one go. Save time and review, model and analyze multiple data sets simultanoeusly. Organize projects and share your favorite templates with colleagues, keep track of important experiments and tools.
Get the Full Picture of Your Surface-Molecule Interactions
Q-Sense is a line of instrumentation for real-time analysis of surface-molecule interactions. They measure mass and thickness changes on the surface even of rapid events with nanogram precision. All with accurate outcomes and high reproducibility.
Our instruments are designed to enable variable measurement conditions, and a wide variety of samples in liquid or air can be analyzed. We also have the broadest sensor surface offering in the market to widen your possibilities even further. Turn-key instruments, intuitive software and support from our experienced team will ensure that you get the most out of your measurements.
All our instrument are based on the Quartz Crystal Microbalance with Dissipation monitoring (QCM-D) technology.