Surface Plasmon Resonance

SPR is a phenomenon in which the reflected light disappears at a specific angle of incidence when light is incident on the side of the prism on which the gold thin film is placed. When biomolecules bind on the sensor chip, the surface refractive index changes and the angle of the reflected light shifts. Molecular interaction is monitored by acquiring sensorgrams that record this angle change in real time.

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SPR measures the binding of various molecules such as antigen-antibody, protein, nucleic acid, carbohydrate, fat, cell, and virus.
In addition, label-free real-time analysis enables kinetic analysis of intermolecular association affinity (affinity) as well as
association rate constant and dissociation rate constant.

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Applications of SPR in Life Science

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Yes/No: Checks whether or not there is a connection. The presence or absence of reaction can be checked by simply flowing the analyte (B)  to the sensor chip on which the ligand (A) is immobilized.
Screening: Multiple analytes can be run sequentially on the same ligand to evaluate which analyte binds best.
Concentration: After acquiring a sensorgram for each concentration of an analyte, a standard quantitation curve can be created through the concentration-signal graph.
Affinity: Evaluate the equilibrium constant after creating a Langmuir isothermal curve by acquiring the association section of the sensorgram for each concentration up to the equilibrium stage.
Kinetics: Evaluate the rate constants ka and kd through curve fitting by acquiring the association/dissociation section of the sensorgram  for each concentration.

Application Note 1

Antibody characterization

Kinetics evaluation of Protein A – Human IgG using iMSPR-mini & COOH-Au chip (2D)

Application Note 2

Protein-chemicals

Kinetics evaluation of CAII– Small compounds using iMSPR-mini & HC1000M

Application Note 3

EPO quality test

Quality test of EPO biopharmaceutical  using iMSPR-ProX & COOH chip

Application Note 4

Chemical inhibition test

Inhibition test ofsmall compoundsbetweenprotein and protein binding

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Article summary 5

Title: Tailor-made mesoporous SiO2/Au thin film with a substitutable interface for highly sensitive and selective room-temperature gas detection of VOCs  

Journal: Sensors & Actuators: B. Chemical 373 (2022) 132763

Correspond Author: Surin Hong, CHA University

First Author: Youngbo Choi, Chungbuk National University

Application: Gas sensor

Model: iMSPR-Lab (modified)

sensor chip: Bare-Au-chip, Lab-made surface

Ligand immobilization: Silica beads based

Article summary 4

Title: A Fully-Human Antibody Specifically Targeting a Membrane-Bound Fragment of CADM1 Potentiates the T Cell-Mediated Death of Human Small-Cell Lung Cancer Cells 

Journal: Int. J. Mol. Sci. 2022, 23(13), 6895

Correspond Author: Sukmook Lee, Kookmin University

First Author: Ji Hyun Lee, Kookmin University

Application: Cancer, antibody

Model: iMSPR-mini (with kinetics package)

sensor chip: COOH-Au-chip

Ligand immobilization: Amine coupling

Article summary 3

Title: An internalizing antibody targeting of cell surface GRP94 effectively suppresses tumor angiogenesis of colorectal cancer 

Journal: Biomedicine & Pharmacotherapy 150 (2022) 113051

Correspond Author: Sukmook Lee, Kookmin University

First Author: Ji Woong Kim, Kookmin University

Application: Cancer, antibody

Model: iMSPR-mini (with kinetics package)

sensor chip: COOH-Au-chip

Ligand immobilization: Amine coupling

Article summary 2

Title: Discovery of Orphan Olfactory Receptor 6M1 as a New Anticancer Target in MCF-7 Cells by a Combination of Surface Plasmon  Resonance-Based and Cell-Based Systems, Journal: Sensors 21 (2021) 3468, Correspond Author:Min Jung Kim, Korea Food Research Institute, First Author:Yae Rim Choi, KFRI & Ewha Womans University, Application: Cancer, chemicals, Model: iMeasy300, sensor chip: Carboxyl Dextran-Au-chip

Ligand immobilization: Amine coupling

Article summary 1

Title: Pig Sera-derived Anti-SARS-CoV-2 Antibodies in Surface Plasmon Resonance Biosensors, Journal: Biochip Journal 14 (2020) 358

Correspond Author: Jae-Chul Pyun, Yonsei University, First Author: Tae-Hun Kim, Yonsei University, Application: Covid-19, antibody

Model: iMSPR-mini, sensor chip: Lab-made Au-chip, Ligand immobilization: Amine coupling

Key Steps for SPR Analysis

1. Ligand Immobilization

The ligand immobilization step is the step of immobilizing the ligand on the surface of the sensor chip.
Substances used as ligands such as antibodies, proteins, nucleic acids, and peptides are very diverse.
Depending on the properties of the ligand material, the surface functional groups (COOH, Biotin, NTA) of the sensor chip and the immobilization method can be determined.

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Immobilization with Amine coupling

2. Analyte binding and regeneration

Analyte binding includes the association step in which the graph rises in real-time by injecting the analyte solution and binding to the ligand. By injecting only the running buffer, some analytes attached to the ligand are separated into the dissociation phase. After that, if the remaining analytes attached to the ligand are removed using a regeneration solution, experiments can be continued with different concentrations or different types of analytes on the same sensor chip.  The regeneration solution is a low pH buffer, high pH buffers, and solutions with high ionic strength can be selected and used according to the properties of the ligand-analyte.

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3. Kinetic Evaluation

Kinetic parameters can be calculated through a sensorgram that observes association and dissociation sections by flowing different concentrations of analyte.
The association rate constant (ka) and dissociation rate constant (kd) are obtained through a 1:1 binding model.The equilibrium dissociation constant (KD) obtained by dividing the dissociation rate constant by the association rate constant can be used as a parameter to evaluate the bonding force between two molecules.

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