Fourier Transform Infrared (FTIR) Spectroscopy
Method Introduction
Fourier transform infrared (FTIR) spectroscopy is a highly valuable technique for monitoring protein structure in liquid and dried states, such as lyophilized states.
FTIR spectra can identify a wide range of compounds by comparing the measured spectra to spectral databases. FTIR spectra from wavenumbers 1,700-1,500 cm-1 can be used to determine the structural properties of proteins. Measuring protein absorbance over these wavenumbers gives two absorption bands, conventionally called Amide I and Amide II, lying between wavenumbers 1,700 – 1,600 cm-1 and 1,600 – 1,500 cm-1, respectively.
The Amide I band is due to C=O stretching vibrations of the peptide bonds, modulated by the secondary structure (α-helix, β-sheet, etc.). Secondary structural content can be obtained by comparing the measured spectra to those obtained for proteins with known secondary structures.
The Amide II band is due to C-N stretching vibrations in combination with N-H bending. For instance, Amide II absorbance can be used to report on protein unfolding based on the extent of hydrogen (H) exchanged for deuterium (D) in H-D exchange experiments.
Water can interfere with FTIR measurements of protein samples because it is strongly absorbed in the Amide I region. Consequently, FTIR is best suited for lyophilized (freeze-dried) protein samples. Nevertheless, measurements can be obtained for protein samples in solution, but a relatively high (typically >5 mg/mL) protein concentration is required. Both liquid (transmission, attenuated total reflection (ATR)) and solid (ATR) samples can be analyzed at Coriolis Pharma.
Applications
Fourier Transform Infrared (FTIR) Spectroscopy has several important application areas:
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FTIR is widely used to study the secondary structure of proteins, including therapeutic monoclonal antibodies and other biopharmaceuticals. It can detect secondary structure elements like α-helices, β-sheets, turns, and random coils, providing protein folding and stability insights. It is frequently used in comparability or biosimilarity studies.
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FTIR is employed to analyze protein-excipient interactions and compatibility during formulation development. It can detect changes in the protein structure upon adding excipients like sugars, salts, and surfactants, helping identify optimal formulation conditions.
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Combined with Coriolis’ Particle ID service, FTIR spectroscopy attached to microscopy supports the identification and homogeneity assessment of unknown particles by their FTIR spectrum.
Quality and Biosafety Level
We provide all our analytical services with the highest quality standards. Experienced scientists carry out each project, and a scientific reviewer comprehensively checks every report or data presentation.
We offer this technology with the following quality and biosafety levels:
R&D level
We offer this method under R&D. Our GRP system assures the highest-quality research standards.
Up to biosafety level 1
This method can be applied to proteins, nucleic acids, and most viral vectors, including AAVs and more.
Analytical Method Development, Qualification and Validation
For common sample types, we can often apply standardized methods with little setup effort. However, when needed, our experienced analytical experts create or optimize custom methods tailored to your active pharmaceutical ingredient, product type and development phase.
Talk to Our Experts or Request a Quote
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