Identification of insulin variants using Raman spectroscopy

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Biochemistry

Background:

• Raman spectroscopy offers molecular fingerprinting capabilities.
• Analyzing complex biological samples like insulin requires sensitive and specific methods.
• Distinguishing between closely related protein variants is crucial for pharmaceutical and diagnostic applications.

Purpose of the Study:

• To demonstrate the utility of Drop Coating Deposition Raman (DCDR) spectroscopy for analyzing dilute insulin solutions.
• To achieve spectroscopic identification and classification of different insulin variants.
• To assess the feasibility of DCDR for chromatographic detection of insulin.

Main Methods:

• Utilized DCDR spectroscopy to acquire normal Raman spectra from small volumes (10 microliters) of dilute insulin solutions (3-400 microM).
• Performed DCDR measurements on insulin solutions obtained from reverse-phase high-performance liquid chromatography (RP-HPLC) eluent fractions.
• Applied data preprocessing techniques including normalized Savitsky-Golay second derivative filtering and partial least squares (PLS) analysis for classification.

Main Results:

• High-quality normal Raman spectra were obtained, enabling spectral identification of insulin.
• Successfully demonstrated the spectroscopic classification of three natural insulin variants: human, bovine, and porcine.
• Showcased the ability to differentiate insulin variants differing by as few as one to three amino acid residues.

Conclusions:

• DCDR spectroscopy is a powerful technique for the sensitive and specific analysis of dilute insulin solutions.
• This method facilitates the accurate spectroscopic identification and classification of insulin variants.
• DCDR shows promise for integration with chromatographic techniques for advanced insulin analysis.