Biomaterials Lab 3: Spectroscopy of Hydrogels

Study Notes

Definition: Infrared spectroscopy examines the interaction of infrared light with matter.
Range: Infrared light spans from 4000 cm⁻¹ to 400 cm⁻¹. Different regions are categorized (near, mid, far).
Mechanism: Atoms in compounds vibrate. Specific vibrational frequencies correspond to chemical bonds and molecular structure. When IR light frequency matches a vibration, the molecule absorbs it, exciting the vibration.
Analysis: IR light passes through the sample, and the absorbed frequencies are analyzed to build an infrared spectrum.
Fourier Transformation (FT): The signal is transformed to produce intensity as a function of wavenumber.

Presents correlations between specific wavenumbers (cm⁻¹) and functional groups (e.g., O-H, C-H, N-H) in molecules.
Provides a guide to identifying functional groups in samples.
Ranges of wavenumbers are associated with different strengths of the correlation between functional groups and spectrum peaks.

Chemical compounds' atoms constantly move and vibrate.
Each vibration happens at a specific frequency related to the chemical bond and structure.
Matching IR light frequency with vibrational frequency causes absorption, exciting molecular vibrations.
Plotted data after IR light passes through the sample creates an IR spectrum.

A technique to analyze samples without prior preparation, especially solid and liquid ones.
Mechanism: IR beam interacts with the sample through an evanescent wave.
Evanescent Wave: Light traveling through a crystal (e.g., ATR crystal), some light slightly penetrates the sample.
Depth: Attenuated total reflection penetrates only a few microns of the sample (0.5-2 µm).
Advantages: Direct examination of samples in their solid or liquid state without further preparation is possible.

Shows the molecular structures of agarose and collagen.
Provides diagrams of the chemical composition and arrangement of the molecules. Agarose has a chain of sugar molecules, while collagen has a repeating amino acid structure.