Rose Bengal Binding to Collagen and Tissue Photobonding

Area of Science:

• Biochemistry
• Photochemistry
• Biophysics

Background:

• Rose Bengal (RB) is a photosensitizer with emerging medical applications.
• Understanding RB's interaction with proteins like collagen is crucial for optimizing these applications.
• The photochemical behavior of RB can be altered by its microenvironment.

Purpose of the Study:

• To investigate the physical binding of RB to collagen.
• To determine the effect of RB binding and amino acids on RB photochemistry.
• To elucidate the photochemical mechanisms of RB within a tissue-mimetic collagen matrix.

Main Methods:

• Molecular dynamics simulations and free-energy calculations.
• Isothermal titration calorimetry.
• Spectroscopic analysis in solution and collagen matrix.

Main Results:

• RB binds to collagen primarily through electrostatic interactions, with strongest binding near positively charged groups.
• Aggregated RB molecules were observed bound to collagen.
• In a collagen matrix, RB photobleaching was rapid, influenced by electron transfer to amino acids like arginine.
• RB generated singlet oxygen and a 510 nm absorbing product, depending on arginine presence and oxygen levels.

Conclusions:

• The binding of RB to collagen is characterized by electrostatic forces.
• The photochemistry of RB is significantly modulated by the collagen environment and specific amino acids.
• These findings provide critical insights into the mechanisms underlying RB-mediated protein cross-linking for medical use.