Misassignment of Fourier-Transform Infrared Spectra for Monitoring the Crosslinking of Collagen: A Critical Analysis

Fourier-transform infrared spectroscopy (FTIR) is acknowledged as a highly effective analytical tool, and is extensively used in chemistry, biochemistry, and biomedical research. In our attempt to establish a method for monitoring the level of photochemical crosslinking of collagen, aiming at therapeutic applications, we have found that there is actually no straightforward FTIR method able to provide unambiguous outcomes needed to evaluate the crosslinking process, either photochemical or chemical. Based on the analysis of the existing literature, the reasons for this situation were appraised, and deficiencies and uncertainties of the results so far reported were discussed in detail. We concluded that, at this stage, the FTIR-based methods will not become reliable until progress in enhancing knowledge of the chemistry of photochemical and chemical crosslinking of collagen would allow more accurate FTIR band assignments.