Crosslinking of Amino Acids Photosensitized by Rose Bengal

                                    Lucie Ludvíková, Petr Klán*
                                                 ^

  Department of Chemistry and RECETOX Faculty of Science, Masaryk University, Kamenice 5, 625 00,
                                       Brno, Czech Republic

                                         lucielud@email.cz

Non-invasive approaches to stitching wounds are gaining importance. The laser welding was shown to
be a successful alternative to the classical chirurgic stitching.^1 Kochevar and co-workers have
introduced another methodology to seal wounds. Rose bengal (RB), a well-known xanthene dye and
oxygen sensitizer,^2 can induce tissue bonding upon irradiation with a green-light laser. Pork and
human tissues were shown to be successfully sealed both in vitro and in vivo.^3-4 However, the
mechanism of this process is not understood well.

We performed a detailed spectroscopic study of photosensitized coupling reactions of selected amino
acids (e.g., Figure 1). Crosslink products of were analyzed by UV–Vis absorption and fluorescent
spectroscopies and LC/MS. The initial step - an electron transfer - was also studied by nanosecond
laser flash photolysis using a 532 nm laser as a source of excitation. We show that these
photoinduced electron transfer processes can play an important role in a complex mechanism of
photochemical tissue bonding.


Fig.1











1 Simhon, D., et al., Lasers Surg Med 2001, 29, 265-273.

2 Neckers, D. C., J. Photochem. and Photobiol. A-Chem. 1989, 47, 1-29.

3 Mulroy, L., et al., Invest Ophthalmol Vis Sci 2000, 41, 3335-3340.

4 Chan, B. P., Kochevar, I. E., and Redmond, R. W. J Surg Res 2002, 108, 77-84.