Laser Soldering of Cartilage Tissue to Collagenous Biomaterial (an in vitro Study)

The aim of the study was to assess the effectiveness of laser soldering of biological tissues and materials for bulk heating of albumin solder on the joints of the intact and chemically modified cartilage of the porcine nasal septum.

The materials for soldering were double-trypsinized and glyceraldehyde-treated plates made from cartilage of the porcine nasal septum, and intact cartilage. A 25% albumin solution was used as a solder. The junction was heated by laser radiation with the wavelengths of 1.56 and 1.68 μm through an optical fiber. The process was monitored using a digital USB microscope. After the materials were soldered, mechanical tests of the samples were conducted, and the fraction of intact collagen in the areas adjacent to the solder was determined. A thermal imager was used to record the dynamics of the temperature field in the area of laser exposure.

The effective soldering of cartilage tissue with collagenous biomaterial occurs with sequential application and laser heating of two/three layers of solder for radiation with wavelengths of 1.68/1.56 μm, respectively. The laser power densities for the solder layers were 0.7/0.8 W/mm² (the average surface temperature ~85°C) for λ=1.68 μm and 1.77/1.34/0.96 W/mm² (the average surface temperature ~100°C) for λ=1.56 μm. The tensile strength of the soldered samples reached ~12% for λ=1.56 μm and ~15% for λ=1.68 μm of the tensile strength of intact cartilage. In the tissue areas adjacent to the first layer of albumin, at a thickness of ~300 μm, most of the collagen network was destroyed. In other areas, collagen was predominantly preserved.

Laser soldering of chemically modified and intact cartilages can be effectively conducted using radiation of λ=1.56 μm and λ=1.68 μm, absorbed not only by the solder, but also by the tissue. However, to minimize the area of degradation, it is necessary to match the diameter of the laser spot and the size of the solder-filled cavity between the construction and the intact cartilage.