Organic dyes in laser surgery of cartilaginous tissues

Abstract

IntroductionOptical surgical technologies were extensively devel oped in the 1990s. This gave rise to laser scalpels, which are common and effective surgical instruments in modern medical centers. Tissue dissection with a laser beam is accompanied by blood coagulation at the incision site. This reduces blood losses and facilitates surgery of such blood filled organs as liver and pancreas. The use of laser scalpels reduces the time of dry field surgery, pain reac tions to surgery, and postsurgical edema. In addition, remote laser surgery and surgery using lightguide disin fects the surgical wound.Flexible fiber optic lightguides are able to transfer optical radiation virtually without losses. This made the laser scalpel an ideal instrument for laparoscopic surgery. Special puncture operations were developed in which the lightguide is applied to the pathological lesion through a thin injection needle.Lack of methods for control of the laser beam direc tion gives rise to undesirable damage to adjacent tissues. Local staining (sensitization) of the treatment zone with laser radiation absorbers provides a solution to this prob lem. The laser radiation absorbers are organic dyes. The dyes have already been used for amplification of laser radiation during welding of small blood vessels and frag ments of human organs, as well as for healing of wound surface. Radiation induced heating causes disruption of cell membranes. The dye contained in cells forms strong intercellular bonds mediated by intermolecular bonds. Similar processes are observed during laser induced ther moplasty of cartilaginous tissues.Simultaneous effects of laser induced heating and heat transfer from adjacent tissues determine the temper ature and area of heated site.The use of organic dyes in laser surgery of cartilagi nous tissues in practical medicine requires solution of a number of theoretical and practical problems of biomed ical optics, laser engineering, and organic chemistry. Use of Organic Dyes in Laser SurgeryNew methods of laser surgery include methods based on injection (application) of organic dyes to biological tissues. Virtually harmless organic dyes, such as indo cyanin green (ICG, cardiogreen), are incorporated in laser solders used for soldering fine fibers of the human body (nerves, small blood vessels, sperm ducts, etc.) [8].The use of ICG for high contrast medical imaging is promising because the spectrum of the dye contains an intense band in the IR range, where intrinsic absorption of biological tissue is small. Suitable IR diode lasers are available. The toxicity of ICG is low, and this dye is easi ly excreted from human body. The dye is adopted for medical use.The spectral absorption maximum of ICG solution λ abs max in water and bovine blood plasma is at 779 and 803 nm, respectively. The bandwidth of the spectral band is ∆λ ≈ 60 nm; extinction coefficient, ε max ≈ 2⋅10 5 liter/ mol⋅cm. Spectral fluorescence maximum of ICG solution λ fl max in water and bovine blood plasma is at 810 and 829 nm, respectively; the luminescence q...

Determination of Mechanical Properties of Biocompatible Three-Dimensional Nanocomposites Manufactured Using Laser Methods

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