Optical and thermal characterization of albumin protein solders

The effect of temperature on the optical and thermal properties of pure and indocyanine green-doped albumin protein solders as a function of wavelengt h has been studied between 25 degrees C and 100 degrees C. An increase in t he group refractive index by up to 4% and a decrease in absorption coeffici ent (similar to 800 nm) by up to 8%, after denaturing the solder specimens in a constant-temperature water bath at temperatures of 60-100 degrees C, w ere not significant. The reduced scattering coefficient, however, increased rapidly with temperature as the solder changed from being a highly nonscat tering medium at room temperature to a highly scattering medium at temperat ures close to 70 degrees C. The thermal conductivity, thermal diffusivity, and heat capacity increased by up to 30%, 15%, and 10%, respectively. Final ly, the frequency factor and activation energy were measured to be 3.17 x 1 0(56) s(-1) and 3.79 x 10(5) J mol(-1), respectively, for liquid protein so lders (25% bovine serum albumin) and 3.50 x 10(57) s(-1) and 3.85 x 10(5) J mol(-1), respectively, for solid protein solders (60% bovine serum albumin ). Incorporation of dynamic optical and thermal properties into modeling st udies of laser tissue interactions could have a significant influence on th e determination of the expected zone of damage. (C) 1999 Optical Society of America.