Photothermal effects in connective tissues mediated by laser-activated gold nanorods

Abstract 

We report a study on the application of laser-activated nanoparticles in the direct welding of connective tissues, which may become a valuable technology in biomedicine. We use colloidal gold nanorods as new near-infrared chromophores to mediate functional photothermal effects in the eye lens capsules. Samples obtained ex vivo from porcine eyes are treated to simulate heterotransplants with 810-nm diode laser radiation in association with a stain of gold nanorods of aspect ratio approximately 4. This stain is applied at the interface between a patch of capsule from a donor eye and the capsule of a recipient eye. Then, by administration of laser pulses of 40 msec and approximately 100–140 J/cm², we achieved the local denaturation of the endogenous collagen filaments, which reveals that the treated area reached temperatures above 50°C. The thermal damage is confined within 50–70 μm in a radial distance from the irradiated area.

Key words: Gold nanorods, Laser-activated nanoparticles, Laser-tissue interactions, Laser welding, Photothermal effects