Detection of biologically synthesized gold nanoparticles in adult zebrafish (Danio rerio) using non-invasive photoacoustic tomography

This paper presented a non-invasive photoacoustic image system capable of imaging an adult zebrafish with photoabsorbers accumulated in its internal organs. The zebrafish (Danio rerio), a vertebrate, is an excellent model organism in which to study human disease. The fish produces large numbers of offspring and has high optical transparency, which makes it an amenable target for photoacoustic tomography. Gold nanoparticles were synthesized by treating AuCl₄ with an aqueous leaves extract of Spinacia oleracea Linn., which was used as a reductant. These gold nanoparticles, which were used as the photoabsorbers, were exposed to the subject for 14 days as it accumulated over the gills, eyes, lungs, and other parts of the zebrafish. The photoacoustic images were acquired with a custom-developed linear array imaging system that used universal back projection algorithm for reconstruction algorithm. The photoacoustic images were overlaid with an ultrasound image to define the location of the accumulated photoabsorbers in the fish. This imaging method can be a versatile tool for case studies in drug delivery to a specific part of a fish. This study also emphasizes the importance of recognizing that marine animals are being polluted with nanoparticles settling in their internal organs.