Molecular specific photoacoustic imaging with plasmonic nanosensors

Gold nanoparticles functionalized with anti-EGFR antibodies undergo molecular specific aggregation on the cellular membrane and later within the cell that leads to a red shift in the plasmon resonance frequency of the gold nanoparticles. Capitalizing on this effect, we previously demonstrated on tissue phantoms that highly sensitive and selective detection of cancer cells can be achieved using the combination of photoacoustic imaging and molecular specific gold nanoparticles. To further evaluate the efficacy of molecular specific photoacoustic imaging technique in detecting deeply situated tumors, small animal experiments were performed. In this study, two gelatin solutions mixed with cells labeled with gold nanoparticles and cells mixed with polyethylene glycol-thiol (mPEG-SH) coated gold nanoparticles were injected in a mouse abdomen ex-vivo. The photoacoustic and ultrasound images from the same crosssection of the region before and after the injections were obtained using a 25 MHz single element ultrasound transducer interfaced with pulsed laser system. The results of our study suggest that the molecular specific photoacoustic imaging with plasmonic nanosensors could be used to detect deeply embedded tumors.