On sensitivity of molecular specific photoacoustic imaging using plasmonic gold nanoparticles

Abstract

Functionalized gold nanospheres undergo receptor mediated aggregation on cancer cells that overexpress the epidermal growth factor receptor (EGFR). This phenomenon leads to a red shift in the plasmon resonance frequency of the EGFR-targeted gold nanoparticles. Previously we demonstrated that highly selective detection of cancer cells can be achieved using the combination of multi-wavelength photoacoustic imaging and molecular specific gold nanoparticles. In this study, we use tissue models to evaluate the sensitivity of molecular specific photoacoustic imaging in detecting cancer cells labeled with EGFR-targeted gold nanoparticles. The results of our study indicate that highly sensitive detection of cancer cells is feasible using photoacoustic imaging and plasmonic gold nanoparticles.

Fig. 1

(a) Block diagram of the combined ultrasound and photoacoustic imaging system. (b) Schematic representation and photograph of the integrated imaging probe consisting of 25 MHz ultrasound transducer and seven 600 μm diameter optical fibers.

Fig. 2

Darkfield images of A431 cells with (a) no gold nanoparticles and (b) anti-EGFR conjugated gold nanoparticles.

Fig. 3

The ultrasound (a-d) and photoacoustic (e-h) images of cell/gelatin samples at different cell concentration. The photoacoustic images were obtained at 720 nm wavelength illumination. The images measure a 2 mm by 3.5 mm field of view.

Fig. 4

Graph depicting the change in photoacoustic signal amplitude with Au NPs concentration. The solid line represents the linear regression fit of the data with R² equal to 0.99.