Graphene Oxide Wrapping of Gold-Silica Core-Shell Nanohybrids for Photoacoustic Signal Generation and Bimodal Imaging

We report the development of graphene oxide (GO) wrapped silica-coated gold nanoparticles (GO-Au-NP@SiO2), which exhibit an unprecedented absorption enhancement in the visible region of the electromagnetic spectrum. GO coating on the core-shell nanohybrid enhances residual plasmonic absorption of the nanohybrid while maintaining its compact size. Finite-difference time domain simulations show an electromagnetic field intensity enhancement owing to GO wrapping over three different gold cores with 10, 20 and 30 nm in diameter and uniform silica thickness of 30 nm. Bimodal imaging using fluorescent microbeads reveals an enhanced photoacoustic signal from GO-Au-NP@SiO2 in an integrated photoacoustic and fluorescence imaging setup. Present approach provides a fundamental platform for photoacoustic signal generation using plasmonic nanoparticles with low toxicity. This unique strategy opens up new avenues for enhancing photoacoustic signals and for combined fluorescence and photoacoustic imaging.