A supramolecular hybrid material constructed from graphene oxide and a pillar[6]arene-based host–guest complex as an ultrasound and photoacoustic signal nanoamplifier

Photoacoustic imaging combines the merits of ultrasound imaging and optical imaging, and allows a fascinating imaging paradigm with deeper tissue penetration than optical imaging and higher spatial resolution than ultrasound imaging. Herein, we develop a supramolecular hybrid material composed of graphene oxide (GO) and a pillar[6]arene-based host–guest complex (CP6⊃PyN), which can be used as an ultrasound (US) and photoacoustic (PA) signal nanoamplifier. Triggered by the near-infrared (NIR) light mediated photothermal effect, CO2 nanobubbles are generated on the surface of GO@CP6⊃PyN due to the decomposition of the bicarbonate counterions, thus strongly amplifying its US and PA performances. Our study, for the first time, demonstrates enhanced US and PA activity in a supramolecular hybrid material on the basis of host–guest chemistry as a photoacoustic nanoplatform.