131I labeled pH-responsive gold nanoparticles for bimodal tumor diagnosis

Abstract

• Preparation of pH-responsive 131 I-labeled gold nano-particle molecular probe. • Aggregation of gold nanoparticles was explored based on the tumor microenvironment. • Dual-modality imaging further improves the diagnostic efficacy of tumors. Considering that each diagnostic method exhibits its disadvantages, such as the poor spatial resolution of SPECT and limited penetration depth of PA imaging, the development of a diagnosis integrated agent with dual-modality imaging performance is of great research interest. Herein, an interesting triggered mechanism, release, and aggregation of radiolabeled Au NPs were explored for tumor diagnosis based on the effect of H + in the tumor microenvironment. In vitro experiments reveal that the pH-responsive Au NPs exhibit an obvious accumulation effect and local surface plasmon resonance (LSPR) coupling effect and generate strong NIR absorption and can be used as the PA imaging agent. Importantly, Au aggregation only appears in the acid tumor microenvironment and displays excellent tumor SPECT diagnostic and photoacoustic imaging performance in vivo. This work provides a new synergistic strategy for SPECT and PA bimodal imaging to further improve the diagnostic efficacy of tumors.