pH-Sensitive assembly/disassembly gold nanoparticles with the potential of tumor diagnosis and treatment

Due to the ability to combine the separately unique characteristics of assembled and disassembled nanoparticles (NPs), the stimuli-responsive self-assembly of NPs has attracted considerable interest in functional material applications especially biomaterials. Here we demonstrate a facile and versatile approach to regulate the self-assembly process and transition pH of Au NPs by fine-tuning the co-modified pH-responsive compounds and poly(ethylene glycol) (PEG). Importantly the transition pH (ΔpH=0.4) of the system can be predetermined in the range of 8.2–5.8 (assembled to disassembled) and 8.2–4.2 (disassembled to assembled), which ideally covers the pH of normal tissue, tumor tissue milieu and organelles. The results of fluorescence imaging, Raman spectroscopy and photothermal conversion of the stimuli-responsive Au NPs shows the potential application for tumor specificity theranostics. In a nutshell this study provides a useful toolkit to design tumor-activatable self-assembled NPs with high specificity and universality.