A heptamethine cyanine with meso-N-induced rearrangement for acid-activated tumour imaging and photothermal therapy.

ABSTRACT

Photothermal therapy has been developed as one of the most attractive strategies for tumour therapy. However, most of the reported photothermal probes still suffer from poor selectivity or specificity for the tumour region during treatment. Herein, a tumour acidic microenvironment activated heptamethine cyanine-based nanoprobe (Cy-TPA NPs) is constructed for fluorescence imaging-guided photothermal therapy with enhanced tumour specificity. Taking advantage of the pH-dependent molecular rearrangement, Cy-TPA NPs under weak acidic conditions exhibit enhanced near-infrared absorption and "turn on" fluorescence and photothermal performance. The "turn on" fluorescence signal in tumour tissues can improve the signal-to-background ratio, providing precise in vivo fluorescence imaging. Moreover, tumour-specific PTT can effectively ablate tumours with reduced damage to the surrounding tissue. Thus, our work presents a promising strategy for significantly improving the precision and specificity of tumour imaging and therapy.