Activatable peptide–AIEgen conjugates for cancer imaging

Abstract

Aggregation-induced emission luminogens (AIEgens) have undergone significant development over the past decade, making substantial and profound contributions to a diverse range of research fields, prominently including cancer/disease diagnosis and therapy. Through the covalent conjugation of AIEgens with functional peptides, the resultant peptide–AIEgen conjugates possess not only the excellent biocompatibility characteristics, along with low systemic toxicity and negligible immunogenicity of peptides, but also the remarkable fluorescence properties of AIEgens. This “win–win” integration has significantly propelled the applications of peptide–AIEgen conjugates, particularly within the domain of cancer imaging. Three principal types of peptide–AIEgen conjugates, namely, tumor-targeting, tumor biomarker-responsive, and biomarker-responsive self-assembling peptide–AIEgen conjugates, are commonly devised. These conjugates confer enhanced targeting capabilities and selectivity towards tumors, thereby facilitating “smart” and precise tumor imaging with high signal-to-background ratios. In light of the crucial significance of peptide–AIEgen conjugates in tumor imaging and the recent inspiring breakthroughs that have not been encompassed in previous reviews, we present this review. We highlight the activatable peptide–AIEgen conjugates developed for tumor imaging over the past three years (from 2022 to the present). Particular attention is directed towards their design rationales, operational mechanisms, and imaging performance. Finally, prospective opportunities within this field are also reasonably deliberated.