Development of a peptide-based AIE probe for selective detection of Cd²⁺ in biological systems

Cadmium ions (Cd²⁺) are highly toxic heavy metals that pose significant environmental and health risks, particularly due to their accumulation in living organisms. Prolonged exposure to Cd²⁺ can lead to severe health issues, including kidney damage, bone disorders, and increased cancer risk. Therefore, sensitive and selective detection of Cd²⁺ is crucial for environmental monitoring and biomedical applications. In this study, a novel "turn-on" peptide-based fluorescent probe for detecting Cd²⁺ was developed. The probe was constructed by conjugating a tripeptide (Glu-His-Cys) with a tetraphenylethylene (TPE) moiety using solid-phase peptide synthesis, resulting in a peptide probe with aggregation-induced emission (AIE) properties. The probe, named TPE-EHC, exhibited excellent selectivity and anti-interference capability towards Cd²⁺ over a range of metal ions and allowed quantitative detection of Cd²⁺ in the concentration range of 0-10 μM. Notably, TPE-EHC demonstrated good cell permeability and low cytotoxicity, making it suitable for fluorescence detection of Cd²⁺ in HeLa cells. Additionally, the probe showed potential for detecting exogenous Cd²⁺ in both in vitro and in vivo biological systems.