Rational design of dual-modalitye peptide-based probe for detection of Cu(II) and -histidine in 100% aqueous solution and its application for living cells, test strips and smartphone

A new fluorometric and colorimetric dual-modalitye probe L for detection of Cu2+ and l-His was constructed based on peptide skeleton via solid phase peptide synthesis (SPPS) technology. L exhibited highly selective recognition towards Cu2+ through formation of L-Cu2+ ensemble with a 2:1 binding stoichiometry, and the limit of detection (LOD) for Cu2+ was determined to be 7.1 nM. Correspondingly, L-Cu2+ ensemble was investigated by fluorescence technique which clearly established the high selectivity towards l-His based on fluorescence “off–on” response, and the limit of detection (LOD) for l-His was calculated to be approximately 15.3 nM. The selective sensing of Cu2+ was efficiently reversible with l-His, which was no loss of fluorescence intensity in 10 cycles. Notably, the sensing behavior of L towards Cu2+ and l-His detections was shown to be available within the wider pH interval (7.0–12.0). Cells imaging studies have shown that L was easily applied to the continuous imaging of Cu2+ and l-His in living cells. Furthermore, the test strips were also prepared for rapid and sensitive identification of Cu2+ and l-His. Combining smartphones and color changes, the semi-quantitative relationship between the R/B and the concentration of Cu2+ was established, and the limit of detection (LOD) reached up to 0.29 µM.