A highly selective and sensitive peptide-based probe for the colorimetric and fluorescent detection of Fe3+, Al3+ and Cr3+ and its application in living cells imaging

Abstract

A new colorimetric and fluorescent dual-responsive probe named Rb-SSC was designed and synthesized using Rhodamine B and tripeptide (SerSerCys-NH2) as raw reactants. The selective recognition properties in detecting 17 metal ions were investigated by UV–Vis spectroscopy and fluorescence spectroscopy in DMF/water (4:6, v/v, 10.0 mM HEPES, pH = 7.4), and the results showed that Rb-SSC had high selectivity fluorescence response and clear colorimetric analysis for trivalent metal ions (Fe3+, Al3+ and Cr3+). These selectivity were attributed to protonation of Rb-SSC, and the Ksp value of the trivalent ions promotes the formation of hydrolyzed H+. Additionally, the limit of detections (LODs) were found to be 27.4 nM for Fe3+, 28 nM for Al3+ and 62.3 nM for Cr3+, respectively. In addition, MTT assay and cells experiments showed that Rb-SSC has low toxicity and achieved fluorescence imaging of trivalent metal ions in living cells. What's more, the G/B ratio has a good linear relationship with the concentrations of Fe3+ based on the smartphone sensing platform (RGB values), and the limit of detection (LOD) was as low as 0.37 μM.