A colorimetric and fluorescent dual-signals probe based on Rhodamine B and tripeptide for highly sensitive detection of trivalent ions and its application in living cells imaging

In this study, a new dual-signals probe Rb-HMD with colorimetric and fluorescent was designed and synthesized by conjugating tripeptide backbone (His-Met-Asp-NH2) with a rhodamine B derivative using solid phase peptide synthesis (SPPS) technology. Rb-HMD exhibited highly selective recognition of trivalent ions (Fe3+, Al3+ and Cr3+) by fluorescence enhancement and colorimetric observation in the presence of other competing metal ions. Notably, the limit of detections (LODs) for Fe3+, Al3+, and Cr3+ were 16.4 nM, 0.12 & mu;M and 0.24 & mu;M, respectively, indicating that Rb-HMD has good application prospects for high sensitive detection of Fe3+, Al3+ and Cr3+ in real samples and biological systems. Additionally, cytotoxicity and cells imaging demonstrated that Rb-HMD has very low toxicity in living cells even at concentrations up to 80.0 & mu;M, and was successfully applied to detect Fe3+, Al3+ and Cr3+ in living cells. Moreover, the gradient change of color of Rb-HMD was captured by smartphone under UV light at 365 nm, and then content analysis was carried out by color recognition APP, which makes it possible to detect Fe3+ in rapid and accurate semi-quantitative way without other large valuable instruments.