A novel fluorescence and colorimetric dual sensing system for rapid and sensitive detection of histidine based on...

Histidine (His) plays an important role in human health and life activities. It will harm human health when His intake is insufficient or excessive. Its residue also will pollute the natural environment. Therefore, establishing a reliable and sensitive method for detecting histidine is particularly important. However, most of the existing detection methods of His rely on the single change of single signal, which are susceptible to interference from testing environmental factors and prone to generating false positive results. In contrast, the fluorescence and colorimetric dual-signal sensing system can not only effectively improve the reliability of detection, but also significantly reduce the risk of false positives. Therefore, the dual-signal sensing system has gradually become the research hotspot. Based on this, 5,10,15,20-tetra-(4-sulfophenyl) porphyrin (TSPP) was selected as the fluorescence and colorimetry dual-signal probe for the rapid detection of His in this study. Since TSPP could interact with many substances due to the specificity of molecular structure, it is the best choice to build an "ON-OFF-ON" sensing system in order to improve the specificity of the sensing system. Therefore, citric acid (CA) as an intermediate based on TSPP probe was successfully developed fluorescence and colorimetric dual-sensing system for the quantitative detection of histidine in real samples. The signal of the dual sensing system was "turned on" when the red TSPP solution obtained the fluorescence emission wavelength of 642 nm at the 514 nm optimal excitation wavelength and the UV-Vis absorption at 413 nm, respectively. The fluorescence intensity and absorbance of TSPP gradually decreased with the introduction of CA. At this time, the signal of the dual-sensing system became "turned off", and the color of the solution changed from light pink to light green. The quenched fluorescence intensity and absorbance, however, was restored upon the introduction of histidine into the system. Simultaneously, the color of the solution changed from light green to light pink, and the dual-sensing system became "turned on". Therefore, a novel fluorescence and colorimetric dual-signal sensing system based on TSPP was proposed for histidine detection. The results indicated that the linear ranges of the fluorescence sensing system were 8.34 × 10^-6 M - 1.51 × 10^-4 M and 1.85 × 10^-4 M - 1.4 × 10^-3 M with detection limits of 0.282 μM and 10.91 μM (LOD, S/N = 3), respectively. The linear range of the colorimetric sensing system was 2.04 × 10^-4 M-4.35 × 10^-4 M with a detection limit of 11.97 μM (LOD, S/N = 3). Meanwhile, the dual-sensing system provided a promising platform for practical samples sensing applications.