Natural red dyes from Beta vulgaris L. extract for gamma-rays color indicator: Physico-chemical and biological characterizations

Abstract

The exposure to ionizing radiation should be monitored. Radiochromic dosimeter is one of the monitoring systems for radiation dose which can be observed directly based on the color changing. This paper reports a color indicator system prepared from Beta vulgaris. The system was tested using gamma ray from a Cobalt-60 source at the medium dose level from 5 to 50 kGy. UV/Vis spectrophotometer was used to investigate the optical density in terms of absorbance. The structural changes occurring after γ-irradiation were studied by Fourier Transform Infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and Electron Paramagnetic Resonance (EPR) techniques, for the first time. Results revealed that the dose sensitivity of beet extract color indicator system increased strongly with increase of absorbed dose. The Hunter color spaces a*, b* and L* suggested that exposure to ionizing radiation was produced significant dose-dependent changes. The calculated color changes (ΔE) showed a linear dose response relationship from 18.31 to 76.3 (R2 = 0.96). The results of FT-IR analysis showed a clear chemical modification in recorded spectra of bands related to C–O, C–COOH groups in a dose-dependent manner. XRD assessment revealed clear structural changes in crystallinity. EPR spectra of beet samples contained a peak at 3510 Gauss which intensity increased with the dose increasing up to 30 kGy. Moreover, γ-irradiation at 50 kGy treatment elevated the Scavenging DPPH radical activity 93.3 ± 0.7%. The extract samples were effective in protecting pHEN4 plasmid DNA. The results obtained suggested the useful dose range of beet extract as color indicator or dosimeter in the range of 5–50 kGy.