Abstract
Rutin (R), a representative flavonoid found in various biomasses, can be used to prepare different fluorescent sensors for environmental, biological and medical fields. In this work, the natural R in Sophora japonica was extracted and purified to prepare fluorescent-responding sensor systems intended to recognize copper ions with both strong selectivity as well as appropriate sensitivity. Results showed that neat R had no obvious fluorescent emission peak in PBS buffer solution. However, when R and (2-hydroxypropyl)-β-cyclodextrin (CD) were introduced within buffer solution, fluorescent emission intensity was significantly increased due to the resultant R-CD inclusion complex. In addition, the formed R-CD inclusion complex was shown to behave as the aforementioned fluorescent sensor for copper ions through a mechanism of quenched fluorescent emission intensity when R-CD became bound with copper ions. The binding constant value for R-CD with copper ions was 1.33 × 106, allowing for quantification of copper ions between the concentration range of 1.0 × 10–7–4.2 × 10–6mol⋅L–1. Furthermore, the minimum detection limit was found to be 3.5 × 10–8mol⋅L–1. This work showed the prepared R-CD inclusion complex was both highly selective and strongly sensitive toward copper ions, indicating that this system could be applied into various fields where copper ions are of concern.
Highlights
As the shortage of oil resources and environmental pollution become more serious, biomass resources have attracted lots of attention as sustainable alternatives
R was extracted from Sophora japonica acquired from Bozhou Good health Food Co., Ltd. 2-Hydroxypropylβ-cyclodextrin was purchased from Aladdin Reagent Co., Ltd
10 g·L−1 was selected as an experimental condition for follow-up experiments. These spectra demonstrated that the interaction between R and CD occurs, and that the R-CD inclusion complex forms
Summary
As the shortage of oil resources and environmental pollution become more serious, biomass resources have attracted lots of attention as sustainable alternatives. Transformation of the constituents (cellulose, hemicellulose, lignin) into value-added products such as reinforcing materials, food additives, adhesive, and more continue to be extensively investigated (Du et al, 2019; Sun et al, 2019; Zhou and Xu, 2019; Zhou et al, 2019; Huang et al, 2020; Pei et al, 2020b; Zhao et al, 2020). Apart from the structural constituents of biomass, there is potential value in the variously minor constituents present, the flavonoids and polyphenols. The polyphenols can showed different physical and biological activity in bio-materials (Dong et al, 2020; Pei et al, 2020a; Zheng et al, 2021). Biological activities of flavonoids are reported and reviewed frequently in the literature
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