Plant hormones influence plant growth and development progress, and response to the environment. Therefore, it is highly significant to know the reasons that cause the above phenomena. Research on the signal transduction mechanism of hormones in plants is insufficient due to the lack of an accurate and sensitive method to measure it. The detection of binding sites between hormones and receptors is the first step in studying the signal transduction of plant hormones. The auxin indole-propionic acid (IPA) is an important plant hormone and can promote rooting and fruiting in plants. By conjugating CdTe/ZnS QDs with the IPA moiety, we constructed the CdTe/ZnS–IPA fluorescence probes for the in situ detection of IPA binding sites in plant tissues. By improving the synthesis conditions, we capped ZnS outside the oil bath-obtained CdTe to prepare red-emitting CdTe/ZnS QDs, and the core/shell structure of the CdTe/ZnS QDs was proved by XRD. The success of conjugation was verified by fluorescence spectra, fluorescence decay lifetime, UV-vis spectra, and DLS. The CdTe/ZnS–IPA with a 5.4% coupling rate were selected for the labelling of IPA binding sites, which are concentrated in the endodermis cells of mung bean root tissues. The existence of the competitive relationship of recognition for IPA binding sites between CdTe/ZnS–IPA and IPA declared that CdTe/ZnS–IPA possessed biological activity for IPA. The red-emitting CdTe/ZnS–IPA can contrast with the background of plant tissues compared to green-emitting CdTe–IPA. In sum, the novel probe showed low toxicity, was plant tissue background-resistant, and this new method for the selective detection of IPA binding sites in plant tissues has the advantages of convenience and easy visualization.
Xinyi Wang,Liubing Kong,Shuqi Zhou,Tao Liang,Hao Wan,Ping Wang
Photoluminescence (PL) sensors based on quantum dots (QDs) are difficult to achieve exact detection in sample waters. In this paper, polyvinyl alcohol (PVA) based CdTe/ZnS/CdS QDs and fluorescein isothiocyanate (FITC) fluorophores were used to build a ratiometric PL sensor. Combining with the homemade smartphone-based PL E-eye, the Cd2+ exact detection can be achieved. PVA was used to connect QDs and FITC fluorophores without unnecessary ligand exchange and purification. For QDs fluorophore, ethylenediaminetetraaceticacid (EDTA) was used on the surface to induce the specifically Cd2+ recognition site. For FITC fluorophore, the PL remains unchanged in this experiment. Thus, the ratio of two fluorophores can be used to provide a built-in correction. The PL changes with the increase of Cd2+ concentrations could be displayed as a visual color change on the smartphone. Further quantitative analysis could be carried out by the RGB value of the picture through the App in less than 1 min The ratio of R/G is linear to Cd2+ concentration in the range of 1–2000 μg l−1 with a low LOD of 0.057 μg l−1 (S/N). Compared with traditional analysis methods, the PL ratiometric method with PL E-eye is portable, rapid, visible and highly selective especially in discriminate Cd2+ from Zn2+.
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