Laser induced breakdown spectroscopy in elemental imaging of plants: the spatial distribution of Cd based Quantum dots in S. Alba

abstract

English

Laser Induced Breakdown Spectroscopy (LIBS) is an optical analytical method used in many different applications for determination of the elemental composition of the sample. It is a relatively inexpensive technique capable of multi-elemental analysis. However, the real added value for plant examination lies in its ability to perform fast large-scale mapping of the complete specimen, precisely revealing the position of observed elements. This information is valuable in the field of toxicology where the information about location can help explain the toxic effect. The need for toxicological studies is connected to the production of new materials. As the new materials, especially on nano- and micro- scale, are being manufactured in quantity, the danger of them leaking into the environment increases, hence their toxic effect on various organisms must be evaluated. The object of this study was Cd-based quantum dots (QDs); semiconductor nanocrystals usually consisting of a core and a shell. Their widespread use is the result of their unique optical and electrical properties, mainly very stable size dependent and thereby tunable fluorescence. Owing to these qualities, QDs could play an important role in both medical and industrial applications. QDs core generally consist of CdTe, CdSe or CdS which can leak very reactive Cd2+ ions into the surrounding environment. Variety of shells are added in order to prevent such leakage, ZnS being the most commonly used one due to its ability to increase chemical stability and fluorescence efficiency. In present study, the toxicity and bioaccumulation of two different types of Cd-based QDs was assessed for model plant white mustard (Sinapis Alba L.): core QDs (CdTe) and core/shell QDs (CdTe/SiO2), while CdCl2 was used as positive control. After 72-h exposure to QDs dispersed in aqueous medium, the overall content of Cd in S. Alba plants was determined using ICP-OES and the root length was observed as a toxicological endpoint. LIBS was used to determine the location of Cd in model plants with 100 μm step. Specific interesting parts of the plant, including the transition of root and stem, were mapped using the μLIBS technique with 25 μm resolution. The result from LIBS measurements have shown differences in both distribution and bioaccumulations patterns from both types of QDs and positive control.

Laser Induced Breakdown Spectoscopy, microLIBS, quantum dots, Sinapis alba

STŘÍTEŽSKÁ, S.; MODLITBOVÁ, P.; PROCHAZKA, D.; ZEZULKA, Š.; KUMMEROVÁ, M.; NOVOTNÝ, K.; POŘÍZKA, P.; KAISER, J.

21. 9. 2020

Kyoto

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