Potential of Spectroscopic Techniques for Prompt Analysis of the Biochemical Profile of Maize Leaves Exposed to Silicon Dioxide Nanoparticles

This study explores the potential of confocal micro-Raman spectroscopy coupled with principal component analysis, laser induced fluorescence and ultraviolet-visible spectroscopy to determine biochemical changes in maize leaves due to the exposure of different concentration of silicon dioxide nanoparticles. The analysis of the acquired Raman spectra shows that the treatment of the 0.2, 0.6, 1.0, 1.4 and 1.8 mM concentrations of the silicon dioxide nanoparticles enhances the level of different biochemicals like pectin, lignin, protein, cellulose, aliphatics, carbohydrates, and carotenoids present in the leaves of maize seedlings. The analyses of the spectral data from laser induced fluorescence depict decreases in fluorescence intensity ratio upon increasing the concentration of the treatment that leads an increase in photosynthetic activity. The quantitative measurements of chlorophyll and carotenoids by the ultraviolet-visible spectroscopy support enhancement in the number of photosynthetic pigments on increasing the concentration of the treatment of silicon dioxide nanoparticles. The principal component analysis of the Raman spectra reveals that the first principal component accounts for 72.88% of the total variation in the dataset and the second principal component explains 19.26% whereas the third principal component captures 0.75% of the total variation. The observed enhancement in the photosynthetic pigments and cell wall components corresponds to the beneficial effect of silicon dioxide nanoparticles on the maize seedlings.