Detection of Vibrational Spectroscopic Biomarkers of the Effect of Gold Nanoparticles on Wheat Seedlings Using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy

Nanoparticles and plants: a focus on analytical characterization techniques

Nanotechnology has brought about significant progress through the use of goods based on nanomaterials. However, concerns remain about the accumulation of these materials in the environment and their potential toxicity to living organisms. Plants have the ability to take in nanomaterials (NMs), which can cause changes in their physiology and morphology. On the other hand, nanoparticles (NPs) have been used to increase plant development and control pests in agriculture by including them into agrochemicals. The challenges of the interaction, internalization, and accumulation of NMs within plant tissues are enormous, mainly because of the various characteristics of NMs and the absence of reliable analytical tools. As our knowledge of the interactions between NMs and plant cells expands, we are able to create novel NMs that are tailored, targeted, and designed to be safe, thus minimizing the environmental consequences of nanomaterials. This review provides a thorough examination and comparison of the main microscopy techniques, spectroscopic methods, and far-field super-resolution methodologies used to examine nanomaterials within the cell walls of plants.

Early detection of stripe rust infection in wheat using light-induced fluorescence spectroscopy

In the current study, the application of fluorescence spectroscopy along with the advanced statistical technique and confocal microscopy was investigated for the early detection of stripe rust infection in wheat grown under field conditions. The indigenously developed Fluorosensor fitted with LED, emitting monochromatic light was used that covered comparatively larger leaf area for recording fluorescence data thus presenting more reliable current status of the leaf. The examined leaf samples covered the entire range of stripe rust disease infection from no visible symptoms to the complete disease prevalence. The molecular changes were also assessed in the leaves as the disease progresses. The emission spectra mainly produce two fluorescence emission classes, namely the blue-green fluorescence (400-600 nm range) and chlorophyll fluorescence (650-800 nm range). The chlorophyll fluorescence region showed lower chlorophyll bands both at 685 and 735 nm in the asymptomatic (early diseased) and symptomatic (diseased) leaf samples than the healthy ones as a result of partial deactivation of PSII reaction centers. The 735 nm chlorophyll fluorescence band was either slight or completely absent in the leaf samples with lower to higher disease incidence and thus differentiate between the healthy and the infected leaf samples. The Hydroxycinnamic acids (caffeic and sinapic acids) showed decreasing trend, whereas the ferulic acid increased with the rise in disease infection. Peak broadening/shifting has been observed in case of ferulic acid and carotenes/carotenoids, with the increase in the disease intensity. While using the LEDs (365 nm), the peak broadening and the decline in the chlorophyll fluorescence bands could be used for the early prediction of stripe rust disease in wheat crop. The PLSR statistical techniques discriminated well between the healthy and the diseased samples, thus showed promise in early disease detection. Confocal microscopy confirmed the early prevalence of stripe rust disease infection in a susceptible variety at a stage when the disease is not detectable visually. It is inferred that fluorescence emission spectroscopy along with the chemometrics aided in the effective and timely diagnosis of plant diseases and the detected signatures provide the basis for remote sensing.

How does aquatic macrophyte Salvinia auriculata respond to nanoceria upon an increased CO2 source? A Fourier transform-infrared photoacoustic spectroscopy and chlorophyll a fluorescence study

With the continued increase of technological uses of cerium oxide nanoparticles (CeO₂ NPs or nanoceria) and their unregulated disposal, the accumulation of nanoceria in the environment is inevitable. Concomitantly, atmospheric carbon dioxide (CO₂) levels continue to rise, increasing the concentrations of bicarbonate ions in aquatic ecosystems. This study investigates the influence of CeO₂ NPs (from 0 to 100 μgL^-1) in the presence and absence of an elevated bicarbonate (HCO₃^-) ion concentration (1 mM), on vibrational biochemical parameters and photosystem II (PSII) activity in leaf discs of Salvinia auriculata. Fourier transform-infrared photoacoustic spectroscopy (FTIR-PAS) was capable of diagnostic use to understand biochemical and metabolic changes in leaves submitted to the CeO₂ NPs and also detected interactive responses between CeO₂ NPs and HCO₃^- exposure at the tissue level. The results showed that the higher CeO₂ NPs levels in the presence of HCO₃^- increased the non-photochemical quenching (NPQ) and coefficient of photochemical quenching in dark (qP_d) compared to the absence of HCO₃. Moreover, the presence of HCO₃^- significantly decreased the NPQ at all levels of CeO₂ NPs demonstrating that HCO₃^- exposure may change the non-radiative process involved in the operation of the photosynthetic apparatus. Overall, the results of this study are useful for providing baseline information on the interactive effects of CeO₂ NPs and elevated HCO₃^- ion concentration on photosynthetic systems.

Boron and pigment content in alfalfa affected by nano fertilization under calcareous conditions

Boron is among the necessary nutrients for plant growth and yield production, and it can improve the nutritional properties of forage crops. However, at higher levels it maybe toxic adversely affecting plant growth and forage quality. Plant boron concentration is affected by different parameters including boron fertilization, soil, climate, plant species, etc. A new era in the field of plant fertilization is the use of nano technology. Accordingly, a factorial field experiment on the basis of a complete block design in six replicates was conducted in a 300-hactare agro-industry area. The objectives were to investigate the effects of different boron treatments on alfalfa (Medicago sativa L.): 1) boron concentration, and 2) pigment contents including chlorophyll a, b, total, and carotenoids. Six regions with different properties were selected for the experiment; the soil samples were collected using GPS. The experimental treatments including: 1) soil type (S1-S6), 2) boron sources including boric acid (B1) and nano boron fertilization (B2), and 3) number of spraying (zero-, one-, two-, and three-time) were tested. The nano structure of boric acid-copper in an aqueous medium was produced using the chemical reduction method. The results indicated that soil type, boron source and number of spraying significantly affected (P ≤ 0.01) alfalfa boron concentration and pigment content. The mean of alfalfa boron concentration by B1 and B2 was 103.52 and 111.52% higher than control. The three-time spraying significantly increased B concentration related to the other spraying treatments (P ≤ 0.05) as it resulted in a 207.81% increase compared with the control treatment. The three-time spraying resulted in the highest increase of pigment contents (P ≤ 0.05) including chlorophyll a, b, total, and carotenoids compared with the other treatments. Although the highest boron and pigment contents were resulted by the three-time spraying, the combined use of B2 and the two-time spraying was the most optimum treatment (non-toxic) significantly increasing alfalfa boron and pigment contents (P ≤ 0.05). It would be possible to produce alfalfa at large amounts and with suitable forage quality using boron nano fertilization (synthesized and tested in this research work) under calcareous conditions.