Non-invasive Monitoring of Biochemical Response of Wheat Seedlings Toward Titanium Dioxide Nanoparticles Treatment Using Attenuated Total Reflectance Fourier Transform Infrared and Laser Induced Fluorescence 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.

A novel synthesis of a chlorophyll b-gold nanoconjugate used for enhancing photodynamic therapy: In vitro study

Chlorophyll, the essential green pigment in plants, is considered a promising natural photosensitizer (PS) for photodynamic therapy (PDT). However, it suffers from lower stability in the physiological conditions that depress its efficacy in the PDT. The combination of nanotechnology and PDT is becoming a promising approach to combat tumors. Gold nanoparticles (Au NPs), for example, are proposed as suitable carriers that can increase chlorophyll stability when conjugating together. In the present work, the impact of Au NPs conjugation in enhancing Chlorophyll b (Chl b) efficiency in the PDT of cancer cells has been emphasized. A chemical method using a natural product synthesized a novel Chlorophyll b-gold nanoparticles nanoconjugate (Chl b-Au NCs). The synthesized Chl b-Au NCs were characterized via UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), Laser-Induced Fluorescence (LIF), Zeta potential, Dynamic light scattering (DLS), and Transmission electron microscopy (TEM). Chl b is characterized by a formyl group (CHO) which is absent in Chl a. This group leads to the formation of an electrostatic reaction between the positive charge of Chl b and the negative charge present on the surface of the gold nanoparticles. Moreover, Chlorophyll b loading on the biosynthesized gold nanoparticles (Au NPs) increases its photostability. The efficiency of the PDT was then studied on the MCF7 and the HepG2 cells using this conjugation. As a result, the prepared Chl b-Au NCs showed low dark toxicity, excellent photostability under laser irradiation of wavelength 650 nm, in addition to a significantly high PDT efficacy against tumor cells in vitro. This is due to the enhanced cellular uptake and the high reactive oxygen species (ROS) production upon laser irradiation. Therefore, the designed Chl b-Au NCs could be a photo-therapeutic agent for enhancing cancer therapy in future applications.

Monitoring chemically and green-synthesized silver nanoparticles in maize seedlings via surface-enhanced Raman spectroscopy (SERS) and their phytotoxicity evaluation

The emergence of nanomaterials in consumer products has increased concern for their potential hazards in the environment and biological systems. Therefore, the monitoring of nanoparticles in biological systems is of great importance. Despite the numerous attempts, the methods to evaluate the uptake, translocation, and accumulation of nanomaterials inside the plant tissue are still limited. In this study, for the first time, we proposed the monitoring of the silver nanoparticles (AgNPs) in different tissues of the plant through surface-enhanced Raman spectroscopy (SERS) approach. For this, chemically (Che-AgNPs) and green-synthesized AgNPs (Gr-AgNPs) were prepared properly and their surfaces were functionalized with Raman-active molecule. With the contribution of electromagnetic enhancement, our NP systems provided high signal-to-noise SERS spectra. After exposure to NPs to maize seedlings as a model plant, we detected that AgNPs were accumulated mainly in the epidermis and cortex of the root and phloem parts of the shoot. Highly distinctive SERS spectra were collected from the root and shoot cross-section of each NP system. Also, the accumulation of the AgNPs was furtherly confirmed through inductively-coupled mass spectrometry and scanning electron microscopy analysis. Moreover, the exposure of AgNPs to maize seedlings led to remarkable alterations in both phytotoxic and biomolecular indicators including chlorophyll, protein and, antioxidant enzymes.

Nitrogen influenced biomolecular changes on Physalis L. species studied using 2DCOS spectral analysis coupled with chemometric and Receiver operation characteristics analysis

The determination of the molecular composition of plant leaves is essential to assist in nutritional management, whether for cultivated or non-cultivated species. In this sense, the study aimed to apply FTIR technique in combination with chemometrics and ROC analysis for the evaluation of changes in compositional of plant leaves of Physalis angulata and Physalis peruviana due to nitrogen fertilization treatments. Both species were grown under different doses of nitrogen (0, 200, 400, and 600 Kg ha^-1) and leaf samples were evaluated using ATR-FTIR. Our results demonstrate that the spectra of both species were influenced by the nitrogen doses. The computed band area from the lipid/amide, lipid/carbohydrates, degree of esterification and calcium oxalate shows nitrogen fertilization due to 400 Kg ha^-1 of N treatment is more effective for a better quality of yield. 2D correlation spectral analysis (2DCOS) reveals cellulose and pectin begins changes followed by amide of proteins due to nitrogen treatment in P. peruviana samples. The P. angulata plants shows hemicellulose changes predominating followed by proteins and polysaccharides. The obtained principle component analysis plot and loading values show the Physalis species samples distinctly separated from control with protein and carbohydrates are predominant in influencing separation among them. Receiver operation characteristic analysis shows a higher value of area under the curve reflecting better reliability of the experiments carried out. Hierarchical cluster analysis shows closed separation for a similar group on dissimilarity scale. Thus the use of 2DCOS coupled with chemometrics helps to identify changes in the composition of leaves of physalis species due to nitrogen doses, constituting a fast and precise measuring for the suitable management of this fertilization.

Research on the Physio-Biochemical Mechanism of Non-Thermal Plasma-Regulated Seed Germination and Early Seedling Development in Arabidopsis

Non-thermal plasma holds great potentials as an efficient, economical, and eco-friendly seed pretreatment method for improving the seed germination and seedling growth, but the mechanisms are still unclear. Therefore, a plant model organism Arabidopsis thaliana was used to investigate the physio-biochemical responses of seeds to non-thermal plasma at different treatment times by measuring the plant growth parameters, redox-related parameters, calcium (Ca²⁺) level and physicochemical modification of seed surface. The results showed that short-time plasma treatment (0.5, 1, and 3 min) promoted seed germination and seedling growth, whereas long-time plasma treatment (5 and 10 min) exhibited inhibitory effects. The level of superoxide anion (O₂ ^•-) and nitric oxide (NO) and the intensity of infrared absorption of the hydroxyl group were significantly higher in short-time plasma treated Arabidopsis seeds, and the level of hydrogen peroxide (H₂O₂) was remarkably increased in long-time plasma treated seeds, indicating that O₂ ^•-, ·OH, and NO induced by plasma may contribute to breaking seed dormancy and advancing seed germination in Arabidopsis, while plasma-induced H₂O₂ may inhibit the seed germination. The intensity of hydroxyl group and the contents of H₂O₂, malondialdehyde, and Ca²⁺ in Arabidopsis seedlings were obviously increased with the plasma treatment time. Catalase, superoxide dismutase, and peroxidase activities as well as proline level in short-time treated seedlings were apparently higher than in control. The etching effects of plasma on seed surface were dose-dependent, spanning from slight shrinkages to detached epidermis, which also significantly increased the oxidation degree of seed surface. Therefore, the improved activities of antioxidant systems, moderate ·OH, H₂O₂, and Ca²⁺ accumulation and seed surface modification induced by plasma all contribute to the enhanced seedling growth of Arabidopsis after short-time plasma treatment.