Rathinam Yuvakkumar

High-purity nano silica powder from rice husk using a simple chemical method

A highly pure, small particle-sized and high surface area nano silica powder was prepared from rice husk using alkali extraction, followed by an acid precipitation method. The composition, phase, morphology, size and surface area of the as-synthesised nano silica powder was investigated by energy-dispersive spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, particle size analyser and BET surface area analyser. High-purity nano silica powder was obtained by sodium hydroxide (NaOH) purification treatment (0.5, 1, 1.5, 2 and 2.5 N). The high purity of silica (∼99.9%) was obtained at 2.5 N NaOH treatment. The pure nano silica powder that is obtained shows an average particle size of ∼25 nm with a high-specific surface area (SSA) of 274 m2 g−1, with an average pore diameter of 1.46 nm.

Influence of Nanosilica Powder on the Growth of Maize Crop (Zea Mays L.)

ABSTRACT A novel approach to study the effect of nanosilica on maize crop improvement was proposed. Nanosilica powders were mixed with soil at different concentrations along with control and conventional silica under in vitro and in vivo conditions. In in vitro, the nanosilica increases seed germination (2–11%), water usage efficiency (up to 53%), and total chlorophyll content (13–17%) of maize crop. In in vivo, influence of nanosilica was analyzed on basic parameters such as stem height, stem width, number of leaves, and silica content. The effect of nanosilica on maize crop was found to be enhanced in all aspects.

Effect of nanosilica and silicon sources on plant growth promoting rhizobacteria, soil nutrients and maize seed germination

The study was aimed at evaluating the effect of nanosilica and different sources of silicon on soil properties, total bacterial population and maize seed germination. Nanosilica was synthesised using rice husk and characterised. Silica powder was amorphous (50 nm) with >99.9% purity. Sodium silicate treated soil inhibited plant growth promoting rhizobacteria in contrast to nanosilica and other bulk sources. Surface property and effect of soil nutrient content of nanosilica treatment were improved. Colony forming unit (CFU) was doubled in the presence of nanosilica from 4 × 105 CFU (control) to 8 × 105 CFU per gram of soil. The silica and protein content of bacterial biomass clearly showed an increase in uptake of silica with an increase in nanosilica concentration. Nanosilica promoted seed germination percentage (100%) in maize than conventional Si sources. These studies show that nanosilica has favourable effect on beneficial bacterial population and nutrient value of soil.

Application of silica nanoparticles in maize to enhance fungal resistance

In this study, maize treated with nanosilica (20-40 nm) is screened for resistance against phytopathogens such as Fusarium oxysporum and Aspergillus niger and compared with that of bulk silica. The resistivity is measured for disease index and expression of plant responsive compounds such as total phenols, phenylalanine ammonia lyase, peroxidase and polyphenol oxidase. The results indicate that nanosilica-treated plant shows a higher expression of phenolic compounds (2056 and 743 mg/ml) and a lower expression of stress-responsive enzymes against both the fungi. Maize expresses more resistance to Aspergillus spp., than Fusarium spp. These results show significantly higher resistance in maize treated with nanosilica than with bulk, especially at 10 and 15 kg/ha. In addition, hydrophobic potential and silica accumulation percentage of nanosilica treated maize (86.18° and 19.14%) are higher than bulk silica treatment. Hence, silica nanoparticles can be used as an alternative potent antifungal agent against phytopathogens.

Screening of in vitro cytotoxicity, antioxidant potential and bioactivity of nano- and micro-ZrO2 and -TiO2 particles

Nanometal oxides are used in tissue engineering and implants. The increased use of nanoparticles suggests the need to study their adverse effects on biological systems. The present investigation explores in vitro cytotoxicity, antioxidant potential, and bioactivity of nano- and micro-particles such as zirconia (ZrO2) and titania (TiO2) on biological systems such as National Institute of Health (NIH) 3T3 mouse embryonic fibroblasts cell line, di(phenyl)-(2,4,6-trinitrophenyl) iminoazanium (DPPH) and simulated body fluid (SBF). The cell line viability % indicated that nano ZrO2 and TiO2 were less toxic than microparticles up to 200µgml(-1). DPPH assay revealed that the free radical scavenging potential of tested particles were higher for nano ZrO2 (76.9%) and nano TiO2 (73.3%) at 100mg than that for micron size particles. Calcium deposition percentage of micro- and nano-ZrO2 particles, after SBF study, showed 0.066% and 0.094% respectively, whereas for micro- and nano-TiO2, it was 0.251% and 0.615% respectively. FTIR results showed a good bioactivity through hydroxyapatite formation. The present investigation clearly shows that nanoparticles possess good antioxidant potential and better biocompatibility under in vitro conditions which are dose and size dependent. Hence, cytotoxicity itself is not promising evaluation method for toxicity rather than particles individual characterisation using antioxidant and bioactivity analysis.

Nano Silicon from Nano Silica Using Natural Resource (Rha) for Solar Cell Fabrication

Abstract High purity (∼99%) nano silica with an average particle size of ∼100 nm was extracted at pH 3 at 650°C from a natural resource, rice husk, using alkaline extraction followed by acid precipitation method. Using nano silica as a precursor, silicon (Si) nanoparticles have been synthesized by high-temperature magnesiothermic reduction method. The prepared sample was characterized by X-ray diffraction, particle size analyzer, Fourier transform infrared spectroscopy, transmission electron microscopy, X-ray fluorescence analyzer, and UV–Vis spectroscopy. The comprehensive characterization studies indicate the pure phase formation of Si and the variation of particle size from 70 nm to 100 nm for samples synthesized at different sintering temperatures. Moreover, the silicon nanoparticles produced at 850°C have pure phase formation, high purity, and good absorption peaks. The efficiency calculated through IV characteristics is found to be increasing in silicon and ruthenium combination (2.67%), which is better than that achieved from the conventional solar cells. The produced silicon nanoparticles could be applied as an anode material for solar cell fabrication. GRAPHICAL ABSTRACT

Foliar Application of Silica Nanoparticles on the Phytochemical Responses of Maize (Zea mays L.) and Its Toxicological Behavior

The study aimed to explore the effect of high surface (360.85 m2 g–1) silica nanoparticles (20–40 nm) on phytochemical responses during maize growth in comparison with bulk silica at 15 g L–1. The maize responses are analyzed for the changes in biochemical components. The expression of organic compounds and silica contents favored to nanosilica treatment than bulk and control. In addition, nanosilica is biologically inert against MG-63 cell line till 125 μg mL–1. Soil amendment is found better than foliar application to maize. This helps to improve sustainable farming as an alternative source of silica fertilizer for food crops.

Influence of Nano Nutrients on Heterocyst-Forming Cyanobacterium Anabaena ambigua Rao

The present study is deals with the influence of nanoparticles on the growth of heterocyst-forming cyanobacterium Anabaena ambigua Rao [A100]. The nano molybdenum and iron particles have been synthesized respectively from molybdenum trioxide (MoO3) and iron chloride (FeCl3) employing sodium borohydride (NaBH4) as a reducing agent and characterized comprehensively. BG11 (N−) media containing micronutrients like molybdenum and iron were replaced respectively by different concentrations of nano molybdenum [BG11 (N−Mo− + nano Mo)] (0, 5, 10, 15, 20, 25, 40, 60, 80, and 100%) and nano iron [BG11 (N−Fe− + nano Fe)] (0, 0.1, 0.2, 0.3, 0.4, 0.5, 1, 2, 3, 4, 5, 10, 15, 20, 25, 40, 60, 80, and 100%) particles for the cultivation. The effect of nano nutrients on cyanobacterial growth parameters like heterocyst formation, chlorophyll content, and protein content was analyzed. The obtained results showed that the high concentrations of nano molybdenum induce heterocyst formation, increase protein content, and decrease chlorophyll content when compared to the control, whereas the nano iron suppresses the growth of cyanobacteria Anabaena ambigua Rao [A 100].

Enhancement of UV Property on Cotton Fabric by TiO2 Nanorods

TiO2 nanoparticles were prepared at low temperature using TiCl3. Rutile phase TiO2 agglomerated nanoparticles showed a rod-like morphology. Diameter of TiO2 nanorods was controlled by varying acidic catalyst and calcination temperature. At 1073 and 1273 K, nanorod was deformed to elliptical like morphology with unagglomerated particles. TiO2 nanoparticles were padded on surface of cotton fabric using silica sol and characterized comprehensively. The effect of ultraviolet protection on TiO2 nanorods coated cotton fabric was determined. High ultraviolet protection factor indicates that the TiO2 nanoparticles coated on cotton fabrics show good ultraviolet protection efficiency.

Catalytic Effect of Iron Nanoparticles on Heterocyst, Protein and Chlorophyll Content of Anabaena sp.

ABSTRACT Iron nanoparticles were synthesized, characterized comprehensively, and were used as catalysts on heterocyst-forming cyanobacteria. A higher induction in heterocyst was observed in all nano iron treated cultures. A low percentage (0.1, 0.3, 0.5, 1, 3, 5, and 15%) of nano iron on heterocyst-forming Anabaena sp. led to an increase in total protein and chlorophyll content. A slight decrease in protein and chlorophyll content was observed at higher concentrations (25, 60, and 100%) of nano iron. An enhanced catalytic activity of nano iron was observed on heterocyst formation, protein, and chlorophyll content of Anabaena sp.