Biogenic synthesis of silica nanoparticles from corn cobs husks. Dependence of the productivity on the method of raw material processing

Greening the pathways: a comprehensive review of sustainable synthesis strategies for silica nanoparticles and their diverse applications

Silica nanoparticles (SiNPs) have emerged as a multipurpose solution with wide-ranging applications in various industries such as medicine, agriculture, construction, cosmetics, and food production. In 1961, Stöber introduced a ground-breaking sol-gel method for synthesizing SiNPs, which carried a new era of exploration both in academia and industry, uncovering numerous possibilities for these simple yet multifaceted particles. Inspite of numerous reported literature with wide applicability, the synthesis of these nanoparticles with the desired size and functionalities poses considerable challenges. Over time, researchers have strived to optimize the synthetic route, particularly by developing greener approaches that minimize environmental impact. By reducing hazardous chemicals, energy consumption, and waste generation, these greener synthesis methods have become an important focus in the field. This review aims to provide a comprehensive analysis of the various synthetic approaches available for different types of SiNPs. Starting from the Stöber' method, we analyze other methods as well to synthesis different types of SiNPs including mesoporous, core-shell and functionalized nanoparticles. With increasing concerns with the chemical methods associated for environmental issues, we aim to assist readers in identifying suitable greener synthesis methods tailored to their specific requirements. By highlighting the advancements in reaction time optimization, waste reduction, and environmentally friendly precursors, we offer insights into the latest techniques that contribute to greener and more sustainable SiNPs synthesis. Additionally, we briefly discuss the diverse applications of SiNPs, demonstrating their relevance and potential impact in fields such as medicine, agriculture, and cosmetics. By emphasizing the greener synthesis methods and economical aspects, this review aims to inspire researchers and industry professionals to adopt environmentally conscious practices while harnessing the immense capabilities of SiNPs.

Silicon nanoparticles in sustainable agriculture: synthesis, absorption, and plant stress alleviation

Silicon (Si) is a widely recognized beneficial element in plants. With the emergence of nanotechnology in agriculture, silicon nanoparticles (SiNPs) demonstrate promising applicability in sustainable agriculture. Particularly, the application of SiNPs has proven to be a high-efficiency and cost-effective strategy for protecting plant against various biotic and abiotic stresses such as insect pests, pathogen diseases, metal stress, drought stress, and salt stress. To date, rapid progress has been made in unveiling the multiple functions and related mechanisms of SiNPs in promoting the sustainability of agricultural production in the recent decade, while a comprehensive summary is still lacking. Here, the review provides an up-to-date overview of the synthesis, uptake and translocation, and application of SiNPs in alleviating stresses aiming for the reasonable usage of SiNPs in nano-enabled agriculture. The major points are listed as following: (1) SiNPs can be synthesized by using physical, chemical, and biological (green synthesis) approaches, while green synthesis using agricultural wastes as raw materials is more suitable for large-scale production and recycling agriculture. (2) The uptake and translocation of SiNPs in plants differs significantly from that of Si, which is determined by plant factors and the properties of SiNPs. (3) Under stressful conditions, SiNPs can regulate plant stress acclimation at morphological, physiological, and molecular levels as growth stimulator; as well as deliver pesticides and plant growth regulating chemicals as nanocarrier, thereby enhancing plant growth and yield. (4) Several key issues deserve further investigation including effective approaches of SiNPs synthesis and modification, molecular basis of SiNPs-induced plant stress resistance, and systematic effects of SiNPs on agricultural ecosystem.

Green biosynthesis of bimetallic selenium-gold nanoparticles using Pluchea indica leaves and their biological applications

Increasing bacterial resistance and the negative impact of currently used antibacterial agents have produced the need for novel antibacterial agents and anticancer drugs. In this regard, nanotechnology could provide safer and more efficient therapeutic agents. The main methods for nanoparticle production are chemical and physical approaches that are often costly and environmentally unsafe. In the current study, Pluchea indica leaf extract was used for the biosynthesis of bimetallic selenium-gold nanoparticles (Se-Au BNPs) for the first time. Phytochemical examinations revealed that P. indica leaf extract includes 90.25 mg/g dry weight (DW) phenolics, 275.53 mg/g DW flavonoids, and 26.45 mg/g DW tannins. X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) techniques were employed to characterize Se-Au BNPs. Based on UV-vis spectra, the absorbance of Se-Au BNPs peaked at 238 and 374 nm. In SEM imaging, Se-Au BNPs emerged as bright particles, and both Au and Se were uniformly distributed throughout the P. indica leaf extract. XRD analysis revealed that the average size of Se-Au BNPs was 45.97 nm. The Se-Au BNPs showed antibacterial properties against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis, with minimum inhibitory concentrations (MICs) of 31.25, 15.62, 31.25, and 3.9 μg/mL, respectively. Surprisingly, a cytotoxicity assay revealed that the IC50 value toward the Wi 38 normal cell line was 116.8 μg/mL, implying that all of the MICs described above could be used safely. More importantly, Se-Au BNPs have shown higher anticancer efficacy against human breast cancer cells (MCF7), with an IC50 value of 13.77 μg/mL. In conclusion, this paper is the first to provide data on the effective utilization of P. indica leaf extract in the biosynthesis of biologically active Se-Au BNPs.

Photocatalytic activity of silver nanoparticles@cellulose nanocomposites, from pistachio husk, in the toxic azo commercial dye degradation

In this work, an over-the-counter commercial dye, containing direct blue 151 in its composition, which is also discarded without any environmental regulation, was efficiency photodegraded using a green chemistry-synthesized nanocomposites type silver nanoparticles (AgNPs) supported on pistachio husk (PH). The green synthesis (GS) of the nanocomposites was carried out using the Anemopsis californica leaf extract (ExAc) as a reducing-stabilizing agent (AgNPs/ExAc-PH), for the first time. The presence of AgNPs on the nanocomposite surface was corroborated by field emission transmission electron microscope (FE-TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The synthesized AgNPs/ExAc-PH has a bimodal size of 24 and 25 nm (4.86 % each) and a 0.72 % of AgNPs on its surface. AgNPs were adhered to the PH surface, through secondary bonds between the Ag and the cellulose of the PH. The optimum conditions, for efficient photocatalytic degradation, were 5 mg of nanocomposite, 3.18 × 10-2 M of NaBH4, natural sunlight, and stirring; this results in a photodegradation efficiency of 100 % almost instantaneously. Furthermore, it was shown that the dye degradation process is primarily due to the photocatalytic degradation of the dye, which occurs almost instantaneously.

Silica nanoparticles mediated insect pest management

Silicon is known for mitigating the biotic and abiotic stresses of crop plants. Many studies have proved beneficial effects of bulk silicon against biotic stresses in general and insect pests in particular. However, the beneficial effects of silica nanoparticles in crop plants against insect pests were barely studied and reported. By virtue of its physical and chemical nature, silica nanoparticles offer various advantages over bulk silicon sources for its applications in the field of insect pest management. Silica nanoparticles can act as insecticide for killing target insect pest or it can act as a carrier of insecticide molecule for its sustained release. Silica nanoparticles can improve plant resistance to insect pests and also aid in attracting natural enemies via enhanced volatile compounds emission. Silica nanoparticles are safe to use and eco-friendly in nature in comparison to synthetic pesticides. This review provides insights into the applications of silica nanoparticles in insect pest management along with discussion on its synthesis, side effects and future course of action.

Nanoparticle Synthesis and Their Integration into Polymer-Based Fibers for Biomedical Applications

The potential of nanoparticles as effective drug delivery systems combined with the versatility of fibers has led to the development of new and improved strategies to help in the diagnosis and treatment of diseases. Nanoparticles have extraordinary characteristics that are helpful in several applications, including wound dressings, microbial balance approaches, tissue regeneration, and cancer treatment. Owing to their large surface area, tailor-ability, and persistent diameter, fibers are also used for wound dressings, tissue engineering, controlled drug delivery, and protective clothing. The combination of nanoparticles with fibers has the power to generate delivery systems that have enhanced performance over the individual architectures. This review aims at illustrating the main possibilities and trends of fibers functionalized with nanoparticles, focusing on inorganic and organic nanoparticles and polymer-based fibers. Emphasis on the recent progress in the fabrication procedures of several types of nanoparticles and in the description of the most used polymers to produce fibers has been undertaken, along with the bioactivity of such alliances in several biomedical applications. To finish, future perspectives of nanoparticles incorporated within polymer-based fibers for clinical use are presented and discussed, thus showcasing relevant paths to follow for enhanced success in the field.

Silicon nanoparticles: Comprehensive review on biogenic synthesis and applications in agriculture

Recent advancements in nanotechnology have opened new advances in agriculture. Among other nanoparticles, silicon nanoparticles (SiNPs), due to their unique physiological characteristics and structural properties, offer a significant advantage as nanofertilizers, nanopesticides, nanozeolite and targeted delivery systems in agriculture. Silicon nanoparticles are well known to improve plant growth under normal and stressful environments. Nanosilicon has been reported to enhance plant stress tolerance against various environmental stress and is considered a non-toxic and proficient alternative to control plant diseases. However, a few studies depicted the phytotoxic effects of SiNPs on specific plants. Therefore, there is a need for comprehensive research, mainly on the interaction mechanism between NPs and host plants to unravel the hidden facts about silicon nanoparticles in agriculture. The present review illustrates the potential role of silicon nanoparticles in improving plant resistance to combat different environmental (abiotic and biotic) stresses and the underlying mechanisms involved. Furthermore, our review focuses on providing the overview of various methods exploited in the biogenic synthesis of silicon nanoparticles. However, certain limitations exist in synthesizing the well-characterized SiNPs on a laboratory scale. To bridge this gap, in the last section of the review, we discussed the possible use of the machine learning approach in future as an effective, less labour-intensive and time-consuming method for silicon nanoparticle synthesis. The existing research gaps from our perspective and future research directions for utilizing SiNPs in sustainable agriculture development have also been highlighted.

Recent Advances in Nanoparticle-Mediated Co-Delivery System: A Promising Strategy in Medical and Agricultural Field

Drug and gene delivery systems mediated by nanoparticles have been widely studied for life science in the past decade. The application of nano-delivery systems can dramatically improve the stability and delivery efficiency of carried ingredients, overcoming the defects of administration routes in cancer therapy, and possibly maintaining the sustainability of agricultural systems. However, delivery of a drug or gene alone sometimes cannot achieve a satisfactory effect. The nanoparticle-mediated co-delivery system can load multiple drugs and genes simultaneously, and improve the effectiveness of each component, thus amplifying efficacy and exhibiting synergistic effects in cancer therapy and pest management. The co-delivery system has been widely reported in the medical field, and studies on its application in the agricultural field have recently begun to emerge. In this progress report, we summarize recent progress in the preparation and application of drug and gene co-delivery systems and discuss the remaining challenges and future perspectives in the design and fabrication.

Synthesis, analysis, and multi-faceted applications of solid wastes-derived silica nanoparticles: a comprehensive review (2010-2022)

The synthesis of silica nanoparticles (SiNPs) has emerged as an extensive area of research in the last century. Owing to their instinctive properties like modifiable mesoporous structure, high surface area, adjustable pore size, and pore volume, SiNPs could be utilized in numerous fields like chemical, biochemical, catalysis, adsorption, and pollution control. Conventionally, SiNPs are produced by tetraethylorthosilicate (TEOS), tetramethylorthosilicate (TMOS), and sodium silicate, which are toxic and expensive. Therefore, the development of green, cost-effective approaches for the synthesis of SiNPs is highly desirable. In this course, during the last decade, silica-rich solid wastes (rice husk, corn cob, sugarcane bagasse, palm ash, fly ash, waste glass, waste packaging materials, photonic industrial wastes, etc.) were acknowledged as economical precursors to produce green SiNPs. In this respect, the present review focuses on reviewing several solid waste materials used for the synthesis of SiNPs, their properties, and different characterization techniques used for the analysis of SiNPs. The present review also accounts for the potential applications of such green SiNPs in several fields like catalysis, adsorption, biomedical applications, and energy storage. Moreover, despite the potential applications of SiNPs, still there is a lot to explore about their synthesis and utilization. Hence, in the last section of this review, future scope, challenges, and risk assessment of SiNPs have been discussed.

Closing the Nutrient Loop-The New Approaches to Recovering Biomass Minerals during the Biorefinery Processes

The recovery of plant mineral nutrients from the bio-based value chains is essential for a sustainable, circular bioeconomy, wherein resources are (re)used sustainably. The widest used approach is to recover plant nutrients on the last stage of biomass utilization processes-e.g., from ash, wastewater, or anaerobic digestate. The best approach is to recover mineral nutrients from the initial stages of biomass biorefinery, especially during biomass pre-treatments. Our paper aims to evaluate the nutrient recovery solutions from a trans-sectorial perspective, including biomass processing and the agricultural use of recovered nutrients. Several solutions integrated with the biomass pre-treatment stage, such as leaching/bioleaching, recovery from pre-treatment neoteric solvents, ionic liquids (ILs), and deep eutectic solvents (DESs) or integrated with hydrothermal treatments are discussed. Reducing mineral contents on silicon, phosphorus, and nitrogen biomass before the core biorefinery processes improves processability and yield and reduces corrosion and fouling effects. The recovered minerals are used as bio-based fertilizers or as silica-based plant biostimulants, with economic and environmental benefits.

Nanoparticles Containing Oxaliplatin and the Treatment of Colorectal Cancer

BACKGROUND

Colorectal cancer (CRC) is a highly widespread malignancy and ranks as the second most common cause of cancer-related mortality.

OBJECTIVE

Cancer patients, including those with CRC, who undergo chemotherapy, are often treated with platinum- based anticancer drugs such as oxaliplatin (OXA). Nevertheless, the administration of OXA is associated with a range of gastrointestinal problems, neuropathy, and respiratory tract infections. Hence, it is necessary to devise a potential strategy that can effectively tackle these aforementioned challenges. The use of nanocarriers has shown great potential in cancer treatment due to their ability to minimize side effects, target drugs directly to cancer cells, and improve drug efficacy. Furthermore, numerous studies have been published regarding the therapeutic efficacy of nanoparticles in the management of colorectal cancer.

METHODS

In this review, we present the most relevant nanostructures used for OXA encapsulation in recent years, such as solid lipid nanoparticles, liposomes, polysaccharides, proteins, silica nanoparticles, metal nanoparticles, and synthetic polymer-carriers. Additionally, the paper provides a summary of the disadvantages and limits associated with nanoparticles.

RESULTS

The use of different carriers for the delivery of oxaliplatin increased the efficiency and reduced the side effects of the drug. It has been observed that the majority of research investigations have focused on liposomes and polysaccharides.

CONCLUSION

This potentially auspicious method has the potential to enhance results and enhance the quality of life for cancer patients undergoing chemotherapy. However, additional investigation is required to ascertain the most suitable medium for the transportation of oxaliplatin and to assess its efficacy through clinical trials.

Mycosynthesis of Silica Nanoparticles Using Aspergillus niger: Control of Alternaria solani Causing Early Blight Disease, Induction of Innate Immunity and Reducing of Oxidative Stress in Eggplant

The threats to the life and production of crops are exacerbated by climate change and the misuse of chemical pesticides. This study was designed to evaluate the effectiveness of biosynthesized silica nanoparticles (SiO₂-NPs) as an alternative to pesticides against early blight disease of eggplant. Antifungal activity, disease index, photosynthetic pigments, osmolytes, oxidative stress, antioxidant enzymes activities were tested for potential tolerance of eggplant infected with Alternaria solani. Silica nanoparticles were successfully biosynthesized using Aspergillus niger through green and ecofriendly method. Results revealed that SiO₂-NPs exhibited promising antifungal activity against A. solani where MIC was 62.5 µg/mL, and inhibition growth at concentration 1000 µg/mL recorded 87.8%. The disease Index (DI) as a result of infection with A. solani reached 82.5%, and as a result, a severe decrease in stem and root length and number of leaves occurred, which led to a sharp decrease in the photosynthetic pigments. However, contents of free proline, total phenol and antioxidant enzymes activity were increased in infected plants. On the other hand, the treatment with SiO₂-NPs 100 ppm led to a great reduction in the disease Index (DI) by 25% and a high protection rate by 69.69%. A clear improvement in growth characteristics and a high content of chlorophyll and total carotenoids was also observed in the plants as a result of treatment with silica nanoparticles in (healthy and infected) plants. Interestingly, the noticeable rise in the content of infected and healthy plants of proline and phenols and an increase in the activity of super oxide dismutase (SOD) and polyphenol oxidase (PPO). It could be suggested that foliar application of SiO₂-NPs especially 100 ppm could be commercially used as antifungal and strong inducer of plant physiological immunity against early blight disease.

Bio-Fabrication of Bio-Inspired Silica Nanomaterials from Orange Peels in Combating Oxidative Stress

Silica nanoparticles were synthesized using the aqueous extract of orange peels by the green chemistry approach and simple method. The physicochemical properties such as optical and chemical banding of as-synthesized silica nanoparticles were analyzed with UV-visible spectroscopy and Fourier transform infrared spectroscopy. Scanning Electron Microscopy with Energy Dispersive X-Ray Analysis and X-ray diffraction analysis were employed to confirm the shape, size and elemental purities of the silica nanoparticles. The thermal stability and mass loss of the silica nanoparticles was examined using thermogravimetric analysis and zeta potential analysis. The surface plasmon resonance band of the silica nanoparticle was obtained in the wavelength of 292 nm. Silica nanoparticles with a spherical and amorphous nature and an average size of 20 nm were produced and confirmed by X-ray diffraction and Scanning Electron Microscopy. The zeta potential of the silica nanoparticles was -25.00 mV. The strong and broad bands were located at 457, 642 and 796 cm^-1 in the Fourier transform infrared spectra of the silica nanoparticles, associated with the Si-O bond. All the results of the present investigation confirmed and proved that the green synthesized silica nanoparticles were highly stable, pure and spherical in nature. In addition, the antioxidant activity of the green synthesized orange peel extract mediated by the silica nanoparticles was investigated with a DPPH assay. The antioxidant assay revealed that the synthesized silica nanoparticles had good antioxidant activity. In the future, green synthesized silica nanoparticles may be used for the production of nano-medicine.

An insight into the green synthesis of SiO2 nanostructures as a novel adsorbent for removal of toxic water pollutants

Green synthesis of nanomaterials is a sustainable, biologically safe, reliable, and eco-friendly approach. Green synthesis is beneficial to reduce the devastating effects of the traditional chemical synthesis methods and particularly aims at decreasing the usage of toxic chemicals. This review deals with the green synthesis of silica nanoparticles (SiO₂ NPs) with emphasis on the engineering surface properties for enhanced adsorption capability and their applications as novel nano-adsorbents for water pollutants removal. Green synthesized SiO₂ NPs have shown excellent adsorption properties with higher adsorption capacity of 150-200 mg/g and more than 95% removal for various toxic water pollutants along with reusability for more than 5 cycles. These SiO₂ NPs show fascinating physical and chemical properties i.e. tunable size (5 nm to more than 100 nm), low toxicity, biocompatibility, high porosity, higher specific surface area (500--700 m²/g) making them attractive/suitable for several applications in biomedical, agriculture, catalysis, construction, water treatment, etc. Commonly, highly pure SiO₂ NPs are synthesized from organic chemicals (very expensive and highly toxic in nature) as a precursor that led to high production costs, high energy consumption, and environmental hazards. On the other hand, green synthesis of SiO₂ NPs from natural resources like biomass that includes rice husk, bamboo leaves/stem, sugarcane bagasse, corn cobs, wheat straw, etc. is cost-effective, less toxic, and eco-friendly which has been discussed in detail. Furthermore, the effect of key synthesis parameters (i.e., temperature, time, concentration, pH, etc.) on the morphology, size, purity, and specific surface area of SiO₂ NPs have been summarized. Finally, the applications of SiO₂ NPs as nano-adsorbents for the removal of toxic water pollutants (i.e., heavy metal cations, anions, dyes, etc.) including the adsorption mechanisms along with the future scope, challenges, and suggestions have been discussed.

Biosynthesis of Silica Nanoparticles Using the Leaf Extract of Punica granatum and Assessment of Its Antibacterial Activities Against Human Pathogens

Plant-mediated nanoparticle synthesis is a revolutionary technique with numerous applications in fields, such as agriculture, food processing, and medicine. This study reports that Punica granatum leaf extract is capable of the green and eco-friendly synthesis of silica nanoparticles that provides a simple, cost-effective, and efficient methodology. P. granatum leaf extract was employed as a capping and stabilizing agent for the formation of silica nanoparticles, which were synthesized by a biological method using tetra ethyl ortho silicate. Biosynthesized silica nanoparticles are characterized by X-ray diffraction analysis, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. All the analyses and characterization determined that the particles were spherical in shape and amorphous in nature with an average size of 12 nm. P. granatum-assisted silica nanoparticles were tested for antibacterial activity by a well-diffusion method against two-gram negative bacterial pathogens (E. coli and Salmonella sp.). The antibacterial studies prove that P. granatum-assisted silica nanoparticles have good antibacterial properties. These studies will help us find a new nano-drug or medicine against multidrug-resistant bacteria.

Smart nanomaterial and nanocomposite with advanced agrochemical activities

Conventional agriculture solely depends upon highly chemical compounds that have negatively ill-affected the health of every living being and the entire ecosystem. Thus, the smart delivery of desired components in a sustainable manner to crop plants is the primary need to maintain soil health in the upcoming years. The premature loss of growth-promoting ingredients and their extended degradation in the soil increases the demand for reliable novel techniques. In this regard, nanotechnology has offered to revolutionize the agrotechnological area that has the imminent potential over conventional agriculture and helps to reform resilient cropping systems withholding prominent food security for the ever-growing world population. Further, in-depth investigation on plant-nanoparticles interactions creates new avenues toward crop improvement via enhanced crop yield, disease resistance, and efficient nutrient utilization. The incorporation of nanomaterial with smart agrochemical activities and establishing a new framework relevant to enhance efficacy ultimately help to address the social acceptance, potential hazards, and management issues in the future. Here, we highlight the role of nanomaterial or nanocomposite as a sustainable as well stable alternative in crop protection and production. Additionally, the information on the controlled released system, role in interaction with soil and microbiome, the promising role of nanocomposite as nanopesticide, nanoherbicide, nanofertilizer, and their limitations in agrochemical activities are discussed in the present review.

Silicon nanoparticles (SiNPs) in sustainable agriculture: major emphasis on the practicality, efficacy and concerns

Silicon (Si), a beneficial element for plants, is known for its prophylactic effect under stress conditions. Many studies have documented the role of biogenic silica (bulk-Si) in alleviating biotic and abiotic stresses in plants. The scarce amount of the plant-available form of Si (monosilicic acid) in most of the cultivated soil and the limited efficacy of silicate fertilizers (bulk-Si) are the major concerns for the exploration of Si-derived benefits. In this regard, recent advances in nanotechnology have opened up new avenues for crop improvement, where plants can derive benefits associated with Si nanoparticles (SiNPs). Most of the studies have shown the positive effect of SiNPs on the growth and development of plants specifically under stress conditions. In contrast, a few studies have also reported their toxic effects on some plant species. Hence, there is a pertinent need for elaborative research to explore the utility of SiNPs in agriculture. The present review summarizes SiNP synthesis, application, uptake, and role in stimulating plant growth and development. The advantages of SiNPs over conventional bulk-Si fertilizers in agriculture, their efficacy in different plant species, and safety concerns have also been discussed. The gaps in our understanding of various aspects of SiNPs in relation to plants have also been highlighted, which will guide future research in this area. The increased attention towards SiNP-related research will help to realize the true potential of SiNPs in agriculture.

Ultrasonic-assisted synthesis of SiO2 nanoparticles and SiO2/chitosan/Fe nanocomposite and their application for vanadium adsorption from aqueous solution

The husk of brown rice, as a source of silica, was applied to synthesize natural SiO₂ nanoparticles via sonochemical method. SiO₂/CH/Fe nanocomposite was synthesized from SiO₂, chitosan (prepared from shrimp shells via sonochemical method), and iron functional groups and detected using BET, EDX-SEM, and FTIR techniques. These natural-based nanostructures (SiO₂ and SiO₂/CH/Fe) have been applied for vanadium adsorption. The influences of initial pH, initial concentration, and adsorption time were studied via a batch process. The analysis of the kinetics data indicated that the chemical adsorption is predominant. The analysis of the equilibrium data indicated the single layer and exothermic adsorption process. The mono-layer adsorption capacity of SiO₂/CH/Fe was 199.540 mg g^-1. The performance of SiO₂/CH/Fe in a continuous column system was investigated in four adsorption and desorption cycles. Results showed that SiO₂/CH/Fe nanocomposite synthesized with the sonochemical method is a candidate with high adsorption ability for use as an industrial adsorbent.

Nanosilica facilitates silica uptake, growth and stress tolerance in plants

Nanobiotechnology has gained considerable momentum in the field of plant sciences in the last few years. Nanomaterials of various metal oxides has been utilized for enhancing growth, productivity and in crop protection strategies. Among them, nanosilica has emerged as a key player in orchestrating plant growth and conferring tolerance to various abiotic and biotic stresses. Nanosilica has increased absorptivity that accounts for an increased uptake of silica, although the exact mechanism is not fully understood. Nanosilica uptake in the roots and leaves reduces the accumulation of reactive oxygen species (ROS) and membrane lipid peroxidation. It is known to restrict the entry of sodium ions and other heavy metals in plants. Concurrently, nanosilica deposition in the leaf tissue enhances the plant defense against pathogens. The present review attempts to provide a novel insight into its uptake mechanism and nanosilica mediated abiotic and biotic stress tolerance in plants. This review will also shed light on the prospects and challenges related to application of nanosilica based fertilizers.