Smart Intelligent Agriculture: Applications of Recent Nanosensors Technology

  Smart Intelligent Agriculture: Applications of Recent Nanosensors Technology

Agriculture requires technical solutions for increasing production while lessening environmental impact by reducing the application of agrochemicals and increasing the use of environmentally friendly management practices. Both biotic and abiotic stresses lead to a massive loss in crop yield, leading to a decrease in agricultural production worldwide. The loss of agricultural products can be minimized by adopting modern technology such as smartphones with nanosensors to detect crop stress at an early stage. Smart and precision agriculture are emerging areas where nanosensors and electronic devices can play an important role for improving crop productivity by monitoring crop health status in real-time. Various types of nanosensors have been reported for detection and monitoring plant signal molecules and metabolic contents related with biotic and abiotic stresses. Nanobiosensors are customized using various properties of nanomaterials to combat various challenges of contemporary techniques.  Nanobiosensors have unprecedented levels of performance for sensing ultra-trace amount of various analytes for in vivo measurement. These nanosensors communicate with and actuate electronic devices for agricultural automation. Thus, both biotic and abiotic plant stresses and nutritional deficiency are monitored in real-time to report crop health status for precise and efficient use of resources. 

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Smart Agriculture

Nanotechnology in Agriculture : Future Prospective

Nanotechnology  in Agriculture

The use of nanomaterials for delivery of pesticides and fertilizers is explored to reduce the dosage and ensure controlled slow delivery but the risk assessment of the use of nanomaterials is still not defined. Toxicity of the ecosystem, potential residue carry-over in foodstuff and nanomaterials phytotoxicity are some of the major concern for application of nanomaterials in agriculture. The health concern of nanomaterials has been reviewed . There is need to evaluate the toxicokinetics and toxicodynamics of nanomaterials used in agricultural production. Nanomaterials owing to increased surface area might have toxic effects that are not apparent in the bulk materials especially in open agricultural ecosystem. The selection of nanomaterials for application in the field may be critical as materials which are non-toxic, biodegradable and biocompatible are desirable. Nanofabrication with hyper-accumulator plant or in combination with soil microorganism will provide the approach of “Designer plant” boosting up the nutrient uptake and phytomining efficiency.  This can be achieved in future by nano-biofarming or particle farming. This is one such field which yields nanoparticles for industrial use by growing plants in defined soil.

Smart precision farming will make use of computers, global satellite positioning system and remote sensing devices to measure highly localized environmental conditions enabling us to know whether crops are growing at maximum efficiency. Nanotechnology may be developed and deployed for real-time monitoring of the crop growth and field conditions including moisture level, soil fertility, temperature, crop nutrient status, insects, plant diseases, weeds. Networks of wireless nanosensors positioned across cultivated fields will provide essential data leading to best agronomic intelligence processes with the aim to minimize resource inputs and maximize output.

Humidity, light temperature, soil conditions, fertilization, insects, and plant diseases all affect the release of volatile organic compounds which could be detected by electronic nose. Electronic noses in agriculture will detect crop diseases, identify insect infestation, and monitor food quality. The electronic nose could also be used in food industry to assess the freshness spoilage of fruits and vegetables during the processing and packaging process. Smart dust technology will be used for monitoring various parameters such as temperature, humidity, insect and disease infestation in future. This is the future of agriculture, an army of nanosensors will be scattered like dust across the farms and fields, working like the eyes, ears and nosed of the farming world. These tiny wireless sensors are capable to communicate the information they sense. These will be programmed and designed to respond various parameters like variation in temperature, nutrients and humidity.

In summary, the development of nanomaterials with good dispersion and wettability, biodegradable in soil, and environment, less toxic and more photo-generative, with well understood toxicokinetics and toxicodynamics, smart and stable, and ease of fabrication and application in agriculture, would be ideal for their effective use in agricultural crop production. 

Nanotechnology: A Brief Introduction

The term ‘Nanotechnology’ was first defined in 1974 by Norio Taniguchi of the Tokyo Science University as the study of manipulating matter on an atomic and molecular scale. The definition of nanotechnology is based on the prefix ‘nano’ which is from the Greek word meaning ‘dwarf’. Technically the word ‘nano’ means one billionth of something. A nanometer is one billionth of a meter. The word nanotechnology is generally used when referring to materials with the size of 1 to 100 nanometers (nm). Nanotechnology is a new branch of science that deals with the generation and alteration of materials to nanosize. Materials with a particle size less than 100 nm at least in one dimension are generally classified as nanomaterials. These materials display different properties from bulk materials due to their size. These differences include physical strength, chemical reactivity, electrical conductance, magnetism and optical effects. Therefore, nanotechnology is the manipulation or self-assembly of individual atoms or molecule or molecular cluster into structures to create materials and devices with new or vastly different properties. Nanosensors and monitoring system enabled by nanotechnology will have a large impact on future precision methodologies. Hence, nanotechnology employs materials (NPs) having one or more dimension in the order of 100 nm or less.

Nanomaterials (NMs) of inorganic and organic origin are used for nanoparticles (NPs) synthesis by a variety of physical and chemical methods. The techniques for making nanoparticles are generally involved either a top-down approach or a bottom-up approach. In top-down approach, size reduction is achieved by various chemical and physical treatments such as milling, high pressure homogenization and sonication while in bottom-up synthesis, the nanostructure building blocks of the nanoparticles are formed first and then assembled to produce the final particle.

Among inorganic materials, metal oxide nanoparticles such as ZnO, TiO_2, AgO, MgO are of particular interest as they are physically and optically stable with tunable optical properties. Metallic nanomaterials are very interesting materials with unique electronic and electrocatalytic properties depending on their size and morphology and include the utilization of nanostructured materials with specific forms like quannologytum dots (QDs). Other inorganic materials such as montmorillionite and other clay nanoparticles have a structure of stacked platelets with one dimension of the platelet in the nanometer scale. Nano-clays have a high aspect ratio that provide more interactive surface when exfoliated and dispersed well. Organic materials such as carbon nanotubes, lipids and polymers are versatile materials with multiple applications.

Carbon nanotubes (CNTs) are hollow cylindrical tubes composed of one, two or several concentric graphite layers capped by fullerenic hemisphere, which are referred to as single-, double-, and multi-walled CNTs. The unique electronic, metallic and structural characteristics make CNTs an important class of materials. The possibility of electron transfer reaction due to their structure dependent metallic character and their high surface area provides ground for unique biochemical sensing system. Solid lipid nanoparticles are delivery systems that comprise of aqueous dispersion of solid lipids or dry powder such as triglycerides, steroids, waxes, long chain fatty acids and emulsifiers prepared by high pressure homogenization. Polymeric nanoparticles made from natural and synthetic polymers by wet synthetic routes are widely used due to their stability and ease of surface modification. Nanoparticles prepared from biopolymers or natural sources possess merits such as available from replenishable agricultural (cellulose, starch, pectin) or marine (chitin and chitosan) resources, biocompatibility, biodegradability and other ecological safety. Chitosan is one of the most promising NMs due to its excellent biocompatibility, complete biodegradiability and non-tixic nature. The degradation products of chitosan are harmless natural metabolites. It is obtained by the deacetylation of chitin, the second most abundant natural polymer after cellulose, which is found in the shells of crustaceans (crabs and shrimp), the cuticles of insects, and the cell walls of fungi. It is suitable for electrochemical sensors due to its transparent nature. Quantum dots (QDs) are inorganic nanocrystals, approximately 1-100 nm in size, with unique properties of broad excitation, narrow size-tunable emission spectra, high photochemical stability and negligible photoleaching. They have been widely used, mainly as alternative to fluorophores,  for the development of optical biosensors to detect ions, organic compounds and biomolecules such as nucleic acids, proteins, amino acids, enzymes, carbohydrates.  Dendrimers are known as organic macromolecules with tridimensional (3D) and highly defined structure functionality. The capability of these dendrimeric structures to stabilize and maintain the integrity of metallic nanoparticles has been reported.

Nanoparticles are generally characterized by their size, shape surface area, and disparity. The common techniques of characterizing nanoparticles are scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), UV-visible spectrophotometery, X-ray diffraction (XRD), dynamic light scattering (DLS), energy dispersive spectroscopy (EDS).

Some nanomaterials and their applications

Nanomaterials

Applications

Inorganic Metal nanoparticles           AgO, TiO2, ZnO, CeO2; Fe2O3,          FePd, Fe-Ni; Silica; CdTe, CdSe   Clay         Montmorillonite layerd double hydroxides Organic  Carbon nanotubes,           nanofibres  Lipids       Liposomes       Lippolyplexes       Solid lipid nanoparticles Poymeric       Natural         Cellulose, Starch, Gelatin, Albumin         Chitin, Chitosan      Synthetic        Dendrimers        Polyethylene oxide        Polyethylene  glycol        Polylactides

Delivery of biomolecules (proteins, peptides, nucleic acids), biosensors, diagnostic techniques, pesticide degradation Delivery of pesticides, fertilizers, plant growth promoting hormones Biocatalysts, sensing, Delivery of DNA  and pesticides, essential oils Biocompatible, biodegradable Delivery of DNA/RNA Delivery of pesticides and DNA/RNA