Biomedical and Environmental Applications of Nanotechnology PDF

INDIAN INSTITUTE OF TECHNOLOGY ROORKEE Biomedical and Environmental Applications of Nanotechnology Introduction: The difference between Nano-biotechnology and Bio- nanotechnology: 1) Nano-biotechnology is the use of nanomaterials as tools for biologica...

INDIAN INSTITUTE OF TECHNOLOGY ROORKEE Biomedical and Environmental Applications of Nanotechnology Introduction: The difference between Nano-biotechnology and Bio- nanotechnology: 1) Nano-biotechnology is the use of nanomaterials as tools for biological/biotechnological applications. For example, using nanoparticles for diagnosing a disease or imaging the disease. 2) Bio-nanotechnology is related to understanding the biological nanostructures and their potential applications. For example, using protein as a construction material instead of genetic material. Biomedical nanotechnology: is the combination of nano-biotechnology as well as bio-nanotechnology. Environmental nanotechnology: is to design and develop sustainable nanomaterials with potential environmental benefits. It deals with various physical, chemical, and biological remediation methods by applying the nanoscale fragments to remove or reduce pollutants 2 Applications of Nanotechnology Food industry Environment Medicine Food packaging Air pollution treatment Drug delivery Food preservation Water pollution treatment Detection and Food processing Groundwater remediation diagnosis Food safety Heavy metal detection and Therapy removal Tissue engineering Agriculture Energy Electronics Nano pesticides Energy storage Quantum dots Nano sensors Energy conversion/solar cells Nanodevices Heavy metal Energy generation, saving, and Sensors and remediation transmission. transistors Nanoparticles fuel additives 3 Nanomaterials in food packaging and preservation Nanofoods is the term used to refer to foods that are subjected to nano-interventions in one of the stages of food production during cultivation, production/post-harvest processing, or packaging of food to extend its shelf life without diminishing its nutritional quality. The main food-related areas where nanotechnologies have great potential are food packaging (nanocomposites, active, bioactive, and intelligent packaging), functional foods, and nutraceuticals (through the use of nanoencapsulation or nanoformulations), food processing (using technologies such as nanofiltration), and food safety and quality (through the use of nanosensors, nanotongues, and nano- noses). 4  Contd…. Nanotechnology can help to improve the safety and quality of foods through packaging by Improving of gas and moisture barrier of packaging materials by means of nanofillers, intelligent packaging based on nanosensors (e.g., sensors that detect spoilage or contamination), and novel antibacterial and antifungal nanocomposite polymer films. A nanocomposite is defined as a composite in which at least one of the phases has one or more dimensions of the order of nanometers, whereas a polymer nanocomposite consists of a polymer or copolymer possessing nanofillers dispersed in the matrix. Nanotechnology in food-packaging applications is based on the use of nanomaterials whose particles have at least one dimension within the nanometric scale (10-9 m), conventionally about 1-100 nm. These nanomaterials are classified into three categories in accordance with their dimensional structure (nanoparticles/isodimensional materials, nanofibers/one-dimensional materials, and nanolayers/bidimensional materials). 5 Nanoparticles in food packaging applications Nanoparticles: Metal nanoparticles (5-100 nm) are composed of elemental metal and thus have free electrons on their surface, which create the plasmonic effect. These nanoparticles (NPs) such as silver nanoparticles (AgNPs), titanium dioxide nanoparticles (TiO2NPs) and zinc oxide nanoparticles (ZnONPs) have been exhaustively used to make nanocomposites for food preservation and food packaging applications owing to their antibacterial and antifungal activity. Of these, silver metallic NPs are most commonly used in food processing. Composites made with AgNPs have been used to extend the shelf-life of various types of food. Why silver nanoparticles? 1. Toxicity against a wide variety of microorganisms (Ag+ ions have more affinity to bind to sulphur and phosphorous-containing compounds like DNA. 2. Stability at high temperatures. 3. Low volatility. 4. Redox properties and catalytic ability. 6 Contd…. How do silver nanoparticles work The basic mechanisms of these AgNPs by the release of silver ions (Ag+) follow the route of adhesion to the cell surface, disruption of the cell membrane, DNA damage, and finally, cell death. 7 Contd…. The antimicrobial mechanism of AgNPs has been summarized in three steps: 1. Disruption of DNA replication and ATP production due to uptake of free Ag+ ions. 2. Generation of reactive oxygen species (ROS) by Ag+ ions and AgNPs in the cell. 3. Deterioration of the cell membrane by the action of AgNPs. A number of factors contribute to the antimicrobial properties of metallic nanoparticles: 1. Size. 2. Shape. 3. Surface area. 4. Chemical functionalization. 5. Retention time for bacterium–nanoparticle interaction. 8 Nanofibers in food packaging applications Nanofibers: are fibres with diameters in the nanometer range (typically, between 1 nm and 1 μm). Nanofibers can be generated from different polymers and hence have different physical properties and application potentials. ✓ Examples of natural polymers: collagen, cellulose, silk fibroin, keratin, gelatin, zein and polysaccharides such as chitosan and alginate. ✓ Examples of synthetic polymers: poly(lacticacid) (PLA), poly(glycolic acid) (PGA), poly(ethylene glycol) (PEG), poly(vinyl alcohol) (PVA), poly(ethylene oxide) (PEO), poly(caprolactone) (PCL) Electrospinning is the most commonly used method to generate nanofibers because of: 1. The straightforward setup. 2. The ability to mass-produce continuous nanofibers from various polymers. 3. The capability to generate ultrathin fibres with controllable diameters, compositions, and orientations. 9 Contd…. Electrospinning assembly consists of three main elements which are: 1) a supply of high-voltage. 2) a spinneret. Nanofibers 3) a collector. One electrode is placed into the polymer solution, and the other electrode is attached to the collector. An electric field is applied to the end of the capillary tube/syringe that contains the polymer solution held by its surface tension and forms a charge on the surface of the liquid. As the intensity of the electric field increases, the hemispherical surface of the fluid at the tip of the capillary tube elongates to form a conical shape known as the Taylor cone. The solution evaporates as the jet travels and very thin nanofibers are collected on the collector plate. 10 Contd…. 11 Contd…. Intelligent Packaging provides information on the quality of packaged food during circulation and storage by monitoring the environmental conditions or food components using freshness indicators, time-temperature indicators (TTI), and leakage indicators. Also, the use of pH-sensitive nano- sensors for smart packaging materials by adding pH-sensitive dyes of several combinations to the polymer solutions so that a high range of pH values can be detected. Antibacterial packaging of electrospinning can be divided into three categories: ❑ Antibacterial nanofibrous films based on electrospinning of the most commonly used antibacterial polymers such as chitosan. 12 Contd…. ❑ Antibacterial nanofibers based on the electrospinning with the substrate as the carrier of an antibacterial agent, which is evaporated into the head space (volatile antibacterial agent) or migrated to the food surface (non-volatile antibacterial agent) by diffusion. ❑ The most common category is to encapsulate antibacterial agents directly in nanofibers. No high-temperature process is involved, and electrospinning can maintain the antibacterial activity of antibacterial agents with poor thermal stability (e.g., essential oils, etc.) to the maximum. 13 Contd…. Antioxidant Packaging Oxidation during food storage is a major cause of reduction in food quality and food nutrition. Electrospun nanofibrous films can encapsulate antioxidants, protect antioxidants and maintain a sustained release of encapsulated antioxidants during storage, thus improving the stability of foods that are sensitive to oxidation. 14 Contd…. Nanofibers properties ✓ High surface area to volume ratio ✓ Biocompatibility (Natural polymer-based nanofibers) ✓ Encapsulation efficiency ✓ High porosity ✓ Excellent mechanical property/Tensile strength ✓ Biodegradability ✓ Light weight ✓ Flexibility in surface functionalization ✓ Gas barrier property ✓ Non-toxic ✓ Thermal property 15 Nanolayers in food packaging applications Nanolayers: are bidimensional materials exhibiting only one dimension within the nanometric scale. They include nanosheets, nanoflakes, nanodisks, nanoplatelets, nanoshells, etc. Owing to their large aspect ratio, nanofibrous and nanolayered materials are usually employed as reinforcing fillers in most polymer nanocomposites, whereas nanoparticles are more adequate to the development of active and intelligent nanocomposites (such as antimicrobial polymers, oxygen scavengers, and biosensors) given their extremely reduced size. Several biopolymers with opposite charges can be used to produce nanolayered films assembled through layer-by-layer. For instance, two polysaccharides with opposite charges, chitosan and sodium alginate. Nanolayers and nanostructured layers made of biopolymers are able to retain transparency and enhance barrier properties without significant changes in mechanical performance. They can be used as food coatings or food packaging materials) for improving food quality and extending shelf life. 16 Contd…. biodegradability Active UV and smart protection packaging Moisture Nanolayers Gas permeability barrier properties control Oxygen Antimicrobial barrier property Mechanical strength 17 Edible nanocoating Nanocoating in food packaging refers to a thin layer of edible material applied to the surface of food products or packaging materials. This coating is designed to provide a barrier to various external factors that can affect the quality and shelf life of the food. These barriers can include: 1. Moisture: Prevents the food from drying out or becoming too moist. 2. Oxygen: Reduces oxidation, which can cause spoilage and degradation of nutrients and flavors. 3. Microbial Contamination: Helps protect against bacteria, fungi, and other microorganisms. 4. Physical Damage: Adds a protective layer that can reduce physical damage during transportation and handling. 5. Chemical Contaminants: Shields the food from environmental pollutants and other harmful chemicals. 18 Contd…. Examples of materials used in Nanocoatings: 1. Polysaccharides: Such as chitosan, alginate, and starch. 2. Proteins: Such as whey protein, soy protein, zein, and gelatine. 3. Lipids: Such as waxes and fatty acids. O2 4. Synthetic Polymers: Designed to be food-safe and biodegradable Edible nanocoating 19 Different types of contaminants and pollutants Methyl Orange Ni Congo Red As Se Dyes Pb Cd Cr Methylene Blue Zn Heavy Cu metals Hg DDT Pesticides Malathion Pathogens Chlorpyrifos 20 Detection of pathogens and contaminants in food using nanotechnology Detection of pathogens and contaminants in food involves the identification and quantification of microorganisms, toxins, chemicals, or other harmful substances that may pose a risk to human health when consumed. This process is crucial for ensuring food safety and quality. Nanotechnology, particularly the use of nanomaterials in biosensors, has enhanced the sensitivity, specificity, and speed of detection methods for pathogens and contaminants in food matrices. Nanomaterials in biosensing: Mycotoxins 1. Elemental metal nanoparticle and nanoclusters. Herbicides 1. Binary metallic nanoparticles. Food 2. Carbon nanoparticles. Toxins 3. Hybrid nanoparticles. Pesticides Pathogens 21 Nanomaterials in biosensing: Elemental Metal Nanoparticles: ✓ Metal nanoparticles (5-100 nm) are composed of elemental metal and thus have free electrons on their surface, which create a plasmonic effect. ✓ Some examples are gold nanoparticles, silver nanoparticles (AgNPs), and other elemental metal nanoparticles are commonly used in biosensors for analysis of food contaminants, toxins, and pathogens due to their optical and catalytic properties. Nanoclusters: ✓ Metal nanoclusters are smaller than conventional nanoparticles, typically less than 5 nm in size. ✓ These nanoclusters exhibit additional properties such as magnetism, insulation, and fluorescent emission over the visible and near-infrared regions. ✓ Metal nanoclusters are increasingly used in fluorescence-based sensing for food applications. 22 Nanomaterials in biosensing: Binary metallic nanoparticles (Oxides and Semiconductors): Metal oxide nanoparticles composed of maghemite (γ-Fe2O3) and magnetite (Fe2O3) are popular in biosensing because of their superparamagnetic property. These magnetic nanoparticles (MNPs) present the unique ability to separate target molecules from other compounds, thereby eliminating significant matrix effects. Semiconductor nanoparticles used in biosensing are generally compounds of metals with nonmetallic elements. For example, quantum dots (QDs) composed of elements like zinc, cadmium, tellurium, and selenium. These nanoparticles exhibit specific properties that make them valuable for biosensing, including fluorescence, quantum confinement, and stability. Binary metallic nanoparticles enhance the sensitivity and selectivity of biosensors, making them valuable tools for detecting contaminants, pathogens, and other analytes in food products. 23 Nanomaterials in biosensing: Carbon Nanoparticles: Carbon-based nanomaterials are most commonly used for biosensing. They mainly include carbon nanotubes (CNTs) and graphene. Graphene is a two-dimensional nanosheet, and CNTs are cylindrical hollow nanomaterials. They are known to have a large surface area, good electron conductivity, energy acceptance ability, flexibility, and mechanical strength. These properties make them popular in electrochemical and fluorescence- quenching-based biosensors for detecting contaminants such as pesticides, heavy metals, and microbial pathogens. Hybrid nanoparticles-Upconversion Nanoparticles: Upconversion nanoparticles are integrated into biosensors to enhance the sensitivity, selectivity, and detection limits for various analytes in food samples. These nanoparticles are utilized in fluorescence-based biosensors for their superior optical properties, enabling the development of sensitive and specific detection platforms for food safety and quality control. 24 Nanomaterial-based biosensors Optical Electrochemical Other detections Aptasensor Biosensors formats Colorimetric Assays Surface Plasmon Without Involving Resonance-Based Potentiometric Nanoparticle Sensors Aggregation Fluorescence-Based DNA Amplification- Sensors Amperometric Based Assays Luminescence- Based Sensors Impedimetric 25 Nano pesticides and nanosensors in agriculture Pesticides and herbicides are used extensively in agricultural production throughout the world to protect plants against pests, fungi, and weeds. They are beneficial in terms of crop protection, disease control, food and material protection. But at the same time, it is toxic to humans, animals and non-target species. They have cumulative effects on the human body and lead to several diseases, ranging from chronic common cough and cold to bronchitis and cancer of the skin, eye, kidney, and prostate gland. Pesticides are widely distributed in drinking waters, groundwaters, and soils. Commonly Used Pesticides: a) Organochlorine Insecticides: for example, endosulfan, aldrin, and Heptachlor. b) Herbicides: for example Atrazine, Diuron and Molinate. c) Organophosphorus Insecticides: for example, Chlorpyrifos and Diazinon. ✓ Pesticides are susceptible to degradation using zero-valent Iron (ZVI). 26 Contd…. Nanopesticids stand for pesticides formulated in nanomaterials to find applications in the agricultural field, whether specially fixed on a hybrid substrate, encapsulated in a matrix or functionalized nanocarriers for external stimuli or enzyme-mediated triggers. The nanopesticide formulations can increase water solubility, and bioavailability and protect agrochemicals against environmental degradation, revolutionizing the control of pathogens, weeds, and insects in the crops. Nanoparticles have high surface to volume ratio, and they are able to linked with other compounds and be used as carrier. Hence, they can be used as nanocarriers or as active ingredients or both. Nanoformulations usually consist of several surfactants, polymers or inorganic (e.g. metal) NPs in the nanometre size range. Nanoparticle-associated pesticides show higher performance in terms of effectiveness, targeted delivery and action with reduced management costs. 27 Contd…. A nanocarrier enables the controlled release of an active compound stored at the core, so that the adequate concentration of this active compound could be preserved during the whole period of insect growth. 28 Contd…. Nanosensors in agriculture: Nanosensors are nanoscale element devices that are engineered to identify a particular molecules/organisms known as the analyte and could be molecules (dyes/colours, toxicants, pesticides, hormones, antibiotics, vitamins, etc.), biomolecules (enzymes, DNA/RNA, allergens, etc.), ions (metals, halogens, surfactants, etc.), gas/vapour (oxygen, carbon dioxide, volatile compounds, water vapors, etc.), organisms (bacteria, fungi, viruses) and environment (humidity, temperature, light, pH, weather, etc.). A typical nanosensor device operation contains three basic components: 1) Sample preparation 2) Recognition: Certain molecules/elements recognize the analytes within the sample. They could be antibodies, aptamers, chemical legends enzymes, etc., and have high affinity, specificity, and selective characteristics to their analytes to quantify them to acceptance levels. 3) Signal transduction: for example, optical, electrochemical, piezoelectric, pyroelectric, electronic, and gravimetric biosensors. 29 The component of nanosensors in agriculture 30 Contd…. These sensors are highly specific, handy, cost-effective, and detect at a level much lower as compared to their macroscale analogs. 31 Nanosensors for Pesticide Detection In general, an optical sensor is composed of a recognition element that is specific for the particular residual pesticidal particle and can network with the other constituent, the transducer, which is employed to produce the signal for the binding of a particular pesticide residue to the sensor. Also, electrochemical nanosensors appear to be an effective tool meant for pesticide detection. Various categories of nanomaterials comprising nanoparticles, nanocomposites and nanotubes are widely found to be engaged in electrochemically determining the residual pesticidal particles. 32 Nanosensors for Detecting Plant Pathogens The most widely used biosensing components for analysing pathogens are bacterial receptors, antibodies, and lectins, owing to their adaptability of amalgamation into biosensors. Nanoparticle-centred “chemical nose” biosensors necessitate the amendment of the surface of the nanoparticle with several ligands where an individual ligand is liable for a distinctive communication with the objective. The mechanism: The addition of nanoparticles to the bacteria leads to the development of aggregates encompassing the bacteria. This process of aggregation promotes a change of colour induced by a swing in localized surface plasmon resonance. The components of the bacterial cell wall which are responsible for this kind of aggregation are teichoic acids in Gram-positive and lipopolysaccharides and phospholipids in Gram-negative bacteria. These aggregation patterns are unique and are motivated by the occurrence of extracellular polymeric substances on the bacterial surface. These varying in patterns are accountable for offering discernible colorimetric responses. 33 Nanofertilizers in agriculture Nanofertilizers are nutrients that are encapsulated or coated within nanomaterial in order to enable controlled release, and its subsequent slow diffusion into the soil. The use of nanoscale fertilizers may help to minimise nutrient loss by leaching/run-off and reduce its fast degradation and volatility, thus enhancing the nutrient quality and the fertility of the soil, and promoting crop productivity in the long run The high surface area to volume ratio and the high penetration ability of nanofertilizers make them a suitable alternative to chemical fertilizers. The composition of nanofertilizers can facilitate: 1. Efficient nutrient uptake and soil fertility restoration. 2. Ultra-high absorption and increased photosynthesis. 3. Increased production and reduced soil toxicity. 4. Increased plant health and reduced environmental pollution. 34 Contd…. Examples of Nanofertilizers: Nano-Zinc: Zinc oxide nanoparticles can provide zinc more efficiently to plants, addressing zinc deficiency in crops. Nano-Phosphorus: Phosphorus nanoparticles or nanocarriers can reduce the fixation of phosphorus in soil, making it more available to plants. Nano-Nitrogen: Encapsulation of nitrogen fertilizers in nanoparticles can minimize nitrogen losses through volatilization and leaching. 35 Contd…. https://doi.org/10.1016/j.eti.2021.101658 36 Nanosensors for Detection of Heavy Metals Heavy metal ions like Pb2+, Hg2+, Ag+, Cd2+, and Cu2+ from different resources have a precarious influence on human beings as well as their surroundings. Optical chemical sensors that are frequently targeted for heavy metal detection fit into a cluster of chemical sensors that primarily employ electromagnetic radiation for engendering a diagnostic signal in an element known as the transduction element. The interactions between the sample and the radiation change a specific optical consideration that can be interrelated to the concentration of an analyte. Colourimetric approaches are advantageous due to their simple operation, economically feasible, transportable instrumentation, and easy-to-use applications. Several compounds are used for stabilizing nanosensors, such as polysaccharides citrates, different polymers, and proteins to improve the attributes of the nanosensors. Fluorescent quantum dots-based sensors are an efficient tool for sensing numerous metal ions. 37 Contd…. The introduction of magnetic nanomaterials (Fe3O4) into the quantum dot- based fluorescence sensors offers several additional advantages owing to their high specific surface area, special magnetic properties, magnetic operability, and low toxicity. 38 Nanomaterials for air and water pollution control The three major applications of nanotechnology in the fields of environment can be classified: 1) Remediation and purification of contaminated material 2) pollution detection (sensing and detection). 3) pollution prevention. Air pollution can be controlled with nano-adsorptive materials, nanocatalysis, and nano filters. Water pollution, nanofiltration and nano sorbents techniques are used. Nanotechnology for clean water: 1) Remediation is the process of removing, minimising or neutralising the water contaminants that can damage human health or ecosystems. 2) Remediation technologies can be divided into three categories, thermal, physicochemical and biological methods. 3) An advanced method that can be used is nanomaterials, with enhanced affinity, capacity and selectivity for heavy metals and other contaminants. 39 Contd…. The advantages of using nanomaterials in water remediation are their higher reactivity, larger surface contact and better disposal capability. Water remediation with iron nanomaterial: ✓ Zero valent Iron (ZVI) is classified into two types: (1) nanoscale ZVI (nZVI) and (2) reactive nanoscale iron product (RNIP). ✓ nZVI particles have a diameter of 100–200 nm composed of iron (Fe) with a valence of zero, whereas RNIP particles consist of 50/50 wt % Fe and Fe3O4. ✓ ZVI has high reactivity to a large number of contaminants, including Cu2+, chlorinated hydrocarbons, CrO22- and NO3-. ✓ Nano-iron could be substituted with other metals. Metals such as zinc and tin have the ability to reduce contaminants such as iron. 40 Contd…. Water remediation with ferritin: Iron stored inside protein ✓ Ferritin is an iron-containing protein that is able to control the formation of mineralized structures. Ferritin has the ability to remediate toxic metals and chlorocarbon un. ✓ The advantages of ferritin over ordinary iron catalysts are: (1) ferritin does not react under photoreduction; and visible light or solar radiation (2) it is also more stable. 41 Nanotechnology in water pollution treatment The major mechanisms used to remove contaminants from contaminated water through nanotechnology include nanofiltration and nano-sorbents. Nanofiltration: 1. Nanofiltration is a membrane process used in water pollution treatment for drinking water and wastewater. 2. Nanofiltration is a low-pressure membrane technique used to separate substances measuring 0.001-0.1 micrometre. 3. Nanofiltration is an effective method used to remove biological pollutants, turbidity, and inorganic compounds. Also, to soften hard water, remove dissolved organic materials, and trace contaminants from surface water, treatment of wastewater, and pre-treatment during the desalination of seawater. 42 Contd…. Nano Sorbents: Nano-sorbents can be used as separation techniques in the process of water purification to eradicate inorganic and organic matter from contaminated matter. Nanoparticles are effective sorbents due to their large surface area and can be enhanced with different reactor compounds to improve their affinity towards specific compounds. 43 Nanotechnology in air pollution treatment Nanotechnology can be used to treat and remedy air pollution through strategies such as the use of nano-adsorptive materials for adsorption, degradation by nanocatalysis, and the use of nano filters to filter and separate air pollutants. Use of Nano-Adsorptive Materials to Adsorb Air Pollutants: ✓ Nano adsorbents: carbon nanostructures have high selectivity, capacity, and affinity due to their physical characteristics, including average pre-diameter, the volume of the pores, and high surface area. ✓ Nano-adsorbents have unique properties that enable effective interactions with organic compounds through non-covalent bonds, including hydrogen bonding, electrostatic forces, hydrophobic interactions, and van der Waal forces. ✓ Carbon nanotubes have been used as adsorbent materials in environmental protection because of their characteristics, including high electrical and thermal conductivity, high strength, the unique potential for adsorption, and high hardness 44 Contd…. Degradation by Nanocatalysis: ✓ Nanotechnology can be used to prevent air pollution in indoor environments in a variety of ways. Semiconducting materials photocatalytic remediation is one effective strategy used to manage indoor pollution through nanotechnology. Reaction mainly occurs on the active surface, which is the significant catalyst structure. A decrease in the size of the catalyst leads to an increase in the surface area to increase the efficiency of the reaction. ✓ Nano-catalysts are considered appropriate materials for improving air quality and reducing pollutants in the air. For instance, titanium dioxide nanoparticles have photocatalytic properties to produce self-cleaning coatings used to decontaminate environmental pollutants, including nitrogen oxides, into materials that have low toxicity levels. Carbon nanostructures, including CNTs and graphene nanosheets, have been utilized to increase titanium dioxide’s photocatalytic effectiveness by facilitating the easy movement of electrons. 45 Contd…. Use of Nano Filters for Separation and Filtration Purposes: ✓ Nano filters are structured membranes with small pores to separate several contaminants from the exhaust to control air pollution by capturing gas pollutants. ✓ Filter media coated with nanofiber is mainly used in industrial plants to remove dust and filter the inlet air for gas turbines. ✓ Silver and copper nanoparticle filters are extensively used in air filtration technology as antimicrobial agents for the removal of biological aerosols such as viruses, bacteria, and fungi that cause infections. 46 Classes of nanomaterials in the removal of organic pollutants from environment Nano-photocatalysts: The term ‘‘photocatalysis’’ refers to the processes where light is used to excite the photocatalyst and accelerate the rate of the reaction, in which the photocatalyst remains unaltered. Nano photocatalysts are photocatalysts with 1 nm and 100 nm of size, in the presence of light, can accelerate the reactions. Nano-sized metals, zero-valent forms, monometallic oxides, bimetallic oxides, semiconductors can be used for the degradation of contaminants in the wastewater such as organic dyes or heavy metal ions. 47 Contd…. Nanophotocatalysts are highly capable of enhancing the mineralization of highly toxic and complex organic substances even at 25 ℃. These nano-sized materials are highly effective in mineralizing and degrading a wide range of organic Contaminants. In mineralization, the complex organic pollutants were decomposed into simpler compounds, whereas the decomposed compounds were completely destructed in the degradation stage, resulting in the formation of much simpler compounds like H2O, CO2. 48 Contd…. Water and Air remediation using nanosize semiconductor photocatalyst: Examples of photocatalysts: 1. Titanium dioxide (TiO2) 2. Zinc oxide (ZnO) 3. Iron oxide (Fe2O3) Photocatalysts are able to oxidize organic pollutants into nontoxic materials. The advantage of using Titanium dioxide (TiO2) for water remediation: 1. low toxicity. 2. high photoconductivity. 3. high photostability. 4. Excellent chemical and biological stability. 5. easily available and inexpensive materials. The advantage of using ZnO for water remediation: ZnO photocatalysts are able to detect and remediate contaminants from water. 49 Contd…. Nano and micromotors: A typical nano-motor is a nano-scale device which is having the ability to convert energy into movement. The nano-motors are capable of generating the forces in the order of few piconewtons. The important aspects of nano and micromotors are their high operational speed, movement specificity, and ability to self-mix. Micro/nanomotors are environmentally friendly and have attractive power units. 50 Contd…. Nano-membranes: Membrane filtration with the aid of nano-materials imparts novel functional groups, better catalytic action, improved permeation and resistance to membrane fouling. These nano-materials are also playing a significant role in the degradation of organic contaminants in the Wastewater. This membrane filtration process is highly effective in the removal or separation of specific inorganic compounds and small organic molecules. Nano-membranes are highly effective in the removal of salts, desalination and heavy metal ions. Nano-sorbents: Carbon and its derivate are the most exploited adsorbents in the removal of heavy metal ions and organic dyes from the aqueous solution. Besides, the role of metal oxides such as cerium oxide, iron oxide, zinc oxide, manganese oxide, etc., finds a prominent role in the remediation process. Carbon-based nano-sorbents: Carbon nanotubes (CNTs) are tubularly structured and fabricated with carbon in nano-dimensional size with the range of 1 nm to several nm. They can be categorized as single-walled CNTs (SWCNTs), and multi-walled CNTs (MWCNTs). 51 Contd…. Chitosan-derived nano-sorbents: Chitin is a natural polysaccharide that can be easily extracted from the shells of shrimp or crabs. With the process of de- acetylation, chitin can be converted into the polymer of de-acetylated-b- glucosamine called chitosan. It can be used for the removal of colloidal particles mediated by either coagulation or flocculation methods. Also, they can be used for the removal of several pollutants including toxic heavy metals, organic dyes, micro- pollutants, and hydrocarbons. Owing to the vital functional groups of amine, 1 and 2 hydroxyl moieties on the surface, chitosan-based adsorbents mediated the transfer of ionic species across the solid-liquid interfaces. 52 Chitosan as an adsorbent 53 Removal of bacterial pathogens from wastewater using nanomaterials Microorganisms are the major pollutants in water bodies as they participate in the process of removing nutrients and adding toxic metabolites in the wastewater. Nanotechnology can be used for the detection and removal of bacteria, viruses and other pathogenic microorganisms. There are several categories of nanoscale materials that remove the microbes in the wastewater. Nanoparticles can be used as biosensors for the in situ detection of waterborne microbes. Nanomaterials as: 1. Zinc oxide (ZnO) nanoparticles 2. Titanium oxide (TiO2) nanoparticles 3. Carbon nanotubes (CNT) 4. Silver nanoparticles (AgNPs) 5. Magnetic nanoparticles like iron oxide nanoparticles. These various nanomaterials were used for the removal of heavy metal and microbial pathogens from wastewater. 54 Contd…. Advantages of using nanomaterials for pathogens removal: 1. High surface area to volume ratio: enhanced interaction with the bacterial cells 2. Strong antimicrobial activity: effective at low concentration 3. Versatility: can be used in various forms like nanoparticles, membranes and coatings 4. Enhanced filtration: improved the removal efficiency for a wide range of pathogens 5. Photocatalysis activity: TiO2 can degrade organic pollutants and kill the microorganisms upon exposure to light. 6. Synergetic effect: Nanomaterials can provide multiple functionalities (e.g., antimicrobial, adsorptive, catalytic) in a single treatment step. 55 Nanotechnology in Health Care 56 Nanomaterials for Biosensors and Diagnostic Tools 57 Components of Biosensors Transducer conveys a signal that must be processed and displayed vis a signal readout and Biosensors detect targets of Converts signal via a processing system. biological importance and transducer element into a recognizes that target in a variety of measurable signal ways (e.g. affinity interaction) 58 Clinical applications of nanostructure-enabled biosensors L-cysteine assisted copper sulfide nanoparticles (Cu7.2S2) for the treatment of rheumatoid arthritis via photothermal therapy (PTT) Liposomal nanoparticles for the treatment and visualization of and photodynamic therapy (PDT). multidrug resistant bacterial pathogens with sonotheranostics. Lu et al. Adv. Healthcare Mater. 2018, 7, 1800013. Pang et al. ACS Nano 2019, 13, 2 Liposomal nanoparticle encapsulated second near-infrared (NIR-II) window A recombinant encapsulin (enc) protein nanocage surrounding magnetic lanthanide fluorophore rare earth-doped nanoparticles for embolic surgical iron oxide nanocomposites for magnetic resonance imaging (MRI)-guided navigation in the NIR-II window allowing surgeons to readily identify abnormal magneto-catalytic combination therapy for the treatment of cancer. vasculature such as tumor angiogenesis. Zhang et al. Nat. Commun. 2020, 11, 1. Li et al. Adv. Sci. 2019, 6,1902042. 59 Role of nanostructures in sensing: 1. Stabilization of biomolecules with nanoparticles: Due to large surface area and high free surface energy, nanoparticles are able to strongly absorb biomolecules to their surface and lead to their stabilization at biosensor surface. Direct adsorption of biomolecules on surface of bare bulk materials leads to denaturation and loss of biological activity of the biomolecule. This does not happen in case of nanoparticle surface due to biocompatibility of nanoparticles. Electrostatic interactions due to surface charge of nanoparticles assist in stabilization of biomolecules 2. Catalysis of reaction with nanoparticles: High surface activity of nanoparticles offer strong catalytic effects. 60  3. Improve electron transfer with nanoparticles: The active sites of redox proteins are surrounded by a thick, non-conducting protein shell, hence have no electrical connection to electrode, inhibiting electron transfer between the electrode and the active site. The conductive properties of nanoparticles (mainly, metal nanoparticles) are useful in increasing electron transfer between the electrode and the active center. 4. Labeling of biomolecules with nanoparticles Labeling of biomolecules such as antigens, antibodies and DNA by nanoparticles assist in development of electrochemical biosensors. Dissolution of nanoparticles (metal/semiconductor nanoparticles) and measurement of dissolved ions by voltammetry stripping offers a powerful analytical technique in measuring the effects of metals and make trace amount measurement of analytes possible. 61 Nanostructures used in Biosensing Nanorods Nanofibers 3D Nanopillars nanostructures Nanowires Nanosheets Nanoparticles Nanopore Quantum dots membrane 62 0D nanostructures in Biosensors and diagnostic tools Optical properties of gold (Au) NPs depend on their size, shape, and structure. The color changes that are observed are a direct result of localized surface plasmon resonance (LSPR). Photon absorption wavelength is a function of particle shape and size (i.e., aspect ratio), thickness of the Au shell (in nanoshells), and galvanic displacement by Au (in nanocages). C-reactive protein (CRP) antibody functionalized gold nanoparticles (AuNPs) were used for CRP detection utilizing LSPR. The binding of the pentameric CRP caused AuNP aggregation, leading to a red shift in absorbance, enabling visual CRP detection Dreaden et al. Chem. Soc. Rev. 2012, 41. Byun et al. Analyst 2013, 138,1538. 63  Magnetic NPs have been utilized within a microfluidic chip for the extraction of genomic DNA from whole blood via magnetophoresis Single microfluidic separator (a-b): a wash buffer is loaded (green), which diffuses into the wash channel (c): The test sample containing lysed whole blood and genomic DNA-bound paramagnetic NPs and output solution are then loaded (red). An elution buffer is also added to the elution well (blue). (d-e): A magnet is applied to move the DNA-bound magnetic NPs through the wash buffer yielding the extracted DNA K. Lee, A. Tripathi, Front. Genet. 2020, 11, 374. 64 1D nanostructures in Biosensors and diagnostic tools ZnO nanorod array that captures the bacteria by recognizing cell surface polysaccharides. Functionalization of ZnO nanorods FESEM images of ZnO nanorod (average diameter: 350 nm; length: 3 μm) Zheng et al. Talanta 2017, 167, 600. 65  Silicon nanowires (SiNW) in biosensing a lab-on-a-chip device containing two SiNW arrays: one for separation and one for detection. Specificity achieved using a immunoglobulin G antibody modified, roughness-controlled SiNW forest. From blood samples Troponin T (used in diagnosis of myocardial infarction) was detected rapidly and selectively, with ultralow sensitivity. immunoglobulin G antibody-modified, roughness-controlled SiNW forest. A magnetic inverted SiNW array being used to capture circulating tumor cells (CTCs). Krivitsky et al. Nano Lett. 2012, 12, 4748; Xu et al. Biomaterials 2017, 138, 69. 66  2D nanostructures in Biosensors and Diagnostic tools Nanowires in Biosensing : Tan et al. J. Am. Chem. Soc. 2015, 137, 10430. Detecting target DNA molecules with a limit of detection (LOD) of 50 pM using a single-layer 𝑇𝑎2 𝑁𝑖𝑆5 nanosheet nano-graphene oxide (nGO) nanosheets functionalized with a dye-labeled single-stranded DNA probe functionalized with DNA probes modified with that exhibits a high capacity for fluorescence quenching unlocked nucleic acids (UNAs). Specifieed for detection of target mRNA. single-step capture-anddetect method developed using a dual-targeting functionalized reduced graphene oxide (rGO) (DTFGF) nanosheet to detect hepatocelluar carcinoma circulating tumor cells (HCC- CTCs) with an LOD as low as 5 cells per mL. Robertson et al. Biosens. Bioelectron. 2017, 89, 551; Wu et al. ACS Appl. Mater. Interfaces 2019, 11, 44999. 67 3D nanostructures in Biosensors and diagnostic tools Self-assembly in order to create hybrid organic-inorganic nanoflowers that can be used in applications including biosensing. Kim et al. J. Colloid Interface Sci. 2016, 484. 68 3D nanostructures in Biosensors and Diagnostic tools A rose petal-mimicking biosensor composed of Transparent microfluidic device containing cactus- Complex hierarchical nano-functionalized surfaces for mimicking hierarchical structures coated with anti- increased capture of rare circulating tumor cells EpCAM antibodies, to enhance capture and analysis of (CTCs). rare CTCs. Dou et al. ACS Appl. Mater. Interfaces 2017, 9, 8508. Yan et al. ACS Appl. Mater. Interfaces 2016, 8, 33457. 69