Nanotechnology

Artificial Nanozyme to prevent abnormal Blood Clots

Context: Researchers at the Indian Institute of Science (IISc.) have developed an artificial metal-based nanozyme that can be used to prevent abnormal blood clotting caused by conditions like pulmonary thromboembolism (PTE).

Relevance of Topic: Prelims: Scope of artificial metal-based nanozyme; Applications of Nanotechnology.

Clotting of blood under normal conditions:

When a blood vessel is injured, specialised blood cells called platelets get activated and cluster together around the vessel to form protective blood clots to stop bleeding. This is the normal blood clotting cascade (haemostasis).
Haemostasis involves a complex series of protein interactions triggered by exposure to proteins like collagen (from the damaged vessel wall) and enzymes like thrombin (key enzyme in clot formation; activates fibrinogen and stabilises the clot.

Under diseases like PTE or COVID-19:

In conditions like PTE or diseases like COVID-19, the oxidative stress and levels of toxic Reactive Oxygen Species (ROS) increases in the body, leading to over-activation of platelets.
This triggers the formation of excess clots in the blood vessel contributing to thrombosis (life-threatening causes blockages in blood vessels).

Artificial metal-based Nanozyme:

To tackle this challenge, researchers have developed a nanomaterial that mimics the activity of natural antioxidant enzymes.
This artificial nanoenzyme is spherical vanadium pentoxide (V2O5). It scavenges reactive oxidative molecules, controls ROS levels, and thereby prevents the over-activation of platelets.

Thus, artificial metal-based nanozyme will help in reducing ROS levels, preventing over-activation of platelets and controlling abnormal blood clotting.

Nanoparticle-based Security Ink to thwart Counterfeiting

Context: Government and financial institutions take painstaking efforts to consolidate banknotes, cheques, and passports with a variety of security features to protect them from counterfeiting. Now, scientists from India have developed a Nanoparticle-based Security Ink that can make counterfeiters’ jobs harder.

Relevance of the Topic: Prelims: Nanoparticles-based security ink.

Nanoparticle-based Security Ink

The scientists from Institute of Nano Science and Technology (INST), Mohali and Bhabha Atomic Research Centre (BARC), Mumbai have developed a fluorescent security ink using nanoparticles that emit different colours under various light conditions.
Composition of the Security Ink:
- Base Material: Sr2BiF7 (Strontium Bismuth Fluoride)
- Dopant: Lanthanide ions (Erbium and Ytterbium)
- Binding agent: Polyvinyl Chloride (PVC) ink.
- Manufactured using: Co-precipitation method.
Co-precipitation Method: Chemical process where all required metal salts are dissolved in a solvent and then precipitated by adding another agent. The desired precipitate is then separated.
Fluorescence Properties of the Ink:
- Under 365 nm Ultraviolet (UV) Light: Emits a blue glow.
- Under 395 nm UV Light: Emits a magenta glow.
- Under 980 nm Near-Infrared (NIR) Light: Emits an orange-red glow.
- Advantage:
  - The ink can overcome the limitations of current covert tags, which are security features usually visible only under UV light and can be easily duplicated.
  - This ink fluoresces under both UV and near-Infrared light, making it harder for counterfeiters to replicate.

Nanotechnology involves the manipulation and control of matter at the nanoscale, typically in the range of 1 to 100 nanometers.
Properties of Nanoparticles:
- Size: 1 to 100 nanometers. (1 nm = 10^-9metres)
- Unique Properties:
  - Enhanced interactions with light, leading to unique opto-electric properties. E.g., Quantum dots.
  - Increased chemical reactivity. E.g., Nanocatalysts.
  - Different response to magnetic fields (altered Magnetic behaviour).
These properties arise due to high surface area-to-volume ratio, exhibition of quantum effects at nanoscale, and interface interactions.

Advantages of the Developed Ink:

Multi-wavelength Fluorescence: Emits different colors under UV and NIR light.
High Security: Difficult to counterfeit due to multi-spectral response.
Low Cost: Made using readily available materials.
Durability: Stable under varying brightness, temperature, and humidity conditions.
Scalable Production: Simple manufacturing process allowing large-scale production.

Potential Applications:

Enhanced security features for currency notes.
More secure identification documents, like passports and government documents.
In product packaging for protection against counterfeit products.

The current method uses screen printing, unsuitable for currency printing. Researchers are aiming to modify the ink for offset printing to make it suitable for high-security applications.

What is Security Printing?

Definition: Security printing refers to the incorporation of various security features in printed materials to prevent counterfeiting.
Common Uses: Currency notes, cheques, passports, and branded products packaging.
Types of Security Features:
- Visible Features: Easily detectable by humans without special tools.
- Optically Variable Ink (OVI): Changes colour when viewed from different angles.
- Watermarks: Embedded symbols or designs visible when held against light.
- Holograms: Three-dimensional images with dynamic visual effects.
- Security Threads: Metallic threads embedded in paper.
- Raised Textures: Designs with a tangible texture detectable by touch.
- Machine-Detectable Features: Require specific devices to verify.
- Radio-Frequency Identification (RFID): Chips embedded in passports for verification.
- Invisible Barcodes: Can be scanned to authenticate documents.
Digital Watermarks: Embedded digital codes detectable through scanners.

Graphene

What is Graphene?

Graphene is an allotrope of carbon, alongside diamond and graphite.
It consists of a single layer of carbon atoms arranged in a honeycomb pattern.

Known for its exceptional properties:

Thinnest compound (one atom thick)
Lightest material
Strongest compound discovered (between 100-300 times stronger than steel)
Best conductor of heat at room temperature
Best conductor of electricity known
Almost perfectly transparent as it absorbs only 2% of light.
Impermeable to gases, even those as light as hydrogen and helium.
Stronger than diamond.
More conductive than silver.
More elastic than rubber.
Lighter than aluminium.

Applications:

Flexible Electronics: Graphene's flexibility and transparency make it suitable for flexible electronic devices. It can be used in wearable electronics, flexible displays, electronic textiles, and bendable sensors.
Energy Storage: Graphene-based materials can enhance the performance and capacity of energy storage systems while reducing charging time. Ideal to create supercapacitors and high-performance batteries.
Water purification: Graphene oxide membranes have nanometer-sized pores that enable selective permeability, which allows passage of water molecules while blocking the passage of ions, salts, and larger molecules. This property makes them suitable for water filtration systems and desalination systems. E.g., Removing pesticides from water.
Biosensors: Graphene can be used to sense chemical and biological agents, explosives, radiation, and other hazardous substances. E.g., Graphene-based sensors can detect CO2 and volatile organic compounds inside buildings with significantly low power usage.
Aerospace and Defense: Graphene's remarkable strength-to-weight ratio makes it an attractive material in the Aerospace sector for developing lightweight and high-strength armour and ballistic protection. E.g., Create lighter impact-resistant helicopter and aircraft structures. Graphene has the potential to absorb and dissipate electromagnetic waves, making it valuable for developing stealth coatings and materials that reduce radar signatures and electromagnetic interference.
Medical Applications: Biomedical applications of graphene-based nanomaterials include biosensing, bioimaging, targeted drug delivery, tissue engineering, phototherapy and cancer treatment.
Other industrial usages: Used as waterproof coatings for industrial machinery, ocean liners, and aircraft. Graphene oxide-based wrappers loaded with preservatives can increase the shelf life of fruits and vegetables. Strengthening car tires, replacing silicon in smartphone chips. Enhancing concrete strength by 25% and reducing carbon intensity.

Unusual Properties:

In 2019, for example, physicists found that when one sheet of graphene is placed above another and rotated by 1.1 degrees relative to the bottom layer, the stack becomes a superconductor at low temperature.

Carbon Nanoflorets

Context: Researchers at IIT Bombay have synthesised particles that absorb three frequencies of sunlight and convert it to heat with an efficiency of 87%.

About Carbon Nanoflorets

The carbon nanostructure has the potential to revolutionise solar energy conversion.
The scientists began their experiments with a white material called dendritic fibrous nanosilica (DFNS) and transformed it into the darkest black carbon nanoflorets.
- To create the carbon nanoflorets, the DFNS powder was heated in a furnace and introduced acetylene gas into the chamber.
- The white powder turned black, indicating that carbon had been deposited on the DFNS.
- After dissolving the DFNS with a strong chemical, what remained were spherical nanostructures made of carbon cones.
The nanoflorets resemble tiny marigold flowers.

Unique properties

Carbon nanoflorets had an unprecedented ability to absorb sunlight at multiple frequencies and convert it into heat with exceptional efficiency.
- They can absorb infrared, visible, and ultraviolet light, unlike traditional solar-thermal conversion materials that only absorb visible and ultraviolet light.
Their cone-like shape minimises reflection allowing for maximum light absorption. Most of the light that falls on the material is reflected internally.
The nanoflorets possess long-range disorder which prevents heat dissipation over long distances, enabling efficient heat retention.

Significance

The material is ripe for commercialisation as carbon is inexpensive and the nanoflorets can generate heat sustainably, without having to burn fossil fuels.
- 1 square metre coating of carbon nanoflorets could vaporise 5 litres of water per hour, surpassing the performance of commercial solar stills.
They can offer a sustainable solution for heating homes and sterilising surfaces in hospitals without relying on fossil fuels. With its wide range of potential applications and minimal environmental impact, the material has potential to play a significant role in the renewable energy sector.