UNIT-II: NANOBIOTECHNOLOGY

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UNIT-II: Biomaterials- Introduction and Types. Biodegradable polymers. Biocompatibility, mechanical properties and Antibacterial Activity. DNA based nanomechanical devices, Biomaterial Nanocircuitry - DNA nanostructures for mechanics, computing and DNA based computation.

Absolutely! Here's your revised and detailed notes for Unit-II with chitosan integrated wherever relevant, all in simple English:

🧬 UNIT-II: Biomaterials and DNA Nanotechnology

1. Biomaterials: Introduction and Types

What are Biomaterials?

  • Materials used in medical devices that interact with the body.
  • Must be safe, non-toxic, and biocompatible.
  • Used in implants, prosthetics, drug delivery, tissue engineering, etc.

Types of Biomaterials:

Type Examples Key Features
Metals Titanium, Stainless steel Strong, durable, used in bone plates, dental implants
Ceramics Alumina, Zirconia Hard, wear-resistant, used in bone grafts, dental crowns
Polymers Polyethylene, Silicone, Chitosan Flexible, biodegradable, used in sutures, drug delivery
Composites Carbon fiber-reinforced polymers Combine properties of different materials
Natural Biomaterials Collagen, Chitosan, Gelatin Biodegradable, biocompatible, used in wound healing, scaffolds

🔍 Chitosan in Biomaterials:

  • Derived from chitin (found in shrimp/crab shells).
  • Biodegradable, biocompatible, and antibacterial.
  • Used in wound dressings, drug delivery, tissue engineering, and scaffolds.

2. Biodegradable Polymers

Definition:

  • Polymers that break down naturally in the body or environment.
  • Avoids need for surgical removal.

Examples:

  • Polylactic acid (PLA)
  • Polyglycolic acid (PGA)
  • Polycaprolactone (PCL)
  • Chitosan – natural, breaks down into harmless sugars.

Applications:

  • Sutures, drug delivery capsules, tissue scaffolds, wound healing patches.

Why Chitosan?

  • It’s non-toxic, biodegradable, and supports cell growth.
  • Excellent for controlled drug release and healing wounds.

3. Biocompatibility

What is Biocompatibility?

  • The ability of a material to safely interact with the body.
  • Should not cause inflammation, toxicity, or immune reaction.

Factors Affecting It:

  • Surface smoothness
  • Chemical composition
  • Degradation products

Chitosan’s Role:

  • Highly biocompatible – supports cell attachment and growth.
  • Used in skin grafts, nerve regeneration, and eye surgeries.

4. Mechanical Properties of Biomaterials

Key Properties:

  • Strength: Withstand force without breaking.
  • Elasticity: Return to original shape.
  • Toughness: Resist cracking.
  • Hardness: Resist surface damage.
  • Fatigue Resistance: Handle repeated stress.

Chitosan’s Mechanical Traits:

  • Moderate strength, but can be blended with other materials to improve.
  • Used in soft tissue engineering and flexible implants.

5. Antibacterial Activity

Why Important?

  • Prevents infections in implants and wounds.

How to Achieve It:

  • Coating with silver, copper, or antibiotics.
  • Using antibacterial polymers like chitosan.

Chitosan’s Antibacterial Power:

  • Naturally kills bacteria by disrupting their cell walls.
  • Used in bandages, catheters, and surgical sutures.

6. DNA-Based Nanomechanical Devices

What Are They?

  • Tiny machines made from DNA strands.
  • Can move, open/close, or carry molecules.

Examples:

  • DNA tweezers-Forceps: Open and close using chemical signals.
  • DNA walkers: Move along a track to deliver drugs.

Applications:

  • Targeted drug delivery
  • Biosensors
  • Nano-robots

Chitosan + DNA Devices:

  • Chitosan can stabilize DNA nanostructures.
  • Used to deliver DNA-based devices into cells safely.

7. Biomaterial Nanocircuitry & DNA-Based Computation

DNA Nanostructures for Mechanics & Computing:

  • DNA can be folded into 2D and 3D shapes (e.g., origami).
  • These structures can move, sense, or compute.

DNA-Based Computation:

  • DNA strands act like logic gates (AND, OR, NOT).
  • Can solve problems, store data, or control nano-devices.

Chitosan’s Role:

  • Used as a carrier for DNA computing elements.
  • Helps in gene delivery and protects DNA from degradation.

🧾 Why Chitosan is Special

Property Chitosan’s Role
Biodegradable Breaks down naturally in the body
Biocompatible Safe for human tissues
Antibacterial Kills harmful bacteria
Mechanical Support Flexible, can be blended for strength
DNA Carrier Helps deliver and protect DNA nanodevices














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