Other Questions on paper

Question 1

2D) Understanding of AFM and its applications (note how it doesn’t say basic so learn advanced techniques)

Answer 1

• Operational mechanism
  o AFM operates by scanning a sharp tip attached to a flexible cantilever over the surface of a sample. The tip interacts with the sample surface through various forces (van der Waals forces, electrostatic forces, magnetic forces, etc.).
• Centilever deflection
  o As the tip scans the surface, interactions between the tip and the sample cause deflections in the cantilever. These deflections are monitored by a laser beam that is reflected off the back of the cantilever into a photodiode detector – turns light into eletrical current
• Feedback loop
  o Feedback loop maintains a constant force between tip and sample by adjusting the vertical position of the cantilever. Adjustment provides the topographical data of surface.
• Imaging modes
  o Contact mode
   The tip is in continuous contact with the sample surface. It provides high-resolution images but can damage soft samples.
  o Tapping mode
   he tip oscillates near its resonance frequency, making periodic contact with the surface. This mode reduces damage to soft samples and provides high-resolution images.
  o Non-contact mode
   The tip does not touch the surface but senses the van der Waals forces from a short distance. This mode is useful for imaging delicate samples without damaging them. (Expensive relative to other modes)
• Applications of AFM
  o Surface topography
   Provides detailed 3D images that help understand the surface roughness, texture, and other morphological features
   Crucial for charecterising coatings, thin films, and nanostructures
  o Biological studies
   Imaging of cells / biomolecules to analyse biocompatibility & usecases for biosensors
  o Nanomechanical properties
   Showcasing elasticity/hardness properties using AFM
  o Force spectroscopy
   application of force spectroscopy using AFM to measure molecular interactions
  o Material charecterisation
   Charecterising various materials using AFM such as metals, semiconductors, and insulators
  o Nano-manipulation
   AFM can be used to mannipulate nanostructures / molecules on surfaces, creating nanostructures, and studying nanoparticles

Question 2

2C) Basic understanding of viscoelastic materials

Answer 2

• Stress (σ): The force applied per unit area of the material (Pa)
• Strain (ε): The relative deformation of the material (dimensionless).
• Viscosity: This is a measure of a material’s resistance to flow. In a purely viscous material, like a liquid, the deformation (flow) is time-dependent and irreversible once the force is removed.
• Elasticity: This refers to a material’s ability to return to its original shape after being deformed. In a purely elastic material, the deformation is instantaneous and fully reversible when the force is removed.
  
  2. Viscoelasticity:
     * Definition: Viscoelastic materials exhibit both viscous and elastic characteristics when deformed. This means they have both fluid-like and solid-like properties.
     * Behavior: Under a constant load, these materials will deform slowly over time (creep), and under a constant deformation, the stress will gradually decrease (stress relaxation).

Examples: Human skin, cartilage, and various synthetic polymers and Hydrogels

Question 3

2B) Key Elements of tissue engineering (I feel there is also an answer for this in the mark scheme which might be more valuable)

Answer 3

• A tissue engineered implant is a biologic-biomaterial in which some component of tissue has been combined with a biomnaterial to create a device for the restoration or modification of tissue or organ function. Engineered tissues are grown in the lab by harvesting cells from a patient or donor and then seeding them on a biomimetic scaffold tht are fabricated from natural / man-made biomaterials
• While culturing tissues biochemical growth factors are often applied for facilitating the proliferation & differentiation of cells that eventually form complex 3D constructs which mimic the biological structure & function of natural tissues

Question 4

3A) Basic understanding of a biosensor (needs to be improved)

Answer 4

Definition and Components:
A biosensor is a self-contained integrated device capable of providing specific quantitative or semi-quantitative analytical information using a biological recognition element in direct spatial contact with a transducer element​​.

Working Mechanism:
The biological component (e.g., enzymes, antibodies, nucleic acids) of a biosensor interacts with the analyte of interest, while the transducer converts this interaction into a measurable signal, which can be electrical, thermal, or optical​​.

Types of Biosensors:
Catalytic biosensors, which involve enzymatic reactions to measure the change in concentration of substrates or products.
Affinity biosensors, where the analyte binds specifically to the biological element, such as antigen-antibody or enzyme-substrate interactions, without a catalytic reaction​​.

Applications:
Biosensors are extensively used across various fields including medical diagnostics (e.g., glucose monitoring in diabetes), environmental monitoring (detecting pollutants), food safety (detecting pathogens), and security (detecting biohazards)​​.

Advantages of Using Biosensors:
They offer rapid, real-time analysis, high specificity due to the biological recognition element, and the ability to function in complex samples with minimal preparation​​.