Molecular Biomimetics

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Molecular Biomimetics

• Polypeptides to Inorganic structures

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Biomimetics
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Biomimetics

• Naturally derived nanostructures can be
  characterised as
• Self directed in their organisation
• Operate in aqueous environment
• Dynamic interactions with their surroundings
• Complex structures and functions
• Self healing capabilities

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Biomimetics

• Biological Hard tissues
• Composite hybrid materials
• Inorganic phases
• Organic phases
• Excellent physical properties

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Biomimetics

• Biocomposites
• Structural macromolecules
• Proteins
• Lipids
• Polysaccharides
• Minerals (hydroxyapatite, silica, magnetite,
  calcite)

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Biomimetics

• Proteins
• Recognition
• Binding
• Self assembly characteristics
• Inorganic surface-specific proteins
• Couplers, growth initiatorsmodifiers,
• Self assembly of materials

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Biomimetics

• Heterofunctional Nanostructure materials
• 1) Identification of Inorganic specific peptides
• Design of Protein/peptide templates through
  directed evolution
• 2) Engineering of peptide building blocks
• Tailoring recognition
• Tailoring assembly properties
• Leading to functional materials Nanoparticles,
  polymers, molecular templates
• 3) Self and Coassembly into ordered structures

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Biomimetics
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Biomimetics
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Biomimetics
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Biomimetics
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Basic Principle

• A binding molecule is bound to the sensor
  surface.(ligand peptide, protein, sugar,
  oligonucleotide))
• Another (the analyte) is passed over the surface
  and binds to it.

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Experimental Design
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Sensor Chip CM-5 Carboxymethylated dextran
coated surface.
Allows covalent coupling via -NH2, -SH, and -CHO
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The Flow Cell
Surface is divided into 4 channels, which can be
used individually or in a number of combinations
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Microfluidic System

• Low reagents consumption
• Efficient mass transport
• Low dispersion
• Highly reproducible injections CV typically less
  than 1
• Wide range of contact times, 1 s - 12 h
• Sample recovery and fractionation

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Measurement of Binding

• Binding is measured as a change in the refractive
  index at the surface of the sensor
• This is due to Surface Plasmon Resonance (SPR)
• The change in refractive index is essentially the
  same for a given mass concentration change
  (allows mass/concentration deductions to be made)
• Binding events are measured in real time
  (allowing separate on and off rates to be
  measured.)

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Theoretical Considerations

• Binding is measured as a change in the refractive
  index at the surface of the sensor

How?
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Total Internal Reflection
At a certain angle of incidence, light entering a
prism is totally internally reflected. (TIR).
Although no photons exit the reflecting surface,
their electric field extends 1/4 wavelength
beyond the surface.
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Resonance Surface Plasmon
If a thin gold film is placed on the reflecting
surface, the photons can interact with free
electrons in the gold surface.
Under the right conditions, this causes the
photons to be converted into plasmons and the
light is no longer reflected.
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Surface Plasmon Resonance

• This occurs when the incident light vector is
  equal to the surface plasmon vector.

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• Effect of binding on SPR

• Plasmons create an electric field (evanescant)
  that extends into the medium surrounding the film
• This is affected by changes in the medium (eg
  binding of analyte), and results in a change in
  the velocity of the plasmons.
• This change in velocity alters the incident light
  vector required for SPR and minimum reflection.

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How does BIACore Measure this?

• Fixed wavelength light, in a fan-shaped form, is
  directed at the sensor surface and binding events
  are detected as changes in the particular angle
  where SPR creates extinction of light.

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The Sensorgram
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Surface Plasmon Resonance
response
time
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Binding Analysis

• How Much?

Active Concentration
Kinetics

• How Fast?

Affinity

• How Strong?

Specificity

• How Specific?

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Concentration

• Signal proportional to mass

• Same specific response for different proteins

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What is QCM ?
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QCM
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QCM
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QCM- Measurement
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QCM Measurement
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QCM Measurement
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QCM Measurement
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QCM Applications
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QCM Applications
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Biomimetics
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Biomimetics
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Biomimetics
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Biomimetics