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Molecular Biomimetics

Molecular Biomimetics. Polypeptides to Inorganic structures. Biomimetics. 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

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Molecular Biomimetics

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  1. Molecular Biomimetics Polypeptides to Inorganic structures

  2. Biomimetics

  3. 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

  4. Biomimetics • Biological Hard tissues: • Composite hybrid materials • Inorganic phases • Organic phases • Excellent physical properties

  5. Biomimetics • Biocomposites: • Structural macromolecules: • Proteins • Lipids • Polysaccharides • Minerals (hydroxyapatite, silica, magnetite, calcite)

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

  7. 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

  8. Biomimetics

  9. Biomimetics

  10. Biomimetics

  11. Biomimetics

  12. 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.

  13. Experimental Design • Direct coupling of Ligand to Surface. • Indirect, via a capture molecule (eg a specific IgG). • Membrane anchoring, where the interacting ligand is on the surface of a captured liposome.

  14. Sensor Chip CM-5:Carboxymethylated dextran coated surface. Allows covalent coupling via -NH2, -SH, and -CHO

  15. F1 & 2 F1 F3 & 4 F2 F1 - 3 F3 F1 - 4 F4 The Flow Cell Surface is divided into 4 channels, which can be used individually or in a number of combinations

  16. 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

  17. 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.)

  18. Theoretical Considerations • Binding is measured as a change in the refractive index at the surface of the sensor… How?

  19. 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.

  20. 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.

  21. Surface Plasmon Resonance • This occurs when the incident light vector is equal to the surface plasmon vector….

  22. 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.

  23. 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.

  24. The Sensorgram

  25. Equilibrium, KD = kd / ka Association - ka Dissociation - kd buffer Surface Plasmon Resonance response time

  26. Binding Analysis • How Much? Active Concentration • How Fast? Kinetics • How Strong? Affinity • How Specific? Specificity

  27. Concentration • Signal proportional to mass • Same specific response for different proteins

  28. What is QCM ?

  29. QCM

  30. QCM

  31. QCM- Measurement

  32. QCM Measurement

  33. QCM Measurement

  34. QCM Measurement

  35. QCM Applications

  36. QCM Applications

  37. Biomimetics

  38. Biomimetics

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  40. Biomimetics

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