Conference on Nanotechnology for Biological and Biomedical Applications (Nano-Bio-Med) October From Bio- to Nano-Interfaces

Transcript

1 Conference on Nanotechnology for Biological and Biomedical Applications (Nano-Bio-Med) October 2011 From Bio- to Nano-Interfaces Kislon VOITCHOVSKY Dept.of Materials Science & Eng. EPFL, STI-IMX-SUNMIL Batiment MXG, Station Lausanne SWITZERLAND

2 Supramolecular NanoMaterials and Interfaces Laboratory department of materials science and engineering Institute of materials - Institut de Matériaux SuNMIL स न मल ΣoυΝΜιΛ From Bio- to Nano-Interfaces Kislon Voitchovsky kislon.voitchovsky@epfl.ch سنمل ICTP-KFAS NanoBioMed Conference, Trieste, 11 October 2011

3 At the interface with biology In nature molecules protein ions lipid vesicles... biological process In nanomedicine drug molecules nanoparticles polymer aggregates... biological material (cell) How do synthetic nano-objects interact with their surrounding?

4 Interfaces at the nanoscale Trypsin + + How are interfaces at the nanoscale? Does the coexistence of hydrophobic and hydrophilic nanoscale domains (e.g. on proteins) provide surfaces with special properties?

5 Solid-Liquid interfaces Medium M γ M Medium M1 γ M1 Medium M2 γ M2 Energy cost: γ MM = γ M + γ M = 2γ M Interfacial energy: γ M1M2 = γ M1 + γ M2 W M1M2

6 Solid-liquid interfaces Thermodynamics at the interface: the work of adhesion Liquid γ L vacuum Solid Interfacial energy γ SL : γ SL = γ S + γ L W SL (Dupré equation) interfacial energy ~ work of adhesion Bulk liquid Solid Interfacial liquid

7 Interfaces at the molecular level

8 Solid-liquid interfaces Probing the solid-liquid interface with AFM < 2nm amplitude ~ interface size

9 A brief introduction to AM-AFM k c A nanoscale tip mounted on a flexible cantilever is used to probe a sample locally

10 A brief introduction to AM-AFM k c A vibrating tip Amplitude Α and phase φ The tip vibration is damped by as the cantilever approaches the surface (here in liquid)

11 AM-AFM Basics A feedback loop keeps the cantilever vibration amplitude A constant Detection: amplitude A and phase ϕ

12 AM-AFM Basics P in = Po + P tip m z γ z + ( k + k ) z = A0 k cos( ωt) TS c TS z( t) = Acos( ω t + ϕ) c Amplitude A Phase φ

13 AM-AFM Basics

14 Biointerfaces at the nanoscale

15 Biointerfaces at the nanoscale liquid substrate

16 Biointerfaces at the nanoscale

17 Biointerfaces at the nanoscale 30 mm 100 mm 300 mm 1000 mm Cytopl. Extrcell. 5 nm bar RMS extracell.: 0.15 nm / 0.15 nm / 0.15 nm / 0.13 nm RMS cytopl.: 0.15 nm / 0.25 nm / 0.25 nm / 0.26 nm Nanoscale (2010) 2,

18 Protein electrostatics Looking at specific ionic effects: Li +, K + and Cs + Purple Membrane cytoplasmic surface at 50mM salt concentration 50nm x 50nm Voitchovsky et al. 2007

19 Biointerfaces at the nanoscale Nanoscale (2010) 2,

20 Biointerfaces at the nanoscale + K + + Na + Alternation of hydrophobic/philic domains Specific ionic effects Controlled local flexibility...

21 Striped nanoparticles as synthetic proteins

22 Metal Nanoparticles Synthesis Metal Salt (AuHCl 4 ) + + Reducing Agent (NaBH 4 ) Direct mixed ligands reaction ** Ligand exchange reaction * 3 nm

23 Imaging Self Assembled Monolayers Scanning Tunneling Microscopy 3 nm OT

24 Mixed Self-Assembled Monolayers Au (111) OT MPA 5 nm

25 STM Images of Striped Nanoparticles b b a c c 2 nm 2 nm d 5 nm

26 A More Realistic Vision Cartoon Simulations Microscopy Images

27 Stripe Formation in Mixed Monolayers Entropy gain in stripe formation Unpublished data TEM, NMR, Noesy Gel Electrophor. AUC Size Unpublished data

28 Striped nanoparticles Diffusion Challenge of cellmembrane penetration Adapted from: Nature Reviews Drug Discovery (2005)

29 Effect of Nanoparticle Coating Protein Interactions

30 Cell Membrane Penetration 4 0 C Experiment A B C D The absence of endocytosis has been independently confirmed via TEM studies

31 Endocytosis Inhibitors Calcein Only PI Staining No sodium azide and 2-deoxyglucose Z-Stack Images CyQuant Calcein and Striped NPs sodium azide and 2-deoxyglucose Calcein and TriMethyl Ammonium NPs

32 The Tale of Two Supramolecular Systems Striped Nanoparticles Lipid Bilayers

33 At the more fundamental level. AFM images of supported bilayers and striped particles 70 nm

34 At the more fundamental level. AFM study of Nanoparticles-bilayer interactions μm nm 1 70 nm μm Poster: Maria RICCI

35 Towards an Understanding V, I V In collab. with Prof. Yann Astier, University of Lisbon, Portugal I t 1,2 diphytanoyl-snglycero phosphocholine lipid bilayer ph 8.1 Tris-HCl 0.1 M, KCl 2 M Reference Ag/AgCl electrodes t

36 Nanoparticle/Bilayer Interactions Blank All TMA/MUS MUS/brOT MUS OT 2:1 Blank T=30min 0.8 mg/ml T=1h 1.6 mg/ml T=1h mg/ml T=2h20 Carney, Stellacci, in preparation

37 Solubility of Rippled Nanoparticles OT MUA HT with N. Marzari, MIT; PNAS 9886, x 1 2 x 2

38 Striped nanoparticles

39 Interfacial Energy (IE) At the micron/nano scale W SL = γ LV (1 + cos θ CA ) γ L (1 + cos θ CA ) Cassie State: (cos θ CA ) obs = = f 1 (cos θ CA ) 1 + f 2 (cos θ CA ) 2 = = f 1 + f 2 (cos θ CA ) 2 Wenzel State: (cos θ CA ) obs = r (cos θ CA )

40 Interfacial Energy Microscopy

41 Interfacial AM-AFM Pressure to remove liquid near the sample and the tip surfaces: } α ~ β

42 Interfacial AM-AFM high-resolution phase φ E cycl, ext phase φ local wetting (work of adhesion)

43 High Resolution Images

44 Effect of structure on interfacial energy

45 Structure Effects on Surface Energy W sl = x A W A sl + x B W B sl x A = component A surface fraction x B = 1 - x A

46 Work of Adhesion Measurements

47 Structure Component to I.E. W SL AB = x A W SL A + x B W SL B Wsl = x A W A sl + x B W B sl + f(structure)

48 Structural Component in I.E. Cavitation From D. Chandler, Nature, 2005

49 Solid-liquid interfaces with structured surfaces Adding salt should decrease cavitation

50 Conclusions

51 Acknowledgements