1. Form and FunctionForm and Function
Engineering approaches on aEngineering approaches on a
cellular levelcellular level
Marc R. DusseillerMarc R. Dusseiller
Groupmeeting @ nanomat, 19 June 2006Groupmeeting @ nanomat, 19 June 2006

2. Groupmeeting June 2006 2
OutlineOutline
• IntroductionIntroduction
• Biomaterials - BiointerfaceBiomaterials - Biointerface
• Cells in CultureCells in Culture
• Form an FunctionForm an Function
• Cell Patterning – Cell shapeCell Patterning – Cell shape
• DimensionalityDimensionality
• My ProjectMy Project
• Micro 3-D Cell Culture ConceptMicro 3-D Cell Culture Concept
• MicrofabricationMicrofabrication
• Surface modificationSurface modification
• Cell experimentsCell experiments
• Conclusions and outlookConclusions and outlook
• AcknowledmentsAcknowledments

3. Groupmeeting June 2006 3
AcknowledgmentsAcknowledgments
Prof. Marcus TextorProf. Marcus Textor DoktorvaterDoktorvater
Mirabai Koch, B. NiederbergerMirabai Koch, B. Niederberger Diploma studentsDiploma students BioInterfaceGroupBioInterfaceGroup
D Falconnet, J Lussi, J VörösD Falconnet, J Lussi, J Vörös DiscussionsDiscussions
Prof. Nic SpencerProf. Nic Spencer Head ofHead of LSSTLSST
Dr. Stefan BlunierDr. Stefan Blunier MicrofabricationMicrofabrication IMES, D-MAVTIMES, D-MAVT
Wulf GlatzWulf Glatz SU-8 processingSU-8 processing Micro, D-MAVTMicro, D-MAVT
Matthias Gössi, Jerome LefèvreMatthias Gössi, Jerome Lefèvre Polymer processingPolymer processing Polymer TechnologyPolymer Technology
Brandon BürglerBrandon Bürgler SEM, mental supportSEM, mental support CeramicsCeramics
Dr. GDr. Gáábor Csbor Csúúcscs CLSMCLSM Light Microscopy CenterLight Microscopy Center
Dr. Ruth KroschewskiDr. Ruth Kroschewski
Dominik Schläpfer, Aldo FerrariDominik Schläpfer, Aldo Ferrari MDCK experimentsMDCK experiments BiochemistryBiochemistry
Judith Zaugg, Luzia ReutimannJudith Zaugg, Luzia Reutimann
Dr. Michael Smith, Sheila LunaDr. Michael Smith, Sheila Luna FN, SoftFN, Soft μμ-wells-wells nanomatnanomat
Prof. Viola VogelProf. Viola Vogel Co-refereeCo-referee
Matthias LütolfMatthias Lütolf stem cells, PEG gelsstem cells, PEG gels Stanford, School of MedicineStanford, School of Medicine
Prof. Jeff HubbellProf. Jeff Hubbell Co-refereeCo-referee LMRP, EPFLLMRP, EPFL

4. IntroductionIntroduction

5. Groupmeeting June 2006 5
Biology
Material Science
&
Engineering
From atom, proteins and cells to human beings and society

6. Groupmeeting June 2006 6
Biomaterials - BiointerfacesBiomaterials - Biointerfaces
Implants Cell culture modelsTissue engineering scaffolds

7. Groupmeeting June 2006 7
Cell – Surface InteractionsCell – Surface Interactions
• Different size scale - atoms, molecules, proteins and cellsDifferent size scale - atoms, molecules, proteins and cells
• Different time scalesDifferent time scales
• Dynamic complex biological systemDynamic complex biological system

8. Groupmeeting June 2006 8
History of cells in cultureHistory of cells in culture
Harrison, R.G., The cultivation of tissues in extraneous media as a method of
morphogenetic study. The Anatomical Record, 1912. 6(1): p. 181-193.

9. Groupmeeting June 2006 9
History of cells in cultureHistory of cells in culture
Harrison, R.G., The reaction of embryonic cells to solid structures.
Journal Of Experimental Zoology, 1914. 17(4): p. 521-544.
....
The behavior of the cells withThe behavior of the cells with
reference to the surface of thereference to the surface of the
cover slip and spider web showscover slip and spider web shows
not only that the surface of a solidnot only that the surface of a solid
is a necessary condition but alsois a necessary condition but also
that when the latter has a specificthat when the latter has a specific
linear arrangement, as in the spiderlinear arrangement, as in the spider
web, it has an action in influencingweb, it has an action in influencing
the direction of the movement, asthe direction of the movement, as
well as upon the form andwell as upon the form and
arrangement of the cells.arrangement of the cells.

10. EngineeringEngineering
approaches on aapproaches on a
cellular levelcellular level

11. Groupmeeting June 2006 11
Soft Lithography – Microcontact printingSoft Lithography – Microcontact printing
Singhvi, R., et al., Engineering Cell-Shape and Function.
Science, 1994. 264(5159): p. 696-698.

12. Groupmeeting June 2006 12
Soft Lithography – Microcontact printingSoft Lithography – Microcontact printing
Singhvi, R., et al., Engineering Cell-Shape and Function.
Science, 1994. 264(5159): p. 696-698.

13. Groupmeeting June 2006 13
Cell shape influences cell behaviorCell shape influences cell behavior
• Surface chemistry and patterningSurface chemistry and patterning
enable new experimentsenable new experiments
• Endothelial cells on adhesive islandsEndothelial cells on adhesive islands
• Cell shape controls cell behaviorCell shape controls cell behavior
• Cell shape is defined by the amountCell shape is defined by the amount
of spreading allowed by the adhesiveof spreading allowed by the adhesive
islandisland
Chen, C.S., et al., Geometric control of cell life and death.
Science, 1997. 276(5317): p. 1425-1428.

14. Groupmeeting June 2006 14
Shape/spreading controls stem cell differentiationShape/spreading controls stem cell differentiation
McBeath, R., et al., Cell shape, cytoskeletal tension, and RhoA regulate
stem cell lineage commitment. Dev Cell, 2004. 6(4): p. 483-95.
• Human mesenchymal cells (hMSCs)Human mesenchymal cells (hMSCs)
on adhesive islands of different sizeson adhesive islands of different sizes
• Cell shape controls stem cell lineageCell shape controls stem cell lineage
commitment into adipocytes orcommitment into adipocytes or
osteoblastsosteoblasts
• Increased spreading leads to anIncreased spreading leads to an
increase in Rho dependant contractilityincrease in Rho dependant contractility
• These studies demonstrate thatThese studies demonstrate that
mechanical cues experienced inmechanical cues experienced in
developmental and adult contexts,developmental and adult contexts,
embodied by cell shape, cytoskeletalembodied by cell shape, cytoskeletal
tension, and RhoA signaling, aretension, and RhoA signaling, are
integral to the commitment of stem cellintegral to the commitment of stem cell
fate.fate.

15. Groupmeeting June 2006 15
ECM geometry guides orientation of mitosisECM geometry guides orientation of mitosis
Thery, M., et al., The extracellular matrix guides the orientation of
the cell division axis. Nat Cell Biol, 2005. 7(10): p. 947-53.
• Geometry of islands of adhesive ECM components (FN) control cell shapeGeometry of islands of adhesive ECM components (FN) control cell shape
and orientation of the mitotic spindle during cell divisionand orientation of the mitotic spindle during cell division

16. Groupmeeting June 2006 16
Multicellular Patterning – Global InfluenceMulticellular Patterning – Global Influence
• Large adhesive patterns to study theLarge adhesive patterns to study the
effect of forces in multicellular systemseffect of forces in multicellular systems
• Contractile forces generated by theContractile forces generated by the
cells lead to an increased proliferationcells lead to an increased proliferation
in those areas with the highest forcesin those areas with the highest forces
Nelson, C.M., et al., Emergent patterns of growth controlled by multicellular
form and mechanics. PNAS, 2005. 102(33): p. 11594-11599.

17. Groupmeeting June 2006 17
Cell Patterning @ BioInterface GroupCell Patterning @ BioInterface Group
• Model surfacesModel surfaces
• Controlled surface chemistryControlled surface chemistry
• Controlled mechanical propertiesControlled mechanical properties
• Surface patterningSurface patterning
• Control of cell shapeControl of cell shape
• Cell shapeCell shape
• cell behaviorcell behavior
• Adhesion sitesAdhesion sites
• cytoskeleton organizationcytoskeleton organization
• cell mechanicscell mechanics
• stem cell differentiationstem cell differentiation
• 2-D !2-D !
Michel, R., et al., Selective molecular assembly patterning: A new
approach to micro- and nanochemical patterning of surfaces for
biological applications. Langmuir, 2002. 18(8): p. 3281-3287.
Falconnet, D., et al., A combined photolithographic and molecular-assembly
approach to produce functional micropatterns for applications in the
biosciences. Advanced Functional Materials, 2004. 14(8): p. 749-756.

18. Groupmeeting June 2006 18
The Third DimensionThe Third Dimension
““3-D culture will allow a lot of basic questions to be3-D culture will allow a lot of basic questions to be
answered before having to turn to whole animalanswered before having to turn to whole animal
research”, Friedlresearch”, Friedl
““Our preliminary analysis shows that the expressionOur preliminary analysis shows that the expression
profile in 3-D is much closer toprofile in 3-D is much closer to in vivoin vivo expressionexpression
profiles than the profile we’ve seen in 2-D”, Griffithprofiles than the profile we’ve seen in 2-D”, Griffith
• adhesion fundamentally differentadhesion fundamentally different
• less prominent actin stress fibersless prominent actin stress fibers
• a lot of unanswered questionsa lot of unanswered questions
• 3-D models difficult3-D models difficult
• limited control of interactionslimited control of interactions
• no control of cell shapeno control of cell shape

19. My ProjectMy Project

20. Groupmeeting June 2006 20
Microenvironment of Cells in CultureMicroenvironment of Cells in Culture
• Soluble cuesSoluble cues
Growth factorsGrowth factors
pHpH
IonsIons
Media supplementsMedia supplements
etc.etc.
• Insoluble cuesInsoluble cues
Cell-cell contactsCell-cell contacts
Cell-matrix contactsCell-matrix contacts
Forces by other cellsForces by other cells
Mechanical properties of ECMMechanical properties of ECM
Transmission of forcesTransmission of forces
• Spatial organizationSpatial organization
of all cuesof all cues

21. Groupmeeting June 2006 21
Micro 3D cell culture systemMicro 3D cell culture system
Dusseiller, M.R., et al., Microfabricated three-dimensional environments
for single cell studies. Biointerphases, 2006. 1(1): p. P1.

22. Groupmeeting June 2006 22
• SiliconSilicon
variety of techniques from microelectronicsvariety of techniques from microelectronics
and MEMS fieldand MEMS field
• PhotolithographyPhotolithography
• deep Reactive Ion Etching (dRIE, Boschdeep Reactive Ion Etching (dRIE, Bosch
process, ICP etching)process, ICP etching)
Microfabrication - Silicon etchingMicrofabrication - Silicon etching

23. Groupmeeting June 2006 23
ReplicationReplication
PDMS PEG-hydrogelPolystyrene
PS (polystyrene)PS (polystyrene)
Young’s Modulus ~ 10Young’s Modulus ~ 1099
PaPa
cheap, transparentcheap, transparent
widely used as cell culture materialwidely used as cell culture material
hot embossinghot embossing
PDMS (polydimethylsiloxane)PDMS (polydimethylsiloxane)
Young’s Modulus ~ 10Young’s Modulus ~ 1044
Pa –10Pa –1066
PaPa
elastomeric, transparentelastomeric, transparent
replica moldingreplica molding
PEG-hydrogelsPEG-hydrogels
Young’s Modulus ~ 100 Pa – 10Young’s Modulus ~ 100 Pa – 1044
PaPa
Tissue like stiffnessTissue like stiffness
Diffusion of nutrients etc.Diffusion of nutrients etc.
Incorporation of functional groupsIncorporation of functional groups

24. Groupmeeting June 2006 24
PDMS thin film devicePDMS thin film device
• Array of microwells in PDMSArray of microwells in PDMS
Different shapes and dimensions (10 to 30 micron diameter)Different shapes and dimensions (10 to 30 micron diameter)
Different mechanical properties by changing the cross linker densityDifferent mechanical properties by changing the cross linker density
• Assembled into a glass bottom petri-dishAssembled into a glass bottom petri-dish
• Selective passivation of plateauSelective passivation of plateau

25. Groupmeeting June 2006 25
Mechanical Properties of PDMSMechanical Properties of PDMS
• Standard tensile testStandard tensile test
• 12 mm dogbones punched out from 1 mm thick cast pdms films12 mm dogbones punched out from 1 mm thick cast pdms films
• Different crosslinker densitiesDifferent crosslinker densities

26. Groupmeeting June 2006 26
Surface ModificationSurface Modification
OO22 plasma treatment of PS or PDMSplasma treatment of PS or PDMS
• PS: surface oxidation – negative chargesPS: surface oxidation – negative charges
(COO(COO--
))
• PDMS: generation of glass like surface (SiOPDMS: generation of glass like surface (SiO22))
PLL-PLL-gg-PEG-PEG
Poly(L-Lysine)Poly(L-Lysine) graftedgrafted Poly(Ethylene Glycol)Poly(Ethylene Glycol)
• self assembles on negatively chargedself assembles on negatively charged
surfacessurfaces
metal oxides, TCPSmetal oxides, TCPS
• resistant to protein adsorptionresistant to protein adsorption
• functional groupsfunctional groups
peptide sequences (cont. RGD - integrinpeptide sequences (cont. RGD - integrin
binding)binding)
specific binding sites (PLL-specific binding sites (PLL-gg-PEG/biotin,-PEG/biotin,
PPB)PPB)
• specific interactions with cellsspecific interactions with cells

27. Groupmeeting June 2006 27
PLL-g-PEG PrintingPLL-g-PEG Printing
• Variety of techniques investigatedVariety of techniques investigated
• Wet printing of PLL-g-PEG usingWet printing of PLL-g-PEG using
a hydrogela hydrogel
• Passivation of plateauPassivation of plateau
• Backfilling with proteinsBackfilling with proteins
• ReproducibilityReproducibility
• HomogeneityHomogeneity

28. Groupmeeting June 2006 28
Cell Experiments using the micro-3-D deviceCell Experiments using the micro-3-D device
• feasibility to put cells in wells using MDCK cellsfeasibility to put cells in wells using MDCK cells
(Madin-Darby Canine Kidney = cocker spaniel = dog)(Madin-Darby Canine Kidney = cocker spaniel = dog)
• Single Cell Polarization of MDCK cellsSingle Cell Polarization of MDCK cells
• epithelial morphologyepithelial morphology - polarized cells in confluent layer- polarized cells in confluent layer
- columnar shape- columnar shape
• 3-D adhesion and fibronectin matrix assembly3-D adhesion and fibronectin matrix assembly
• CLSM - 3d reconstructionCLSM - 3d reconstruction

29. Groupmeeting June 2006 29
Confocal Laser Scanning MicroscopyConfocal Laser Scanning Microscopy

30. Groupmeeting June 2006 30
Control of Cell Shape - MDCKsControl of Cell Shape - MDCKs
yfp-plasma membrane gp58 (green) lateral marker
CLIP170 (red) growing microtubules

31. Groupmeeting June 2006 31
Control of Cell Shape in 3DControl of Cell Shape in 3D

32. Groupmeeting June 2006 32
Single Cell Polarization of MDCKsSingle Cell Polarization of MDCKs
gp58 (green) lateral marker
CLIP170 (red) growing microtubules

33. Groupmeeting June 2006 33
FN Matrix assemblyFN Matrix assembly
actin (green)
FN (red)

34. Groupmeeting June 2006 34
Control of Cell Shape - cytoskeletonControl of Cell Shape - cytoskeleton

35. Groupmeeting June 2006 35
Conclusions & OutlookConclusions & Outlook
• New tool for model studies on single cellsNew tool for model studies on single cells
• simple replication methodssimple replication methods
• different mechanical propertiesdifferent mechanical properties
• passivation of plateau surface (further optimization needed)passivation of plateau surface (further optimization needed)
• functionalization of microwell surface withfunctionalization of microwell surface with
proteins and PLL-g-PEG/func (other chemistries inside the wells)proteins and PLL-g-PEG/func (other chemistries inside the wells)
• practical devicepractical device
• Applied to different biological questionsApplied to different biological questions
• optimized culture and microscopy conditionsoptimized culture and microscopy conditions
• controlled 3-D shape of single cells (depends on volume of microwell)controlled 3-D shape of single cells (depends on volume of microwell)
• first interesting resultfirst interesting result
• further investigation will lead to a deeper understanding of how the 3-Dfurther investigation will lead to a deeper understanding of how the 3-D
shape controls cell functionshape controls cell function

36. Groupmeeting June 2006 36
Future ApplicationsFuture Applications
Deeper understanding of cells in cultureDeeper understanding of cells in culture
Advanced cell culture modelsAdvanced cell culture models
Integration & MultiplexingIntegration & Multiplexing
• Fundamental Cell BiologyFundamental Cell Biology
• mechanostransductionmechanostransduction
• stem cell differentiationstem cell differentiation
• Pharmaceutical IndustryPharmaceutical Industry
• high through put drug testinghigh through put drug testing
• reduce animal testsreduce animal tests
• Cell based sensorsCell based sensors
• Environmental monitoringEnvironmental monitoring
• Antigen detectionAntigen detection
• Hybrid devicesHybrid devices
• Bio Fuel CellsBio Fuel Cells

38. Groupmeeting June 2006 38
The EndThe End

39. Groupmeeting June 2006 39
AcknowledgmentsAcknowledgments
Prof. Marcus TextorProf. Marcus Textor DoktorvaterDoktorvater
Mirabai Koch, B. NiederbergerMirabai Koch, B. Niederberger Diploma studentsDiploma students BioInterfaceGroupBioInterfaceGroup
D Falconnet, J Lussi, J VörösD Falconnet, J Lussi, J Vörös DiscussionsDiscussions
Prof. Nic SpencerProf. Nic Spencer Head ofHead of LSSTLSST
Dr. Stefan BlunierDr. Stefan Blunier MicrofabricationMicrofabrication IMES, D-MAVTIMES, D-MAVT
Wulf GlatzWulf Glatz SU-8 processingSU-8 processing Micro, D-MAVTMicro, D-MAVT
Matthias Gössi, Jerome LefèvreMatthias Gössi, Jerome Lefèvre Polymer processingPolymer processing Polymer TechnologyPolymer Technology
Brandon BürglerBrandon Bürgler SEM, mental supportSEM, mental support CeramicsCeramics
Dr. GDr. Gáábor Csbor Csúúcscs CLSMCLSM Light Microscopy CenterLight Microscopy Center
Dr. Ruth KroschewskiDr. Ruth Kroschewski
Dominik Schläpfer, Aldo FerrariDominik Schläpfer, Aldo Ferrari MDCK experimentsMDCK experiments BiochemistryBiochemistry
Judith Zaugg, Luzia ReutimannJudith Zaugg, Luzia Reutimann
Dr. Michael Smith, Sheila LunaDr. Michael Smith, Sheila Luna FN, SoftFN, Soft μμ-wells-wells nanomatnanomat
Prof. Viola VogelProf. Viola Vogel Co-refereeCo-referee
Matthias LütolfMatthias Lütolf stem cells, PEG gelsstem cells, PEG gels Stanford, School of MedicineStanford, School of Medicine
Prof. Jeff HubbellProf. Jeff Hubbell Co-refereeCo-referee LMRP, EPFLLMRP, EPFL

40. Form and FunctionForm and Function

41. Groupmeeting June 2006 41
Aristotle – Form and FunctionAristotle – Form and Function
• The material causeThe material cause
• The efficient causeThe efficient cause
• The formal causeThe formal cause
• The final causeThe final cause
From „On the Parts of Animals“From „On the Parts of Animals“
Moreover, when any one of the parts or structures, be it which itMoreover, when any one of the parts or structures, be it which it
may, is under discussion, it must not be supposed that it is itsmay, is under discussion, it must not be supposed that it is its
material composition to which attention is being directed ormaterial composition to which attention is being directed or
which is the object of the discussion, but the relation of suchwhich is the object of the discussion, but the relation of such
part to the total form. Similarly, the true object of architecturepart to the total form. Similarly, the true object of architecture
is not bricks, mortar, or timber, but the house;…is not bricks, mortar, or timber, but the house;…

42. Groupmeeting June 2006 42
Lloyd Wright - Form and FunctionLloyd Wright - Form and Function
American architect (1867–1959)American architect (1867–1959)
““Form follows function- that has beenForm follows function- that has been
misunderstood. Form and function should bemisunderstood. Form and function should be
one, joined in a spiritual union."one, joined in a spiritual union."

43. Groupmeeting June 2006 43
TensegrityTensegrity
Ingber, D.E., Cellular mechanotransduction: putting all the pieces together
again. FASEB J., 2006. 20(7): p. 811-827.

44. Groupmeeting June 2006 44
Single Cell Polarization of MDCKsSingle Cell Polarization of MDCKs
gp58 (green) lateral marker
CLIP170 (red) growing microtubules

45. Groupmeeting June 2006 45
Goal of this Work -Goal of this Work - Micro-3-D Cell CulturingMicro-3-D Cell Culturing
• 2.5 dimensional cell array2.5 dimensional cell array
• single cells (or small clusters)single cells (or small clusters)
• control of 3-D shapecontrol of 3-D shape
• closer tocloser to in vivo ?in vivo ?
• Material engineering aspectsMaterial engineering aspects
• microfabrication techniquesmicrofabrication techniques
• optical propertiesoptical properties
• mechanical propertiesmechanical properties
• area selective surface chemistryarea selective surface chemistry
• device developmentdevice development

46. Groupmeeting June 2006 46
FN Matrix assemblyFN Matrix assembly
actin (green)
FN (red)

47. Groupmeeting June 2006 47
History of cells in cultureHistory of cells in culture
Harrison, R.G., The reaction of embryonic cells to solid structures.
Journal Of Experimental Zoology, 1914. 17(4): p. 521-544.

48. Groupmeeting June 2006 48
Cell Culture ModelsCell Culture Models
• Petri dish -Petri dish - German bacteriologist Julius Richard PetriGerman bacteriologist Julius Richard Petri
(1852-1921) who invented it in 1877(1852-1921) who invented it in 1877

49. Groupmeeting June 2006 49
Cell PatterningCell Patterning
• Cell shape is randomCell shape is random
• The complex ECM protein mixtureThe complex ECM protein mixture
triggers various intracellular signalstriggers various intracellular signals
Tissue culture polystyreneTissue culture polystyrene
Serum proteinsSerum proteins
100 µm
Biologically designed model surfaceBiologically designed model surface
100 µm
• Cell shape is controlledCell shape is controlled
• Defined ligand chemistry onDefined ligand chemistry on
adhesive spotsadhesive spots
• Controlled density of ligandsControlled density of ligands
(peptides or proteins)(peptides or proteins)
Falconnet, D.; Koenig, A.; Assi, T.; Textor, M.Falconnet, D.; Koenig, A.; Assi, T.; Textor, M. Advanced Functional MaterialsAdvanced Functional Materials 2004,2004, 1414, 749-756., 749-756.

50. Groupmeeting June 2006 50
Cell BiologyCell Biology
• Kidney tubuleKidney tubule
Single epithelial layerSingle epithelial layer
• Cell - ECM contactCell - ECM contact
ECM proteins (fibronectin, RGD sequence)ECM proteins (fibronectin, RGD sequence)
αβαβ Integrin binding (transmembrane)Integrin binding (transmembrane)
connection to actin cytoskeletonconnection to actin cytoskeleton
regulation of cell behaviorregulation of cell behavior
spreadingspreading
actin stress fibersactin stress fibers

51. Groupmeeting June 2006 51
Cell BiologyCell Biology
• Polarized epithelial cellPolarized epithelial cell
typical columnar morphologytypical columnar morphology
apical / basal part (outside / inside)apical / basal part (outside / inside)
• Cell partsCell parts
membranemembrane
nucleusnucleus
organellesorganelles
cell - cell contacts, cell - ECM contactscell - cell contacts, cell - ECM contacts
• CytoskeletonCytoskeleton
regulation of cell behaviorregulation of cell behavior
transport and communicationtransport and communication
actin filamentsactin filaments
mechanical structuremechanical structure

52. Groupmeeting June 2006 52
3-D Microscopy3-D Microscopy
• Confocal Laser Scanning Microscopy (CLSM)Confocal Laser Scanning Microscopy (CLSM)
local probe scanning microscopy (STM, AFM, SEM)local probe scanning microscopy (STM, AFM, SEM)
local fluorescence is detectedlocal fluorescence is detected
confocal planes - pinholeconfocal planes - pinhole
3 dimensional, confocal slices3 dimensional, confocal slices
z resolution (600nm) lower than xy (200 nm)z resolution (600nm) lower than xy (200 nm)
crosssection through single well
left unstamped; right 2x stamped
below projection of all confocal
slices

53. Groupmeeting June 2006 53
XPS of embossed PSXPS of embossed PS ↔↔ TCPSTCPS
• After plasma treatmentAfter plasma treatment
embossed PS very similarembossed PS very similar
surface chemistry to TCPSsurface chemistry to TCPS
• ContaminationsContaminations
PDMS (Si)PDMS (Si)
FF
Zn (NW / B-stock)Zn (NW / B-stock)

54. Groupmeeting June 2006 54
MechanotransductionMechanotransduction