Biomedical Engineering Reference
In-Depth Information
Cells
PDMS
100 µm
FIGURE 2.42
Cells.selectively.attached.on.microtextured.surfaces..(From.Albert.Folch.and.Mehmet.
Toner,.“Cellular.micropatterns.on.biocompatible.materials,”.
Biotechnol. Prog.
14,
388-s392,.1998..
Figure.contributed.by.the.author.)
ibronectin-coated PDMS mesas. he inverse is also possible: by perfusing a PDMS microchan-
nel with ibronectin and using the PDMS surface as the cell culture surface to seed the cells in
trenches, Mehmet Toner's group at Harvard Medical School succeeded in creating “quasi-3-D”
cell cultures that wrapped around the walls of the trenches (
Figure 2.42
). An extension of this
method is the trapping of cells in microwells (see Section 5.3.1).
2.6.3 Cells on Chemisorbed Patterns of Speciic Peptide Sequences
Cell attachment and spreading may be promoted on surfaces derivatized with RGD and similar
peptide sequences identiied by cell adhesion receptors on the cell membrane (see Section 2.1.3).
In light of these indings, several groups have developed eforts to micropattern cell attachment
peptides on a range of materials.
2.6.3.1 Selective Attachment of Peptides on Heterogeneous Surfaces
In 1995, Patrick Aebischer and coworkers, then at Lausanne University in Switzerland, hydroxy-
lated selected areas of a luoropolymeric surface by radiofrequency glow discharge through a
stencil mask. Oligopeptides containing the laminin fragments YIGSR and IKVAV could be
immobilized by their C-terminus via a nucleophilic substitution reaction (in the presence of
potassium carbonate) or, alternatively, by their N-terminus using carbonyldiimidazole as a cou-
pling agent. Neuroblastoma cells were shown to attach preferentially to the peptide-derivatized
surface in 10% fetal calf serum.
Similarly, Wolfgang Knoll's group from the Max Planck Institute for Polymer Research in
Mainz, Germany, created in 1996 micropatterns of a synthetic peptide derived from the neurite
outgrowth-promoting domain of the B2 chain of laminin (
Figure 2.43
). First, a glass surface
was derivatized with an aminosilane SAM. hen, the SAM was photoablated on certain areas
by exposure to a high-radiance (~10 J/cm
2
) deuterium lamp through a chrome mask. Once the
aminosilane pattern was created, the cysteine-labeled peptide was coupled to the aminosilane
areas via a cross-linker,
N
-(γ-maleimidobutyryloxy) sulfosuccinimide ester, which reacts with
amines and thiol groups (in this case, the amine groups on the SAM and the thiol group on the
cysteine). he irradiated areas were observed to be cell repellent. he peptide-modiied stripes
guided the growth of rat hippocampal neurons with a morphology resembling that of neu-
rons cultured on laminin-coated surfaces. he same chemistry has been used to make neurons
adhere onto a ield-efect transistor array.
