AVS 50th International Symposium
    Biomaterial Interfaces Wednesday Sessions
       Session BI+SS-WeM

Paper BI+SS-WeM3
Molecular Assembly Patterning by Lift-off (MAPL): A Novel Approach to Produce Biologically Designed Micropatterns for Biosensor Applications and Cell-Surface Interaction Studies

Wednesday, November 5, 2003, 9:00 am, Room 307

Session: Cell Interactions with Patterned Surfaces
Presenter: D. Falconnet, Swiss Federal Institute of Technology (ETH) Zurich
Authors: D. Falconnet, Swiss Federal Institute of Technology (ETH) Zurich
F. Assi, Swiss Federal Institute of Technology (ETH) Zurich
A. Koenig, Swiss Federal Institute of Technology (ETH) Zurich
M. Textor, Swiss Federal Institute of Technology (ETH) Zurich
Correspondent: Click to Email
A new chemical micropatterning technique is presented for cell-surface interaction studies. The MAPL technique allows creating patterns of bioactive molecules (such as biotin, peptides, oligonucleotides) at a controlled surface density and embedded in a background resistant to the adsorption of proteins. A simple photoresist lift-off process is exploited in conjunction with the spontaneous assembly of polycationic poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG) onto negatively charged metal oxide surfaces. A positive photoresist on a metal-oxide-coated substrate (e.g. niobium oxide coated on glass) is developed resulting in a micropattern of resist and bare metal oxide areas. Bio-functionalized (e.g., biotin or cell-adhesive peptide) PLL-g-PEG is immobilized at the bare metal oxide regions by spontaneous assembly from aqueous solutions of the polymer. The photoresist is lifted off in an organic solvent without affecting the integrity of the adsorbed functionalized PLL-g-PEG monolayer. Subsequently, the background is backfilled with protein- and cell-resistant PLL-g-PEG. The resulting pattern of bio-interactive and non-adhesive areas shows an excellent contrast on the protein level, demonstrated by fluorescence microscopy using labeled streptavidin to specifically decorate the PLL-g-PEG/PEG-biotin patches. Cell attachment to such micropatterns consisting of PLL-g-PEG/PEG-RGD-peptide was tested using human foreskin fibroblasts. This lift-off-based biochemical patterning is a 'soft', robust, simple and reproducible technique that does not require specialized clean room and heavy etching facilities. It is an interesting alternative to microcontact printing because it circumvents many disadvantages of the printing technique. The high signal-to-noise ratio and the feasibility of tailoring the bioligand (capture molecule) density in the interactive patches make MAPL a promising technique also for biosensor microarray applications.