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Laser based functionalization for graded immobilization of biomolecules on biocompatible polymer surfaces

: Nottrodt, N.; Leonhäuser, D.; Elling, L.; Bremus-Köbberling, E.; Gillner, A.

CeNTech, Münster:
Nanobio Europe. 10th international congress & exhibition on nanobiotechnology. Program and abstracts : Münster, June 2-4, 2014
International congress and exhibition on nanobiotechnology (Nanobio) <10, 2014, Münster>
Fraunhofer ILT ()

Surface modification is a powerful tool for the development of cell
guiding structures for tissue engineering as well as for the development
of in vitro assays for molecular screening. In both applications
the biomolecule concentration linked to the surface is an important
functionalization property. While cell guiding structures need continuous
linear gradients of either increasing or decreasing signaling molecule
concentration, assays for molecular screening need distinct areas
of functionalization for testing of various molecule concentrations.
Therefore a laser based method for local surface activation is under investigation.

Laser irradiation is a powerful tool, which provides a high
temporal and spatial resolution for the generation of structures in the
micrometer range. In the current research we investigated the influence
of UV-Laser irradiation with the wavelengths of 193nm and
248nm on the activation of poly(methyl metacrylate) (PMMA) and
poly-ε-caprolactone (PCL). We demonstrate that PMMA and PCL can
be locally activated. In a subsequent wet chemical step the activated
groups can be functionalized with amine groups. These amines can be
used for immobilization of bioactive compounds like RGD (Arginine-
Glycine-Aspartate)-peptides or lactose. RGD-peptides will serve as
cell recognition domain and enhance cell adhesion, while lactose
serves as a model molecule for further surface modification. We found
out that by defined pulse accumulation the activation dose can be increased.
This leads to an increase of the surface activation and therefore
the increase of the functionalization density.

The successful activation and amination of the surfaces was shown by
staining with an amino-specific fluorescent dye and XPS-analysis. The
process window for PMMA and PCL activation with irradiation of
193nm differ, but the increasing fluorescence signal corresponds to
the increasing irradiation dose. Activation with irradiation of 248nm
leads to a weak surface activation The RGD-peptide functionalized
surfaces have been seeded with neuronal B35-cells which differentiate
under serum deprived conditions. We could successfully demonstrate
that cells favor areas with higher concentration of RGD-peptides.
Finally we showed that lactose can be successfully linked to the
amines. The specific binding of lactose could be demonstrated by
staining with a FITC labeled Erythrina cristagally Lectin.