Design and Synthesis of Photoreactive Polymers for Biomedical Applications - Biomimetics: Advancing Nanobiomaterials and Tissue Engineering - page 262

azidoaniline groups, respectively, as shown in Figure 11.10b. The poly-
mer was photoimmobilized onto polyester disks for surface modifi cation.
The effects of this surface modifi cation on the hydrophilic and biofouling
properties were investigated. Static contact angle measurements showed
that the polymeric surface was modifi ed to be comparatively hydrophilic
in the polymer-immobilized region. Micropattern immobilization was car-
ried out with a photolithographic method. AFM measurements showed
that the polymer was formed on the disks in response to UV irradiation.
Protein adsorption was reduced on the polymer-immobilized regions, and
spreading and adhesion of mammalian cells in these regions were reduced
compared with the nonimmobilized regions. Thus, this novel histidine-
containing polymer was immobilized photoreactively onto a conventional
polymer surface and showed reduced interaction with proteins and cells.
11.3.1.4 AmphiphilicPolymers
Polyethylene glycol (PEG) is amphiphilic, and related polymers have non-
ionic hydrated grafted tails that make them hydrophilic. This prevents
biofouling and is helpful in reducing nonspecifi c protein interactions
and ensuring biocompatibility of the biomaterials. We prepared a pho-
toreactive PEG-containing polymer as shown in Figure 11.10c and it was
used to make nonadherent or bio-nonfouling surfaces and for microarray
applications [45]. PEG-methacrylate was copolymerized with acryloyl-
4-azidobenzoic acid in the presence of AIBN as an initiator. The prepared
polymer was coated and photoimmobilized onto plastic, glass, and tita-
nium surfaces. The micropatterned surfaces with photoreactive PEG were
characterized using TOF-SIMS and AFM analyses, which showed that
photoimmobilization had been attained onto the surfaces. Protein adsorp-
tion onto the immobilized regions was reduced and COS-7 cells did not
adhere to the photoreactive PEG-immobilized regions.
Photoimmobilization using photoreactive non-biofouling polymers
has been developed for the preparation of microarray biochips [46-50].
The method is shown in Figure 11.5b. This photoimmobilization method
makes it possible to easily covalently immobilize various types of organic
molecules and cells on a chip as shown in Figure 11.11. In addition, by
using bio-nonfouling polymers as matrixes, it is possible to reduce non-
specifi c interactions with biological components as shown in Figure 11.12.
Various proteins, antibodies, and cells have been microarrayed using this
technique and interactions between these proteins, antibodies, and cells
have been investigated. Because the immobilization method provided
randomly oriented immobilization of proteins including antigens, it is
useful to detect polyclonal antibodies as shown in Figure 11.13. This type
of microarray biochip will be important for applications such as genomics,
proteomics, cellomics, and clinical analyses.