Artificial Scaffolds and Mesenchymal Stem Cells for Hard Tissues - Tissue Engineering: Cell-Surface Interactions for Tissue Culture - page 172

nanoparticles of carboxymethylchitosan/poly(amido amine) dendrimer have been
synthesized and used as intracellular drug delivery systems. Results proved a non-
cytotoxic in vitro behavior, supporting cell attachment and incorporation. In vivo
experiments using rats could demonstrate a good performance of dendron-like
nanoparticles for intracellular delivery of dexamethasone [ 114 ].
In addition, conventional surface coating can be performed via chemical and
physical vapour deposition (CVD, PVD) methods. CVD and PVD are well-known
technologies mainly used in the microelectronics industry to modify surfaces.
Werner and co-workers used ammonia plasma treatment and studied maleinic
acid-based co-polymer surfaces immobilized with amines. Plasma-immobilized
hydrogels of poly(N-alkylacrylamide)-g-poly(ethylene glycol) were prepared
using ammonia plasma treatment of poly(3-hydroxybutyrate). A platform of
thin polymer coatings was introduced for the functional modulation of immobi-
lized bioactive molecules at solid-liquid interfaces. The approach is based on
covalently attached alternating maleic acid anhydride copolymers with a variety of
co-monomers and extended through conversion of the anhydride moieties by
hydrolysis, reaction with functional amines, and other conversions of the anhy-
dride moieties. We demonstrated that these options permit control of the physi-
cochemical constraints for bioactive molecules immobilized at interfaces to
influence important performance characteristics of biofunctionalized materials
for medical devices and molecular diagnostics. Examples concern the impact of
the substrate-anchorage of fibronectin on the formation of cell-matrix adhesions,
the orientation of endothelial cells according to lateral anti-adhesive micropatterns
using grafted PEO, and the spacer-dependent activity of immobilized synthetic
thrombin inhibitors [ 144 ].
4.1.2 Modification of Surface Topography
Cellular behavior can be influenced and even dictated in a controlled manner by
topographically patterned surfaces [ 145 ]. Surface roughness at the micro- and even
nanoscale is known to influence biocompatibility of synthetic materials used for
tissue engineering applications. Furthermore, adhesion and alignment strongly
depends on micro- and nanotopographical features. Symmetry and regularity of
surface patterns (isotropic versus anisotropic grinding) causes differences in cell
responses. Conventional surface modification strategies can be divided into two
groups. The first one covers methods which changing surface chemistry and
topography: e.g., chemical adsorption, plasma treatment methods, and chemical
etching. The second group alters surface topography: mechanical roughening, the
so-called substrate templating methods (e.g., lithography), electro and vapour
deposition methods, and novel moulding processes [ 146 ]. In the last decade,
material surfaces used for tissue engineering applications have been micro- and
nanostructured during scaffold fabrication via solid freeform techniques, e.g., 3D
printing, 3D plotting [ 117 , 147 ]. Rapid prototyping processes do show differences
in resolution and all are characterized by advantages and certain limitations.