Bioactive Glass-Based Coatings and Modified Surfaces: Strategies for the Manufacture, Testing, and Clinical Applications for Regenerative Medicine - Biological and Biomedical Coatings: Processing and Characterization - page 420

TABLE 9.24
Range of Cellular Reactions to Nanomorphology

CellProperty CellType TopographicalFeature CellularReaction

Adhesion Fibroblasts Nanopits Decrease

27-nm high nanoislands Increase

Nanopillar Depends on spacing

Osteoblasts Nanopits (near-square) on

PMMA and silica

Decreased

Pyramids on Ti Decreased

Activation Platelets and monocytes Nanodeep grooves Increase

Random hills Increase

Movement Smooth muscle cells Nanodeep grooves Increase

Fibroblasts Nanopillar Depends on spacing

Morphology Smooth muscle cells Nanodeep grooves Alignment

Epithelia Nanodeep grooves on silica

oxide

Alignment

Fibroblasts Nanoprojections

(pores, gratings, columns,
dots, pits)

Alignment

Shape Fibroblasts Random surface roughness Spreading

Proliferation Fibroblasts (corneal) Nanodeep grooves Little effect

Fibroblasts Nanoprojections Lower

Osteogenesis Osteoblasts Random nanoislands Raised

Nanopits Raised

Nanogrooves Raised

Nanofeatures can be created using either top-down or bottom-up manufacturing pro-
cess. Top-down methods include electron beam lithography (via e-beam, x-ray beam, ion
beams) and holographic writing methods, while bottom-up methods include colloidal
lithography and polymer demixing.
There are limited reports of top-down methods being applied to bioceramic substrates as
these techniques have been developed for metallic substrates. In the bottom-up approach,
the nanofeatures are assembled from nanometric-sized components, for example nano-
powders and nanofibers. The powders and fibers can themselves be used as the topologi-
cal features coated on an implant surface [55-57, 59].

Nanoparticles
The work by Watari and coworkers [58] gives an indication of possible effects of engi-
neered nano-sized features on biological activity. Using various-sized particles (range
500 nm-150 μm) of pure Ti, Fe, Ni, TiO 2 , and carbon nanotubes (CNTs), they investigated
the effect of material nanosizing on cell proliferation and animal implantation testing.
They found:

• Increase in specific surface area caused the enhanced release of ionic dissolution
products resulting in local toxicity.
• For nonresorbable particles, there was a critical size for the transition of cellular
behavior at approximately 100 μm, 10 μm, and 200 nm. Below 100 μm, the particles