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 416

surface modification was achieved by washing in a hexane solution followed by immer-
sion in a silicone solution further diluted with hexane. BG particles were then applied by
cold pressing, by hand, onto the tubing circumferentially in BG powders. The tubes were
air dried and then placed in an oven at 65°C at ambient humidity for approximately 12 h.
Tubes were then washed in a 1% solution of Triton-X 100 and then gas-sterilized using
ethylene oxide. In vivo testing via subcutaneous implantation in a rat model was per-
formed. No in vivo toxicity was observed. The BG coating demonstrated good bioactivity
in vivo, inducing soft tissue adhesion without the formation of a fibrous tissue coating
(Figure 9.16).

Slurry Dipping
In this technique, coatings have been applied using a suspension of bioactive glass par-
ticles in either a diluted binder or water prior to either:

1. No surface processing of the polymeric material

2. Surface functionalization, via washing with ethanol, of the polymeric material

Without pretreating the scaffold, polyurethane (PUR) foam scaffolds were coated with
bioactive glass (SiO 2 -P 2 O 5 -CaO-MgO-Na 2 O-K 2 O system) particles using slurry dipping
followed by drying at room temperature (see Figure 9.17). PVA (6% polyvinyl alcohol (PVA),
64% water) was used to bind the bioactive glass particles to the scaffold. The glass coating
increased the scaffold stiffness while no statistically significant differences in terms of
failure strength were observed between uncoated and coated scaffold. HA was observed
on scaffold surface after 7 days of soaking in SBS solution.
Using a slurry dipping method including pretreatment with ethanol to reduce substrate
hydrophobicity, macroporous poly(dl-lactide) (PDLLA) foams have been coated with 45S5
Bioglass ® particles [48, 49]. Slurry dipping technique was used in conjunction with pretreat-
ment of the foam with ethanol to produce bioactive glass coatings of uniform thickness
on the internal and external surfaces of the foams. The coating exhibited good adhesion.

SEI 1.0 KV × 270 100 µm WD 40.3 mm JEOL SEI 1.0 KV × 65 100 µm WD 39.8 mm

JEOL

(a) (b)

FIGURE 9.16
Scanning electron micrographs of the bioactive glass-coated silicone tubing segment in (a) the outer surface,
magnification times 270, and (b) cross section, magnification times 65. (Ross et al., Kidney Int. , 63, 702-708, 2003.
With permission [46].)