[nanoPost] Biocompatible nanocoatings

Company Germany

Surface-modified Silicone Rubber poly(dimethylsiloxane) [PDMS]

• The very first step towards "bio"compatibility.
• Silicone articles like contact lenses, tubing, catheters, gaskets  ... obtain new surfaces.
• Stands for equipping the (wettable) surface of silicone components with functional groups, e.g.
  -COO-
   carboxylate
  -NH3+
   ammonium 
  -OH
   hydroxy 
  -...
   other groups  
   
• Allows the bonding of biologically active compounds
  proteins (antibodies, enzymes)
  polysaccharides
  pharmaceuticals
  metals
  dyes
  other compounds (covalently or ionically) 
• Properties of the modified silicone surface: 
  reduced tack compared with untreated surfaces
  smoother surfaces with reduced friction
  hydrophilic i.e. water-wettable
  - concave menisci with water
  - contact angles drop from 105° to 30°
  - surface free energy increases from 22 mN/m to approx. 56 mN/m
  reduced electrostatic charging
  - surface resistivity drops from 1015 to 106 Ohm
  altered permeability
  - increased permeability to polar compounds, e.g. water
  - decreased permeability to lipophilic (hydrophobic) compounds, e.g. oil
• Tune these and other properties according your requirements.
• is accomplished by a specific wet-chemical process.
  Essentially two steps are adding value to silicone components (e.g. medical devices).
  The density of functional groups per cm2 is tailorable according your needs.