September 9, 2009

Bacteria used to make better bone implants

British scientists say they've discovered bacteria that produce hydroxyapatite, a mineral form of calcium, could be used to make better bone implants.

Researchers at the University of Birmingham, led by Professor Lynne Macaskie, said they discovered serratia bacteria cells stick tightly to surfaces such as titanium alloy, polypropylene, porous glass and polyurethane foam.

The cells form a biofilm layer containing biopolymers that acts as a strong adhesive. The scientists said a hydroxyapatite coating then builds up over the surface. For practical use, the coating must stick tightly, then the material is dried and heated to destroy the bacteria.

They said they determined the bioglue adhesion stuck 20 times more tightly than fresh biofilm. And, when coated with hydroxyapatite, the adhesion became even stronger.

Current bone implant materials are made by spraying-on hydroxyapatite, but the researchers said that does not have good mechanical strength and the spraying only reaches visible areas. They said their new biocoating method reaches all hidden surfaces.

The bacteria are destroyed by heating, leaving just the (hydroxyapatite) stuck to the surface with their own glue -- rather akin to a (burned) milk saucepan, said Macaskie, We need to do more work actually to turn the materials into materials we can use in biomedicine and the environment.

The study was presented this week in Edinburgh, Scotland, during a meeting of the Society for General Microbiology.