Gold nanoparticles on orthopedic implants prevent infection

Destructive electron extraction from bacterial membranes by plasmonic gold nanoparticles--Courtesy of Jinhua Li/SICCAS

Gold nanoparticles help prevent the formation of antibiotic resistant biofilm on the surface of orthopedic implants, researchers at the Shanghai Institute of Ceramics discovered.

"Implant-associated infections have become a stubborn issue that often causes surgery failure," said Xuanyong Liu, the team's primary investigator. In fact, speakers at an FDA hearing on topic in February said that infection was responsible for 27,000 hip and knee revision surgeries in 2010 at a cost of $1 billion. The 5-year survival rate of patients with prosthetic joint infections is 65%, lower than of some types of cancer.

In experiments, gold nanoparticles achieved their antibacterial properties by interacting with titanium dioxide, the surface of many implants. Titanium dioxide is a potent electron acceptor when exposed to light, and that process degrades bacteria, the researchers said. But the inside of the body is a dark place, they point out. 

However, the researchers found that gold nanoparticles can pass electrons to titanium dioxide instead due to a phenomenon known as localized surface plasmon resonance, which they describe as the "collective oscillations of electrons that occur at the interface between conductors and dielectrics--such as between gold and titanium dioxide."

Titanium infused with gold nanoparticles proved inhospitable to Staphylococcus aureus and Escherichia coli bacteria, according to the release. 

Silver is often added to orthopedics to combat biofilm, but the researchers say gold is the more chemically stable and biocompatible element. Biofilm forms, when bacteria colonize a surface (such as the surface of an implant), create an extracellular matrix that shields them from the body's immune system as well as antibiotics.

 - read the release

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