Student Research

Biofilm Formation on Human Prosthetic Metal Alloys

Human prosthetics are being utilized more frequently as the populations that require their use expand. Solid biomaterials with characteristics, such as high biocompatibility or corrosion resistance, are now being implanted in the human body more frequently for wide range of purposes. However, implant-related infection is generally the most common serious complication. When bacteria adhere to and proliferate on the biomaterial surface, the bacteria produce extracellular polymeric substances, primarily polysaccharides, which mediate cell-to-cell adhesion and form a biofilm. Our long-term goal is to extend the life of a prosthetic implant by identifying new metal alloys that are less susceptible to bacterial colonization. Using two major biofilm-producing bacteria commonly found to colonize surgical implants, Staphylococcus epidermidis and Pseudomonas aeruginosa, we investigated the biocompatibility of novel metal alloys with regard to their susceptibility to biofilm propagation. We examined stainless steel (SS), commercially pure titanium (CPTi), titanium alloy (Ti64), dental grade titanium (Ty) and titanium-boron metal alloys. Biofilm formation was analyzed using crystal violet staining and fluorescent microscopy. Ideal experimental conditions were obtained using flasks or a biofilm reactor. Biofilm reactor experiments were performed with (continuous culture) or without (batch culture) a constant infusion of growth media during biofilm formation. Results indicate that, compared to SS, Titanium-boron metal alloys displayed the least biofilm formation by both bacteria. Specifically, Ti64+0.04%B and Ti64+0.1%B for Staphylococcus epidermidis and CpTi+0.1%B for Pseudomonas aeruginosa. Thus, we show that, compared to traditional metals such as SS and CPTi, Titanium-boron metal alloys may be better alternatives as a modern prosthetic biometals.

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