New alloy mix boosts 3D implants, cuts 87% of staph bacteria

Amit Bandyopadhyay, corresponding author on the paper and Boeing Distinguished Professor in WSU's School of Mechanical, stated: 

"Infection is a problem for which we do not have a solution. In most cases, the implant has no defensive power from the infection. We need to find something where the device material itself offers some inherent resistance—more than just providing drug-based infection control. Here we're saying, why not change the material itself and have an inherent antibacterial response from the material itself?"

it's also made to be more compatible with the body and stronger than previous implant materials. This indicates that supports the body better, relieves stress without wearing out quickly, and even integrates more effectively with the surrounding bones.

This invention essentially creates a new kind of implant material that fights off bacterial infections better while also being more compatible with the body and stronger, potentially improving the success rates of orthopedic implants and reducing complications for patients.

Researchers conducted the study on bacterial colonization of orthopedic implants, fabrication of Ti3Al2V alloy, and analysis of Ti-Tantalum (Ta)–Copper (Cu) alloys. 

According to the study, scientists implemented laser powder bed fusion to create a Ti3Al2V alloy using a mixture of CpTi and Ti6Al4V powders. The new metal was further modified by adding Ta and Cu to enhance biocompatibility and impart bacterial resistance. 

The biological, mechanical, and tribo-biocorrosion properties of these alloys were evaluated, focusing on resistance against Pseudomonas aeruginosa and Staphylococcus aureus bacteria.

Copper effectively fights bacteria

Upon analysis, they found by adding a bit of copper to a certain metal mix, they made something that could fight off bad bacteria effectively. Furthermore, it can handle lots of pressure without deteriorating quickly.

The study noted that the addition of 3 wt. percent Copper (Cu) to the Ti3Al2V alloy significantly improved its antibacterial effectiveness. This modification exhibited a notable 78 percent–86 percent efficacy against Pseudomonas aeruginosa and Staphylococcus aureus strains, surpassing the performance of CpTi.

According to the study, Ti3Al2V–10Ta–3Cu alloy exhibited remarkable mechanical properties, including fatigue resistance, enhanced strength, and improved tribological and tribo-biocorrosion characteristics compared to the commonly used Ti6Al4V alloy.

Moreover, in vivo studies conducted on a rat distal femur model revealed enhanced early-stage osseointegration for alloys containing 10 wt. percent Tantalum (Ta), surpassing the osseointegration observed with CpTi and Ti6Al4V. This implied a more reasonable integration of the implant with surrounding bone tissue.

The qualities displayed by the new metal blend suggested it could be a strong contender for upcoming load-bearing metallic implants.

Susmita Bose, co-author and Westinghouse Distinguished Professor in the school, said that the biggest advantage of this type of multifunctional device is that one can use it for infection control as well as for good bone tissue integration. 

"Because infection is such a big issue in today's surgical world, if any multifunctional device can do both things, there's nothing like it."

The study was published on November 17 in the journal – IOP Science.

Study abstract:

Bacterial colonization of orthopedic implants is one of the leading causes of failure and clinical complexities for load-bearing metallic implants. Topical or systemic administration of antibiotics may not offer the most efficient defense against colonization, especially in the case of secondary infection, leading to surgical removal of implants and in some cases even limbs. In this study, laser powder bed fusion was implemented to fabricate Ti3Al2V alloy by a 1:1 weight mixture of CpTi and Ti6Al4V powders. Ti-Tantalum (Ta)–Copper (Cu) alloys were further analyzed by the addition of Ta and Cu into the Ti3Al2V custom alloy. The biological, mechanical, and tribo-biocorrosion properties of Ti3Al2V alloy were evaluated. A 10 wt.% Ta (10Ta) and 3 wt.% Cu (3Cu) were added to the Ti3Al2V alloy to enhance biocompatibility and impart inherent bacterial resistance. Additively manufactured implants were investigated for resistance against Pseudomonas aeruginosa and Staphylococcus aureus strains of bacteria for up to 48 h. A 3 wt.% Cu addition to Ti3Al2V displayed improved antibacterial efficacy, i.e. 78%–86% with respect to CpTi. Mechanical properties for Ti3Al2V–10Ta–3Cu alloy were evaluated, demonstrating excellent fatigue resistance, exceptional shear strength, and improved tribological and tribo-biocorrosion characteristics when compared to Ti6Al4V. In vivo studies using a rat distal femur model revealed improved early-stage osseointegration for alloys with 10 wt.% Ta addition compared to CpTi and Ti6Al4V. The 3 wt.% Cu-added compositions displayed biocompatibility and no adverse inflammatory response in vivo. Our results establish the Ti3Al2V–10Ta–3Cu alloy's synergistic effect on improving both in vivobiocompatibility and microbial resistance for the next generation of load-bearing metallic implants.