Effects of cathode design parameters on in vitro antimicrobial efficacy of electrically-activated silver-based iontophoretic system

  • Zhuo Tan
  • Anirudh Ganapathy
  • Paul E. Orndorff
  • Rohan A. Shirwaiker
Engineering and Nano-engineering Approaches for Medical Devices
Part of the following topical collections:
  1. Engineering and Nano-engineering Approaches for Medical Devices


Post-operative infection is a major risk associated with implantable devices. Prior studies have demonstrated the effectiveness of ionic silver as an alternative to antibiotic-based infection prophylaxis and treatment. The focus of this study is on an electrically activated implant system engineered for active release of antimicrobial silver ions. The objective was to evaluate the effects of the cathode design, especially the cathode material, on the in vitro antimicrobial efficacy of the system. A modified Kirby-Bauer diffusion technique was used for the antimicrobial efficacy evaluations (24 h testing interval). In phase-1 of the study, a three-way ANOVA (n = 6, α = 0.05) was performed to determine the effects of cathode material (silver, titanium, and stainless steel), cathode surface area and electrode separation distance on the efficacy of the system against Staphylococcus aureus. The results show that within the design space tested, none of these parameters had a statistically significant effect on the antimicrobiality of the system (P > 0.15). Subsequently, one-way ANOVA (n = 6, α = 0.05) was conducted in phase-2 to validate the inference regarding the non-significance of the cathode material to the system efficacy using a broader spectrum of pathogens (methicillin-resistant S. aureus, Escherichia coli, Streptococcus agalactiae and Aspergillus flavus) responsible for osteomyelitis. The results confirmed the lack of statistical difference between efficacies of the three cathode material configurations against all pathogens tested (P > 0.58). Overall, the results demonstrate the ability to alter the cathode material and related design parameters in order to minimize the silver usage in the system without adversely affecting its antimicrobial efficacy.


Cathode Material Implantable Device Orthopaedic Implant Antimicrobial Efficacy Streptococcus Agalactiae 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



This work was supported by a research Grant from NC State’s 2013 Research and Innovation and Seed Funding (RISF) program. The authors thank Ms. Patty Spears and Ms. Mitsu Suyemoto from NC State University’s College of Veterinary Medicine, and Dr. Gary Payne, Mr. Gregory O’Brian and Dr. Xiaomei Shu from NC State University’s Department of Plant Pathology for their valuable and constructive suggestions during the antimicrobial efficacy testing experiments.


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Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  • Zhuo Tan
    • 1
    • 2
  • Anirudh Ganapathy
    • 1
    • 2
  • Paul E. Orndorff
    • 3
  • Rohan A. Shirwaiker
    • 1
    • 2
    • 4
  1. 1.Edward P. Fitts Department of Industrial and Systems EngineeringNorth Carolina State UniversityRaleighUSA
  2. 2.Medical Implants and Tissue Engineering (MITE) LabNorth Carolina State UniversityRaleighUSA
  3. 3.Department of Population Health and PathobiologyNorth Carolina State UniversityRaleighUSA
  4. 4.UNC-NCSU Joint Department of Biomedical EngineeringRaleighUSA

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