Document Type

Honors Capstone Project

Date of Submission

Spring 5-1-2012

Capstone Advisor

Dr. Jeremy Gilbert

Honors Reader

Dr. Dacheng Ren

Capstone Major

Biomedical and Chemical Engineering

Capstone College

Engineering and Computer Science

Audio/Visual Component

no

Capstone Prize Winner

no

Won Capstone Funding

no

Honors Categories

Sciences and Engineering

Subject Categories

Biomedical Engineering and Bioengineering

Comments

This study was undertaken to investigate whether inducing electrical currents in Ti6Al4V alloy implants in organic systems holds promise as a means to combat the growth of biofilm infections. Prior research has shown the electrochemical reactions occurring on the surface of titanium alloys allow implants placed in contact with ionic solutions found in the body to negatively affect the viability of MC3T3 cells. If this holds true for bacteria, then the study of biofilms and their electrochemical interaction with titanium alloy implants may therefore lead to novel approaches to combating multidrug tolerant infections in implant patients.

Imaging analysis was conducted utilizing a Scanning Electron Microscope (SEM). Live/Dead cytotoxicity staining assay and fluorescent microscopy were also performed. E. coli HM22 was cultured and plated on Ti6Al4V discs, then inserted into custom-made electrochemical cell culture chambers under fresh LB media, and further incubated. Electrical contacts were attached to the Ti6Al4V disc and used to expose the sample to a voltage potential. Samples were tested at static potentials between -800 mV and +800 mV for a period of 24 hours versus Ag/AgCl. Samples were either fixed and dehydrated with formaldehyde and ethanol for SEM imaging or stained for live/dead imaging.

The results of this study indicate that cathodic polarization below -400 mV dramatically reduces the viability of E. coli biofilm cultured directly upon Ti6Al4V within 24 hours. Anodic polarization above -400 mV did not display statistical differences in viability as compared to OCP conditions after 24 hours. SEM imaging found no statistical difference in surface coverage between OCP and samples treated with anodic potentials below -200 mV. Cathodic potentials above OCP did, however, display increased surface coverage as compared to samples at OCP.

These outcomes may have clinical significance for titanium modular orthopedic implants. Via corrosion, the potential of such implants can shift down into cathodic ranges that exhibit poor biofilm viability and performance. These outcomes indicate that it might be possible to design improved metal alloy implants that naturally generate or through added active electronics generate specific cathodic potentials that might in the future be used to reduce or eliminate bacterial infections in implant patients.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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