Development of Smart Sensing Film with Nonbiofouling Properties for Potentiometric Detection of Local pH Changes Caused by Bacterial and Yeast Infections Around Orthopedic Implants

The local peri-implant pH changes caused by sterile inflammation and bacterial and fungal infections are studied herein. Then, a sensing electrode based on polyaniline and poly(2-methyl-2-oxazoline) on a titanium alloy support is developed for potentiometric detection of peri-implant pH changes to enable early detection of the aforementioned pathologies. The infected endoprosthesis area is shown to have an average pH of 0.79 units lower than the aseptic sample. The pH measurements of the individual pathogenic bacteria or pathogenic yeast reveal that Escherichia coli decreased the pH by 1.24 units, Staphylococcus aureus decreased the pH by 1.33 units and the methicillin-resistant Staphylococcus aureus bacteria decreased the pH from 7.2 to 5.6 during 10 h, followed by a subsequent increase to 6.4. The results are statistically significant (alpha = 0.01). Pseudomonas aeruginosa is not shown to change pH levels. On the other hand, the pathogenic yeast has the lowest recorded pH, which decreases from 5.8 to 4.8. This difference in pH can be used to identify the nature of the infection. The developed electrodes have a pH response between pH 5 and 8, with a Nernstian slope of -59.6/pH. The developed electrode can contribute to the next generation of biosensors.