Development of Smart Potentiometric Sensors Covered with Non-Biofouling Layer for Detection of Early Stages of Inflammatory Processes Around Joint Replacements

Abstract

One of the problems occurring after the joint replacement is connected with the post-surgery infections which are caused by bacteria that form biofilms on surfaces and are referred to as biofilm-related infections (BRI). It is also worth noting that due to the bioresponse, strong pathophysiological changes in the microclimate of an affected surface occur (decrease in pH, formation of various reactive oxygen species (ROS), depletion of Fe ions, and increase in the concentration of Ca ions). In this work we have prepared a robust selective potentiometric sensor of ROS and pH sensor for the detection of pH changes caused by sterile inflammation and bacterial and fungal infections. The ROS sensor consists of a conductive polymer layer based on polythiophene with an incorporated porphyrin-metal complex that potentiometrically detects the presence of ROS (H2O2 and ClO– ions). This sensor is connected by the covalent bonds with a non-biofouling layer of poly(2-methyl-2-oxazoline), which works as a bio-compa­tibilizer. It was shown that the potentiometric sensor shows a rapid response to hydrogen peroxide, does not record any interference with bovine serum albumin as a model serum protein, and is able to fully reversibly detect ROS with a linear response within a wide range of biological relevant concentrations (from 0.05 μM to 10 μM). The sensing electrode based on polyaniline and poly(2-methyl-2-oxazoline) on a titanium alloy support was developed for the potentiometric detection of peri-implant pH changes to enable early detection of the aforementioned pathologies. The developed electrodes show the changing of pH in the range between 5 and 8 for the individual pathogenic bacteria or pathogenic yeast, with a Nernstian slope of −59.6/pH.