Electrochemical Biosensor to Detect Implant-Derived Metal Ions: A Mice Model

Joint replacement surgeries are progressing at an increased rate in the USA, with around 1 million surgeries being performed annually. While these orthopedic implants provide a solution for a damaged joint, debris such as metal ions generated due to the wear and corrosion of the implants prove to be of considerable risk of systemic and local toxicity. As an effective diagnostic tool, there is a need to develop a patient-friendly, cost-effective, and rapid mode of metal ion detection in orthopedic patients with various implants. In this study, an electrochemical biosensor chip (Dropsens) is proposed as a diagnostic tool to detect metal ions through changes in impedance. In vivo studies were conducted using CoCrMo particles intraarticularly injected into mice. Then, blood was collected on 0th day, 14th day, and 28th day after injection and was centrifuged to obtain serum. The serum was subject to various electrochemical techniques, such as Electrochemical Impedance Spectroscopy (EIS) and cyclic voltammetry (CV). Additionally, standardization experiments were performed using different concentrations of CoCrMo wear particles suspended in PBS and mice serum. EIS results reveal a negative correlation between impedance (Rp) and the metal ion concentration in the standardization experiments. EIS and CV standardization data were used to obtain a regression equation which were later used to estimate the metal ion concentrations in experimental samples. Here, the positive control group shows the highest impedance at any frequency followed by the 28th-day experimental mice serum as seen on the bode plot. CV experimental data reveal a possible correlation between CV area and the metal ion concentrations. In this study, experimental mice models were established to mimic the possible diffusion of metal particles from implants. Dropsens electrochemical biosensors were efficiently employed to detect metal ions in serum through changes in impedance.