The goal is to image surface specific changes, for example, pH, on the surface of implanted medical devices in order to detect and monitor implant associated infection. Early diagnosis of implant-associated infection and noninvasive continuous monitoring of infection is a challenge and the treatment is highly dependent on the detection of infection at its onset. Low pH is believed to be associated with infection as bacteria and inflammatory responses cause a pH drop in affected area and pH shifts to acidic from physiological pH. We are developing a sensor coating to detect these pH changes and thus indicate infection. It consists of a two layered structure: 1) a layer of phosphors (Gd<sub>2</sub>O<sub>2</sub>S:Eu) that act as an in situ X-ray irradiated light source emitting red light, 2) a polymer layer doped with a pH dye that differentially absorbs the phosphor emission depending on the pH, therefore modulating the signal and providing surface specific pH value of the region. These changes in pH are noninvasively imaged using X-ray Excited Luminescence Chemical Imaging (XELCI) through the tissue with high spatial and pH resolution while minimizing tissue scattering effects. This technique allows point by point mapping of the surface with minimum background and high spatial resolution mainly limited by the X-ray beam width. We imaged the pH changes on the implant surface through tissue in vitro, ex-vivo (cadaver study) and in vivo (animal model studies). In future, we plan to study the pH changes on the device surface during infection and antibiotic treatment in animal models. Coating the medical implants with the dye-doped polymer and phosphor based coatings can help to diagnose implant associated infection and assess treatment.

Using dye-doped polymer and phosphor based coatings to image surface specific changes in pH on implanted medical devices through tissue

255th National Meeting (2018)

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