DESIGN, DEVELOPMENT, AND VALIDATION OF A NOVEL OPTICAL IMAGING DEVICE FOR BIOMEDICAL APPLICATIONS

Abstract

Fluorescence and luminescence imaging are two promising optical techniques for diagnosing a variety of critical pathologies in vivo, including wound healing, inflammation, and vascular diseases. Despite this, there is a lack of imaging devices in research and commercially available that are capable of these imaging modalities in large animal applications. This work describes the progressive development of several optical imaging devices to fill this void, culminating in a final design with robust fluorescence and luminescence functionality designed for large animal and human applications. These devices are used to gather new data about various physical parameters in small and large animal models. First, a portable imager developed for real-time imaging of cutaneous wounds in research settings is described. The device is demonstrated to have competitive performance with a commercial animal imaging enclosure box setup in beam uniformity and sensitivity. Specifically, the device was used to visualize the bioluminescence associated with increased reactive oxygen species (ROS) activity during the wound healing process in a cutaneous wound inflammation model. In addition, this device was employed to observe the fluorescence associated with the activity of matrix metalloproteinases (MMPs) in a mouse lipopolysaccharide (LPS)-induced infection model. Our results support the use of the portable imager design as a non-invasive and real-time imaging tool to assess the extent of wound inflammation and infection. The second component of this work details the development and characterization of a portable luminescence imaging device for detecting inflammatory responses and infection in skin wounds. This imager was used to quantify in real time the extent of 2D reactive oxygen species (ROS) activity distribution using a porcine wound infection model. The imager was used to successfully visualize ROS-associated luminescent activities in vitro and in vivo. Using a pig full-thickness cutaneous wound model, the luminescence imager was further demonstrated to be capable of detecting the change of ROS activities and their relationship with vasculature in the wound environment. Finally, by analyzing ROS intensity and distribution, an imaging method was developed to distinguish infected from uninfected wounds. These results demonstrate the potential discovery of a distinct ROS pattern between bacteria-infected and control wounds corresponding to the microvasculature. The final piece of this work describes the design, manufacture, and testing of several fluorescence imagers improving on the design developed in the first part of this work, as well as the development of a penultimate combination fluorescence/luminescence imaging device. This device is compared against a robust industry-standard device and found to be suitable for large animal and potential clinical applications.