Assessing the efficiency of reactive oxygen species colorimetric sensors for use in environmentally & biologically relevant samples
Date
2020
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Publisher
University of Delaware
Abstract
A longstanding interest in reactive oxygen species (ROS) stems from their role in many environmental, biological, clinical, and industrial processes. Molecular spectroscopic methods have largely dominated the field of ROS detection due to its many advantages for real–time, localized, in situ analysis, with comparatively modest equipment cost and expertise requirements. This has led to a focus on spectral detection of ROS, and many advances in ROS sensor technologies for spectrophotometric (colorimetric) and luminescence measurements. Although many advances in ROS sensor technologies for spectrophotometric and luminescence measurements have been made to enhance selectivity and time response in ROS detection, there has been less attention given to the impact of sample complexity on sensor measurements. ROS are typically generated and evolve in complex settings, making their detection and quantification challenging. Often, detecting a change in a system’s redox status is generally attainable, but accurate quantification is not, and poor selectivity of many classic and novel ROS sensors increases the incidence of overinterpretation of results by the scientific community. ☐ The objective for the research contained in this dissertation is to demonstrate the efficiency, or lack thereof, of select commercially available colorimetric ROS sensors for their use in environmentally and biologically relevant samples, as well as investigate potential improvements to the analysis of optical data resulting from sensor measurements using a vigorous series of control measurements and numerical analysis strategies. In this dissertation sensor stability was evaluated using two types of assay control measurements: broadband molar absorptivity, and photostability under broadband simulated sunlight. Then, an efficiency comparison of the imidazole plus RNO method for singlet oxygen detection in biorelevant solvents was compared to reference solvents using Rose Bengal photosensitization to produce 1O2 and time-resolved, broadband UV–Vis absorbance measurements to simultaneously monitor sensor and sensitizer response profiles. In the final chapter, the impact of combining the results of systematically varied assays and controls on the analysis of colorimetric data collected using the Imd plus RNO method was investigated using a combination of numerical analysis strategies.
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Keywords
Colorimetric sensors, Optical detection, Photosensitization, Reactive oxygen species, Singlet oxygen, Superoxide