With support from the Chemical Measurement and Imaging (CMI) Program in the Division of Chemistry, Professor Samuel Thomas at Tufts University and his group will develop a new approach to signal amplification in fluorescent assays. Fluorescent sensors and assays are a key set of technologies in analytical science, and amplification of fluorescent response to a specific molecule or other stimulus is critical to the required high sensitivity of many technologies such as ELISA. There is a need, however, to develop new approaches that improve performance through increased quantitative accuracy, robustness in challenging environments, and reduced false positives and negatives. The objective of this project is to test the hypothesis that combining two forms of amplification: 1) chemical amplification of singlet oxygen (1O2) through photosensitization, and 2) light harvesting and exciton mobility will yield multiplicatively amplified fluorescent response that is useful in bioanalytical applications. The group will pursue the following two objectives to test their central hypothesis: 1) Demonstrate multiplicative amplification of fluorescence response of conjugated polymers substituted with traps that react with singlet oxygen, and 2) Use singlet oxygen-responsive polymers to detect target biomolecules at 1.0 pM or lower with high selectivity using sandwich assays. Successful realization of this approach would yield a unique and useful combination of features, such as a ratiometric response and the lack of a requirement for a large enzyme label, which overcomes limitations of current approaches and is potentially useful across a range of analytical applications. The broader impacts of the proposed work will be twofold: 1) a new method for amplifying fluorescent signal has the capability to improve to experimental techniques that rely on sandwich assays such as analysis of clinical samples and high-throughput drug discovery; 2) a program that integrates this research in organic photochemistry with demonstrations and experiments at Bunker Hill Community College, with which Prof Thomas already has a working relationship.
Signal amplification?processes that convert a small quantity of sample into a comparatively large readout?are an underlying key to the high sensitivity of modern sample analysis both in the clinic and in the field, in applications such as analysis of DNA or proteins by fluorescence. Limitations of current gold standard methods of amplification, however, are preventing the development of next-generation technologies that can detect targeted molecules at lower levels with reduced false positives and false negatives, especially outside the clinic, where there is a lack of control over environmental conditions. By combining two known methods of signal amplification with specially designed fluorescent materials, this proposed interdisciplinary research will yield a new approach to amplifying fluorescent signal that will be generally useful in a range of bioanalytical applications. Advantages of this approach over state-of-the-art technologies include 1) a more robust readout method of fluorescent signal, 2) no requirement for large enzyme labels, which can cause problems with both stability and sensitivity of an assay, to achieve amplification, and 3) increased sensitivity due to the combination of two forms of amplification. In addition to the benefit to society that such research achievements would provide, the group will also integrate their research into an outreach program at Bunker Hill CC, a nearby community college in Boston where 80% of the students belong to minority groups and over 50% are women, to develop experiments and demonstrations to give students hands-on experience with photochemistry, including using materials they develop in the research.
