Abstract

Early Diagnosis of Infectious Diseases via a New Biomarker: the Activity of Essential DNA-Modifying Enzymes

Megan Yi-Ping Ho, Assistant Professor, The Chinese University of Hong Kong

Infectious disease, such as malaria and tuberculosis, represents a major threat to global health causing millions of human lives often due to late diagnosis. Although the disorder of enzymatic activities has been associated with many different diseases and stages of diseases, many of the currently prevalent detection methods are not preferred in the clinics because they rely heavily on pre-amplification or post-separation steps. Motivated by the appeal of a sensitive, yet easy-to-assay, sensor system for DNA-modifying enzymes, this talk will highlight the potential of combining DNA-based nanosensors and microfluidics for diagnostics of infectious diseases via a new class of biomarker, the activities of DNA-modifying enzymes. The developed assay has been evaluated for the detection of malaria-causing Plasmodium and tuberculosis-causing mycobacteria, using the activities of plasmodium and mycobacteria topoisomerases, respectively. Moving forward, future development of enzyme based assays hinges on efficient extraction of “active” enzymes from the living organisms, especially from the “hard-to-break” cells, such as bacteria, fungi, and spores. However, many existing technologies fail to maintain the integrity of biochemical contents during the extraction process. We therefore present a new approach by simply entrapping cells in small-volume microdroplets. The microdroplets-based extraction enjoys the benefits of improved reaction kinetics in a confined microenvironment, providing a gentle yet effective approach to break the cells without damaging the biological contents. Taken together, our effort represents a breakthrough in the diagnostics of infectious diseases, particularly in the clinical setting, and is also highly potential for therapeutics applications, such as evaluations of treatment outcome.