We have developed a novel method to analyze deoxyribonuclease (DNase) activity using conjugation-free fluorescence polarization in a droplet-based microfluidic chip. DNase is a crucial enzyme that cleaves DNA and plays a significant role in maintaining normal cellular functions. Changes in DNase activity are linked to various cancers and autoimmune diseases. Traditional methods for analyzing DNase activity are costly, requiring large sample volumes and fluorescent dye conjugation. Our approach uses ethidium bromide (EtBr), a DNA intercalating agent, as a fluorescent reporter without needing prior DNA conjugation or modification. The degradation of DNA by DNase 1 is monitored by changes in EtBr fluorescence polarization within 330 picoliter droplets at a frequency of 40 Hz under visible light. This technique successfully determined the half-maximal inhibitory concentration (IC50) of ethylenediaminetetraacetic acid (EDTA) for inhibiting DNase 1 activity to be 1.56 ± 0.91 mM. -Scientific Journal cover design by scapiens

https://pubs.rsc.org/en/content/articlelanding/2020/an/c9an02380a#!divAbstract