Enhanced fluorescent detection of nucleosomes using functionalized magnetic beads on a digital microfluidic device
Epigenetics, the study of inheritable mechanisms that regulate gene expression, has clinical ramifications from cancer to autoimmune disorders to psychiatric pathologies. The main tool to study epigenetics is chromatin immunoprecipitation (ChIP), which probes the relationship between DNA and its structural nucleosome-forming histone proteins. Standard benchtop ChIP has three major drawbacks: (1) it requires a large input volume of cells, (2) it is very time consuming and work intensive, and (3) it is low throughput. Digital microfluidic biochips (DMFB) have proven to be successful at utilizing small volumes of reagents and samples to perform high throughput bioanalyses and assays of macromolecules. Their ease of configurability, automation, and high sensitivity make them an ideal platform for ChIP adaptation. Previously, we demonstrated the first step towards ChIP implementation on a DMFB by detecting specifically modified nucleosomes, the building blocks of chromatin, in a semi-quantitative nucleosome immunoprecipitation (NuIP) assay. Herein, we modify the prior 'sweep-through' DMFB design to enhance the capture and detection of analyte-bound magnetic beads. With this modification, we can increase both the level of detection and granularity when probing a sample. Furthermore, this new 'pull-through' design presents a novel method for bead collection using an on-chip magnetic source.
