Lossless Altered Histone Modification Analysis System (LAHMAS).

Miniaturized biological assays using microfluidics have the potential to enhance assay sensitivity, reduce reagent consumption, and increase throughput. However, challenges to miniaturization include increased platform complexity and increased surface to volume ratios leading to risk of evaporation and analyte loss through surface binding. Exclusive Liquid Repellency (ELR) enables open microfluidic systems that minimize these challenges through an oil phase that protects small aqueous volumes from temperature fluctuation and evaporation while eliminating surface fouling that leads to sample loss. Here we report a novel microfluidic platform leveraging ELR and Exclusion-based Sample Preparation (ESP) for the miniaturization of CUT&Tag, a complex multistep biological assay. The resultant Lossless Altered Histone Modification Analysis System (LAHMAS) employs a PDMS-silane treated glass surface immersed in silicone oil to facilitate lossless liquid handling and prevent sample evaporation. The device design, compatible with standard laboratory equipment, allows effective processing of cell inputs as low as 100 cells with higher specificity than macroscale CUT&Tag facilitating accurate chromatin profiling of low input and rare cell samples.