Supporting data: 3D projection electrophoresis for single-cell immunoblotting (Part 2)

Immunoassays and mass spectrometry are powerful single-cell protein
analysis tools; however, interfacing and throughput bottlenecks remain.
Here, we introduce three-dimensional single-cell immunoblots to detect
both cytosolic and nuclear proteins. The 3D microfluidic device is a
photoactive polyacrylamide gel with a microwell array-patterned face (x-y)
for cell isolation and lysis. Single-cell lysate in each microwell is
‘electrophoretically projected’ into the 3rd dimension (z-axis),
separated by size, and photo-captured in the gel for immunoprobing and
confocal/light-sheet imaging. Design and analysis are informed by the
physics of 3D diffusion. Electrophoresis throughput is >2.5 cells/s
(70X faster than published serial sampling), with 25
immunoblots/mm2 device area (>10X increase over previous
immunoblots). The 3D microdevice design synchronizes analyses of hundreds
of cells, compared to status quo serial analyses that impart hours-long
delay between the first and last cell. Here, we introduce projection
electrophoresis to augment the heavily genomic and transcriptomic
single-cell atlases with protein-level profiling.