Fig. 1

Overall process flow schematic. a LNCaP cells are injected into a mouse and prostate cancer xenograft obtained. b Xenograft is resected and immediately frozen and embedded in optimal cutting temperature compound (OCT). c A 7-µm tissue cryosection is loaded onto our microchip. d A cured PDMS block is loaded on top of tissue-chip assembly. e, f The PDMS shears and partitions the tissue into small pixels at sharp well edges and pushes them into wells under centripetal force in a standard centrifuge. The pixelated tissue adheres to the silanized (APTES) well surfaces and the PDMS is removed. We call this process “tissue pixelation” (time = 2 min). g Post pixelation, the tissue is fixed with acetone (time = 10 min). A proteinase K digestion is performed after this to create a pathway for amplification enzymes to reach the target nucleic acids inside the cells (time = 30 min). h RT-LAMP reagents are pipetted on chip in bulk (5 µL). i Compressed air is blown on it at an angle inside the mineral oil. j Excess reagents are sheared away and only fluid inside the wells is retained due to capillary forces. In the above steps, picoliter volume RT-LAMP reagents (~175 pL/well) are loaded onto the chip through a rapid instrument-free technique we call “bulk picoliter reagent loading” (time = 2 min). k Quantitative gene expression is visualized through real-time imaging of the amplification reaction in each well performed using only a hot plate at 65 °C and a fluorescence microscope (time = 45 min). Images created by Janet Sinn-Hanlon, The DesignGroup@VetMed, University of Illinois at Urbana Champaign