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. Author manuscript; available in PMC: 2019 Nov 5.
Published in final edited form as: Methods Cell Biol. 2018 Nov 5;148:35–50. doi: 10.1016/bs.mcb.2018.09.010

Figure 4. Single-cell mRNA probing from the ultra-thin PDMS membrane-sealed microfluidic trapping array.

Figure 4.

(A) SEM image of the DENT probe (scale bar: 200 nm). (B) Schematic illustration of single-cell mRNA extraction using DENT after it penetrates through the PDMS film and enters into the cytoplasm. Application of AC field between the inner Si core and the outer metal layer creates a DEP attractive force to attract mRNA molecules toward the probe-end. (C) Bright-field microscopic image capturing the single-cell probing process. White dashed box indicates the cell of interest. The probe was moved downward toward a target cell, penetrated through the PDMS membrane and inserted into the target cell to extract mRNAs by DEP. Scale bars: 30 μm. (D) Bright-field image of trapping single cells of SK-BR-3 and U937 in the microwell array. Scale bar: 100 μm. The RT-qPCR fingerprints of the 4 target mRNAs (CD45, EpCAM, HER2 and ACTB) extracted by DENT from a trapped SK-BR-3 cell and a trapped U937 cell are shown in (E) and (F), respectively. (G) Fabrication process for the ultra-thin PDMS membrane-sealed microfluidic trapping array. (H)The thickness of the PDMS membrane according to the different ratios of hexane to PDMS pre-polymer at the spin coating condition of 5000 RPM, 5 min.