Fig. 4.
Detection of TNF-α secreted from LPS-stimulated THP-1 cells using the MIPA device (a) Standard curve for TNF-α detection. TNF-α with a known concentration (0–10 000 pg mL−1) was spiked in the complete cell growth medium and detected using AlphaLISA and the customized optical setup. (b) Plot of TNF-α concentration secreted by LPS-stimulated THP-1 cells as a function of cell number and LPS concentration. (c and d) Plots of average TNF-α concentration secreted by individual cells as a function of LPS concentration (c) or LPS concentration per cell (d). (e) Plot of TNF-α concentration secreted by normal and LPS-deactivated THP-1 cells trapped on the PMM (n = 20 000 cells). P-values calculated using the paired Student’s t-test are indicated for significant differences (P < 0.05 (*) and P < 0.005 (**)). NS, statistically not significant.