title: Microfluidic compartments with sensing microbeads for dynamic monitoring of cytokine and exosome release from single cells.
abstract: Monitoring activity of single cells has high significance for basic science and diagnostic applications. Here we describe a reconfigurable microfluidic device for confining single cells along with antibody-modified sensing beads inside 20 picoliter (pL) microcompartments for monitoring cellular secretory activity. An array of ∼7000 microchambers fabricated in the roof of the reconfigurable microfluidic device could be raised or lowered by applying negative pressure. The floor of the device was micropatterned to contain cell attachment sites in registration with the microcompartments. Using this set-up, we demonstrated the detection of inflammatory cytokine IFN-γ and exosomes from single immune cells and cancer cells respectively. The detection scheme was similar in both cases: cells were first captured on the surface inside the microfluidic device, then sensing microbeads were introduced into the device so that, once the microcompartments were lowered, single cells and microbeads became confined together. The liquid bathing the beads and the cells inside the compartments also contained fluorescently-labeled secondary antibodies (Abs). The capture of cell-secreted molecules onto microbeads was followed by binding of secondary antibodies - this caused microbeads to become fluorescent. The fluorescence intensity of the microbeads changed over time, providing dynamics of single cell secretory activity. The microdevice described here may be particularly useful in the cases where panning upstream of sensing is required or to analyze secretory activity of anchorage-dependent cells.
authors.affiliation: Department of Biomedical Engineering, University of California, Davis, California 95616, USA. arevzin@ucdavis.edu.
authors.forename: Kyung Jin
authors.initials: KJ
authors.lastname: Son
authors.affiliation: Department of Biomedical Engineering, University of California, Davis, California 95616, USA. arevzin@ucdavis.edu.
authors.forename: Ali
authors.initials: A
authors.lastname: Rahimian
authors.affiliation: Department of Biomedical Engineering, University of California, Davis, California 95616, USA. arevzin@ucdavis.edu and Department of Medical & Pharmaceutical Sciences, Sookmyung Women's University, Seoul, Korea.
authors.forename: Dong-Sik
authors.initials: DS
authors.lastname: Shin
authors.affiliation: Department of Biomedical Engineering, University of California, Davis, California 95616, USA. arevzin@ucdavis.edu.
authors.forename: Christian
authors.initials: C
authors.lastname: Siltanen
authors.affiliation: Department of Cancer Biology, Mayo Clinic, Jacksonville, Florida 32224, USA.
authors.forename: Tushar
authors.initials: T
authors.lastname: Patel
authors.affiliation: Department of Biomedical Engineering, University of California, Davis, California 95616, USA. arevzin@ucdavis.edu.
authors.forename: Alexander
authors.initials: A
authors.lastname: Revzin
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism*; D055354:Exosomes / Q000378:metabolism*; D056945:Hep G2 Cells; D006801:Humans; D056656:Lab-On-A-Chip Devices; D008863:Microspheres; D059010:Single-Cell Analysis / Q000295:instrumentation*
chemical_list: D016207:Cytokines