title: Jetting microfluidics with size-sorting capability for single-cell protease detection.
abstract: Activated proteases such as matrix metalloproteinases (MMPs) secreted from cancer cells can degrade the extracellular matrix (ECM) and contribute to tumour formation and metastasis. Measuring MMP activity in individual cancer cells can provide important insights on cancer cell heterogeneity and disease progression. Here, we present a microfluidic platform combining a droplet jetting generator and a deterministic lateral displacement (DLD) size-sorting channel that is capable of encapsulating individual cancer cells inside picoliter droplets effectively. Droplet jetting with cell-triggered Rayleigh-Plateau instability was employed which produced large droplets capable of cell encapsulation (diameter, ~25µm) and small empty droplets (diameter, ~14µm), which were then size-separated using a DLD size-sorting channel to enrich the single-cell encapsulated droplets (~78%), regardless of the cell density of input sample solutions. The droplets containing encapsulated cancer cells were collected in an observation chamber to determine the kinetic profiles of MMP secretion and the inhibitory response in the presence of the drug doxycycline at the single-cell level to reveal their heterogeneous MMPs secretion activities.
authors.affiliation: Department of Biomedical Engineering, National University of Singapore, Singapore 117575, Singapore; Singapore-MIT Alliance for Research and Technology (SMART) Centre, Singapore 1385602, Singapore.
authors.forename: Tengyang
authors.initials: T
authors.lastname: Jing
authors.affiliation: Department of Biomedical Engineering, National University of Singapore, Singapore 117575, Singapore.
authors.forename: Ramesh
authors.initials: R
authors.lastname: Ramji
authors.affiliation: Singapore-MIT Alliance for Research and Technology (SMART) Centre, Singapore 1385602, Singapore; School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: Majid Ebrahimi
authors.initials: ME
authors.lastname: Warkiani
authors.affiliation: Singapore-MIT Alliance for Research and Technology (SMART) Centre, Singapore 1385602, Singapore; Department of Electrical Engineering & Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States. Electronic address: jyhan@mit.edu.
authors.forename: Jongyoon
authors.initials: J
authors.lastname: Han
authors.affiliation: Department of Biomedical Engineering, National University of Singapore, Singapore 117575, Singapore; Singapore-MIT Alliance for Research and Technology (SMART) Centre, Singapore 1385602, Singapore; Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore. Electronic address: ctlim@nus.edu.s.
authors.forename: Chwee Teck
authors.initials: CT
authors.lastname: Lim
authors.affiliation: Department of Biomedical Engineering, National University of Singapore, Singapore 117575, Singapore; Singapore-MIT Alliance for Research and Technology (SMART) Centre, Singapore 1385602, Singapore; Singapore Institute for Neurotechnology (SINAPSE), Singapore 117456, Singapore. Electronic address: biecch@nus.edu.sg.
authors.forename: Chia-Hung
authors.initials: CH
authors.lastname: Chen
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D045744:Cell Line, Tumor; D004318:Doxycycline / Q000494:pharmacology; D057075:Enzyme Assays / Q000295:instrumentation*; D004867:Equipment Design; D006801:Humans; D061965:Matrix Metalloproteinase Inhibitors / Q000494:pharmacology; D020782:Matrix Metalloproteinases / Q000032:analysis* / Q000378:metabolism; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D009369:Neoplasms / Q000188:drug therapy / Q000201:enzymology; D059010:Single-Cell Analysis / Q000295:instrumentation
chemical_list: D061965:Matrix Metalloproteinase Inhibitors; D020782:Matrix Metalloproteinases; D004318:Doxycycline
keywords: Cell encapsulation; DLD droplet sorting; Jetting microfluidics; Protease biosensor; Single-cell analysis