Joo H Kang

Harvard University, Cambridge, Massachusetts, United States

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Publications (3)18.72 Total impact

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    ABSTRACT: Microfluidic water-in-oil droplets that serve as separate, chemically isolated compartments can be applied for single-cell analysis; however, to investigate encapsulated cells effectively over prolonged time periods, an array of droplets must remain stationary on a versatile substrate for optimal cell compatibility. We present here a platform of unique geometry and substrate versatility that generates a stationary nanodroplet array by using wells branching off a main microfluidic channel. These droplets are confined by multiple sides of a nanowell and are in direct contact with a biocompatible substrate of choice. The device is operated by a unique and reversed loading procedure that eliminates the need for fine pressure control or external tubing. Fluorocarbon oil isolates the droplets and provides soluble oxygen for the cells. By using this approach, the metabolic activity of single adherent cells was monitored continuously over time, and the concentration of viable pathogens in blood-derived samples was determined directly by measuring the number of colony-formed droplets. The method is simple to operate, requires a few microliters of reagent volume, is portable, is reusable, and allows for cell retrieval. This technology may be particularly useful for multiplexed assays for which prolonged and simultaneous visual inspection of many isolated single adherent or nonadherent cells is required.
    Proceedings of the National Academy of Sciences of the United States of America. 07/2014;
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    ABSTRACT: A cancer nanotherapeutic has been developed that targets the extracellular matrix (ECM)-modifying enzyme lysyl oxidase (LOX) and alters the ECM structure. Poly(d,l-lactide-co-glycolide) nanoparticles (∼220 nm) coated with a LOX inhibitory antibody bind to ECM and suppress mammary cancer cell growth and invasion in vitro as well as tumor expansion in vivo, with greater efficiency than soluble anti-LOX antibody. This nanomaterials approach opens a new path for treating cancer with higher efficacy and decreased side effects.
    Nano Letters 05/2012; 12(6):3213-7. · 13.03 Impact Factor
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    ABSTRACT: Here we describe a combined microfluidic-micromagnetic cell separation device that has been developed to isolate, detect and culture circulating tumor cells (CTCs) from whole blood, and demonstrate its utility using blood from mammary cancer-bearing mice. The device was fabricated from polydimethylsiloxane and contains a microfluidic architecture with a main channel and redundant 'double collection' channel lined by two rows of dead-end side chambers for tumor cell collection. The microdevice design was optimized using computational simulation to determine dimensions, magnetic forces and flow rates for cell isolation using epithelial cell adhesion molecule (EpCAM) antibody-coated magnetic microbeads (2.8 μm diameter). Using this device, isolation efficiencies increased in a linear manner and reached efficiencies close to 90% when only 2 to 80 breast cancer cells were spiked into a small volume (1.0 mL) of blood taken from wild type mice. The high sensitivity visualization capabilities of the device also allowed detection of a single cell within one of its dead-end side chambers. When blood was removed from FVB C3(1)-SV40 T-antigen mammary tumor-bearing transgenic mice at different stages of tumor progression, cells isolated in the device using anti-EpCAM-beads and magnetically collected within the dead-end side chambers, also stained positive for pan-cytokeratin-FITC and DAPI, negative for CD45-PerCP, and expressed SV40 large T antigen, thus confirming their identity as CTCs. Using this isolation approach, we detected a time-dependent rise in the number of CTCs in blood of female transgenic mice, with a dramatic increase in the numbers of metastatic tumor cells appearing in the blood after 20 weeks when tumors transition to invasive carcinoma and exhibit increased growth of metastases in this model. Importantly, in contrast to previously described CTC isolation methods, breast tumor cells collected from a small volume of blood removed from a breast tumor-bearing animal remain viable and they can be easily removed from these devices and expanded in culture for additional analytical studies or potential drug sensitivity testing.
    Lab on a Chip 03/2012; 12(12):2175-81. · 5.70 Impact Factor

Publication Stats

44 Citations
18.72 Total Impact Points

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  • 2012–2014
    • Harvard University
      • Wyss Institute for Biologically Inspired Engineering
      Cambridge, Massachusetts, United States