Lab on a Chip PAPER Cite this: Lab Chip, 2016, 16, 3833 Received 3rd June 2016, Accepted 22nd August 2016 DOI: 10.1039/c6lc00719h www.rsc.org/loc Magnetic separation of acoustically focused cancer cells from blood for magnetographic templating and analysis† C. Wyatt Shields IV, ab Jeffrey L. Wang, b Korine A. Ohiri, ac Eric D. Essoyan, c Benjamin B. Yellen, abc Andrew J. Armstrong d and Gabriel P. López* abce Liquid biopsies hold enormous promise for the next generation of medical diagnoses. At the forefront of this effort, many are seeking to capture, enumerate and analyze circulating tumor cells (CTCs) as a means to prognosticate and develop individualized treatments for cancer. Capturing these rare cells, however, represents a major engineering challenge due to their low abundance, morphology and heterogeneity. A variety of microfluidic tools have been developed to isolate CTCs from drawn blood samples; however, few of these approaches offer a means to separate and analyze cells in an integrated system. We have de- veloped a microfluidic platform comprised of three modules that offers high throughput separation of can- cer cells from blood and on-chip organization of those cells for streamlined analyses. The first module uses an acoustic standing wave to rapidly align cells in a contact-free manner. The second module then sepa- rates magnetically labeled cells from unlabeled cells, offering purities exceeding 85% for cells and 90% for binary mixtures of synthetic particles. Finally, the third module contains a spatially periodic array of micro- wells with underlying micromagnets to capture individual cells for on-chip analyses (e.g., staining, imaging and quantification). This array is capable of capturing with accuracies exceeding 80% for magnetically la- beled cells and 95% for magnetic particles. Overall, by virtue of its holistic processing of complex biological samples, this system has promise for the isolation and evaluation of rare cancer cells and can be readily ex- tended to address a variety of applications across single cell biology and immunology. 1. Introduction The isolation and examination of circulating tumor cells (CTCs) represents a critical goal in cancer medicine, as these compartmentalized biomarkers may aid our understanding of how cancer spreads and provide a direct means to profile can- cer cells over time during therapy as a marker of response or resistance. 1,2 As such, capturing CTCs from drawn blood (in so-called liquid biopsies) could eliminate the need for inva- sive diagnostic procedures, while yielding the same, or simi- lar, information that could shed light onto the regulatory pathways of native tumor sites. 3,4 At the most basic level, the enumeration of CTCs has been shown to provide direct prog- nostic value in the metastatic setting for some cancers such as prostate, breast and colorectal. 5,6 Ensuing studies have shown that post-isolation CTC biomarker analyses (e.g., im- munofluorescence, fluorescence in situ hybridization (FISH) and reverse transcription quantitative polymerase chain reac- tion (RT-qPCR)) can provide useful phenotypic, genetic and regulatory information. 7,8 More recent studies have demon- strated the ability to create viable cultures from CTCs, thus potentially enabling ex vivo drug testing that could give rise to new medical insights and personalized medicine by guid- ing doctors towards administering patient-specific therapeutic interventions. 9 To these ends, enormous interest has been generated to develop technologies that isolate CTCs from whole blood both rapidly and with high purity. The leading technology for this is CellSearch by Janssen Diagnostics (a Johnson & John- son Company), which is the only FDA approved assay for CTC enumeration as a prognostic test for certain types of cancer. CellSearch works by lysing erythrocytes from 7.5 mL of drawn blood, magnetically separating CTC candidates by EpCAM, and staining cells with anti-CD45, anti-cytokeratin and Hoechst DNA stain. This type of analysis is useful, for Lab Chip, 2016, 16, 3833–3844 | 3833 This journal is © The Royal Society of Chemistry 2016 a NSF Research Triangle Materials Research Science and Engineering Center, Duke University, Durham, NC 27708, USA b Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA c Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC 27708, USA d Department of Medicine, Duke University, Durham, NC 27710, USA e Department of Chemical and Biological Engineering, University of New Mexico, Albuquerque, NM 87131, USA. E-mail: gplopez@unm.edu † Electronic supplementary information (ESI) available. See DOI: 10.1039/ c6lc00719h Published on 01 September 2016. Downloaded by DTU Library on 23/09/2016 15:17:58. View Article Online View Journal | View Issue