2012

W. Zhao, C. H. Cui, S. Bose, D. Guo, C. Shen, W. P. Wong, K. Halvorsen, O. C. Farokhzad, G. S. L. Teo, J. Philips, D. M. Dorfman, R. Karnik, and J. M. Karp. A bioinspired multivalent dna network for capture and release of cells. Proc. Natl. Acad. Sci. (USA) (in press). We report high-throughput capture and release of cells from blood enabled by long DNA aptamers in microfluidic devices.


C. Salvador-Morales, P. M. Valencia, W. Gao, R. Karnik, and O. C. Farokhzad. Spontaneous formation of heterogeneous patches on polymer-lipid core-shell particle surfaces during self-assembly. Small (in press). We report spontaneous formation of patches on a variety of particles using methods that are currently used for particle synthesis in medicine. These results indicate that surface heterogeneity needs to be considered for development of particles and interpretation of their interactions in vitro and in vivo.


S. C. O'Hern, C. A. Stewart, M. S. H. Boutilier, J.-C. Idrobo, S. Bhaviripudi, S. K. Das, J. Kong, T. Laoui, M. Atieh, and R. Karnik. Selective molecular transport through intrinsic defects in a single layer of CVD graphene. ACS Nano (in press). We fabricate centimeter-scale membranes comprising s single layer of CVD graphene on a porous support and show selective transport due to defects present in the graphene. This work is potentially the first to demonstrate selective transport through macroscopic areas of a single sheet of graphene.


M. A. Cartas-Ayala, M. Raafat, and R. Karnik. Self-sorting of deformable particles in an asynchronous logic microfluidic circuit. Small (in press). We present a microfluidic circuit that can automatically sort deformable particles based on the hydrodynamic resistance that the particles induce in a constrained microfluidic channel while flowing through it.


P. M. Valencia, O. C. Farokhzad, R. Karnik, and R. Langer. Microfluidic technologies for accelerating the clinical translation of nanoparticles. Nature Nanotechnology 7, 623-629 (2012). We discuss in this review how microfluidic technologies can tackle some of the challenges in translating nanoparticles to the clinic. This article outlines these advances and offers an assessment of the near- and long-term impact of microfluidic technologies in nanomedicine.


P. M. Valencia, E. M. Pridgen, B. Perea, S. Gadde, C. Sweeney, P. W. Kantoff, S. J. Lippard, R. Langer, R. Karnik, and O. C. Farokhzad. Synergistic cytotoxicity of irinotecan and cisplatin in dual-drug PSMA-targeted polymeric nanoparticles. Nanomedicine (in press). We report synergistic toxicity due to targeted dual-drug encapsulating nanoparticles synthesized by microfluidic rapid mixing.


E. N. Wang and R. Karnik. Water desalination: Graphene cleans up water. Nature Nanotechnology 7, 552-554 (2012). We provide a perspective on Cohen-Tanugi and Grossman's work on the promise of graphene for water desalination at throughputs much higher than state-of-the-art membranes.


J. Lee, F. Rahman, T. Laoui, and R. Karnik. Bubble-induced damping in displacement-driven microfluidic flows. Physical Review E 86, 026301 (2012). Bubble damping in displacement-driven microfluidic flows was theoretically and experimentally investigated for microfluidic networks. The model was able to predict experimentally observed damping of fluctuations with excellent agreement. A flowmeter with high resolution was demonstrated as an application of the bubble-aided stabilization.


C. Duan, R. Karnik, M. Lu and A. Majumdar. Evaporation-induced cavitation in nanofluidic channels. Proc. Natl. Acad. Sci. (USA) (in press). We demonstrate cavitation phenomenon in evaporating nanofluidic channels that result in fast evaporation kinetics. Bubbles formed at the entrance of the nanochannels rapidly migrate to certain fixed positions within the channels that depend only on nanochannel height. The dynamics reflect interplay of thermocapillary flow and convection.


S. Choi, J. M. Karp, and R. Karnik. Cell sorting by deterministic cell rolling. Lab on a Chip 12, 1427-1430 (2012). (Front cover article) This communication presents the concept of deterministic cell rolling, which leverages transient cell-surface molecular interactions that mediate cell rolling to sort cells with high purity and efficiency in a single step.


Y.-H. Sen, T. Jain, C. A. Aguilar, and R. Karnik. Enhanced discrimination of DNA molecules in nanofluidic channels through multiple measurements. Lab on a Chip 12, 1094-1101 (2012). We describe fabrication and testing of a nanochannel device that enhances measurement resolution by performing multiple measurements (exceeding 100) on single DNA molecules.


M. A. Cartas-Ayala, and R. Karnik. Local temperature profile measurement in microchannels using temperature sensitive Leuco-dye microbeads. International Journal of Micro-Nano Scale Transport 2, 41-56 (2012). We study use of thermochromic beads for temperature measurement in microfluidic devices.

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2011

D. Sarkar, J. A. Spencer, J. A. Phillips, W. Zhao, S. Schafer, D. P. Spelke, L. J. Mortensen, J. P. Ruiz, P. K. Vemula, R. Sridharan, S. Kumar, R. Karnik, C. P. Lin, and J. M. Karp. Engineered cell homing. Blood 118, e184-e191 (2011).


W. Zhao, W. Loh, I. A. Droujinine, W. Teo, N. Kumar, S. Schafer, C. H. Cui, L. Zhang, D. Sarkar, R. Karnik, and J. M. Karp. Mimicking the inflammatory cell adhesion cascade by nucleic acid aptamer programmed cell-cell interactions. The FASEB Journal 25, 3045-3056 (2011).


T. Humplik, J. Lee, S. C. O'Hern, B. A. Fellman, M. A. Baig, S. F. Hassan, M. A. Atieh, F. Rahman, T. Laoui, R. Karnik, and E. N. Wang. Nanostructured materials for water desalination. Nanotechnology 22, 292001 (2011).


W. Zhao, S. Schafer,J. Choi, Y. J. Yamanaka, M. L. Lombardi, S. Bose, A. L. Carlson, J. A. Phillips, W. Teo, I. A. Droujinine, C. Cui, R. K. Jain, J. Lammerding, J. C. Love, C. P. Lin, D. Sarkar, R. Karnik, and J. M. Karp. Cell-surface sensors for real-time probing of cellular environments. Nature Nanotechnology 6, 524-531 (2011).


P. M. Valencia, M. H. Hanewich-Hollatz, W. Gao, F. Karim, R. Langer, R. Karnik, and O. C. Farokhzad. Effects of ligands with different water solubilities on self-assembly and properties of targeted nanoparticles. Biomaterials 26, 6226-6233 (2011).


M. Rhee, P. M. Valencia, M. I. Rodriguez, R. Langer, O. C. Farokhzad, and R. Karnik. Synthesis of size-tunable polymeric nanoparticles enabled by 3D hydrodynamic flow focusing in single-layer microchannels. Advanced Materials 23, H79-H83 (2011).


C. Lee, S. Bose, K. J. Van Vliet, J. M. Karp, and R. Karnik. Studying cell rolling trajectories on asymmetric receptor patterns. Journal of Visualized Experiments 48, (2011).


C. Lee, S. Bose, K. J. Van Vliet, J. M. Karp, and R. Karnik. Examining the lateral displacement of HL60 cells rolling on asymmetric P-selectin patterns. Langmuir 27, 240-249 (2011).
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2010

S. Bose, S. K. Das, J. M. Karp, and R. Karnik. A semi-analytical model to study the effect of cortical tension on cell rolling. Biophysical Journal 99, 3870-3879 (2010).


N. Kolishetti, S. Dhar, P. M. Valencia, L. Q. Lin, R. Karnik, S. J. Lippard, R. Langer, and O. C. Farokhzad. Engineering of self-assembled nanoparticle platform for precisely controlled combination drug therapy. Proc. Natl. Acad. Sci. (USA) 107, 17939-17944, (2010).


D. Sarkar, P. K. Vemula, W. Zhao, A. Gupta, R. Karnik, and J. M. Karp. Engineered mesenchymal stem cells with self-assembled vesicles for systemic cell targeting. Biomaterials 31, 5266-5274 (2010).


J. Lee and R. Karnik. Desalination of water by vapor-phase transport through hydrophobic nanopores. Journal of Applied Physics 108, 044315 (2010).


P. M. Valencia, P. Basto, L. Zhang, M. Rhee, R. Langer, O. C. Farokhzad, and R. Karnik. Single-Step Assembly of Homogenous Lipid-Polymeric and Lipid-Quantum Dot Nanoparticles Enabled by Microfluidic Rapid Mixing. ACS Nano 4, 1671-1679 (2010).
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2009

Y-H. Sen and R. Karnik. Investigating the translocation of λ-DNA molecules through PDMS nanopores. Analytical and Bioanalytical Chemistry 394, 437-446, (2009).
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2008

D. Sarkar, P. K. Vemula, G. S. L. Teo, D. Spelke, R. Karnik, L. Y. Wee, and J. M. Karp. Chemical Engineering of Mesenchymal Stem Cells to Induce a Cell Rolling Response. Bioconjugate Chemistry 19, 2105-2109 (2008).


R. Karnik, F. Gu, P. Basto, C. Cannizzaro, L. Dean, W. Kyei-Manu, R. Langer, and O. C. Farokhzad. Microfluidic platform for controlled synthesis of polymeric nanoparticles. Nano Letters 8, 2906-2912 (2008).


R. Karnik, S. Hong, H. Zhang, Y. Mei, D. G. Anderson, J. Karp, and R. Langer. Nanomechanical control of cell rolling in two dimensions through surface patterning of receptors. Nano Letters 8, 1153-1158, (2008).
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2007

F. Gu, R. Karnik, A. Z. Wang, F. Alexis, E. Levy-Nissenbaum, S. Hong, R. S. Langer, and O. C. Farokhzad. Targeted nanoparticles for cancer therapy. Nano Today 2, 14-21, (2007).


R. Karnik, C. Duan, K. Castelino, A. Majumdar. Rectification of ionic transport in a nanofluidic diode. Nano Letters 7, 547-551, (2007).
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2006

M-C Lu, S. Satyanarayana, R. Karnik, A. Majumdar and C-C Wang. Mechanical-electrokinetic battery by using a nano-porous membrane. Journal of Micromechanics and Microengineering 16, 667-675 (2006).


R. Karnik, K. Castelino, C. Duan and A. Majumdar. Diffusion-limited patterning of molecules in nanofluidic channels. Nano Letters 6, (2006).


R. Karnik, K. Castelino and A. Majumdar. Field-effect control of protein transport in a nanofluidic transistor circuit. Applied Physics Letters 88, 123114 (2006).


K. Dunphy, R. Karnik, J. Newman and A Majumdar. Spatially controlled microfluidics using low-voltage electrokinetics. Journal of Microelectromechanical Systems 15, 237-245 (2006).
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2005

R. Fan, M. Yue, R. Karnik, D. Li, A. Majumdar and P. Yang. Polarity switching and transient responses in single nanotube nanofluidic transistors. Physical Review Letters 95, Art. No. 086607 (2005).


K. Dunphy, R. Karnik, C. Trinkle and A. Majumdar. Analysis of governing parameters of silver-silver chloride electrodes in microfluidic electrokinetic devices. Microscale Thermophysical Engineering 9, 199-211 (2005).


R. Fan, R. Karnik, M. Yue, D. Li, A. Majumdar and P. Yang. DNA translocation in inorganic nanotubes. Nano Letters 5, 1633-1637 (2005).


S. Satyanarayana, R. Karnik and A. Majumdar. Stamp-and-stick room-temperature bonding technique for microdevices. Journal of Microelectromechanical Systems 14, 392-399 (2005).


A. Liau, R. Karnik, A. Majumdar and J. Doudna-Cate. Mixing biological crowded solutions in milliseconds. Analytical Chemistry 77, 7618-7625 (2005).


R. Karnik, K. Castelino, R. Fan, P. Yang and A. Majumdar. Effects of biological reactions and modifications on conductance of nanofluidic channels. Nano Letters 5, 1638-1642 (2005).


R. Karnik, R. Fan, M. Yue, D. Li, P. Yang and A. Majumdar. Electrostatic control of ions and molecules in nanofluidic transistors. Nano Letters 5, 943-948 (2005).
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Conferences & Presentations

Please see CV.

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