T. Jain, M. Aernecke, V. Liberman, and R. Karnik. High resolution fabrication of nanostructures using controlled proximity nanostencil lithography. Applied Physics Letters (in press) We develop an improved method of nanostencil lithoraphy to enable nanofabrication of thick nanostructures with sub-15 nm gap resolution.
S. C. O'Hern, M. S. H. Boutilier, J. Idrobo, Y. Song, J. Kong, T. Laoui, M. Atieh, and R. Karnik. Selective ionic transport through tunable subnanometer pores in single-layer graphene membranes. Nano Letters (in press) We create a high density of subnanometer pores in a centimeter-scale layer of graphene and demonstrate tunable selectivity in the resulting membranes. MIT news
M. S. H. Boutilier, J. Lee, V. Chambers, V. Venkatesh, and R. Karnik. Water filtration using plant xylem. PLoS ONE, 9, e89934 (2014). We demonstrate that a small piece of sapwood can filter out more than 99 percent of the bacteria E. coli from water. MIT news
C. Sun, M. S. H. Boutilier, H. Au, P. Poesio, B. Bai, N. G. Hadjiconstantinou, and R. Karnik. Mechanisms of molecular permeation through nanoporous graphene membranes. Langmuir (in press) We systematically study gas permeation through graphene and develop a model to delineate regimes where selectivity can be obtained regardless of the presence of defects.
M. S. H. Boutilier, C. Sun, S. C. O'Hern, H. Au, N. G. Hadjiconstantinou, and R. Karnik. Implications of permeation through intrinsic defects in graphene on the design of defect-tolerant membranes for gas separation. ACS Nano (in press) We systematically study gas permeation through graphene and develop a model to delineate regimes where selectivity can be obtained regardless of the presence of defects.
S. Choi, O. Levy, M.B. Coelho, J.M.S.Cabral, J.M. Karp and R. Karnik. A cell rolling cytometer reveals the correlation between mesenchymal stem cell dynamic adhesion and differentiation state. Lab on a Chip, 14, 161–166 (2014). (Inside cover article) We report quantitative studies of the dynamic adhesion behavior of mesenchymal stem cells (MSCs) enabled by the combination of cell-surface receptor–ligand interactions and three-dimensional hydrodynamic control by microtopography.
P. M. Valencia, E. M. Pridgen, M. Rhee, R. Langer, O. C. Farokhzad, and R. Karnik. Microfluidic platform for combinatiorial synthesis and optimization of targeted nanoparticles for cancer therapy. ACS Nano, 7, 10671–10680 (2013). We report a microfluidic platform that enables combinatorial synthesis of nanoparticles and enables rapid selection of optimal nanoparticles for targeting of postate cancer in mice.
M. A. Cartas-Ayala, R. Karnik. Time limitations and geometrical parameters in the design of microfluidic comparators. Microfluidics and Nanofluidics. (in press) (2013). We study the dynamics of microfluidic manometers and show that their temporal resolution is limited by the timescale for convective displacement of fluid.
J. Lee, M.S.H. Boutilier, V. Chambers, V. Venkatesh, and R. Karnik. Water filtration using plant xylem. arXiv.1310.4814. We show that plant xylem from the sapwood of coniferous trees can remove bacteria from water by simple pressure-driven filtration.
M.A. Cartas-Ayala, L. Gilson, C. Shen, and R. Karnik. Oscillations in light-triggered logic microfluidic circuit. Microsystem Technologies DOI 10.1007/s00542-013-1899-4 (2013). We report observations of oscillations in a microfluidic circuit capable of sorting curable droplets on demand by triggering the circuit with UV-light.
E.M. Pridgen, F. Alexis, T.T. Kuo, E. Levy-Nissenbaum, R. Karnik, R.S. Blumberg, R. Langer, and O.C. Farokhzad. Transepithelial transport of Fc-targeted nanoparticles by the neonatal Fc receptor for oral delivery. Science Translational Medicine, 5, 213ra167 (2013). We report nanoparticles that use Fc receptor-mediated transport across the intestinal barrier for effective oral delivery of insulin.
J.M. Lim, N. Bertrand, P.M. Valencia, M. Rhee, R. Langer, S. Jon, O.C. Farokhzad, and R. Karnik. Parallel microfluidic synthesis of size-tunable polymeric nanoparticles using 3D flow focusing towards in vivo study. Nanomedicine: Nanotechnology, Biology, and Medicine (in press) (2013). We we report the parallelization of controlled nanoparticle synthesis by rapid mixing using 3D hydrodynamic flow focusing in a multilayer microfluidic system to enable in vivo studies.
S. Bose, R. Singh, M. Hanewich-Hollatz, C. Shen, C. H. Lee, D. M. Dorfman, J. M. Karp, and R. Karnik. Affinity flow fractionation of cells via transient interactions with asymmetric molecular patterns. Scientific Reports, 3, 2329 (2013). We demonstrate a method to separate cells directly from blood with high purity in a single step by using weak molecular interactions to deflect the trajectories of cells in continuous flow. MIT news
H. Yang, Z. Han, S. Yu, K. L. Pey, K. Ostrikov, and R. Karnik. Carbon nanotube membranes with ultrahigh specific adsorption capacity for water desalination and purification. Nature Communications, 4, 2220 (2013). We report that plasma-modified ultralong carbon nanotube membranes exhibit ultrahigh capacity for adsorption of salt.
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, 8, 687-698 (2013). We report synergistic toxicity due to targeted dual-drug encapsulating nanoparticles synthesized by microfluidic rapid mixing.
M. A. Cartas-Ayala, M. Raafat, and R. Karnik. Self-sorting of deformable particles in an asynchronous logic microfluidic circuit. Small, 9, 375-381 (2013). (Front cover article) 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.
Jain, T., Guerrero, R. S., Aguilar, C. A. and R. Karnik. Integration of solid-state nanopores in microfluidic networks via transfer printing of suspended membranes. Analytical Chemistry, 85, 3871-3878 (2013). We report a fabrication process to embed solid-state nanopores in microfluidic devices, yielding better signal-to-noise ratio and possibility for building complex circuits.
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, 9, 511-517 (2013). 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.
Cho, W. K., Ankrum, J. A., Guo, D., Chester, S. A., Yang, S. Y., Kashyap, A., Campbell, G. A., Wood, R. J., Rijal, R. K., Karnik, R., Langer, R. and J. M. Karp. Microstructured barbs on the North American porcupine quill enable easy tissue penetration and difficult removal. Proc. Natl. Acad. Sci. (USA), 109, 21289-21294 (2012). We study the penetration and adhesion mechanism of porcupine quills, which reveals that barbs reduce penetration force by cutting the tissue, and barbs at different positions on the quill cooperate to maximize adhesion.
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), 109, 19626-19631 (2012). We report high-throughput capture and release of cells from blood enabled by long DNA aptamers in microfluidic devices.
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, 6, 10130-10138 (2012). 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.
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.
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), 109, 3688-3693 (2012). 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.
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).
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).
Y-H. Sen and R. Karnik. Investigating the translocation of λ-DNA molecules through PDMS nanopores. Analytical and Bioanalytical Chemistry 394, 437-446, (2009).
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).
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).
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).
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).
Conferences & Presentations