Bulletin of the American Physical Society
2008 APS March Meeting
Volume 53, Number 2
Monday–Friday, March 10–14, 2008; New Orleans, Louisiana
Session H16: Focus Session: Biochip Physics I |
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Sponsoring Units: DBP DFD Chair: Peter Kiesel, Palo Alto Research Center Room: Morial Convention Center 208 |
Tuesday, March 11, 2008 8:00AM - 8:12AM |
H16.00001: Size Scaling of Protein Sensitivity on the BioCD Kevin O'Brien, Ming Zhao, Xuefang Wang, David Nolte We investigate size scaling of the surface-height sensitivity of spinning-disk interferometry (SDI) implemented on the in-line-quadrature BioCD as a function of laser focal radius. The in-line-quadrature BioCD consists of a silicon wafer with a 120 nm layer of silicon dioxide that creates a quadrature condition between the incident and reflected light. When a laser beam is focused on the BioCD, proteins printed on the silicon dioxide substrate create a phase shift leading to quadrature interference, which is detectable in the far field as an intensity shift. The purpose of this scaling experiment is to determine the practical and fundamental limits on the sensitivity of the BioCD, and how those limits change as a function of the size of the focal spot. We imaged a single 100 micron wide protein spot with focal spot sizes of 1, 5 and 10 microns and observe a square-root scaling as a function of the number of pixels per protein spot. [Preview Abstract] |
Tuesday, March 11, 2008 8:12AM - 8:24AM |
H16.00002: Detection Limits of Captured Protein on the BioCD David Nolte, Xuefang Wang, Kevin O'Brien, Ming Zhao The BioCD is an interferometric biosensor that detects protein captured by antibody arrays. The sensor readout is performed on a spinning disc using a common-path interferometric configuration that is stable and sensitive to sub-monolayer coverage of captured protein. Protein is detected using phase quadrature that converts phase to intensity modulation using local generation of signal and reference to lock the relative phase of the waves. The purpose for spinning is to move far from 1/f noise to achieve high surface mass sensitivity. Several different classes of the BioCD have been developed, differentiated by the means of generating the phase-locked reference. These include the microdiffraction (MD) class, the phase contrast (PC) class, the adaptive optical (AO) class and the in-line (IL) class of BioCD. Of these different quadrature classes, the in-line BioCD has the highest sensitivity with a detection sensitivity of 0.25 pg/mm. The minimum detectable mass is set by simple scaling relations. The metrology limit is set by surface roughness combined with repositioning offset between pre- and post-incubation scans. Optimal sensitivity is achieved by critical sampling of protein spots in radial arrays. [Preview Abstract] |
Tuesday, March 11, 2008 8:24AM - 8:36AM |
H16.00003: Docetaxel-loaded Nanohorn-streptavidin-antibody for Anti-cancer Drug Delivery Jianxun Xu, Masako Yudasaka, Minfang Zhang, Sumio Iijima Single wall carbon canohorn (SWNH) is a new kind of nano-carbon tubule having horn-like structure at its tip. The tube diameters are 2 to 5 nm, and about 2,000 SWNHs assemble to form a spherical aggregate. SWNH is an attractive candidate for drug delivery, especially promising to carry anticancer drug, many of which are not water soluble and highly toxic. We incorporated Docetaxel (Doc), an anticancer drug used for stomach cancer and others, into hydrogen peroxide treated SWNH (SWNHox). By using carboxylic groups on SWNHox, we attached amine-PEO3-biotin, and then streptavidin to biotin. The streptavidin moiety on SWNH makes it easy to attach some other biotinylated molecules, thus we introduced a cancer targeting ligand, anti-tumor associated glycoprotein, to the SWNH system. Due to the targeting effect of the antibody, the cells were effectively killed when they were incubated with the Doc SWNHox-streptavidin-andtibody system. [Preview Abstract] |
Tuesday, March 11, 2008 8:36AM - 9:12AM |
H16.00004: Detection limits and scalability of miniaturized antibody assays in real-world applications Invited Speaker: |
Tuesday, March 11, 2008 9:12AM - 9:24AM |
H16.00005: InAs quantum well $\mu$-Hall sensors for magnetic biosensing Khaled Aledealat, S. Hira, K. Chen, G. Mihajlovic, P. Xiong, G. Strouse, P.B. Chase, S. von Molnar, M. Field, G. Sullivan Magnetic sensing is potentially a sensitive and rapid technique for monitoring DNA-DNA and protein-DNA interactions. Here we present an effort on the noise characterization and selective biofunctionalization of InAs $\mu $-Hall sensors for magnetic detection of DNA hybridization. Room-temperature noise measurements were performed in the frequency range from 20 Hz to 104 kHz. The noise equivalent magnetic moment resolutions were estimated to be $\sim $10$^{6} \quad \mu _{B}$/$\sqrt {Hz} $ and $\sim $10$^{4} \quad \mu _{B}$/$\sqrt {Hz} $ at 92 Hz and 23 kHz respectively. The active region of the InAs $\mu $-Hall device was covered with sputter-deposited SiO$_{2}$ and Au pads were patterned on top of some of the Hall crosses. Thiolated ssDNA were assembled on the Au pads and the rest of the device platform was passivated with PEG-silane. Biotinylated and fluorescently-tagged complementary ssDNA were labeled with commercial streptavidin-coated 350 nm superparamagnetic beads, which were found to assemble selectively onto the Au pads through DNA hybridization using laser scanning confocal microscopy. This work was supported by NIH NIGMS GM079592. [Preview Abstract] |
Tuesday, March 11, 2008 9:24AM - 9:36AM |
H16.00006: Ligand-receptor binding kinetics in surface-plasmon resonance devices: A Monte Carlo simulation study Matthew T. Raum, Manoj Gopalakrishnan, Kim Forsten-Williams, Uwe C. Tauber We use lattice Monte-Carlo simulations to probe the kinetics of ligand-receptor association and dissociation. Simulations were run under conditions approximating the geometric configuration of surface plasmon resonance devices. These conditions include viscous flow of ligands over a surface of receptors which is achieved by using a spatially varying biased random walk. Our simulations allow for the occurrence of multiple rebinding events which result in strong deviations from the standard mean-field rate equation approximation. Our simulations also allow us to test improved theoretical predictions for the binding dynamics and to determine their range of applicability. [Preview Abstract] |
Tuesday, March 11, 2008 9:36AM - 9:48AM |
H16.00007: Comparative study of different DNA chip preparation methods by means of Surface Plasmon Resonance Yannick Sartenaer, Ryuji Hara, Haruma Kawaguchi, Paul A. Thiry Recently, we demonstrated that SFG vibrational spectroscopy allows the detection of the specific recognition between the two molecules of a model ligand-protein biosensor. Moreover, we studied by this technique, the formation of thiolated single stranded DNA (ssDNA) monolayers immobilized on metallic substrates which are the basis for various biotechnology applications. Before going further into monitoring the hybridisation process in DNA based sensors, it is important to identify a preparation method providing good quality DNA chips with respect to the recognition process. Therefore, we performed investigations by Surface Plasmon Resonance (SPR). Practically, we used four different methods of chip preparation on gold surfaces and we measured the amount of deposited molecules when the sensor is exposed to a target DNA solution. By this way, we monitored for each case the sensitivity and the selectivity of the sensor by comparing the hybridisation of complementary and non complementary target ssDNA, respectively. [Preview Abstract] |
Tuesday, March 11, 2008 9:48AM - 10:24AM |
H16.00008: Nanoscale Building Blocks for Biosensor Development Invited Speaker: The development of new technologies based on nano- and microscale phenomenon is important and significant for many reasons. One of the most prominent of these is biological sensors for the diagnosis of diseases, detection of environmental toxins, and drug discovery. Research in our group focuses on the microscopic and spectroscopic analysis of the optical properties of nanostructures and their integration with microfluidic devices with applications in biological sciences. In this talk, we will show results for an optical sensor based on localized surface plasmon resonance spectroscopy. It will be demonstrated that this nanoparticle based sensor can be used to detect a variety of ligands, including a biomarker for Alzheimer's disease. [Preview Abstract] |
Tuesday, March 11, 2008 10:24AM - 10:36AM |
H16.00009: Predictive Model for Label-free Electrical Detection of Bio-molecules Pradeep Nair, Muhammad Alam Biosensors based on MOSFETs, silicon nanowires, and carbon nanotube nanocomposites \textit{promise }highly sensitive, dynamic, label-free, electrical detection of bio-molecules with potential applications in genomics and proteomics. Although tremendous improvements in sensitivity have been reported in electrical detection of bio-molecules, many aspects of experimentally observed sensor response (S) are unexplained within the theoretical frameworks of kinetic response or electrolyte screening. In this paper, we combine analytic solutions of Poisson-Boltzmann and reaction-diffusion equations to show that the electrostatic screening within an ionic environment limits the response of nanobiosensor such that $S\left( t \right)\sim c_1 \left( {\ln \left( {\rho _0 } \right)-\frac{\ln \left( {I_0 } \right)}{2}+\frac{\ln \left( t \right)}{D_F }+\left[ {pH} \right]} \right)+c_2 $ where $c_i $ are geometry-dependent constants, $\rho _0 $ is the concentration of target molecules, $I_0 $ the salt concentration, and $D_F $ the fractal dimension of sensor surface. Our analysis provides a coherent theoretical interpretation of wide variety of puzzling experimental data that have so far defied intuitive explanation and have important implications for the design and optimization of nanoscale biosensors. [Preview Abstract] |
Tuesday, March 11, 2008 10:36AM - 10:48AM |
H16.00010: Hybrid CMOS/Microfluidic Dielectrophoresis and Magnetic Manipulator Chip David Issadore, Thomas P. Hunt, Keith A. Brown, R.M. Westervelt We present hybrid CMOS/microfluidic chips that combine the biocompatibility of microfluidics with the programmability of CMOS integrated circuits (ICs). The chips use a two-dimensional array of RF-electrode pixels that use dielectrophoresis (DEP) to simultaneously and independently control the location of many objects, including biological cells and chemical droplets [1]. We highlight our next generation of CMOS/microfluidic chips that combine a two-dimensional array of high voltage (50 V) RF pixels to produce large DEP forces, a microelectromagnetic matrix [2] that can independently trap and move magnetic beads, and integrated temperature sensors. We show the design, fabrication, and testing of the hybrid chips as well as ongoing work to interface and package the chips for robust biological and chemical experiments. [1] T.P. Hunt, D. Issadore, R.M. Westervelt, Lab Chip, 2008, DOI: 10.1039/b710928h. [2] H. Lee, A.M. Purdon and R.M. Westervelt, Appl. Phys. Lett. 85, 1063 (2004). [Preview Abstract] |
Tuesday, March 11, 2008 10:48AM - 11:00AM |
H16.00011: Hybrid CMOS/Microfluidic Chip Applications Keith A. Brown, David Issadore, Thomas P. Hunt, R.M. Westervelt We present our continuing work on hybrid CMOS/microfluidics systems that enable programmable experiments on single biological cells and picoliter chemistry. A 128x256 array of 10x10 micron RF-electrode pixels in the integrated circuit (IC) allows positioning of cell-sized objects using dielectrophoresis in a microfluidic chamber observed using a fluorescence microscope[1]. The fluid environment in the chamber is controlled through external piping, integrating the hybrid chip into a complete microfluidic system. We demonstrate the use of this integrated circuit as a cell-sorting stage. Applications and prototypical experiments with relevance to biologically motivated research will be presented. We highlight single cell experiments made possible by the ability to move, combine and separate picoliter droplets using computer control with video feedback. \newline [1] Thomas P. Hunt, et al. Lab Chip, 2008, DOI: 10.1039/b710928h [Preview Abstract] |
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