Saurabh Vyawahare

Surface-Plasmon Enhanced Bright Emission from CdSe Quantum-Dot Nanocrystals

We obtained very bright light emission from CdSe quantum dots (QDs) by using surface plasmon coupling. Both the photoluminescence intensities and decay rates are dramatically increased when QDs are located on evaporated gold films.

Effect of NRG1, GDNF, EGF and NGF in the Migration of a Schwann Cell Precursor Line

The Schwann cells are the myelinating glia of the peripheral nervous system that originated during development from the highly motile neural crest. However, we do not know what the guidance signals for the Schwann cell precursors are. Therefore, we set to test some of the known neurotrophins that are expressed early in developing embryos and have been shown to be critical for the survival and patterning of developing glia and neurons. The goal of this study was to determine more specifically if GDNF, NRG1 and NGF are chemoattractants and/or chemokinetic molecules for a Schwann cell precursor line, the Spl201. We performed live chemoattraction assays, with imaging and also presented these molecules as part of their growing substrate. Our results show for the first time that GDNF and NRG1 are potent chemoattractive and chemokinetic molecules for these cells while NGF is a chemokinetic molecule stimulating their motility.

Spectrographic microfluidic memory

Recent advancements in micro- and nanoscale fluidic manipulation have enabled the development of a new class of tunable optical structures which are collectively referred to as optofluidic devices. In this paper we will introduce our recent work directed towards the development of a spectrographic optofluidic memory. Data encoding for the memory is based on creating spectrographic codes consisting of multiple species of photoluminescent nanoparticles at discrete intensity levels which are suspended in liquids. The data cocktails are mixed, delivered and stored using a series of soft and hard-lithography microfluidic structures. Semiconductor quantum dots are ideally suited for this application due to their narrow and size tunable emission spectra and consistent excitation wavelength. Both pressure driven and electrokinetic approaches to spectral code writing have been developed and will be experimentally demonstrated here. Novel techniques for data storage and readout are also discussed and demonstrated.

Field-based multiplex and quantitative assay platforms for diagnostics

The U.S. military has a continued interest in the development of handheld, field-usable sensors and test kits for a variety of diagnostic applications, such as traumatic brain injury (TBI) and infectious diseases. Field-use presents unique challenges for biosensor design, both for the readout unit and for the biological assay platform. We have developed robust biosensor devices that offer ultra-high sensitivity and also meet field-use needs. The systems under development include a multiplexed quantitative lateral flow test strip for TBI diagnostics, a field test kit for the diagnosis of pathogens endemic to the Middle East, and a microfluidic assay platform with a label-free reader for performing complex biological automated assays in the field.

Erratum to: Effect of NRG1, GDNF, EGF and NGF in the Migration of a Schwann Cell Precursor Line

1. The recombinant EGF-like domain of NRG1-a (not NRG1-b) was used throughout the paper where NRG1 results are mentioned. 2. Culture medium described as containing 10% FBS is better described as containing 8–9% FBS (with the exception mentioned below). The same medium also contained *1.8 mM L-glutamine rather than 2 mM. 3. The SpL201 cells used for experimentation were at times observed to have a very low level of bacterial contamination. Specific Corrections/Clarifications:

Optofluidic integration for medical diagnostics and spectroscopy

We show the capabilities of the applications of microlithography techniques optimized for the microelectronic industry for integrating optics with fluidics and electronics in integrated micro-chips. We also show the opportunities of silicon photonics to generate inexpensive optical systems for data communications and analysis.

Combining Shape Memory Alloys and Microfluidic Chips on Printed Circuit boards

Integrated multi-layer fluidic chips, with hundreds of elastomeric valves, are useful in immunoassays, protein crystallization, cell culture and several other applications. Although the devices are micro-scale, because valves are actuated pneumatically, each chip requires a relatively large pneumatic control system for operation. Fulfilling the great promise of microfluidics, for instance building throwaway, portable, massively parallel, point-of-care diagnostic systems is unlikely until there is a solution for actuating micro-valves electrically. We introduce a combination of materials—shape memory alloys (SMAs) and elastomersto solve this problem. SMAs offer among the highest work per unit volume of any actuator, and elastomers have the ability to absorb the energy and return the SMA to its original configuration, while providing electric and thermal insulation. Using this marriage of materials, with PDMS (elastomer) and Ni/Ti wires (SMA), we built electrically activated micro-fluidic valves, peristaltic pumps and multiplexers. The first generation valve design needs 50 to 250 mA current in the on state, with power requirements of about 0.5 W. It can hold back >1 atmosphere of pressure and run for thousands of cycles, actuating at sub-second speeds. The dead volume is <1 nano-liter. Crucially, these devices are assembled on printed circuit boards, like conventional electronic components. Thus, the technology used in assembling electronics is applicable to assembling fluidic chips, and both electronics and fluidics can be integrated on one platform for biomedical applications.

Surface plasmon enhanced light emission from CdSe quantum dot nanocrystals

We obtained very bright light emission from CdSe quantum dots (QDs) by using surface plasmon coupling. Both the photoluminescence intensities and decay rates are dramatically increased when QDs are located on evaporated gold films.