The advantages of using 1, 96, or 384 precision glass syringes in automated high-throughput microdispensers in creating highly uniform and reproducible DNA, protein, and organic compound array filters and slides are described. Using the Hydra Microdispenser and Tango Liquid Handling system, 0.1-5 ng (in 50-300 nL) PCR-amplified, human cancer-related genes and housekeeping genes were spotted onto nylon membranes and coated slides. Protein solutions of 50 microg/mL to 1 mg/mL were spotted onto coated slides or onto MaxiSorp 96-well plates. Up to 6144 spots/membrane and up to 1000 spots/slide were printed. The size of the spots created by glass syringes was uniform and reproducible (precision variation of less than 5%) from spot to spot and membrane to membrane. Using a Tango 384 system, a total of ten 6144-spot filters can be produced in approximately 25 min, translating into a spotting speed of 2.5 min/membrane.
We have studied the enhancement factors (EF) in Surface Enhanced Raman Scattering (SERS) substrates prepared with self assembled ZnO nanorod arrays and Au nanocrystals. The ZnO/Au composite nanoarrays present experimental EF values as high as ~10 7 for detection of Rhodamine 6G (R6G) using an excitation wavelength of 633 nm. We have study the EF via numerical simulations of a single ZnO/Au composite nanorod using a FDTD algorithm. Our results indicate that the coupling between the photonic wave guiding in the ZnO nanorod and the plasmonic resonance in the Au nanocrystals plays a significant role in the observed EF and need to be considered to fully understand and optimize the development of high efficiency, reproducible, and stable SERS substrates.
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