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ABSTRACT: A microfluidic technique was employed to fabricate polydiacetylene (PDA)-embedded hydrogel microfibers. By taking advantage of calcium ion-induced insoluble hydrogel formation, supramolecularly assembled diacetylene (DA)-surfactant complexes were successfully immobilized in the calcium alginate fibers. Thus, instantaneous microfiber formation was observed when the core flow of DA supramolecules-containing alginate solution met the sheath flow of calcium ions. UV irradiation of the resulting fibers afforded blue colored PDAs, and the formation of a conjugated polymer was confirmed by heat-induced phase transition and by Raman spectroscopy. By adjusting the core and sheath flow rates, PDA-embedded hydrogel fibers of various sizes were obtained.
Macromolecular Rapid Communications 04/2012; 33(15):1256-61. · 4.60 Impact Factor
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ABSTRACT: We inferred the phylogenetic and phylogeographic relationships in ticks, which were identified morphologically as Ixodes holocyclus and Ixodes cornuatus, from mitochondrial cytochrome oxidase subunit 1 (COX1) and nuclear internal transcribed spacer 2 (ITS2) sequences. We obtained COX1 (640bp) and ITS2 (527-568bp) sequences from 429 ticks from 49 localities in Tasmania, Victoria, New South Wales and Queensland, Australia. Our analyses show that there are two species of Ixodes in eastern Australia that cause paralysis in dogs and other mammals: I. holocyclus and I. cornuatus. Further, we conclude that the morphological criteria used to differentiate female I. holocyclus and I. cornuatus are equivocal but I. holocyclus can be distinguished from I. cornuatus using COX1 and/or ITS2 sequences. Intraspecific genetic variation in I. holocyclus and I. cornuatus was less than 0.86% and 0.19% for COX1 and ITS2, respectively. Ixodes holocyclus could be genetically distinguished between different geographic ranges. There were no significant genetic differences between I.cornuatus from Tasmania and mainland Australia, but there are some COX1 haplotypes of I. cornuatus from the mainland that were not detected in Tasmanian and vice versa.
International journal for parasitology 07/2011; 41(8):871-80. · 3.39 Impact Factor
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ABSTRACT: Polymerizable supramolecular monomer vesicles are readily fabricated by employing a hydrodynamic focusing method on a microfluidic chip. The polymerized diacetylenene nanovesicles, generated using the microfluidic method, display an improved fluorescence property compared to those prepared by employing a conventional bulk method. The flexibility of the vesicle size control by manipulating the flow conditions is another significant feature of the new microfluidic approach.
Langmuir 11/2010; 26(23):17840-2. · 4.19 Impact Factor
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ABSTRACT: A new, microfluidic temperature sensor system, based on a thermoresponsive conjugated polymer supramolecule, has been developed. By generating blue-phase polydiacetylene (PDA) sensor droplets using hydrodynamic instability, we were able to monitor the variation of fluorescent intensity of the droplets with respect to the flow temperature.
Journal of the American Chemical Society 03/2009; 131(11):3800-1. · 9.91 Impact Factor
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Advanced Materials 04/2008; 20(9):1690 - 1694. · 13.88 Impact Factor
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Analytical and Bioanalytical Chemistry 02/2006; 384(1):41-3. · 3.78 Impact Factor
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ABSTRACT: Laser-patterning of nanoporous membranes at the junction of a cross channel in a microchip is used to integrate protein concentration with an electrokinetic injection scheme. Upon application of voltage, linear electrophoretic concentration of charged proteins is achieved at the membrane surface because buffer ions can easily pass through the membrane while proteins larger than the molecular weight cutoff of the membrane (>5700) are retained. Simple buffer systems can be used, and the concentration results constitute outward evidence that the uniformity of buffer ion concentration is maintained throughout the process. Local and spatially averaged concentration are increased by 4 and 2 orders of magnitude, respectively, upon injection with moderate voltages (70-150 V) and concentration times (100 s). The degree of concentration is limited only by the solubility limit of the proteins. The porous polymer membrane can be used repeatedly as long as care is taken to avoid protein precipitation.
Analytical Chemistry 08/2004; 76(15):4589-92. · 5.86 Impact Factor
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ABSTRACT: Chip-level integration of microdialysis membranes is described using a novel method for in situ photopatterning of porous polymer features. Rapid and inexpensive fabrication of nanoporous microdialysis membranes in microchips is achieved using a phase separation polymerization technique with a shaped UV laser beam. By controlling the phase separation process, the molecular weight cutoffs of the membranes can be engineered for different applications. Counterflow dialysis is used to demonstrate extraction of low molecular weight analytes from a sample stream, using two different molecular weight cutoff (MWCO) membranes; the first one with MWCO below 5700 for desalting protein samples, and the second one with a higher MWCO for size-based fractionation of proteins. Modeling based on a simple control volume analysis on the microdialysis system is consistent with measured concentration profiles, indicating both that membrane properties are uniform, well-defined, and reproducible and that diffusion of subcutoff analytes through the membrane is rapid.
Analytical Chemistry 05/2004; 76(8):2367-73. · 5.86 Impact Factor
