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Biomedical subjects

Andrew J de Mello

Publications and source records attributed to Andrew J de Mello.

9 recordsLinked to original sources
PubMed2005

Thermal optimisation of the Reimer-Tiemann reaction using thermochromic liquid crystals on a microfluidic reactor.

Microreactors incorporating thin film resistive heating elements for continuous flow organic synthesis are presented. Internal thermal conditions were monitored in real time using reflectance spectra of temperature sensitive thermochromic liquid crystals (TLC) in a collateral microfluidic network. To demonstrate the precise temperature control provided by this method, the thermal optimisation of the Reimer-Tiemann formylation of beta-naphthol was performed under hydrodynamic pumping regimes.

Crystallization↗
PubMed2004

Precise temperature control in microfluidic devices using Joule heating of ionic liquids.

Microfluidic devices for spatially localised heating of microchannel environments were designed, fabricated and tested. The devices are simple to implement, do not require complex manufacturing steps and enable intra-channel temperature control to within +/-0.2 degrees C. Ionic liquids held in co-running channels are Joule heated with an a.c. current. The nature of the devices means that the internal temperature can be directly assessed in a facile manner.

Equipment Design↗
PubMed2004

Microfluidic systems for high-throughput and combinatorial chemistry.

Demands on modern combinatorial chemistry have necessitated massive investment in new synthetic technologies that will allow the production of highly pure drug candidates on short timescales. The advent of microfluidic reactor technologies has recently provided a new tool for the combinatorial chemist, offering the promise of ultra-high-throughput solution-phase chemistries. This review describes why such microscale systems provide unique environments for performing high-efficiency molecular synthesis, details some of the most important recent developments in the field and assesses the true applicability of micro-engineered reactors in high-throughput compound synthesis.

Combinatorial Chemistry Techniques↗
PubMed2003

Single particle confocal fluorescence spectroscopy in microchannels: dependence of burst width and burst area distributions on particle size and flow rate.

This article presents a non-invasive, optical technique for measuring particulate flow within microfluidic channels. Confocal fluorescence detection is used to probe single fluorescently labeled microspheres (200-930 nm diameter) passing through a focused laser beam at a variety of flow rates (100 - 1000 nL/min). Simple statistical methods are subsequently used to investigate the resulting fluorescence bursts and generate single-particle burst width and burst area distributions. Analysis of such distributions demonstrates that the average burst width and burst area decrease as particle size increases. In addition, both burst width and burst area (for a given particle size) are observed to decrease as volumetric flow rate is increased. The dependence of such distributions on particle size is proposed as a potential route to sizing single particles and molecules in microfluidic systems.

Journal Article↗
PubMed2002

Electrophoretic analysis of amines using reversed-phase, reversed-polarity, head-column field-amplified sample stacking and laser-induced fluorescence detection.

This paper describes the use of reversed-phase, reversed-polarity head-column field-amplified sample stacking (HCFASS) for on-line sample concentration in conventional capillary electrophoresis. The effective stacking efficiency was determined as a function of sodium hydroxide concentration in the sample matrix. Results concur with theoretical predictions where stacking efficiency depends on the conductivity (electric field strength) and electrophoretic mobility in the sample matrix solution. Fluorescein isothiocyanate-derivatized aniline and 2,4-dimethylaniline were dissolved in sodium hydroxide (800 microM), separated in a phosphate running buffer (0.05 M, pH 9.0) and detected utilising laser-induced fluorescence. The use of reversed-phase, reversed-polarity HCFASS with laser-induced fluorescence detection yielded sensitivity improvements with respect to normal injection schemes in excess of three orders of magnitude, and a limit of detection as low as 10(-13) M.

Amines↗
PubMed2002

A polydimethylsiloxane/glass capillary electrophoresis microchip for the analysis of biogenic amines using indirect fluorescence detection.

A polydimethylsiloxane-glass capillary microchip is fabricated for the rapid analysis of a mixture of common biogenic amines using indirect fluorescence detection. Using a running buffer of phosphate and 2-propanol, and Rhodamine 110 as a background fluorophore, both co-ionic and counter-ionic systems are explored. Studies demonstrate the separation and analysis of cations using indirect fluorescence detection for the first time in a chip-based system. Resulting electrophoretic separations are achieved within a few tens of seconds with detection limits of approximately 6 microM. The reduced sample handling and rapid separations afforded by the coupling of indirect fluorescence detection with chip-based capillary electrophoresis provide a highly efficient method for the analysis and detection of molecules not possessing a chromophore or fluorophore. Furthermore, limits of detection are on a par with reported chip-based protocols that incorporate precolumn derivatisation with fluorescence detection. The current device circumvents lengthy sample preparation stages and therefore provides an attractive alternative technique for the analysis biogenic amines.

Animals↗