CDTE quantum dots – preparation, physico-chemical properties and application as fluorescent markers

A set of water-soluble CdTe quantum dots (QDs) was prepared by the chemical reaction between cadmium chloride and sodium hydrogen telluride in the presence of 3-mercaptopropionic acid (MPA). QDs were characterized using fluorescence spectroscopy, lifetime measurements, slab-gel and capillary electrophoresis. The particle sizes, determining the wavelength of the fluorescence emission, were evaluated to be from 2.5 nm (500 nm) to 5.2 nm (750 nm). The fluorescence lifetimes determined by the time-resolved fluorescence spectrometry, increases from 3.05 to 20.5 ns with the increasing size of particles. The uptake of non-conjugated QDs into the living cells, which has a potential for single cell analyses, was apparent for human lymphocytes and yeast cells (Saccharomyces cerevisiae) after 30 minutes and 3 hours, respectively. The cell manipulation, lysis and monitoring was performed in microfluidic devices with laser-induced fluorescence detection. The conjugation of QDs with functional biomolecules allows the selective labeling and localization of specific molecules. Several coupling agents such as N-hydroxysulfosuccinimide (NHS) and 1-ethyl-3-(3- dimethylaminopropyl)carbodiimide hydrochloride (EDC) or carbonyldiimidazole (CDI) were used. The concentrations of reaction products were checked by capillary electrophoresis with laser-induced fluorescence detection

Micro-Injection Moulding of Polymer Microfluidic Devices

Microfluidic devices have several applications in different fields, such as chemistry, medicine and biotechnology. Many research activities are currently investigating the manufacturing of integrated microfluidic devices on a mass- production scale with relatively low costs. This is especially important for applications where disposable devices are used for medical analysis. Micromoulding of thermoplastic polymers is a developing process with great potential for producing low-cost microfluidic devices. Among different micromoulding techniques, micro-injection moulding is one of the most promising processes suitable for manufacturing polymeric disposable microfluidic devices. This review paper aims at presenting the main significant developments that have been achieved in different aspects of micro-injection moulding of microfluidic devices. Aspects covered include device design, machine capabilities, mould manufacturing, material selection and process parameters. Problems, challenges and potential areas for research are highlighted