An investigation of the photoinduced fluorescence enhancement (PFE) behavior of CdSe/ZnS core/shell quantum dots deposited at low densities, under anhydrous and controlled water humidity, under oxygen or argon, is presented. The photoluminescence properties of CdSe/ZnS QDs are highly dependent upon the local gaseous environment. Under anhydrous conditions, under either oxygen or argon, there was no observed PFE, even though there were remarkable differences in the photoluminescence spectra. Under argon, (i) the initial photoluminescence properties are independent of humidity level; however, (ii) the PFE effect observed is highly dependent on the environmental humidity levels. Under oxygen, (i) the initial photoluminescence properties (spectra and yield) are dependent on humidity levels and (ii) the PFE effect observed is highly dependent on the humidity levels. Comparing D 2 O versus H 2 O humidity level effects on the photoluminescence properties of CdSe/ZnS QDs provides evidence for a water-molecule-stabilized state that facilitates luminescence processes. The products of CdSe/ZnS QDs exposed under a humid oxygen environment were evaluated by X-ray photoelectron spectroscopy. Oxidation of both the CdSe core and the ZnS shell was established. Oxidation of the ZnS shell is suggested to be a result of reaction with peroxide products resulting from the oxygen radical anion. These results highlight the important sensitivity of QDs to water and prove the existence of competing electronic and chemical effects on different time scales.

The emission of CdSe quantum dots linked to the 5'-end of a DNA sequence is efficiently quenched by hybridisation with a complementary DNA strand with a gold nanoparticle attached at the 3'-end; contact of the quantum dot and gold nanoparticle occurs.

The design of a novel, microfluidic chip with an integrated micro peristaltic pump and chambers for DNA amplification is described. This chip contains three reaction chambers stable at 90 • C, 72 • C and 55 • C for PCR amplification, a bi-directional peristaltic pump and optical integrated detection of the droplet. A reactant droplet is to be introduced into the device, pumped back and forth between the chambers by the micro peristaltic pump for sample processing. The static behaviour of the micro pump was modelled theoretically in order to evaluate the optimal dimensions for the pump membranes and to obtain the maximum flow rate. Thermal analysis by the finite element method was performed to optimize the location of the heaters and the temperature uniformity over the three reaction chambers. Transient thermal analysis indicates that the reactant droplet can be heated/cooled in the proposed device in less than 1 s to achieve the desired temperatures.