David Rioux

Silicon nanoparticles produced by femtosecond laser ablation in water as novel contamination-free photosensitizers

We report the synthesis of novel inorganic contamination-free photosensitizers based on colloidal silicon nanoparticles prepared by laser ablation in pure deionized water. We show that such nanoparticles are capable of generating singlet oxygen ((1)O(2)) under laser irradiation with a yield estimated at 10% of that of photofrin, which makes them a potential candidate for therapeutics, antiseptics, or disinfectants. We also discuss a model of (1)O(2) generation and the possibility for optimizing its release. Potential advantages of such novel inorganic photosensitizers include stable and nonphotobleaching (1)O(2) release, easy removal, and low dark toxicity.

Wide-field hyperspectral 3D imaging of functionalized gold nanoparticles targeting cancer cells by reflected light microscopy

We present a new hyperspectral reflected light microscopy system with a scanned broadband supercontinuum light source. This wide-field and low phototoxic hyperspectral imaging system has been successful for performing spectral three-dimensional (3D) localization and spectroscopic identification of CD44-targeted PEGylated AuNPs in fixed cell preparations. Such spatial and spectral information is essential for the improvement of nanoplasmonic-based imaging, disease detection and treatment in complex biological environment. The presented system can be used for real-time 3D NP tracking as spectral sensors, thus providing new avenues in the spatio-temporal characterization and detection of bioanalytes. 3D image of the distribution of functionalized AuNPs attached to CD44-expressing MDA-MB-231 human cancer cells.

SiC as a Biocompatible Marker for Cell Labeling

This chapter focuses on the application of SiC quantum dots (QDs) for fluorescent cell labeling. Two different top-down processes are investigated to produce SiC QDs from bulk or polycrystalline SiC substrates: electrochemical etching and laser ablation. In both cases, a broad size distribution of crystalline SiC nanoparticles is obtained (ranging from few tens of nanometers down to 2nm in diameter). In electrochemical etching, the original polytype is conserved, whereas in laser ablation, some stacking faults are found in the naoparticles. The mechanism of photoluminescence has been investigated as a function of QD spatial and chemical configuration, i.e., interconnected QDs in a freestanding nanoporous layer, dry and wetted nanopowder obtained from the nanoporous layer, dispersion of QDs in various solvents (with different dielectric constants) and with various surfactants, and centrigugated solutions of QDs to keep the smallest ones. From all these experiments, both surface-related photoluminescence, probably due to C═O double bonds, and photoluminescence, due to discrete levels of quantum-confined carriers, have been evidenced.