Device for real-time monitoring of oil-in-water and suspended solids based on thermal lens spectrometry and light scattering.

A novel system suitable for simultaneous monitoring of both oil-in-water and suspended solids based on thermal lens spectroscopy and forward light scattering is presented. The technique measures the concentration of dissolved hydrocarbons and simultaneously detects single oil droplets and suspended particles separately. The device was tested with injection water samples from an on-field water treatment plant, and hydrocarbon concentrations were measured with a precision better than 5% in the range of up to 100 ppm, reaching resolutions as low as 0.

Laser-based single-axon transection for high-content axon injury and regeneration studies.

The investigation of the regenerative response of the neurons to axonal injury is essential to the development of new axoprotective therapies. Here we study the retinal neuronal RGC-5 cell line after laser transection, demonstrating that the ability of these cells to initiate a regenerative response correlates with axon length and cell motility after injury. We show that low energy picosecond laser pulses can achieve transection of unlabeled single axons in vitro and precisely induce damage with micron precision.

Ischemic neurons prevent vascular regeneration of neural tissue by secreting semaphorin 3A.

The failure of blood vessels to revascularize ischemic neural tissue represents a significant challenge for vascular biology. Examples include proliferative retinopathies (PRs) such as retinopathy of prematurity and proliferative diabetic retinopathy, which are the leading causes of blindness in children and working-age adults. PRs are characterized by initial microvascular degeneration, followed by a compensatory albeit pathologic hypervascularization mounted by the hypoxic retina attempting to reinstate metabolic equilibrium.

Rapid multicomponent optical protein patterning.

Cells sense spatial distributions of molecules which trigger signal transduction pathways that induce the cell to migrate or extend by remodelling the cytoskeleton. However, the influence of local and small variations of extracellular protein concentration on chemotaxis is not fully understood, due in part to the lack of simple and precise methods to pattern proteins in vitro. We recently developed a new technology to fabricate such patterns which relies on photobleaching fluorophores to adsorb proteins on a cell culture substrate: laser-assisted protein adsorption by photobleaching (LAPAP).

Single photon fluorescent microlithography for live-cell imaging.

Using fluorescent dyes to trigger the polymerization of a commercial polyurethane resin allows a rapid fabrication of micrometer and submicrometer sized fluorescent structures by one-photon absorption. Here, we show that standard He-Ne lasers emitting at 632.8 nm can be used to start the photopolymerization and that very low laser power is required.