Lab-on-chip systems for integrated bioanalyses.

Biomolecular detection systems based on microfluidics are often called lab-on-chip systems. To fully benefit from the miniaturization resulting from microfluidics, one aims to develop 'from sample-to-answer' analytical systems, in which the input is a raw or minimally processed biological, food/feed or environmental sample and the output is a quantitative or qualitative assessment of one or more analytes of interest. In general, such systems will require the integration of several steps or operations to perform their function. This review will discuss these stages of operation, including fluidic handling, which assures that the desired fluid arrives at a specific location at the right time and under the appropriate flow conditions; molecular recognition, which allows the capture of specific analytes at precise locations on the chip; transduction of the molecular recognition event into a measurable signal; sample preparation upstream from analyte capture; and signal amplification procedures to increase sensitivity. Seamless integration of the different stages is required to achieve a point-of-care/point-of-use lab-on-chip device that allows analyte detection at the relevant sensitivity ranges, with a competitive analysis time and cost.

Modulation of alpha-synuclein toxicity in yeast using a novel microfluidic-based gradient generator.

Parkinson's disease (PD) is a common age-associated neurodegenerative disorder. The protein α-synuclein (aSyn) is a key factor in PD both due to its association with familial and sporadic cases and because it is the main component of the pathological protein aggregates known as Lewy bodies. However, the precise cellular effects of aSyn aggregation are still elusive. Here, we developed an elastomeric microfluidic device equipped with a chemical gradient generator and 9 chambers containing cell traps to study aSyn production and aggregation in Saccharomyces cerevisiae. This study involved capturing single cells, exposing them to specific chemical environments and imaging the expression of aSyn by means of a GFP fusion (aSyn-GFP). Using a galactose (GAL) gradient we modulated aSyn expression and, surprisingly, by tracking the behavior of single cells, we found that the response of individual cells in a population to a given stimulus can differ widely. To study the combined effect of environmental factors and aSyn expression levels, we exposed cells to a gradient of FeCl3. We found a dramatic increase in the percentage of cells displaying aSyn inclusions from 27% to 96%. Finally, we studied the effects of ascorbic acid, an antioxidant, on aSyn aggregation and found a significant reduction in the percentage of cells bearing aSyn inclusions from 87% to 37%. In summary, the device developed here offers a powerful way of studying aSyn biology with single-cell resolution and high throughput using genetically modified yeast cells.