Catherine Hansel

Porous silicon nanoneedles for live single cell enzymatic profiling

Catherine Hansel - 3rd year PhD


Intracellular enzymatic activity is fundamental to cell metabolism and for the interaction of cells with the environment. Disruption of enzymatic activity is essential to the onset and progression of chronic degenerative diseases, such as cancer. We are developing a novel strategy to monitor in real time at the cellular level the disruption of enzymatic activity, to help understand the role of intracellular enzymes in cancer development.

We have developed a vertical array of nanoneedles (nNeedles) functionalized with enzymatic sensors based on peptides. These sensors can map the enzymatic activity in live cells at the cellular level (Figure 1): a formidable task, to which a universal solution has not been found yet. The student will develop the nNeedles sensor to map the activity of Cathepsin B (CTSB) protease both in cell lines and in tissue. CTSB activity pattern is altered in several several epithelial cancers and cancer cell lines, and has an important yet poorly understood contribution to metastasis. Once able to map CTSB expression, the student will investigate the effect of its localization and activity with respect to cell motility and metastatic potential.

Figure 1:

Overview of the nanoneedle system. (a) confocal image of fluorescent nanoneedles penetrating within cells. (b) confocal image overlay of nanoneedles simultaneously loaded (throughout their porous structure) with cy3-siRNA (yellow), quantum dots (red), and FITC-.BSA (green) (c-d) Schematic depiction of the nanoneedle sensor. (c) The nanoneedles are interfaced with cells presenting the peptide-Fluo within the cytosol. The Fluo is cleaved and released in the cytosol proportionally to CTSB expression. (d) once the nanoneedles are removed from the cells fluorescence originates from the cell cytosol proportionally to cytosolic CTSB expression