An Innovative Cell Microincubator for Drug Discovery Based on 3D Silicon Structures

Recently, we applied three-dimensional (3D) silicon microstructures (SMSs), consisting of arrays of ?3 "m-thick silicon walls separated by 50 "m-deep, ?5 "m-wide gaps, as microincubators suitable for monitoring the biomechanical properties of tumor cells in culture.The same structures were here employed to investigate the in vitro behavior of tumor cells driven to apoptosis by a chemotherapeutic compound. HT1080 human fibrosarcoma cells were grown on silicon dice incorporating the 3D-SMSs, treated with the proapoptotic drug Bleomycin (200 "g/mL for 24 h, 48 h, and 72 h), and fixed and stained for fluorescence microscopy analyses. Results of our investigation demonstrated that HT1080 cells exhibited a great ability to colonize the grooves, entering the narrow, deep gaps of the 3D-SMS. We also observed that cells grown on 3D-SMS, when treated with the DNA damaging agent Bleomycin under conditions leading to apoptosis, tended to shrink, reducing their volume and mimicking the normal behavior of apoptotic cells, and to leave the gaps. Visual inspection performed bymeans of fluorescencemicroscopy allowed us to demonstrate that cells grown on 3D-SMS exhibited the morphological alterations typical of apoptosis. In view of future applications of the 3DSMS as the core element of a lab-on-a-chip suitable for screening the effect of new molecules potentially able to kill tumor cells, we also performed label-free detection of a cell adherent to the vertical siliconwall, inside the gap of 3D-SMS, by exploitingOptical Low Coherence Reflectometry using infrared, low power radiation.This kind of lab-on-a-chip combined with label-free cell detection may become a new tool for increasing automation in the drug discovery area.