Mohammadali Tabatabaei

Microfluidic channel with embedded SERS 2D platform for the aptamer detection of ochratoxin A

AbstractA selective aptameric sequence is adsorbed on a two-dimensional nanostructured metallic platform optimized for surface-enhanced Raman spectroscopy (SERS) measurements. Using nanofabrication methods, a metallic nanostructure was prepared by electron-beam lithography onto a glass coverslip surface and embedded within a microfluidic channel made of polydimethylsiloxane, allowing one to monitor in situ SERS fingerprint spectra from the adsorbed molecules on the metallic nanostructures. The gold structure was designed so that its localized surface plasmon resonance matches the excitation wavelength used for the Raman measurement. This optofluidic device is then used to detect the presence of a toxin, namely ochratoxin-A (OTA), in a confined environment, using very small amounts of chemicals, and short data acquisition times, by taking advantage of the optical properties of a SERS platform to magnify the Raman signals of the aptameric monolayer system and avoiding chemical labeling of the aptamer or the OTA target. FigAptamer detection of OTA within a SERS/microfluidic channel

Directing GPCR-transfected cells and neuronal projections with nano-scale resolution.

Surface modification technology has made significant advances in recent years towards the miniaturization and organization of traditional cell culture systems. However, the capability of directing transfected cells and neuronal connections to probe small structures such as spines is still under development. In the current work, interactions of different micropatterned substrates with HEK 293, CF10 cell lines, and primary neuronal cultures are evaluated. Using conventional and confocal fluorescence microscopies, several morphological and behavioral aspects of all three cell types were investigated. The immortalized cell lines were able to attach to the substrate and interact with neighboring cells. Similarly, cortical neurons formed connections guided by the micropatterns. Transfection of HEK 293 or CF10 cell lines with specific members of the G protein-coupled receptor family did not alter the behavior of these cells in the micropatterns. On the other hand, neuronal projections were efficiently isolated by the patterns, simplifying the localization of spines with nano-scale resolution probed by atomic force microscopy. This work presents a valuable approach to isolate cells or to constrain important cell structures to grow along a desired pattern, thus facilitating advanced biological studies.