I am graduated within Biological Science - Bio-molecular field; I got a Biochemical and Biomolecular Science PhD at the University of Catania, working on Bio-molecules immobilization on SiO2 surface for biomedical, environmental and microelectronics applications. I carried out the work of degree thesis and PhD thesis into the Microelectonic and Micrositem Institute of CNR of Catania. During the PhD period I work on immobilization protocol of biomolecules in SiO2; I had optimized the covalent immobilization protocol, using XPS, AFM, SEM-EDX investigation techniques. I spent a part of my PhD time at CEA-LETI-MINATEC, Grenoble in order to work on hybrid organic molecules / silicon devices. This topic was better developed during a post-Doc position, which I got in the same laboratory of CEA Grenoble. Through this experience I acquired new competencies in the field of electrical device testing and physics. I attended a summerschool on "micro and nanotechnology for label free sensing" at Technical University of Denmark in August 2012. I worked in the NBS group of Institute for Health and Consumer Protection (Joint Research Centre) as post-Doc to work on Radar project. The mission was to develop the sensing layer for a label-free biosensor, using SPR sensor detection. I worked in the DTSi service of CEA Grenoble for identifying an innovative bio-marker detection platform.
During my PhD and my working experiences I acquire expertise in numerous fields including optical and structural characterization of biological material immobilized into Si or SiO2, preparation methods of biological samples for TEM and SEM assays, surface chemical functionalization and chemical immobilization methods of biological molecules on SiO2. I developed my team work skills and the capacity to work in multidisciplinary environment acquiring versatility and communication abilities.
Development and surface characterization of a nanoporous platform for biomarkers detection. In charge to follow the process in clean room environment and to biomedical detection by mass spectrometry; networking with the different labs involved in the project.
Development of new devices using organic molecules
Detailed Description
The physical-chemical characterization of various organic layer has been performed for possible applications in the microelectronic field. Physical phenomena at the base of the device functioning have been also studied and the Si-based surface functionalization has been done using Cyclic Voltammetry and X-ray Photoelectron Spectroscopic-XPS) for the chemical part, Atomic Force Microscopy- AFM for the morphology and Current measurements for the electrical part. Chemical characterization has been used to demonstrate the presence of organic molecules on the surface and to verify the maintenance of molecules activity also after their grafting. Morphological measures have highlighted the uniformity of organic layer, while electrical tests have allowed to study the possible electrical influence of organic layer on the devices.
Optimization of biomolecules immobilization protocol in SiO2
Detailed Description
Aim of PhD work was the study and the definition of an “universal platform” for the fabrication of an innovative biosensor. To carry out this purpose, it was needed to optimize an immobilization protocol that can be efficiently used to anchor different biological molecules on solid support, such as silicon and materials based on its technology. In particular, in this work it was studied and optimized a protocol to covalently bond bio-molecules having a free NH2 termination at the SiO2 support, consisting of four. The supports used were both bulk SiO2 and porous Si oxide (pSiO2). The immobilization protocol was optimized using the Glucose oxidase (GOx) enzyme and its versatility tested using amino terminated single strand DNA oligonucleotides and Methallotionein (MT) proteins. The investigation was carried out using techniques usually employed in the microelectronic field: Atomic Force Microscopy (AFM), X-ray Photoelectron Microscopy (XPS) and Electron Didispersive X-ray coupled with Scanning Electron Microscopy (SEM-EDX) or Transmission Electron Microscopy (TEM-EDX). The demonstration of the retained protein activity was performed by spectrophotometric measurements. In particular, to monitor and optimize the immobilization protocol of GOx on bulk SiO2, contact angle measurements, AFM and XPS techniques were used. Once the protocol on bulk SiO2 samples was fully characterized, we applied the optimized immobilization procedure on porous SiO2 (pSiO2) samples. To demonstrate directly the enzyme presence into the samples Energy Dispersive X-ray (EDX) in cross-section with and without gold-labelling was performed. These measurements provided an experimental direct evidence of the GOx immobilization within the porous SiO2 matrix. To detect the maintenance of the activity of the immobilized enzyme, a simple, colorimetric assay was used. The enzyme activity of the GOx immobilized on Si-bulk and pSiO2 samples was monitored. The activity was present in both samples, but the pSiO2 fully processed sample exhibited a much stronger activity, due to the higher concentration of immobilized enzyme, thanks to the wider surface available for immobilization with respect to the bulk SiO2 sample. To demonstrate that it is applicable to a large variety of bio-molecules, single strand DNA (ssDNA) and MT from rabbit liver were used. These molecule could be used as new sensitive element for the detection in biomedical field (DNA) or of heavy metal ions presence in liquid environment (MTs). To demonstrate the presence of both bio-molecules on the SiO2 surfaces support XPS and EDX measurements were carried out The least step of this work was to attest to the possibility to use the electrical detection as transduction method. Both GOx and DNA oligonucleotides 20 bases long were used as immobilized bio-molecules. The electrical characterization of MOS-like capacitors having the biological molecules directly immobilized on SiO2, was carried out directly dropping 1.5 µl of PBS solution on the SiO2+organic layer. MOS-like structures tested are sensitive to the biological species immobilized on the dielectric. The obtained data show a potential for the development of MOS-based biosensors.
This work consisted in the structural characterization of functionalized Silicon surface through Atomic Force Microscopy (AFM ), Scanning Tunneling Microscope (STM) and Scanning Transmission Electron Microscopy (STEM). A Redox molecule (Ferrocene) was grafted in Si surface using two methods: direct and indirect (by linker). The results obtained in this work allowed to show the uniformity of organic layers in both case.