Coordinators |
Dr. Diego Vozzi, Dr. Ivan Vallini |
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Keywords |
lab on chip, fluidics, extraction, micro-PCR, fluorescence detection |
The strategic global objective of this research activity is the development of advanced microfluidic devices for genomics, post-genomics, proteomics and molecular analysis (Lab-on-a-Chip). The implementation we are currently carrying out introduces great improvements compared to the existing ones in terms of sensitivity, cost reduction, speed, predisposition to automation, reliability and repeatability.
In particular, we are developing three different modules respectively for extraction/purification of DNA from whole blood, DNA amplification through PCR and hybridization/detection through a traditional fluorescence approach implementing the APEX protocol for SNPs detection. The technological process has been preceded by Finite Element Analysis and Behavioral simulations with commercial tools (CoventorWare and Comsol) to properly design the microfluidic circuitry and the efficiency of thermal cycling.
All the three modules are actually developed in parallel with traditional microelectronic and micromechanical materials such as silicon, glass and metals and they will be assembled in a hybrid solution. Currently the first prototypes for the microfluidic characterization are under test together with biological protocols customized for the scaled reagents volumes involved.
Further improvements will involve several aspects of the current implementation of the device. In particular work in progress is related to the employment of polymeric materials (PDMS, COC, PC, PMMA, …) in substitution of the standard silicon/glass pair; these materials offer several advantages in terms of optical properties and surface treatments for DNA adhesion. In this case, patterning will be achieved through hot embossing technique (COC, PC, PMMA) or casting in situ (PDMS)
Coordinators |
Dr. Carlo Ricciardi |
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Keywords |
microcantilevers, functionalization |
Aim of this research activity is the improvement in the efficiency of the actual detection techniques for the mentioned micro-devices. To this end, two solutions are currently under investigation: (i) microcantilevers to be used as microbalances and (ii) electrochemical luminescence (ECL).
Application of micro- and nano-cantilevers to molecular recognition is a recent breakthrough in life science and biochemistry and has rose great expectations in the scientific community for its fundamental and technological perspectives. The use of a cantilever system for genomics, post-genomics and proteomics may result in larger sensitivity, quantitative analyses and label-free detection, opening a wide range of applications in genome analysis and molecular diagnostics. Mass sensitivity of a few femtograms was recently reported using nanoscale resonators. The detection principle is simple and rather well known: the cantilever is functionalised with a proper probe which can selectively bind to the target molecule (typical examples of probe-target partners are antibodies and proteins or complementary DNA strands). The interactions between the binding sites of probe and target change the mechanical response of the system.
Besides a large variety of successful experiments in literature, a deeper comprehension of fundamental mechanics and physical chemistry of the MC based molecular recognition systems is needed. We are working on this aim coupling ab initio simulations with FEM (Finite Elements Methods) modeling of the cantilever mechanics. Experimentally, SAM and/or biomolecule elastic constants could be estimated by non-contact AFM measurements, while surface stress effects on home-made cantilevers will be checked by means of our dynamic mode set-up.
Finally, silicon and polymers microfabrication techniques offer new exciting opportunities for the realization of miniaturized biotechnological devices. For these applications specific modification of surfaces is crucial. Depending on the final application, proper functional moieties are introduced on the surface either to create reactive sites able to covalently anchor biomolecules and to improve the compatibility of materials by preventing nonspecific adsorption which may have an adverse effect on the performance of bio-devices. This is why in the Laboratory a team with multidisciplinary competences is working on the specific subject of surface functionalization with important expectations for all the other research activities.
Coordinators |
Prof. Luca Prodi, Prof. Francesco Paolucci |
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Keywords |
ECL, microelectrodes, functionalization |
Aim of this research activity is the improvement in the efficiency of the actual detection techniques for the mentioned micro-devices. To this end, two solutions are currently under investigation: (i) microcantilevers to be used as microbalances and (ii) electrochemical luminescence (ECL).
ElectroChemical Luminescence (ECL) is another potentially disruptive alternative to the standard fluorescence detection approach. We are actually working on the development of a complete detection scheme, starting from the synthesis of new ECL markers, through the fabrication of customized microelectrodes, up to the development of a readout dedicated optoelectronic system. Performances of each step of our system will be compared to actual commercial solutions.
Coordinators |
Dr. Ivano Alessandri |
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Keywords |
Nanogap, nanoelectrodes, piezoelectric nanostructures |
This project aims to explore novel possibilities for detection of oligonucleotides and small biomolecules by exploiting some of the key functional properties achievable through the synthesis and the integration of nanostructured systems. The project outlines are specifically addressed to a fundamental research activity which could open to completely new perspectives.
For more informations:
- Alessandri I, Bergese P, Depero LE, “ZnO whiskers in chestnut husk-like structures: sequential synthesis and proof of chemomechanical transduction”, to be published in the special issue of Journal of Nanoscience and Nanotechnology dedicated to the proceedings of ChinaNANO2007.
- Bergese P, Oliviero G, Alessandri A, Depero LE, “On Thermodynamics of Mechanical Transduction of (Bio)Chemical Reactions”, J. Coll. Int. Sci., in press
Coordinators |
Dr. Michele Vinante, Dr. Simone Musso |
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Keywords |
Carbon Nanotubes, functionalization, biocompatibility |
Aim of this project is the production, characterization, modification and biological properties investigation of carbon based nanostructured materials (nanotubes and nanographite) for biosensing applications and in particular for the development of a DNA detection device.
The first stage of this project is aimed to produce worthwhile quantities of vertically well-oriented multi-walled carbon nanotubes (MWCNTs) on uncoated silicon substrates by a simple and economical chemical vapor deposition process.
Subsequently, the as-grown material will be characterized and then chemically modified. In particular, the chemical modification plays a key role in the tuning of the chemical properties of the CNTs, allowing a different response to different biomolecules. Several functionalization treatments, previously reported in literature, will be attempted in order to tailor the CNT properties for the foreseen applications. The presence of reactive groups on the material surface will allow the chemical insertion of nucleic acids, proteins and other biological molecules on CNTs, which consequently will make possible to produce nano-biological sensors. Moreover, the presence of ferromagnetic particles trapped inside the CNT hollow cavities, can enable the production of systems that can migrate below a magnetic field effect.
The interaction of biomolecules with CNTs will be studied with the final aim to make them biocompatible and useful as biosensors or as coatings for biomedical devices. The interaction mechanisms between CNT surface and blood are characterized by a complex series of events that are yet not clearly understood. The aim of this research activity is to investigate the relationship between surface properties (chemistry, hydrophobicity-hydrophilicity and topography) and biological responses such as the composition and structure of the adsorbed plasma protein layer and platelet adhesion/activation properties. In this work the behavior of CNTs compared to various forms of carbon (pyrolitic carbon, nanocrystalline graphite and amorphous carbon) will be investigated.
Besides the study of conformation and orientation of adherent proteins, the adhesion extent of various DNA (oligonucleotides, genomic DNA) structures will be evaluated to gain fundamental knowledge useful for both the development of CNT based biosensors and the development of an innovative materials for genomic DNA isolation (see Latemar project on Lab-on-Chip).
Coordinators |
Prof. Francesco Geobaldo, Dr. Fabrizio Giorgis |
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Keywords |
SERS, SEIRA, nanoparticles, SPR, fluorescence enhancement |
This project deals with the synthesis and characterization of metallic/dielectric nanostructures and nanoparticles aimed to obtain efficiency enhancement of Raman, Infrared and Fluorescence spectroscopies. Such enhancements will be exploited for detecting biomolecules in assays with very low concentration.
Raman Enhancement: Surface-enhanced Raman scattering (SERS) is a spectroscopic technique which combines modern laser spectroscopy with the exciting optical properties of metallic nanostructures, resulting in strongly increased Raman signals when molecules are attached to nanometer-sized gold and silver structures. The effect provides the structural information content of Raman spectroscopy together with ultrasensitive detection limits. Actually, when molecules are attached or are in close proximity to gold and silver nanostructures the Raman scattering can take place in the enhanced local optical fields of the metallic surfaces (electromagnetic field enhancement); indeed, particular scattering enhancement occurs when excitation and scattered electro-magnetic fields are in resonance with the surface plasmons of the nanostructures. Besides the electromagnetic mechanism, also a chemical enhancement can contribute to enhance the Raman efficiency, particularly when molecules are ‘chemisorbed’ on the metal surface. Among the most effective nanostructures devoted to SERS, metallic nanoparticles with spherical/ellipsoidal shape can be synthesized in liquid solution by metal hydrosols or by salt reduction in templates consisting of nano and mesoporous dielectric matrices, while ordered structures constituted by nanosized cylinder/ellipsoid/emisphere arrays can be fabricated by using nanolithography tools.
Infrared absorption/reflection Enhancement: an effect quite similar to SERS occurs in the mid-infrared region. Molecules on metal surfaces show infrared absorption 10–1000 times more intense than would be expected from conventional measurements without the metal. This effect is referred to as surface-enhanced infrared absorption/reflection (SEIRA) to emphasize the analogy to SERS. The electromagnetic interactions of the incident photon field with the metal and molecules play predominant roles in this effect; on the other hand, chemical interactions of the molecules with the surface can give additional enhancement. Enhanced spectra can be observed in the transmission, attenuated total-reflection (ATR), external-reflection and diffuse-reflection modes.
Fluorescence enhancement: fluorescence is the product of two processes, excitation by the incident field influenced by the local environment, and emission of radiation influenced by the balance of radiative and nonradiative decay. If the excitation of the system analyte-nanostructure is closely tuned with the energy of the plasmon resonance of the metal, the radiative rate can be enhanced; on the other side, if the emitting analyte is in close contact with the metal surface, nonradiative energy transfer to the metal nanostructure leads to a decrease of the quantum yield, bringing to fluorescence quenching. Thus, in order to have a dominant fluorescence enhancement activated by metallic nanostructures, the distance between emitter and metal structure have to be tuned at nanometric level.
The research activities of this project will consider different strategies devoted to enhance the efficiency of the above mentioned spectroscopies. As far as SERS and SEIRA techniques are concerned, metallic structures synthesized on semiconductor and glass substrates are being developed, using electron-beam lithography and lift-off process for the fabrication of ordered matrix of Ag and Au pillars, while nano and meso-porous silicon processed by electrochemical etching is used as template for the synthesis of metallic nanoparticles obtained by reduction of salts. For what concerns fluorescence spectroscopy, the sensitivity enhancement will be obtained by optical confinement in stratified porous silicon based structures (Fabry-Perot microcavities) and by confining thousands of organic and metallo-organic chromophores embedded in silica nanoparticles.
Coordinators |
Ing. Matteo Cocuzza |
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Keywords |
Polymeric lab on chip, fluidics, interconnections, extraction, micro-PCR, fluorescence detection |
Since the introduction of lab-on-a-chip (LOC) devices in the early 1990s, silicon and glass have been the dominant substrate materials for their fabrication. This is primarily driven by the fact that fabrication methods were well established and surface properties and derivatization methods were well characterized and developed. Several material properties of silicon and glass make them very attractive materials for use in microfluidic systems; however, the cost of producing systems in silicon or glass is driving commercial producers to seek other materials. Commercial manufacturers of microfluidic devices see many benefits in employing polymers that include reduced cost and simplified manufacturing procedures, particularly when compared to glass and silicon. An additional benefit that is extremely attractive is the wide range of available polymer materials which allows the manufacturer to choose materials’ properties suitable for their specific application.
Aim of the project is the realization of three different microfluidic modules (Lab-on-a-chip) respectively devoted to the extraction of DNA, PCR and detection through hybridisation. Integration of microfluidic interconnections and fluidic actuation and control is envisioned. The modules and the different complementary tools will be produced through hot embossing of thermoplastic polymers (PMMA, COC, PC) and casting of soft elastomeric siloxane polymers such as PDMS.
Suitable strategies for polymer surface conditioning for the different applications have been stated and under development, both through wet and plasma processing.
Coordinators |
Prof. Barbara Onida |
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Keywords |
Separation, nanochannels, mesostructures |
High-resolution separations is extremely challenging: besides opening new possibilities in separation science, it could permit to reduce drastically the length of separation system and to achieve dimensions comparable with a microchip format.
Nanostructured porous materials, prepared by a bottom-up approch using sol-gel process with surfactant micelles acting as templates, are promising systems for these applications. To this purpose, a strict control of dimension and direction of channels is necessary. Control of channels orientation may be achieved in oriented films and by exploiting the confinement effect of microstructured enviroments, such as ceramic porous membranes.
Research in this field is being carried out in order to obtain oriented nanoporous silica with pores size in the range 2-10 nm and test the systems in separation of biomelecules, such as oligonucleotides and peptides.