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Biosensors for Point Detection of Biological and Chemical Agents based on Nanostructured Optical Components
In the last ten years the increase in terrorism threats against civilian population has lead to an incentive research in the development of a novel generation of portable and efficient sensing devices for the fast detection of u!tra trace concentrations in air of explosives, biologica! and chemical toxic agents. Such techniques can al so be very useful in military and homeland security activity to detect illicit production of these substances, realization of improvised weapons. The sensor can be used as early alarm systems or forensic analisys in a defence and security scenario. Due to their versatility, optical sensors are powerful detection and analysis tools which can be employed in various applications: environmental and industrial monitoring, defense and border security, surveillance of airports. Aiming at developing a Lab-on-Chip technology for the early detection of toxic substances, we recently achievedi the accurate detection of DMMP at a 20 ppb level (114 µg/m3 of equivalent Sarin) in the gas phase using photonic integrated circuits (PICs) combined to biologica! recognition receptors. The technology is based on the changes in the refractive index (RI) occurring on the photonic ring resonator when the propagated light encounters an adsorbed molecule of the target. This results in a wavelength shift (Dl) of the light which can be measured with a resol ution as low as 3.4 pm. Functionalizing the surface of the ring resonators with specifically tuned odorant binding proteins (OBPs), allows performing a highly selective and sensitive detection. A schematic view of the wavelength shifts measured in the case of specific sensing and on blank chips. The biophotonic system leads to a signal only in the case of a specific detection. The detection can also be achieved in a liquid media by preconcentrating the sampled target in a l iquid before detection. The detectìon in l iquid results in weaker performances compared to the gas phase (table I ) due to a lower change in the refractive index when proteins binds target in the liquid (DRI = 0.07) than in the gaseous. However, such feature authorizes the detection of aerosols-contained spores and toxic biological organisms (Anthrax, Ricin toxin) present or released in the atmopshere. By combaining photonic technology with biological odorant-protein based specific receptors we develop a novel generation of photonoc devices which are portable, insensitive to magnetic interferences, higly sensitive and achieve a true selective detection by specifically tuning immobilized proteins for the recognition of one single target. The possibility to functìonalize up to ten ring resonators on a chip with different tuned OBPs allows a very specific multi-target detection. Thus the efficiency of the technology in both liquid and gaseous media permits the detection of both chemical and biological threats. To our knowledge this is the first time that biologica! receptors are combined with optical detection, despite chemical recognition has been already used in such systems.
Bonnot Karine, Cuesta-Soto Francisco, Rodrigo Manuel, Varriale Antonio, Sanchez Nuria, D'Auria Sabato, Lopez-Royo Francisco, Pierno Luigi, Meloni Andrea, Spitzer Denis, Gransee Rainer, Plaza del Olmo Julio
Paper for Seminar/Symposium/Conference
mTAS 2013 - International Conference on Miniaturized Systems for Chemistry and Life Science (27-31 October, Freiburg 2013, Germany)
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