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Toward an Optofluidic gene Sensor based on Fluorescence Enhancement in a Hollow Bottle Microresonator

My thesis work was carried out at the Optoelectronic Research Centre (ORC) in the United Kingdom. [...]
In first chapter the widely used method for detection of nucleic acids strings, known as hybridization, is presented with the explanation of the basics of the nucleic acids biology.
The optical approach exploited in this work requires an understanding of the concept of fluorescence that is the physical effect that provides the signal and is explained in chapter 2.
Chapter 3 is dedicated to the state of the art in biosensing, illustrating basics, requirements and several possible approaches, focussing on optofluidic biosensors.
The state of the art specifically relevant for the optical resonator device used in this work is described in chapter 4 after summarizing its physics principle.
Materials exploited in this work came from many disciplines and are listed in chapter 5, in addition to the chemical methods employed for the research and the optical scheme used for measurements.
The experimental work is reported in chapter 6 where the functionalization of the device with the bioreceptor and the characterization of the performance of the transducer are described in detail.
The project, due to its multidisciplinary characteristic, was continued within the Inte-grated Photonic Devices Group that traditionally exploited mainly planar photonic de-vices, for various applications included diagnostics in medicine, but, more recently, also integrated microsphere resonators fabricated with fibre technologies. The project meets the demand of small integrated biological sensors which could eliminate the lengthy and hard laboratory work traditionally required to perform gene detection. For these devices, the biochemical functionalization of the device is the first aspect to consider, which con-fer to the optical device its specificity, i.e., the way to interact with biological entities. For optical methods the sensitivity and speed is considerably enhanced respect to elec-trochemical approaches; moreover, optical detection can be integrated with a capillary fabricated with fibre technology that provides the advantages of microfluidics. For bio-logical measurements, optics offers different approaches. In particular, label-free meth-ods are very interesting since do not require the use of any marker and achieve among the best sensitivity in biosensing. Unfortunately, the label-free technique was found not suitable for the fluidic device considered and it was necessary to consider the use of flu-orescent markers. A characterization of the device was carried out in order to verify the principle of optical transduction: it was aimed to the spatial and spectral visualization of the resonances by the excitation of specific fluorophores.

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6 Introduction My thesis work was carried out at the Optoelectronic Research Centre (ORC) in the United Kingdom. Founded in 1989, the ORC is situated within the Faculty of Physics and Applied Science of the University of Southampton and is considered, in the interna- tional scientific community, as one of the leading institution in the field of photonics and optoelectronics. Its facilities include the EPSRC (Engineering and Physical Scienc- es Research Council) Centre for Innovative Manufacturing in photonics, which offers the opportunity to the institute to develop fibres and materials that can meet market needs, and to identify commercially viable ways of manufacturing them. New genera- tion of fibres are the main key of research, used for every application such as communi- cations, laser manufacturing, sensing, infrared fibres and defence countermeasures. For this reason, it supports the growth of companies, not only in the UK (as for SPI Laser company of Southampton), but all over Europe and even in Italy as for Selex Galileo and Pirelli, at least before the telecommunication bubble. The project was started in the Optical Biosensors and Biophotonics Group that is more oriented to the area of micro and nanofabricated devices, for bio-analyses or for bio- medical applications, either based on optics, microfluidics or self-assembled techniques. The project, due to its multidisciplinary characteristic, was continued within the Inte- grated Photonic Devices Group that traditionally exploited mainly planar photonic de- vices, for various applications included diagnostics in medicine, but, more recently, also integrated microsphere resonators fabricated with fibre technologies. The project meets the demand of small integrated biological sensors which could eliminate the lengthy and hard laboratory work traditionally required to perform gene detection. For these devices, the biochemical functionalization of the device is the first aspect to consider, which con- fer to the optical device its specificity, i.e., the way to interact with biological entities. For optical methods the sensitivity and speed is considerably enhanced respect to elec- trochemical approaches; moreover, optical detection can be integrated with a capillary fabricated with fibre technology that provides the advantages of microfluidics. For bio- logical measurements, optics offers different approaches. In particular, label-free meth- ods are very interesting since do not require the use of any marker and achieve among the best sensitivity in biosensing. Unfortunately, the label-free technique was found not suitable for the fluidic device considered and it was necessary to consider the use of flu-

Tesi di Laurea Magistrale

Facoltà: Ingegneria

Autore: Giulio Negri Contatta »

Composta da 105 pagine.

 

Questa tesi ha raggiunto 45 click dal 24/05/2013.

Disponibile in PDF, la consultazione è esclusivamente in formato digitale.