OPTICAL DETECTION OF MOLECULAR INTERACTIONS ON THE SURFACE OF MATERIALS INDEX-MATCHED TO WATER.
Tesi di Dottorato
Data di Pubblicazione:
2015
Citazione:
OPTICAL DETECTION OF MOLECULAR INTERACTIONS ON THE SURFACE OF MATERIALS INDEX-MATCHED TO WATER / R. Lanfranco ; supervisor: M. Buscaglia ; coordinatore: M. Bersanelli. DIPARTIMENTO DI BIOTECNOLOGIE MEDICHE E MEDICINA TRASLAZIONALE, 2015 Dec 14. 28. ciclo, Anno Accademico 2015. [10.13130/lanfranco-roberta_phd2015-12-14].
Abstract:
The idea to have highly effective autonomous sensors able to measure and share information
about the quality of our environment, and particularly water, in our lakes and
rivers, our water supply system and the outputs of municipal and industrial wastewater
treatment systems is revolutionary and fascinating. These sensors could be densely deployed
at multiple locations, and the information may be available to citizens through
the Internet. This idyllic vision, nowadays, is far away from being reality, despite the
huge effort made to develop innovative molecular sensors. The main challenges related
to the realization of these autonomous sensors network are the biofouling, power supply
and compactness. In fact, despite thousands of papers in literature about development
of novel nanostractured materials for sensing, for instance, there is still not a single
example of any of these device being used in direct contact with water for long-term
environmental monitoring.
The work presented in this thesis proposes a new kind of optical sensor that combines
a fast and low cost method to detect water pollutant with good performance and robustness.
In particular, this work is focused on the detection of small molecular pollutants,
as oils compounds and surfactants. An innovative aspect of the proposed approach relies
on the use of a novel class of materials as sensing substrate which have peculiar and
fascinating optical properties: these are amorphous perfluorinated polymers with refractive
index similar to that of water. When immersed in aqueous solutions, they provide
extremely low reflection or scattering of light, hence they become barely visible. For this
reason, this class of materials is called phantom. In this limit, when a thin molecular layer
spontaneously adsorbs on the surfaces of these materials, the reflected or scattered light
increases, providing the basis for optical detection of molecules.
In this work, three different phantom materials made of perfluorinated polymers
are exploited in the framework of the detection of water contaminants: a prism, microporous
membranes and micro-beads, that represent the building blocks for the assembly
of an invisible chromatography column. The membrane and the micro-beads were produced
for the first time during this work. The use of fluoropolymer prism substrate for
molecular detection was already proposed in recent works to realize label-free biosensors
based on the functionalization of the surface with antibodies. Here I extend the
exploitation of this system to the detection of molecular pollutant through their adsorption
on the bare surface of the fluoropolymer materials, without the need of any surface
treatment. Despite the lack of surface functionalization, a selectivity in the adsorption of
various classes of molecules is demonstrated.
Tipologia IRIS:
Tesi di dottorato
Keywords:
surfactant adsorption, perfluorinated materials, label-free biosensor, light scattering, reflictive phantom interface, low refractive index colloids, emulsions, micro-porous membrane
Elenco autori:
R. Lanfranco
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