Introduzione del corso Prof C

Pagina 1

1 Marzo 2018 Carminati LEZIONE 1 Biosensor can be defined using two different definitions, stronger and a weaker one. One of the first sensors: if the bird dies, the miner has to go quickly outside of the cave. Categories of sensors that we take from nature. If we want to identify the specific molecule X we may use a receptor that’s specifically complementary to X. When they combine together something change in the environment (or propriety of the receptor), we want to transform this into some kind of measurable signal (electrical). Tipically, receptor is taken from nature and put in to a artificial system: we have a solid substrate on which its attached, and tipically they are inside in a support, a liquid solution (a ionic one most of times). The receptor operates in a liquid environment. There are different technological challenges regarding the isolation, the extraction of receptor from nature, the biocompatibility and so on. The task of microfluidics to control that the molecule can actually reach the receptor. There are several molecular affinity: most common couple is the antibody-antigen; enzyme- substrate, or key-lock mechanism or selectivity in engineering way or specificity in biological way; DNA and nucleic acids. Of course, another task is to obtain a device adapt to the small biological environment sizes (order of magnitude): we are in the range of or nanometer or micrometer according to the application, but of course we have to obtain a manipulable device. We can take into account some geometrical parameters for the molecules we considerate: the contour length and the radius of gyration (equivalent radius to cover an equal surface with a circle). The enzymes are macromolecules that increase the probability that a reaction it’s able to take place: binding…