Light represents an innovative paradigm in the field of bio-stimulation, allowing precise and non-destructive control over a wide range of biological effects. In these regards, the use of optical switches can be seen as a promising alternative to optogenetics in photo-stimulation, as they can confer reversible light-sensitivity to bio-targets. In this perspective, azobenzene-based molecules seem to be promising candidates as optical switches since they can undergo isomerization under illumination. Recently, a new amphiphilic azobenzene molecule named Ziapin2 has been synthesised. It has been shown that his molecule predominantly localizes in the plasma membrane and effectively modulates neuronal firing in vitro, as well as in vivo via an opto-mechanical effect. In this thesis work, we study the role of the local environment in the photophysics of Ziapin2, to evaluate its sensitivity to viscosity and polarity of the solvent. By employing steady-state and time-resolved optical spectroscopies, we found that the azobenzene relaxation pathways are sensitive to the molecular environment and to the lipid membrane composition. By means of cells membrane models, we investigated the probe affinity for lipid rafts, which are specialized membrane lipid micro-domains that are thought to influence many cellular processes. Further studies in biological environments are ongoing, to establish a reliable relationship between the spectroscopic observable and photoinduced biological effects both in cells models and in vivo.
Nell'ambito della stimolazione di tessuti biologici, la fotostimolazione è un metodo innovativo, che permette il controllo di molti processi fisiologici in modo preciso e non distruttivo. In particolare, l'utilizzo di switch ottici è un'alternativa all'optogenetica, in quanto queste molecole possono conferire sensibilità alla luce ad alcuni bio-target. In quest'ottica, le molecole azobenzeniche sono buoni candidati come switch ottici, poiché, in seguito a eccitazione ottica, possono isomerizzare. Recentemente, è stata sintetizzata una nuova molecola a base di azobenzene, chiamata Ziapin2. È stato osservato che questa molecola ha un'affinità per la membrana plasmatica e controlla efficacemente l'attività dei neuroni sia in vitro, sia in vivo. In questa tesi, studiamo l'effetto dell'ambiente sulla fotofisica della Ziapin2, per valutare la sensibilità della molecola alla viscosità e alla polarità del solvente in cui si trova. Attraverso tecniche di spettroscopia ottica, sia in continua, sia risolte in tempo, abbiamo osservato che i cammini di diseccitazione della molecola azobenzenica sono sensibili all'ambiente e al diverso contenuto lipidico della membrana. Utilizzando modelli di membrana cellulare, abbiamo esaminato l'affinità della molecola per i lipid rafts, micro-domini della membrana che sembrano ricoprire un ruolo significativo in molti processi biologici. Ulteriori studi sono in corso, per stabilire una relazione precisa tra le osservabili spettroscopiche e gli effetti biologici fotoindotti sia in modelli cellulari, sia in vivo.
Amphiphilic azobenzene for phase recognition in model membranes
MAGNI, ARIANNA
2018/2019
Abstract
Light represents an innovative paradigm in the field of bio-stimulation, allowing precise and non-destructive control over a wide range of biological effects. In these regards, the use of optical switches can be seen as a promising alternative to optogenetics in photo-stimulation, as they can confer reversible light-sensitivity to bio-targets. In this perspective, azobenzene-based molecules seem to be promising candidates as optical switches since they can undergo isomerization under illumination. Recently, a new amphiphilic azobenzene molecule named Ziapin2 has been synthesised. It has been shown that his molecule predominantly localizes in the plasma membrane and effectively modulates neuronal firing in vitro, as well as in vivo via an opto-mechanical effect. In this thesis work, we study the role of the local environment in the photophysics of Ziapin2, to evaluate its sensitivity to viscosity and polarity of the solvent. By employing steady-state and time-resolved optical spectroscopies, we found that the azobenzene relaxation pathways are sensitive to the molecular environment and to the lipid membrane composition. By means of cells membrane models, we investigated the probe affinity for lipid rafts, which are specialized membrane lipid micro-domains that are thought to influence many cellular processes. Further studies in biological environments are ongoing, to establish a reliable relationship between the spectroscopic observable and photoinduced biological effects both in cells models and in vivo.File | Dimensione | Formato | |
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2019_12_Magni.pdf
Open Access dal 28/11/2022
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https://hdl.handle.net/10589/151373