Photoactive (supra)molecular devices in double layer membranes

Biological systems are complex and highly organized architectures governed by non-covalent interactions responsible for the regulation of essential tasks in all living organisms. These systems are a constant source of inspiration for supramolecular chemists aiming to design multicomponent molecular assemblies able to perform elaborated tasks, thanks to the role and action of the components that constitute them. Artificial supramolecular systems exploit non-covalent interactions to mimic naturally occurring events. In this context, stimuli-responsive supramolecular systems have attracted attention due to the possibility to control macroscopic effects through modifications at the nanoscale. This thesis is divided in three experimental chapters, characterized by a progressive increase in molecular complexity. Initially, the preparation and studies of liposomes functionalized with a photoactive guest such as azobenzene in the bilayer were tackled, in order to evaluate the effect of such photochrome on the vesicle properties. Subsequently, the synthesis and studies of thread-like molecules comprising an azobenzene functionality was reported. Such molecules were conceived to be intercalated in the bilayer membrane of liposomes with the aim to be used as components for photoresponsive transmembrane molecular pumps. Finally, a [3]rotaxane was developed and studied in solution. This system is composed of two crown ether rings interlocked with an axle containing three recognition sites for the macrocycles, i.e. two pH-switchable ammonium stations and a permanent triazolium station. Such molecule was designed to achieve a change in the ratio between the recognition sites and the crown ethers as a consequence of acid-base inputs. This leads to the formation of rotaxanes containing a number of recognition sites respectively larger, equal or lower than the number of interlocked rings and connected by a network of acid-base reactions.

Hybrid portable systems for bio-nanosensors

The promising development in the routine nanofabrication and the increasing knowledge of the working principles of new classes of highly sensitive, label-free and possibly cost-effective bio-nanosensors for the detection of molecules in liquid environment, has rapidly increased the possibility to develop portable sensor devices that could have a great impact on many application fields, such as health-care, environment and food production, thanks to the intrinsic ability of these biosensors to detect, monitor and study events at the nanoscale. Moreover, there is a growing demand for low-cost, compact readout structures able to perform accurate preliminary tests on biosensors and/or to perform routine tests with respect to experimental conditions avoiding skilled personnel and bulky laboratory instruments. This thesis focuses on analysing, designing and testing novel implementation of bio-nanosensors in layered hybrid systems where microfluidic devices and microelectronic systems are fused in compact printed circuit board (PCB) technology. In particular the manuscript presents hybrid systems in two validating cases using nanopore and nanowire technology, demonstrating new features not covered by state of the art technologies and based on the use of two custom integrated circuits (ICs). As far as the nanopores interface system is concerned, an automatic setup has been developed for the concurrent formation of bilayer lipid membranes combined with a custom parallel readout electronic system creating a complete portable platform for nanopores or ion channels studies. On the other hand, referring to the nanowire readout hybrid interface, two systems enabling to perform parallel, real-time, complex impedance measurements based on lock-in technique, as well as impedance spectroscopy measurements have been developed. This feature enable to experimentally investigate the possibility to enrich informations on the bio-nanosensors concurrently acquiring impedance magnitude and phase thus investigating capacitive contributions of bioanalytical interactions on biosensor surface.