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Astrocytes are responsible for maintaining homoeostasis and cognitive functions through calcium signalling, a process that is altered in brain diseases. Current bioelectronic tools are designed to study neurons and are not suitable for controlling calcium signals in astrocytes. Here, we show that electrical stimulation of astrocytes using electrodes coated with graphene oxide and reduced graphene oxide induces respectively a slow response to calcium, mediated by external calcium influx, and a sharp one, exclusively due to calcium release from intracellular stores. Our results suggest that the different conductivities of the substrate influence the electric field at the cell–electrolyte or cell–material interfaces, favouring different signalling events in vitro and ex vivo. Patch-clamp, voltage-sensitive dye and calcium imaging data support the proposed model. In summary, we provide evidence of a simple tool to selectively control distinct calcium signals in brain astrocytes for straightforward investigations in neuroscience and bioelectronic medicine.

We describe a fast and versatile method to functionalize high-quality graphene with organic molecules by exploiting the synergistic effect of supramolecular and covalent chemistry. With this goal, we designed and synthesized molecules comprising a long aliphatic chain and an aryl diazonium salt. Thanks to the long chain, these molecules physisorb from solution onto CVD graphene or bulk graphite, self-assembling in an ordered monolayer. The sample is successively transferred into an aqueous electrolyte, to block any reorganization or desorption of the monolayer. An electrochemical impulse is used to transform the diazonium group into a radical capable of grafting covalently to the substrate and transforming the physisorption into a covalent chemisorption. During covalent grafting in water, the molecules retain the ordered packing formed upon self-assembly. Our two-step approach is characterized by the independent control over the processes of immobilization of molecules on the substrate and their covalent tethering, enabling fast (t< 10 s) covalent functionalization of graphene. This strategy is highly versatile and works with many carbon-based materials including graphene deposited on silicon, plastic, and quartz as well as highly oriented pyrolytic graphite.

Graphene and its related materials have attracted much interest in sensing applications because of their optimized ratio between active surface and bulk volume. In particular, several forms of oxidized graphene have been studied to optimize the sensing efficiency, sometimes moving away from practical solutions to boost performance. In this paper, we propose a practical, high-sensitivity, and easy to fabricate gas sensor based on high quality graphene oxide (GO), and we give the rationale to the high performance of the device. The device is fabricated by drop-casting water-dispersed single-layer GO flakes on standard 30 μm spaced interdigitated Pt electrodes. The exceptional size of the GO flakes (27 μm mean size and ∼500 μm maximum size) allows single GO flake to bridge adjacent electrodes. A typical p-type response is observed by testing the device in both reducing and oxidizing environments. The specific response to NO2is studied by varying the operating temperature and the gas concentration. Sensing activity is demonstrated to be mainly mediated by the oxygen functional groups. A 20 ppb detection limit is measured. Besides illustrating a simple and efficient approach to gas sensing, this work is an example of the versatility of graphene oxide, accomplishing tasks that are complementary to graphene.

We report an optical contrast study of graphene oxide on 72 nm Al2O3/Si(100) and 300 nm SiO2/Si(100) as a function of its reduction degree. The reduction has been performed by means of ultrahigh vacuum thermal annealing from 25 °C (pristine graphene oxide) to 670 °C. In parallel to the optical contrast investigation, performed with optical microscopy, the graphene oxide films have been characterized with core level X-ray photoemission spectroscopy and micro-Raman spectroscopy. The optical contrast of graphene oxide (normalized to the one measured for pure graphene) on both substrates ranges from ∼0.4 to 1.0 for pristine and 670 °C annealed graphene oxide, respectively. Optical microscopy and X-ray photoemission spectroscopy data have been cross-correlated, leading to calibration graphs that demonstrate that just by simply measuring the optical contrast of graphene oxide one can determine with very good approximation the fraction of sp2hybridized carbon.

PS‐b‐PMA block copolymers carrying terminal anionic groups have been studied. Their synthesis is achieved by mean of 3‐(benzylsulfanyl thiocarbonylsulfanyl) propionic acid and 3‐(1‐phenylethylsulfanyl thiocarbonylsulfanyl) propanesulfonic acid sodium salt as RAFT agents. These block copolymers, when dispersed in methanol, display a pseudo‐amphiphilic behaviour and provide micelles that can be suspended in water by osmosis. During the self‐assembling process, the anionic terminations lead to the formation of nanosized monodispersed particles and confer stability to the micelles in aqueous media. The core of the micelles is loaded with Nile Red to achieve the intracellular delivery of a lipophilic substance; this has been demonstrated by Confocal Laser Scanning Microscopy. The particles, when loaded with Doxorubicin, are able to overcome the intrinsic resistance of LoVo‐MDR cancer cells. A further stabilization is given to the micelles by covalent shell crosslinking provided by triethylene glycol diacrylate. The increased intracellular stability of the crosslinked micelles makes them stain, when loaded with Nile Red, the aqueous cytosol instead of the lipophilic cellular compartments. The unimers constituting the micelles have been covalently labelled with fluorescein to follow their fate once incorporated into the cells.

In the search for new ways to combine the appealing simplicity of solution processing methods and the need for a high performance of the active layer of organic (opto)electronic devices, the possibilities given by the joint use of well‐established casting techniques and post‐treatment procedures are explored, as well as new and unconventional deposition protocols to tailor self‐assembled architectures with a high degree of order at different length scales, from the subnanometer up to the macroscopic scale. In fact, even the same organic molecule can give rise to different molecular architectures which, in turn, may offer the possibility to exploit a large variety of new functionalities of the deposited materials, paving the way towards the fabrication multifunctional organic‐based devices.

Versatile synthetic methods towards a variety of thiophene‐nucleobase hybrid systems are reported. Adenine‐ and thymine‐based modified nucleosides characterized by a bithiophene unit linked to the C5′ or C8 position through an ethylenamino or an ethylensulfanyl bridge were synthesized and successfully polymerized in the presence of FeCl3. The self‐organization properties of the pure polymers as well as their mixtures ‐ with complementary nucleobases ‐ were investigated by means of optical microscopy and AFM in cast film showing complex supramolecular structures resulting from the interplay of multiple intermolecular interactions.

In the search for new ways to combine the appealing simplicity of solution processing methods and the need for a high performance of the active layer of organic (opto)electronic devices, the possibilities given by the joint use of well‐established casting techniques and post‐treatment procedures are explored, as well as new and unconventional deposition protocols to tailor self‐assembled architectures with a high degree of order at different length scales, from the subnanometer up to the macroscopic scale. In fact, even the same organic molecule can give rise to different molecular architectures which, in turn, may offer the possibility to exploit a large variety of new functionalities of the deposited materials, paving the way towards the fabrication multifunctional organic‐based devices.