Recent advances in upscalable wet methods and ink formulations for printed electronics

This review deals with the use of solution processing approaches for organic electronics with a focus on material ink formulations as well as on their applicability. The solution processing techniques include methods like gravure printing, screen printing and ink-jet printing. Basic principles of each approach are understood and fundamental correlations between material (metals, semiconductors, and dielectrics) ink properties and final device performances can be drawn. Nevertheless, solution processing methods have the potential to evolve as the most promising tools in organic device fabrication techniques and have already been applied successfully in the fields of organic thin film transistors, solar cells and biosensing devices

Semitransparent Perovskite Solar Cells for Building Integration and Tandem Photovoltaics: Design Strategies and Challenges

Over the past decade, halide perovskite systems have captured widespread attention among researchers since their exceptional photovoltaic (PV) performance was disclosed. The unique combination of optoelectronic properties and solution processability shown by these materials has enabled perovskite solar cells (PSCs) to reach efficiencies higher than 25% at low fabrication costs. Moreover, PSCs display enormous potential for modern unconventional PV applications, since they can be made lightweight, semitransparent (ST), and/or flexible by means of appropriate design strategies. In particular, by enabling transparency and high efficiency simultaneously, ST-PSCs hold great promise for future versatile utilization in the context of building-integrated PVs (BIPVs) or as top cells to be coupled with conventional lower-bandgap bottom cells in tandem PV devices. The present Review wants to provide a detailed overview of latest research about ST-PSCs for BIPVs and tandems, by critically reporting on the most updated and effective design strategies in view of these two possible future applications. The differences and similarities between the available approaches are punctually highlighted, emphasizing the importance of a rigorous application-orientated ST-PSC design. Last but not least, the main challenges and issues about device design, operation, and stability that need to be addressed before commercialization are thoroughly scanned

Artificial Biosystems by Printing Biology

The continuous progress of printing technologies over the past 20 years has fueled the development of a plethora of applications in materials sciences, flexible electronics, and biotechnologies. More recently, printing methodologies have started up to explore the world of Artificial Biology, offering new paradigms in the direct assembly of Artificial Biosystems (small condensates, compartments, networks, tissues, and organs) by mimicking the result of the evolution of living systems and also by redesigning natural biological systems, taking inspiration from them. This recent progress is reported in terms of a new field here defined as Printing Biology, resulting from the intersection between the field of printing and the bottom up Synthetic Biology. Printing Biology explores new approaches for the reconfigurable assembly of designed life-like or life-inspired structures. This work presents this emerging field, highlighting its main features, i.e., printing methodologies (from 2D to 3D), molecular ink properties, deposition mechanisms, and finally the applications and future challenges. Printing Biology is expected to show a growing impact on the development of biotechnology and life-inspired fabrication

Oxidation effects in antiaggregogenic properties of Epigallocatechingallate

Epigallocatechin-gallate (EGCG), the most abundant flavonoid in green tea, has been extensively studied for its potential in the treatment of amyloid related disorders. This molecule was found to modulate abnormal protein self-assembly, reducing resulting cellular toxicity. EGCG is known to suppress or to slow down the aggregation processes of several proteins, thus supporting the idea that general mechanisms regulate its anti-aggregogenic effects and, interestingly, in the oxidised form it demonstrated an higher efficiency in reducing protein aggregation with respect to intact molecule. We here investigate the effects of intact and oxidized EGCG the thermal aggregation pathway of Bovine Serum Albumin (BSA), a well-known model protein whose aggregation processes are known in details. By means of different spectroscopic methods, we evaluate similarities and differences of the two molecules during protein aggregation. Different solution conditions are investigated, close and away from the isoelectric point of the protein, with the aim of eliciting the role of electrostatics in the observed EGCG-Protein interaction and in the supramolecular assembly which are dramatically dependent on solution conditions

On the Interaction between 1D Materials and Living Cells

One-dimensional (1D) materials allow for cutting-edge applications in biology, such as single-cell bioelectronics investigations, stimulation of the cellular membrane or the cytosol, cellular capture, tissue regeneration, antibacterial action, traction force investigation, and cellular lysis among others. The extraordinary development of this research field in the last ten years has been promoted by the possibility to engineer new classes of biointerfaces that integrate 1D materials as tools to trigger reconfigurable stimuli/probes at the sub-cellular resolution, mimicking the in vivo protein fibres organization of the extracellular matrix. After a brief overview of the theoretical models relevant for a quantitative description of the 1D material/cell interface, this work offers an unprecedented review of 1D nano- and microscale materials (inorganic, organic, biomolecular) explored so far in this vibrant research field, highlighting their emerging biological applications. The correlation between each 1D material chemistry and the resulting biological response is investigated, allowing to emphasize the advantages and the issues that each class presents. Finally, current challenges and future perspectives are discussed

Boosting the Performance of One-Step Solution-Processed Perovskite Solar Cells Using a Natural Monoterpene Alcohol as a Green Solvent Additive

The perovskite film is the core of a perovskite solar cell (PSC), and its quality is crucial for the performance of such devices. The morphology, crystallinity, and surface coverage of the perovskite layer greatly affect the power conversion efficiency (PCE), hysteresis, and long-term stability of PSCs. The incorporation of appropriate solvent additives in the perovskite precursor solution is an effective strategy to control the film morphology and reduce the defects and grain boundaries. However, the commonly used solvent additives are environmentally harmful and highly toxic. In this work, α-terpineol (a nontoxic, eco-friendly, and low-cost monoterpene alcohol) is employed for the first time as an alternative green solvent additive to improve the quality of one-step solution-processed CH3NH3PbI3–xClx films and to restrain nonradiative recombination in the corresponding devices. An in-depth investigation of the physicochemical effects induced by such a high-boiling-point, polar protic solvent when incorporated into a conventional perovskite solvent system is provided. The collected data demonstrate that the addition of a precise amount of α-terpineol can generate uniform and highly crystalline perovskite films with improved photovoltaic performances. Through this approach, the PCE of planar n–i–p PSCs is boosted up to 17.5% (against 16.1% of the top control device) with reduced hysteresis and enhanced ambient stability

Electrostatics regulate Epigallocatechin-Gallate effects on Bovine Serum Albumin aggregation

Protein aggregation processes are complex phenomena often involved in the etiology of several pathologies. It is now assessed that all proteins, in suitable conditions, may undergo supramolecular assembly. Aggregation pathways are known to be controlled by solution conditions which regulate protein-protein and protein-solvent interactions affecting binding mechanisms, morphology and inherent toxicity of the aggregate species. In this context, the presence of small molecules was indicated as a promising method to modulate protein-protein interactions reducing pathogenic aggregation. In the light of the idea that common mechanisms regulate anti-aggregogenic properties of small molecules, we here investigate Epigallocatechin-Gallate (EGCG) effects on the thermal aggregation pathway of Bovine Serum Albumin (BSA), a well-known model protein. EGCG is a small molecule extracted from green tea, which is known to reduce aggregation of key proteins involved in neurodegenerative diseases [1]. Fundamental mechanisms which regulate EGCG effectiveness as therapeutic molecule are still not clearly elucidated. The interaction of EGCG with BSA and its effects on thermal aggregation pathway were investigated by means of spectroscopic methods and Isothermal Titration calorimetry as a function of solution conditions. Results show that electrostatic forces modulated by pH play a key role in regulating EGCG interactions with BSA. Data shows that close to the isoelectric point of the protein, EGCG is found to promote the supramolecular assembly, whilst away from the isoelectric point, EGCG is found to reduce aggregation mechanisms increasing protein conformational stability. These results reveal the large impact of electrostatics in small molecules effects on the protein aggregation phenomena requiring larger investigation aimed at rationalizing their effects on related pathogenic mechanisms

Label-free approaches for extracellular vesicle detection

Extracellular vesicles (EVs) represent pivotal mediators in cell-to-cell communication. They are lipid-membranous carriers of several biomolecules, which can be produced by almost all cells. In the current Era of precision medicine, EVs gained growing attention thanks to their potential in both biomarker discovery and nanotherapeutics applications. However, current technical limitations in isolating and/or detecting EVs restrain their standard use in clinics. This review explores all the state-of-the-art analytical technologies which are currently overcoming these issues. On one end, several innovative optical-, electrical- and spectroscopy-based detection methods represent advantageous label-free methodologies for faster EV detection. On the other end, microfluidics-based lab-on-a-chip tools support EV purification from low-concentrated samples. Altogether, these technologies will strengthen the routine application of EVs in clinics

On the Effect of Downscaling in Inkjet Printed Life-Inspired Compartments

The fabrication of size-scalable liquid compartments is a topic of fundamental importance in synthetic biology, aiming to mimic the structures and the functions of cellular compartments. Here, inkjet printing is demonstrated as a customizable approach to fabricate aqueous compartments at different size regimes (from nanoliter to femtoliter scale) revealing the crucial role of size in governing the emerging of new properties. At first, inkjet printing is shown to produce homogenous aqueous compartments stabilized by oil-confinement with mild surfactants down to the hundreds of picoliter scale [1]. Raster Image Correlation Spectroscopy allows to monitor few intermolecular events by the involvement of protein-binding assays within these compartments [2]. Subsequently, in order to reduce droplet size at values below the nozzle size, a theoretical model from Eggers et al. [3] is experimentally reproduced permitting to obtain femtoliter-scale aqueous droplets from picoliter-scale microchannels [4]. As a remarkable difference to picoliter scale droplets, downscaling at the femtoliter-size triggers the spontaneous formation of molecularly crowded shell structures at the water/oil interface stabilized by a mixture of biocompatible surfactants. The shells have typical thickness in order of hundreds of nanometers, in accordance with theoretical models [5]. Molecular crowding effects in these systems are tested by using fluorescence lifetime imaging under the phasor plot approach [6], revealing different characteristic lifetimes of specific probe molecules in the confined volumes with respect to bulk solutions. The femtoliter-scale compartments autonomously trigger the formation of unique features (e.g., up-concentration, spatial heterogeneity, molecular proximity) that are mediated by the intermolecular interactions in these novel environments, ultimately permitting to mimic the native conditions of sub-cellular scale compartments. The crowding conditions in femtoliter-scale droplets do not to affect the conformation variation of a model DNA hairpin in presence of molecular triggers and of a CYP2E1-catalyzed enzymatic reaction. Our results can be a first step towards the fabrication of size-scalable lab-on-a-chip compartments mimicking sub-cellular environments. References 1. G. Arrabito, F. Cavaleri, V. Montalbano, V. Vetri, M. Leone, B. Pignataro, Lab on Chip, 2016, 16, 4666. 2. M.A. Digman, C. M. Brown, A. R. Horwitz,W.W. Mantulin, and E. Gratton, Biophysical Journal, 2016, 94, 2819. 3. J. Eggers, Phys. Rev. Lett. 1993, 71, 3458. 4. G. Arrabito, F. Cavaleri, A. Porchetta, F. Ricci, V. Vetri, M. Leone, B. Pignataro, Adv. Biosys. 2019, 1900023. 5. M. Staszak, J. Surfactants Deterg., 2016, 19, 297. 6. C. Stringari, A. Cinquin, O. Cinquin, M. A. Digman, P.J. Donovan, and E. Gratton, Proc. Natl. Acad. Sci. USA 2011, 108, 13582

Printing ZnO Inks: From Principles to Devices

Solution-based printing approaches permit digital designs to be converted into physical objects by depositing materials in a layer-by-layer additive fashion from microscale to nanoscale resolution. The extraordinary adaptability of this technology to different inks and substrates has received substantial interest in the recent literature. In such a context, this review specifically focuses on the realization of inks for the deposition of ZnO, a well-known wide bandgap semiconductor inorganic material showing an impressive number of applications in electronic, optoelectronic, and piezoelectric devices. Herein, we present an updated review of the latest advancements on the ink formulations and printing techniques for ZnO-based nanocrystalline inks, as well as of the major applications which have been demonstrated. The most relevant ink-processing conditions so far explored will be correlated with the resulting film morphologies, showing the possibility to tune the ZnO ink composition to achieve facile, versatile, and scalable fabrication of devices of different natures