In neural tissue engineering (NTE), topographical, electrical, mechanical and/or biochemical stimulations are established methods to regulate neural cell activities in in vitro cultures. Aerosol Jet® Printing is here proposed as enabling technology to develop NTE integrated devices for electrically combined stimulations. The printability of a poly(3,4 ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT: PSS) commercial ink onto a reference substrate was firstly investigated and the effect of the process parameters on the quality of printed lines was analyzed. The study was then extended for printing thick electrodes and interconnects; the print strategy was finally transferred to a silicon-based wafer with patterned microchannels of proven cellular adhesion and topographical guidance. The results showed values of electrical resistance equal to ~16 Ω for printed electrodes which are ~33 μm thick and ~2 mm wide. The electrical impedance of the final circuit in saline solution was detected in the range of 1 – 2 kΩ at 1 kHz, which is in line with the expectations for bioelectronic neural interfaces. However, cells viability assays on the commercial PEDOT: PSS ink demonstrated a dose dependent cytotoxic behavior. The potential cause is associated with the presence of a cytotoxic co-solvent in the ink’s formulation, which is released in the medium culture, even after a post-sintering process on the printed electrodes. This work is a first step to develop innovative in vitro NTE devices via a printed electronic approach. It also sheds new insights the transfer of AJ® print strategies across different substrates, and biocompatibility of commercial PEDOT: PSS inks.

lial cells, and pericytes. [2] The intricate interconnections and spatial organization between neurons as well as between neuronal and non-neuronal cells enable the functional complexity and diversity of the brain, which ultimately generates motor and sensory function, as well as cognitive processes such as memory, learning, and emotions.Despite its critical functions, the brain has very limited ability to self-repair and regenerate upon neurological disease or injury. [3] The regeneration of damaged tissue in the brain after trauma is primarily impeded by glial scar formation and reactive astrocytes. [4] Conversely, neurodegenerative diseases are characterized by progressive dysfunction and loss of subpopulation of specialized cells such as dopaminergic neurons and oligodendrocytes. [5] Moreover, a number of changes occur in the brain extracellular matrix (bECM) in pathological situations, such as alterations in the expression of proteoglycans, protein aggregation, and amyloidosis during the progression of Alzheimer's disease (AD). [6] To investigate the mechanisms of regeneration and degeneration as well as those which regulate neural circuit formation, morphogenesis, and development, animal models have traditionally been the main research modality. However, these models have presented major challenges due to their genetic, biochemical, and metabolic differences to human physiology, along with the need for expensive and time-consuming protocols and associated ethical issues. In vitro models have been established as efficient alternatives, allowing recreating in vivolike micro-environments to study cellular differentiation, electrical activity, and their relationship to molecular signaling. Additionally, 3D in vitro models represent processes such as cell adhesion, migration, as well as of nutrient and metabolic waste transport in a more biomimetic context than conventional 2D culture. [7][8][9] Multidisciplinary approaches in the field of tissue engineering have emerged since the 1990s with the goal of fabricating biocompatible 3D bioengineered architectures composed of predefined compositions of cells, biomaterials, and biological factors. Ideally, these elements can be combined to generate biomimetic ECM formation and cellular phenotypes. [10][11][12] In parallel with technical advances in materials and fabrication techniques, the development of stem cell biology, and in particular the advent of 3D in vitro neural cultures have gained interest in recent years as promising biomimetic micro-environments which can regulate cell response to neural guidance cues. Several bioengineered technologies have been developed in combination with biomaterials to produce 3D models, such as scaffoldbased neural constructs, neurospheres, cerebral organoids, and brain-onchip devices. While the strategic selection of bioengineering approaches and associated biomaterials has opened a multitude of opportunities in building increasingly advanced neural tissues, technical limitations remain a challenge in modeling the complexity of ...

In this study, an original and green procedure to produce water-based solutions containing nanometric recycled carbon particles is proposed. The nanometric particles are obtained starting from carbon waste ashes, produced by the wooden biomass pyro-gasification plant CMD (Costruzioni motori diesel) ECO20. The latter is an integrated system combining a downdraft gasifier, a spark-ignition internal combustion engine, an electric generator and syngas cleaning devices, and it can produce electric and thermal power up to 20 kWe and 40 kWth. The carbon-based ashes (CA) produced by the CMD ECO20 plant were, first, characterized by using differential scanning calorimetry (DSC) and microcomputed tomography (microCT). Afterward, they were reduced in powder by using a milling mortar and analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectrometry, thermogravimetric analysis (TGA), X-ray diffraction (WAXD) and Fourier-transform infrared (FTIR) spectroscopy. The optimization of an original procedure to reduce the dimensions of the ashes in an aqueous solution was then developed by using ball milling and sonication techniques, and the nanometric dimensions of the particles dispersed in water were estimated by dynamic light scattering (DLS) measurements in the order of 300 nm. Finally, possible industrial applications for the nanomaterials obtained from the waste ashes are suggested, including, for example, inks for Aerosol Jet® Printing (AJ® P).

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