Nebulized jet-based printing of bio-electrical scaffolds for neural tissue engineering: a feasibility study

Abstract

In this paper we investigate the application of a direct writing technique for printing conductive patterns onto a biocompatible electrospun-pyrolysed carbon-fibre-based substrate. The result is a first study towards the production of bio-electrical scaffolds that could be used to enhance the promotion of efficient connections among neurons for in vitro studies in the field of neural tissue engineering. An electrospinning process is employed for production of the materials derived from the precursor polyacrylonitrile, in which the embedding of carbon nanotubes (CNTs) is also investigated. Subsequently, the methodology of research into suitable parameters for the printed electronics, using a commercial silver nanoparticle (Ø avg,particle size ∼100 nm) ink, is described. The results show values of 2 Ω cm for the resistivity of the carbon-fibre materials and conductive printed lines of resistance ∼50 Ω on glass and less than ∼140 Ω on carbon-fibre samples. Biocompatibility results demonstrate the possibility of using electrospun-pyrolysed mats, also with embedded CNTs, as potential neural substrates for spatially localized electrical stimulation across a tissue. In addition, the data concerning the potential toxicity of silver suspensions are in accordance with the literature, showing a dosedependent behaviour. This work is a pioneering feasibility study of the use of the flexible and versatile printed electronic approach, combined with engineered biocompatible substrates, to realize integrated bio-electrical scaffolds for in vitro neural tissue engineering applications.

Aerosol Jet® printing 3D capabilities for metal and polymeric inks

“…If properly encapsulated, these structures can be also exploited in life science applications, such as bioelectronic sensing, lab-on-a-chip, and tissue engineering devices. As demonstrated by the same authors, the release of Ag + ions in medium culture, from exposed AgNPs printed patterns, indeed generates high levels of cytotoxicity on different cellular lineages [20]. Therefore, in the context of life science, the use of biocompatible inks is preferable, such as PEDOT:PSS-and collagen-based inks.…”

Emerging Three‐Dimensional Integrated Systems for Biomimetic Neural In Vitro Cultures

“…Note: Synthetic biomaterials include also Polyurethane (PU), [126] poly(glycolic acid) (PGA), poly(lactic acid) (PLA), poly (2-hydroxyethyl methacrylate) (pHEMA), poly(glycerol sebacate) (PGS), and others. [2,15,21,52,[127][128][129] Conductive polymers Polypyrrole (PPy)…”

“…two-photon polymerization), as well as more recently developed nebulized jet-based printing techniques. [21,[144][145][146][147][148] An example of hydrogel printed via two-photon lithography for neural tissue engineering is shown in Figure 3A, where nanoscales pores are achieved. When the ink is initially delivered without cells, cell seeding occurs post-fabrication, with the ink referred to as a "biomaterial ink."…”

“…The combination of these two approaches allows for the generation of hybrid models, and the additional use of embedded instruments such as microelectrode arrays (MEAs) [20] or printed electronics to record and stimulate electrophysiological activity can enhance model capabilities. [21][22][23] Eventually, the integration of technologyand cell-driven neural models, along with support technologies, could lead to multifunctional platforms able to replicate complex in vitro neural activities. Such integrated hybrid platforms can be achieved by combinations of biomaterials and (bio-)fabrication technologies, including microfluidics, [24,25] lab-on-chip, or organ-on-chip (OOC).…”

Bioprinting of Collagen Type I and II via Aerosol Jet Printing for the Replication of Dense Collagenous Tissues

“…Aerosol jet ® printing (AJP) is a printing method that forms an aerosol from an ink and carrier gas, and forces the aerosol to coalesce on a substrate via impaction. It was developed as a way to print electronic components on to virtually any surface topography, which has made some impact in bio-electrical applications (Sarreal and Bhatti, 2020;Seiti et al, 2020). AJP has also been investigated for the deposition of DNA, enzymes, and silk fibroin with moderate success (De Silva et al, 2006;Grunwald et al, 2010;Williams et al, 2019;Xiao et al, 2020).…”