Electrical Differentiation of Mesenchymal Stem Cells into Schwann‐Cell‐Like Phenotypes Using Inkjet‐Printed Graphene Circuits

Abstract

Graphene-based materials (GBMs) have displayed tremendous promise for use as neurointerfacial substrates as they enable favorable adhesion, growth, proliferation, spreading, and migration of immobilized cells. This study reports the first case of the differentiation of mesenchymal stem cells (MSCs) into Schwann cell (SC)-like phenotypes through the application of electrical stimuli from a graphene-based electrode. Electrical differentiation of MSCs into SC-like phenotypes is carried out on a flexible, inkjet-printed graphene interdigitated electrode (IDE) circuit that is made highly conductive (sheet resistance < 1 kΩ/sq) via a postprint pulse-laser annealing process. MSCs immobilized on the graphene printed IDEs and electrically stimulated/treated (etMSCs) display significant enhanced cellular differentiation and paracrine activity above conventional chemical treatment strategies [≈85% of the etMSCs differentiated into SC-like phenotypes with ≈80 ng mL of nerve growth factor (NGF) secretion vs. 75% and ≈55 ng mL for chemically treated MSCs (ctMSCs)]. These results help pave the way for in vivo peripheral nerve regeneration where the flexible graphene electrodes could conform to the injury site and provide intimate electrical simulation for nerve cell regrowth.

Cryoconcentration of flavonoid extract for enhanced biophotovoltaics and pH sensitive thin films

“…Inkjet printing of the extract closely followed our similar procedures for printing graphene inks . For preparing inkjet‐printed thin film biodetectors, aliquots (3 mL) of extract were filtered through a 0.45 µm.…”

“…The printed line morphology resulting from the drop spacing and the working temperature control edge effects (known as the coffee ring effect). Our previous work shows that average film thickness is between 3 and 5 µm, classifying this structure as a thin film . A circular array was designed using computer‐aided design (CAD software) and inkjet printed.…”

“…Based on I-E curves, the short circuit current density (J sc ), open circuit voltage (V oc ), maximum power output (P max ), voltage at max power (V mp ), current density at max power (J mp ), form factor (FF), and solar conversion efficiency (g) were calculated using the methods reported by Hug et al 52 Inkjet printing of the extract closely followed our similar procedures for printing graphene inks. [53][54][55] For preparing inkjet-printed thin film biodetectors, aliquots (3 mL) of extract were filtered through a 0.45 mm. Polytetrafluoroethylene (PTFE) syringe filter and then loaded into an inkjet printer cartridge (1.5 mL max.…”

“…Our previous work shows that average film thickness is between 3 and 5 mm, classifying this structure as a thin film. [53][54][55] A circular array was designed using computer-aided design (CAD software) and inkjet printed. For unbuffered calibration tests, pH was adjusted with 3M HCl or 2M NaOH, and then 5 mL aliquots were drop cast onto the pH sensitive film.…”

Enabling Inkjet Printed Graphene for Ion Selective Electrodes with Postprint Thermal Annealing

“…20 Furthermore, the ink jet printing process can be used to make microcircuits with line resolution of approximately 60 μm thus eliminating the need for UV lithographic techniques that utilize a prefabricated photomask followed by dry etching of active materials or screen printing techniques that use a prefabricated metal stencil to pattern surfaces with defined circuit geometries. 21,22 Subsequently, inkjet printing has been used for a wide variety of functional devices including thin film transistors, 19,23 acoustic actuators, 24 dipole antennas, 25 interdigitated electrodes for electrically induced stem cell differentiation, 26 and sensors such as a NO 2 , Cl 2 vapor sensor, 27 a temperature sensor, 28 and a hydrogen peroxide sensor. 34 Herein we develop, for the first time, a solid-contact ISE (potassium selective) with IPG.…”