Electroactive Materials Surface Charge Impacts Neuron Viability and Maturation in 2D Cultures

Abstract

Since neurons were first cultured outside a living organism more than a century ago, a number of experimental techniques for their in vitro maintenance have been developed. These methods have been further adapted and refined to study specific neurobiological processes under controlled experimental conditions. Despite their limitations, the simplicity and visual accessibility of 2D cultures have enabled the study of the effects of trophic factors, adhesion molecules, and biophysical stimuli on neuron function and morphology. Nevertheless, the impact of fundamental properties of the surfaces to which neurons adhere when cultured in vitro has not been sufficiently considered. Here, we used an electroactive polymer with different electric poling states leading to different surface charges to evaluate the impact of the net electric surface charge on the behavior of primary neurons. Average negative and positive surface charges promote increased metabolic activity and enhance the maturation of primary neurons, demonstrating the relevance of considering the composition and electric charge of the culture surfaces. These findings further pave the way for the development of novel therapeutic strategies for the regeneration of neural tissues, particularly based on dynamic surface charge variation that can be induced in the electroactive films through mechanical solicitation.

Revealing an important role of piezoelectric polymers in nervous-tissue regeneration: A review

“…In some articles, piezoelectric scaffolds have been shown to support the adhesion, growth, differentiation, and myelination of SCs as well as neurite extension [ 31 , [46] , [47] , [48] ]. Negative and positive surface charges generated by piezoelectric substrates have also been found to promote metabolic activity and maturation of neurons in primary culture [ 96 ]. Piezoelectric composite scaffolds promote proliferation and differentiation of PC12 cells [ 12 , 97 , 98 ].…”

“…Meanwhile, piezoelectricity rather than the nanotopography of the stripe array enhanced neuron-like differentiation [ 67 ] PVDF Solvent-cast films. Surface potentials of positively and negatively charged films were 6 V and −4 V, respectively d 33 of −24 pC/N Rat neurons in primary culture Negatively charged PVDF film promoted cell metabolism and maturation 1.7 times better than electrically neutral PVDF did [ 96 ] In vivo P(VDF-TrFE) Heat-melt extrusion followed by high-voltage corona poling Polarization of 150 pC/cm 2 upon a 0.2 mm deformation Rat sciatic nerve defect (10 mm) A significantly greater number of myelinated axons as compared to the unpoled conduit group at 4 weeks postimplantation. Nerves regenerated successfully throughout only 50 % of each conduit owing to the lack of permeability in the rigid melt-extruded conduits [ 69 , 100 ] P(VDF-TrFE) filled with SCs Electrospun conduits with fiber diameters of 548 ± 139 and 711 ± 222 nm (for aligned and randomly aligned conduits, respectively) and a porosity of ∼87–88 %.…”

Electrospun drug‐loaded scaffolds for nervous system repair

“…Conversely, when cultured in 2D on polyvinylidene fluoride (PVDF), βIII expression of primary neurons was higher for positively charged substrates at day 7, but by day 14 was shown to be higher on negatively charged substrates. Moreover, neurite length was observed to be elevated on negatively charged PVDF (Marques‐Almeida et al, 2023).…”

Rapid Surface Charge Mapping Based on a Liquid Crystal Microchip

“…Monitoring the charge distribution of tissues could predict its associated wound healing process [6,7]. The surface charge of materials enables their functions in directing cell attachment, mobility, proliferation, differentiation, signaling and protein adsorption [8][9][10][11]. Therefore, the rapid surface charge mapping of a solid surface can provide a powerful tool to facilitate the development of new biomarkers and the design of advanced materials [12][13][14][15][16].…”