Analysis of a poly(ε-decalactone)/silver nanowire composite as an electrically conducting neural interface biomaterial

Katarzyna Krukiewicz; Jorge Fernandez; Małgorzata Skorupa; Daria Więcławska; Anup Poudel; Jose-Ramon Sarasua; Leo R Quinlan; Manus J P Biggs

doi:10.1186/s42490-019-0010-3

Analysis of a poly(ε-decalactone)/silver nanowire composite as an electrically conducting neural interface biomaterial

BMC Biomed Eng. 2019 Apr 15:1:9. doi: 10.1186/s42490-019-0010-3. eCollection 2019.

Authors

Katarzyna Krukiewicz^{1

2}, Jorge Fernandez³, Małgorzata Skorupa², Daria Więcławska², Anup Poudel¹, Jose-Ramon Sarasua⁴, Leo R Quinlan⁵, Manus J P Biggs¹

Affiliations

¹ Centre for Research in Medical Devices (CURAM), Galway Biosciences Research Building, 118 Corrib Village, Newcastle, Galway, Ireland.
² Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, M.Strzody 9, 44-100 Gliwice, Poland.
³ Polimerbio, S.L, Paseo Mikeletegi 83, 20009 Donostia-San Sebastian, Spain.
⁴ Department of Mining-Metallurgy Engineering and Materials Science, POLYMAT, University of the Basque Country (UPV/EHU), School of Engineering, Alameda de Urquijo s/n, 48013 Bilbao, Spain.
⁵ Department of Physiology, National University of Ireland, Galway, University Road, Galway, Ireland.

Abstract

Background: Advancement in polymer technologies, facilitated predominantly through chemical engineering approaches or through the identification and utilization of novel renewable resources, has been a steady focus of biomaterials research for the past 50 years. Aliphatic polyesters have been exploited in numerous biomedical applications including the formulation of soft-tissue sutures, bone fixation devices, cardiovascular stents etc. Biomimetic 'soft' polymer formulations are of interest in the design of biological interfaces and specifically, in the development of implantable neuroelectrode systems intended to interface with neural tissues. Critically, soft polymer formulations have been shown to address the challenges associated with the disregulation of mechanotransductive processes and micro-motion induced inflammation at the electrode/tissue interface. In this study, a polyester-based poly(ε-decalactone)/silver nanowire (EDL:Ag) composite was investigated as a novel electrically active biomaterial with neural applications.Neural interfaces were formulated through spin coating of a polymer/nanowire formulation onto the surface of a Pt electrode to form a biocompatible EDL matrix supported by a percolated network of silver nanowires. As-formed EDL:Ag composites were characterized by means of infrared spectroscopy, scanning electron microscopy and electrochemical methods, with their cytocompatibility assessed using primary cultures of a mixed neural population obtained from the ventral mesencephalon of Sprague-Dawley rat embryos.

Results: Electrochemical characterization of various EDL:Ag composites indicated EDL:Ag 10:1 as the most favourable formulation, exhibiting high charge storage capacity (8.7 ± 1.0 mC/cm²), charge injection capacity (84.3 ± 1.4 μC/cm²) and low impedance at 1 kHz (194 ± 28 Ω), outperforming both pristine EDL and bare Pt electrodes. The in vitro biological evaluation showed that EDL:Ag supported significant neuron viability in culture and to promote neurite outgrowth, which had the average length of 2300 ± 6 μm following 14 days in culture, 60% longer than pristine EDL and 120% longer than bare Pt control substrates.

Conclusions: EDL:Ag nanocomposites are shown to serve as robust neural interface materials, possessing favourable electrochemical characteristics together with high neural cytocompatibility.

Keywords: Neural interfaces; Neural stimulation; Poly(ε-decalactone); Polyesters; Silver nanowires.