Conducting polymer microspherical cups for organic bioelectronics

Abstract

Event Abstract Back to Event Conducting polymer microspherical cups for organic bioelectronics Milad Khorrami1, Martin Antensteiner1 and Mohammad Reza Abidian1 1 University of Houston, Biomedical Engineering, United States Current metallic-based implantable microscale bioelectronics have high impedance and low charge storage capacity, which result in both low signal-to-noise ratio and low charge injection electrode-tissue interfaces. Moreover, these electrodes without anti-inflammatory compounds are less likely to maintain their functionality due to unfavorable reactive tissue responses. Therefore, there is need to produce devices capable of delivering therapeutic compounds while maintaining their electrical performance. Poly(pyrrole) (PPy) has gained significant interest for biomedical applications owing to its excellent biocompatibility, electrical properties, and mechanical actuation. Poly(lactic-co-glycolic) acid (PLGA) is biodegradable and highly biocompatible, making it an ideal matrix for drug encapsulation. In this study, we have produced PPy microspherical cups from template PLGA microspheres. These conductive microstructures have large surface areas, granting low impedance values and high charge storage capacities for bioelectronics applications. PPy, poly(styrenesulfonate), benzyltriethylammonium chloride, PLGA, silicon wafer (Si) substrates and chloroform were used as purchased. Gold (Au) electrodes were fabricated on Si wafers (two circles with diameters 1.5mm and 5.0mm connected with a rectangle 1mm X 10mm). A thin layer of titanium (10nm) was deposited to support Au layer (100nm). Briefly, 4/2wt% PLGA/BTEAC was dissolved in chloroform and sprayed onto the Si using an applied electrical field of 100kVm-1 and 500μl/hr flow rate. PLGA particles were then coated with PPy/PSS using electrochemical deposition with current density 0.5mA/cm2 for 5 different time durations. The PLGA cores were then dissolved in chloroform to create PPy microspherical cups. Impedance spectroscopy (IS) and cyclic voltammetry (CV) were performed on all samples and a gold reference to investigate the impedance and charge storage capacity. The size and shape of PPy microstructures were characterized using Scanning Electron Microscopy. Fig. 1 shows the electropolymerized PPy on the surface of Au electrodes and around PLGA microspheres after 1, 2, 4, and 6 min. Fig. 2 demonstrates PPy cups after removal of PLGA cores. Fig. 3A shows the IS data for bare Au, PPy cups, and fully PPy-coated PLGA cores (8 min of deposition) from 1 to 10kHz. Electrodeposition of PPy on PLGA cores followed by removal of the PLGA significantly decreased the bare Au impedance (e.g. from 445 ± 63 Ω to 354 ± 39 Ω for 8 min coating at 1kHz, a difference of 20%). The additional surface area obtained by removal of the PLGA cores significantly increased the effective surface area of electrode, thus lowering the impedance. Fig. 3B shows the CV for bare gold, PPy cups, and fully PPy-coated PLGA microspheres. The PPy coating significantly increased the charge storage capacity from 2.5mC/cm2 (bare gold) to 47.5mC/cm2 (8 min), an increase of nearly 95%. We successfully demonstrated: (1) electrochemical deposition of PPy around the electrosprayed PLGA microspheres, (2) degradation of PLGA microspheres to fabricate PPy microspherical cups, and (3) improvement of electrical properties of Au electrodes by decreasing impedance and increasing charge storage capacity. This study demonstrates the potential of our conductive microstructures for neural interfacing and neural regeneration while retaining functionality for drug delivery. The authors would like to thank Fatemeh Fallahianbijan and support from National Institute of Health R01 NS087224. Keywords: electric, microstructure, polymer, biomedical application Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016. Presentation Type: Poster Topic: Regenerative medicine: biomaterials for control of tissue induction Citation: Khorrami M, Antensteiner M and Abidian M (2016). Conducting polymer microspherical cups for organic bioelectronics. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.02641 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Mar 2016; Published Online: 30 Mar 2016. Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Milad Khorrami Martin Antensteiner Mohammad Reza Abidian Google Milad Khorrami Martin Antensteiner Mohammad Reza Abidian Google Scholar Milad Khorrami Martin Antensteiner Mohammad Reza Abidian PubMed Milad Khorrami Martin Antensteiner Mohammad Reza Abidian Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.