Multiphoton fabrication of bioelectronics

Hardy, John and Baldock, Sara and Cummings, Damian M. and Edwards, Frances (2020) Multiphoton fabrication of bioelectronics. In: UNSPECIFIED.

Abstract

Electromagnetic fields affect a variety of tissues (e.g. bone, muscle, nerve and skin) and play important roles in a multitude of biological processes (e.g. nerve sprouting, prenatal development and wound healing), mediated by subcellular level changes, including alterations in protein distribution, gene expression, metal ion content, and action potentials. This has inspired the development of electrically conducting devices for biomedical applications, including: biosensors, drug delivery devices, cardiac/neural electrodes, and tissue scaffolds. It is noteworthy that there are a number of FDA approved devices capable of electrical stimulation in the body, including cardiac pacemakers, bionic eyes, bionic ears and electrodes for deep brain stimulation; all of which are designed for long term implantation. Polymers are ubiquitous in daily life, and conducting polymers (e.g. polyaniline, polypyrrole, poly(3,4-ethylenedioxythiophene)) have shown themselves to be capable of electrically stimulating cells. Furthermore, when implanted in mammals their immunogenicities are similar to FDA-approved polymers such as poly(lactic-co-glycolic acid) (PLGA), supporting their safety in vivo. These preclinical studies suggest that conducting polymer-based biomaterials are promising for clinical translation. We have an interest in the use of multiphoton fabrication to print conducting biomaterials for use as neural electrodes, characterize their physicochemical and electrical properties, and to validate the efficacy of the bioelectronic devices to interact with brain tissue ex vivo.1 Clinically approved electrodes are manufactured from inorganic materials (e.g. titanium nitride, platinum, and iridium oxide), however, their mechanical properties are far from those of soft tissues in the central and peripheral nervous system, and such mechanical mismatch leads to local tissue inflammation and their encapsulation in fibrous scar tissue that impedes the successful function of the neural electrode (in some cases this necessitates the application of up to 7V to stimulate the nerve tissue which leads to tissue damage). The development of neural electrodes with biomimetic chemical and mechanical properties is highly attractive as it may facilitate the widespread use of such electronic devices.1,2 An update on recent progress will be presented.