Reducing the burden of neurological disorders has become a top research priority. Insights into the basic mechanisms of brain function have enabled the discovery of key concepts regarding brain dysfunction. However, the necessary knowledge for diagnosis and treatment is limited because of the complex interplay between ionic and biomolecular communication in massively interconnected neural networks. State-of-the-art implantable biomedical tools for probing brain functions can only sense local electric field potentials and lack the ability to release drugs. In addition, they show poor biocompatibility, leading to scarring of brain tissue. The EU-funded project 'Organic bio-electronic neural probe for in vivo molecular sensing and stimulation' (BIOPROBE) developed a new generation of chronically implantable probes with multi-sensing recording and chemical stimulation devices for local delivery of drugs. This should drastically improve the ability to interface with the nervous system. BIOPROBE used organic electronic materials and devices — often targeted for their low-cost processing and chemical tunability of their properties. Due to their softness, flexibility and ion permeability, these materials can significantly improve signal transduction and cell stimulation at the biological interface. To record the neurological activity, scientists used organic electrochemical transistors (OECTs), which have been recently demonstrated as sensitive biosensors for metabolites such as glucose. Use of organic electronic ion pumps helps deliver biochemical stimuli to neurons with precise spatial and temporal control. Project activities included design and fabrication of the actual probes, as well as optimisation and investigation of the individual recording sites and ion release elements. These allow for in vivo monitoring of neuronal activity and simultaneous stimulation. Scientists devoted considerable efforts to validate the proof-of-principle device both in vitro and in vivo. Focus was placed on culturing of rat hippocampal neurons on the device, recording of hippocampal slices, and in vivo testing of OECT-based probes on epileptic rat models. BIOPROBE's innovative biomedical research tool should have important implications for neuroscience research, offering new opportunities for many brain diseases that remain difficult to treat.
Bioelectronic, neuronal activities, brain function, neural probe, molecular sensing