A drug-loaded flexible substrate improves the performance of conformal cortical electrodes

Cortical electrodes are a powerful tool for the stimulation and/or recording of electrical activity in the nervous system. However, the inevitable wound caused by surgical implantation of electrodes presents bacterial infection and inflammatory reaction risks associated with foreign body exposure. Moreover, inflammation of the wound area can dramatically worsen in response to bacterial infection. These consequences can not only lead to the failure of cortical electrode implantation but also threaten the lives of patients. Herein, we prepared a hydrogel made of bacterial cellulose (BC), a flexible substrate for cortical electrodes, and further loaded antibiotic tetracycline (TC) and the anti-inflammatory drug dexamethasone (DEX) onto it. The encapsulated drugs can be released from the BC hydrogel and effectively inhibit the growth of Gram-negative and Gram-positive bacteria. Next, therapeutic cortical electrodes were developed by integrating the drug-loaded BC hydrogel and nine-channel serpentine arrays; these were used to record electrocorticography (ECoG) signals in a rat model. Due to the controlled release of TC and DEX from the BC hydrogel substrate, therapeutic cortical electrodes can alleviate or prevent symptoms associated with the bacterial infection and inflammation of brain tissue. This approach facilitates the development of drug delivery electrodes for resolving complications caused by implantable electrodes.