must be biocompatible to avoid harming the brain or spinal cord. This means they shouldn't cause toxicity, inflammation, or other bad reactions. Good ensures safety, long-term function, and stable signal recording.
Implanted electrodes can trigger immune responses like inflammation and scarring. This creates barriers between the electrode and neurons, weakening signals over time. Scientists are developing strategies to improve biocompatibility, like special coatings and anti-inflammatory treatments.
Biocompatibility and Immune Responses
Biocompatibility in neural electrodes
Top images from around the web for Biocompatibility in neural electrodes
Frontiers | Neurohybrid Memristive CMOS-Integrated Systems for Biosensors and Neuroprosthetics View original
Is this image relevant?
Frontiers | Advances in Carbon-Based Microfiber Electrodes for Neural Interfacing View original
Is this image relevant?
Frontiers | Biomedical and Tissue Engineering Strategies to Control Foreign Body Reaction to ... View original
Is this image relevant?
Frontiers | Neurohybrid Memristive CMOS-Integrated Systems for Biosensors and Neuroprosthetics View original
Is this image relevant?
Frontiers | Advances in Carbon-Based Microfiber Electrodes for Neural Interfacing View original
Is this image relevant?
1 of 3
Top images from around the web for Biocompatibility in neural electrodes
Frontiers | Neurohybrid Memristive CMOS-Integrated Systems for Biosensors and Neuroprosthetics View original
Is this image relevant?
Frontiers | Advances in Carbon-Based Microfiber Electrodes for Neural Interfacing View original
Is this image relevant?
Frontiers | Biomedical and Tissue Engineering Strategies to Control Foreign Body Reaction to ... View original
Is this image relevant?
Frontiers | Neurohybrid Memristive CMOS-Integrated Systems for Biosensors and Neuroprosthetics View original
Is this image relevant?
Frontiers | Advances in Carbon-Based Microfiber Electrodes for Neural Interfacing View original
Is this image relevant?
1 of 3
Biocompatibility refers to the ability of a material or device to perform its intended function without eliciting an adverse biological response in the host tissue
Crucial for ensuring the safety and long-term functionality of neural electrodes and neuroprosthetics (cochlear implants, deep brain stimulation devices)
Biocompatible materials should not induce toxicity, inflammation, or other harmful reactions in the surrounding tissue (brain, spinal cord)
Minimizes the risk of tissue damage and neuronal loss
Promotes stable and reliable signal recording and stimulation
Enhances the longevity of the implanted device (reduces need for replacement surgeries)
Immune responses to implanted electrodes
Inflammation:
Acute occurs immediately after electrode implantation
Characterized by the infiltration of immune cells, such as macrophages and neutrophils
Releases pro-inflammatory cytokines (IL-1, TNF-α) and chemokines
may persist if the is not resolved
Fibrosis:
Formation of a dense, fibrous capsule around the implanted electrode (scar tissue)
Caused by the activation and proliferation of fibroblasts
Increases the barrier between the electrode and target neurons, leading to signal attenuation
:
Reactive astrocytes and microglia form a glial scar around the implanted electrode
Acts as a physical and biochemical barrier, hindering neuron-electrode interaction
Contributes to the deterioration of electrode performance over time (reduced signal quality, increased impedance)
Foreign body response mechanisms
Foreign body response (FBR) is a cascade of cellular and molecular events triggered by the implantation of a foreign material
Mechanisms of FBR:
onto the electrode surface
Initiates the recruitment and activation of immune cells (complement system, antibodies)
and fusion to form (FBGCs)
FBGCs attempt to phagocytose the foreign material but fail due to size disparity
Release of reactive oxygen species (ROS) and degradative enzymes by FBGCs
Leads to oxidative stress and local tissue damage (neuronal death, axonal degeneration)
and (ECM) deposition
Results in the formation of a fibrous capsule around the electrode
Impact on long-term functionality:
Increases the distance between the electrode and target neurons
Reduces the signal-to-noise ratio and recording/stimulation efficiency
Alters the local microenvironment, affecting neuronal health and survival
Compromises the mechanical stability of the electrode-tissue interface
May lead to electrode displacement or failure (lead fracture, insulation damage)
Strategies for electrode biocompatibility
:
Coating electrodes with biocompatible materials, such as (PEDOT) or hydrogels
Minimizes protein adsorption and cell adhesion
Provides a soft, tissue-like interface
with biomolecules, such as (RGD) or (NGF)
Promotes neuronal attachment and survival
Encourages the integration of the electrode with the surrounding tissue
, such as nanoporous or nanotextured coatings
Mimics the extracellular matrix, enhancing cell-electrode interactions
Reduces the foreign body response by modulating immune cell behavior
:
Local delivery of anti-inflammatory drugs, such as dexamethasone or ibuprofen
Suppresses the initial inflammatory response
Mitigates the foreign body reaction and glial scarring
Incorporation of anti-inflammatory coatings, such as nitric oxide-releasing polymers
Provides a sustained release of anti-inflammatory molecules
Modulates the immune response and promotes tissue regeneration
Delivery of biologics, such as cytokine inhibitors (IL-1Ra) or growth factors (BDNF)
Targets specific inflammatory pathways or promotes neuronal survival
Can be delivered through controlled release systems (microspheres) or genetically engineered cells