Retinal prosthesis planar electrode array covered with biocompatible polymer. Electrodes and wires (black) are covered with a polymer bolus, the edge of which is seen in the lower part of the image. The circular structure ringed by arrows is a surgical suture hole. Scale bar, electrode = 400 mm.

Tissue Engineered Coatings to Enhance Biocompatibility of Neural Prostheses

One of the major limitations of neural prosthetic devices is the formation of scar tissue surrounding the device over time. This scar tissue increases the electrical parameters for successful stimulation reducing device performance. We are creating polymer coatings to improve the biocompatibility of neural prostheses. These polymers possess inherent biocompatible properties; however, we are also modifying them with cell adhesion molecules to improve the physical contact between the device and neighboring tissue. Additionally, the coatings contain drug or biomolecules which are released to the body over time allowing for the application of therapeutic molecules to the implantation site. Our primary platforms for this investigation are the retinal implant and deep brain stimulation devices, which are used to treat Parkinson’s disease.

Latest publication

Cellular Nanoprobes for the Nervous System

SK-N-SH neuroblastoma cells labeled with CdS quantum dots (yellow). Quantum dots are targeted to cell surface receptors (integrins) using peptides.

Nanoparticles have already made a substantial impact in the field of biological imaging because of their small size, bright fluorescent signals, narrow bandwidths, and long-lived fluorescence. However, nanoparticles display many unique properties that result from their size, which is on the order of 5-10 nm. Certain nanomaterials can be moved using magnetic field, other materials produce heat when the absorb light, and yet other materials produce an electric field upon light absorption. Several of these properties could be used to directly manipulate and investigate cellular features, which display similar size scales to the nanoparticles themselves. In previous work, we investigated the later phenomenon, attempting to create particles that could convert light to electrical energy (similar to a photodiode) used to stimulate of nerve cells placed near the particles. [ Insert Figure quantumdot.jpg]. Most present applications of active nanoprobes investigate similar phenomenon taking place on the cell surface. Introducing particles to the cell interior is a significant challenge. We are creating cellular nanoprobes designed to enter a cell and interact with its individual components. These particles are multifunctional containing both an imaging and interactive component (e.g., magnetism) which allows for direct manipulation of cellular features. Particles also contain targeting molecules providing a mechanism for their precise placement within the cell. These particles represent a significant advance in cellular engineering, the ability to manipulate the subcellular environment, and will provide biologists with new tools for biological investigation.

Nanopatterns for Directed Neuronal Growth

The interaction of a cell with its physical environment is a critical determinant of cell adhesion, migration, survival, and differentiation. However, this is one of the most understudied areas of biology. Some work has been performed to understand how cells respond to environments of various stiffness and also microscale features. Yet, cell-environment interactions are primarily mediated by integrins, 10 nm diameter proteins embedded in the cell membrane that experience a conformational change when binding components of the outside environment. It is logical that nanometer scale patterns of integrin binding domains could have a huge impact on cell function, but little work has been performed in this area because of the difficulty in creating reproducible, stable nanometer scale patterns that extend to cellular dimensions (~ 10 mm). We are developing new techniques for creating ordered nanometer scale patterns that can be used to investigate cell-surface interactions.