Researcher Highlights: Alberto Esteban Linares and Simon Ward
Alberto Esteban Linares, PhD candidate of Mechanical Engineering in the Li lab
Microfluidic platforms can play a transformative role in ex vivo tissue culture and physiological and pathological studies as they allow for precise control of cell microenvironment alike in vitro models, while the cellular matrix architecture similar to in vivo settings. Various microfluidic platforms have been reported for tissues such as brain, colon, and aorta, among others. However, few reports have focused on studying retinal explants. The retina is a main part of the central nervous system that receives and transmits visual information to the brain, which then processes this information and enables us to see. Given the importance of retina, it is important to create microfluidic platforms that can enable novel assays to probe retina.
Several diseases in the eye occur due to cell death from aging or ocular and brain injuries. Of particularly importance, the degeneration of retinal ganglion cells (RGCs) has been closely linked with irreversible blindness in humans through diseases like glaucoma or diabetic retinopathy. While great progress in this has been made and is ongoing, it could greatly benefit from platforms for ex vivo retina cultures that allow researchers to first observe how this tissue responds to both ocular injury and therapeutic biomarkers.
In our research, we develop novel devices with probing and sensing capabilities to study the response of RGCs in ex vivo retinal tissue to different stimulations. Using state-of-the-art microfabrication techniques, we construct graphene electrode-based microfluidic perforated microelectrodes arrays (µpMEAs) that are able to monitor the dynamic extracellular electrical activity of neurons. Further, we introduce the capability to locally deliver chemical stimulation directly to the RGC layer in the µpMEAs, and study the response of cells that are directly and indirectly in contact with the stimulant. In addition, graphene transistors are integrated into our platforms to enable mapping of the electrical activities of whole retina with scanning photocurrent microscopy, which provides high spatiotemporal resolution. The results could enable new understanding of neuronal functions and help establish a new electrophysiology technology.
Simon Ward, PhD candidate of Electrical and Computer Engineering in the Weiss Lab
The past few years have been a reminder of the importance of infectious disease testing, and the cost in human life of inaccurate results. Fortunately, cheap tests have been developed relying on capture-agents, which specifically bind to a target molecule, often indicative of a certain disease. However, developing nations in need of these cheap tests, may experience extreme climates in which these capture agents can break-down, leading to unreliable diagnosis.ature has provided a solution, able to detect trillions of different molecules without using capture-agents: our noses. They incorporate many cross-reactive sensors that, in general, each give different responses to a molecule, forming a unique fingerprint. Our brains use pattern recognition to identify molecules from these fingerprints.
My research copies how our noses work, using arrays of porous silicon sensors, formed by electrochemically etching nanoscale pores in silicon. Molecules diffuse into the pores and adsorb to the internal sensor surface, which we measure optically. To ensure sensors respond differently to different molecules, we can change properties such as the size and shape of pores, or surface charge of molecules. We use machine learning algorithms to analyze this information and recognize molecular fingerprints. Currently, we can distinguish molecules in simple solutions, but are working on applying this approach to complex media like blood or saliva, to diagnose infectious diseases in parts of the world where they have a particularly devastating impact.