Improving the Differentiation of Stem Cells
Todd McDevitt, director of the Stem Cell Engineering Center at Georgia Tech and an associate professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, is working on improving the process by which stem cells differentiate into objects such as muscle, skin, blood vessels, bone or neurons.
“Stem cells don’t make any decisions in isolation; their decisions are spatially and temporally directed by biochemical and mechanical cues in their environment,” said Todd McDevitt, “We have designed systems that allow us to tightly control these properties during stem cell differentiation, but also give us the flexibility to introduce a new growth factor or shake the cells a little faster to see how changes like these affect the outcome.”
Current laboratory methods consist of allowing cells to aggregate into three-dimensional clumps, called embryoid bodies, during differentiation. McDevitt and team have incorporated biomaterials into these aggregates to help modulate differentiation. They also included magnetic particles in the embryoid bodies so that they could control the location of the aggregate and its overall assembly with others.
“With biomaterial and magnetic microparticles, we are beginning to be able to recreate the types of complex geometric patterns seen during early development, which require multiple cues at the same time and the ability to spatially and temporally control their local presentation,” noted McDevitt.
Microspectrometer may help address issues of Integrated Lab-on-Chip Systems
Spectrometers are used to identify molecules inside a sample by shining light on it and measuring the different wavelengths of emitted and absorbed light. Traditionally they have been large and expensive instruments, but researchers at Georgia Tech have been working to develop microspectrometers. The development of these microspectrometeres could help in developing Lab-on-Chip systems, which currently require traditional spectrometers.
“For spectrometers, it is better to be small and cheap than big and bulky provided that the optical performance targets are met,” said Ali Adibi , a professor in the School of Electrical and Computer Engineering at the Georgia Institute of Technology. “We were able to achieve high resolution and wide bandwidth with a compact single-mode on-chip spectrometer through the use of an array of microdonut resonators, each with an outer radius of two microns.”
Currently, the spectrometer consists of an 81 channel chip that acheives a 0.6 nanometer resolution over a spectral range of more than 50 nanometers with a footprint less than one square millimeter. Adibi's group is designing the next generation of these spectrometers, which are being designed to contain 1000 resonators, 0.15 nanometer resolution with a spectral range of 150 nanometers and a foot print of 200 micrometers squared.
“The microspectrometer we designed may allow individuals to replace the big, bulky, high- resolution spectrometers with a large bandwidth they are currently using with an on-chip spectrometer the size of a penny,” noted Adibi. “Our device has the potential to be a high-resolution, lightweight, compact, high-speed and versatile microspectrometer with a large dynamic range that can be used for many applications.”