Manipulating the response and behavior of living cells using incorporated nanoelectronic components is a desirable feature for future environmental, biomedical, and defense applications. Up to date, most studies have solely focused on the understanding and characterizations of cellular communication mechanisms through various types of nano device sensors. These sensors or sensor arrays are typically pre-fabricated on substrates followed by patterning growth of living cells onto the devices. Alternatively, people also press nanowire or nanotube based sensor devices through the cell membranes to detect cellular activities. The key disavantage of this kind of approach is that the yield of the sensor devices is low and the the size of the functional “cyborgcell” is limited by the microfabrication. My group is studying the direct growth of living stem cells and bacterias with nanowire naturally incorporated into the living cell structures. More importantly, the electrical, thermal, and mechanical parameters of these nanowires can be tuned in growth to achieve desirable properties, which could be used to protect, control cell activities and metabolism.

Research Area:

1. Telluride nanowires have many potential applications owing to their unique electronic, optical, and thermal properties. However, their use in medical applications is seldom considered, mainly due to the unclearness of their nanotoxicity. We are conducting a series of studies on the cytotoxicity of nanowires through live/dead cell viability testing, bright-light image analysis, and surface area calculations. The on-going preliminary studies on incorporating nanowires into organoids (minigut) stem cells. We are using nanowires as a stable material inside the human body for the construction of a tight junction-like structure to prevent cell shedding and provide a solution for curing inflammatory bowel diseases. They could also be used as synthetic microvilli to treat microvillus inclusion disease, which causes significantly high death rates among newborns.

2. We are looking to combine synthesis of red-light-emitting nanowires with cell growth to attract and perhaps induce attachment of photosynthetic organisms. For example, oxygenic phototrophs such as cyanobacteria and algae are able to grow on just red light. On the contrary, halophilic (salt-loving) Archaea are able to utilize green light through the transmembrane protein, bacteriorhodopsin, which converts the light energy into chemical energy. The advantage of the control of photosynthetic organisms is that they require just water, inorganic nitrogen and CO₂ to grow. They do not require any organic carbon source such as sugar and hence can be maintained in a relatively sterile condition. It is also envisioned a second set of nanowires would be incorporated to monitor the membrane potential by measuring the proton motive force (PMF) around the cells. Small perturbations in the environment of the cells can be correlated to changes in the PMF. Thus immobilized algae cells could be utilized as sensors of pollutants found in the growth environment. The converse process of linking bioluminescence with nanowires as detectors is also ripe with possibilities for sensitive detection. We envision utilizing the luciferase protein as a system to convert chemical energy into light that can be detected by neighboring semiconductor nanowires of the appropriate band gap. The luciferase can be placed in either photosynthetic cells which can provide the necessary ATP for light emission reaction or in non-photosynthetic cells such as E. coli to express luciferase by synthetic biology which emits at specific wavelengths. Connecting the expression of luciferase to promoters than respond to environmental would enable the detection of environmental toxins at extremely low concentrations and require extremely small volumes.