Lab-on-a-chip based biosensors for fundamental space biology research.

摘要

The space environment poses significant challenges to the development and survival of biological organisms. Particularly the altered gravity of space is known to have an adverse affect on development of animals, plants and human beings. How organisms react to different gravity regimes such as the micro-g environment faced during space flight or the reduced gravity on Moon and Mars is an exciting area of research. One way to characterize physiological changes particularly in cultured cells and microorganisms is to measure the concentrations of extracellular biomolecules that play a central role in growth, development, form and function. Such studies are possible using modern electrochemical biosensors. The reduced payload requirements of spaceflight pose a constraint on the size of these biosensors. With the advent of Micro-Electro-Mechanical-Systems (MEMS) based biosensors or BioMEMS, it is now possible to produce miniaturized biosensors that can easily address this requirement. This work focuses on two such MEMS fabricated lab-on-a-chip based biosensors for understanding the fundamental space biology of model organisms. The first device is called the Cell Electrophysiology Lab-on-a-chip or the CEL-C biochip. This biochip was designed with the specific science objective of studying the gravity-sensing dynamics of the spore of the fern Ceratopteris richardii. The CEL-C biochip combines calcium sensing chemistries with microfabricated electrodes. After integration with signal processing electronics and an automated data acquisition system the biochip can perform simultaneous measurements on 16 spores simultaneously. The CEL-C biochip served as the enabling technology for ground based and reduced gravity studies on the C. richardii system. The results unearthed a previously unknown mechanism of gravity sensing in the spores possibly involving mechanosensory ion channels and pumps. The second lab-on-a-chip is called the CHO biochip and was developed with the goal of studying gravitational physiology of cyanobacteria in a space environment. This is a multianalyte sensing biochip which integrates sensors for pH, carbonate/bicarbonate and O2 on the same device. These three parameters play a central role in photosynthesis and carbon fixation in cyanobacteria. While both these biochips were designed to address a specific scientific problem, they can serve as general purpose tools for fundamental research, biological and biomedical applications. These foundation technologies have now opened doors for new lab-on-a-chip devices for neurophysiology research, biomedical diagnostics, environmental monitoring and agricultural applications.