Biomedical applications in the area of space flight aim at the reduction of medical risks for astronauts. As critical risks, the following should be mentioned among other things:
• Bone loss,
• Heart and blood circulation problems,
• Performance loss,
• Distortion of the sense of balance,
• Distortion of the immune system,
• Muscle loss,
• Radiation damages,
• Insufficient methods for on-board medical therapy and diagnostics.
Biomedical Applications in Space that Might Benefit from Nanotechnology
Within the biomedical range, NASA aims at the development of the following applications with possible contributions from nanotechnology:
• Minimal, invasive, efficient and mobile detection systems for malfunctionings in the entire organism (e.g. biomolecular sensors for measurements of the bone density/condition, blood chemistry or the radiation load);
• Methods of early diagnosis of cancer (in particular important for longer manned missions);
• Biomolecular imaging (sensor technology and visualization);
• Miniaturized diagnostics (e.g. lab-on-a-chip systems) whereby both the measuring and the analysis unit should be miniaturized;
• Autonomous therapy forms for a multiplicity of possible diseases and health damage.
The Focus of Current NASA Research Projects in the Life Sciences
At present, numerous research programs of NASA are accomplished in the area of Life Sciences in co-operation with other federal institutions (e.g. NIH) or industrial partners. To be mentioned here, among other things, are the following research sectors of priority:
• Fundamental technologies for the development of biomolecular sensors (NASA/NIH),
• Advanced human support technology programme (NASA),
• Human operations in space (NASA, Johnson Space Center, Small Business Technology Transfer Program).
How Nanotechnology Analytical Devices and Nanoparticles Might Aid Medical Diagnostics
Application potentials for nanotechnology can be identified, for example, in the range of miniaturized analytical devices for medical diagnostics, e.g. lab-on-a-chip-systems. Although biochips or lab-on-a-chip-systems are microfluidic devices, they are often discussed in context with nanotechnology. One of the underlying reasons for this is the fact that, frequently, nanoparticles are used for the detection of the analyte molecules. For example, gold nanoparticles, semiconductor nanocrystals (so-called quantum dots) or also magnetic nanoparticles are used as markers for the substances to be determined (proteins, DNA etc.). The detection methods are based on different methods such as fluorescence spectroscopy, magnetic field measurings, electron microscopy or optical color change. The last-named procedure offers the advantage that the test result is indicated without further reading instruments and, therefore, is, in principle, suitable for self-diagnosis of patients.
Processes and Space Applications for Biochips and Lab on a Chip Systems
The manufacturing of high-density oligonucleotide biochips (e.g. for gene analysis) is performed frequently by means of optical lithography, serving to produce binding positions for the individual nucleotide molecules. The advantages of biochips are the simultaneous detection of different analytes, the high speed of analyses, as well as small and compact test kits. In development, are lab-on-a-chip systems, which allow complex analysis sequences by individual controllable micro valves and channels. Particularly, in human space flight, biochips and lab-on-a-chip systems will improve an autonomous self-diagnostics of astronauts.
Using Biomolecular and Biomimetic Sensors to Check Cellular Processes
Rather visionary, at present, are nanotechnological approaches which aim at the development of biomolecular and biomimetic sensors for the online monitoring of cellular processes, for example, by utilization of carbon nanotubes as molecular probes. Major obstacles for such kind of applications are the connection of such molecular probes to macroscopic measuring devices, as well as the amplification of the measuring signals, for which, at present, no technological solutions exist.
Controlled and Targeted Drug Delivery Systems
In medical therapy, a substantial application field for nanotechnology is the controlled and targeted transport of drugs ("drug delivery"). The use of nanoscale transportation vehicles should make it possible to achieve, that the active drugs affect selectively the targeted regions of the human body only, minimizing unwanted side effects.
Drug Transportation Systems Based on Nanoscale Cage Molecules, Nanoparticles and Nanoscale Suspensions
Such transportation systems could be realized, in principle, from nanoscale cage molecules (e.g. liposomes, fullerenes or other cage molecules such as dendrimers) or by coupling with nanoparticles. The goal here is to carry the active drugs selectively to the targeted cells, by means of nanoparticles with specific surface functionalization. Nanoparticles are small enough to penetrate cell membranes and overcome physiological barriers (e.g. blood-brain barrier) in the organism. Furthermore, nanoparticles and nanoscale suspensions improve the solubility and bio-availability of drugs and allow the application of drugs which are, so far, not applicable.
Benefits of Coupling Drugs with Nanoparticles
By the coupling of drugs with nanoparticles, less burdening application procedures can be realized like inhalation instead of infusions, for example. By functionalised nanostructured coating of the drug particles, the deposition speed can be controlled and smaller doses can be applied reducing unwanted side effects.
How Medical Nanotechnology Techniques Might Be Used on Long Space Journeys
With the help of nanotechnological therapy procedures, a distinct progress in the autonomous self-medication of astronauts is expected in the future, including counter measures for acute intoxication. An autonomous medical supply for astronauts is an important prerequisite for the realization of long, manned space missions outside of the earth orbit. During a manned Mars mission, which is considered as a long-term objective both of NASA and the European Space Agency (ESA), there would be no possibility of external medical supply for the astronauts for a period of up to three years, apart from the capabilities of tele-medicine, which will be developed until then.