NANO IN DRUG DELIVERY

Drug delivery is an area that is already showing significant impact from nanotechnology, with some approaches using nanoparticles or nanocapsules to deliver drugs through the skin, lungs, stomach and eyes already in clinical trials and many more in preclinical trials.

The advantages of these approaches are varied, such as increased solubility, resistance to gastric enzymes (offering oral delivery of drugs previously needing intravenous delivery), controlled release or the ability to direct the drug, through various means, to where it is needed—almost all current medications are delivered to the body as a whole, which is fine as long as they only become active in the areas you want them to, but this is not usually the case. When the treatment is designed to kill cells, as in the case of cancer, the side effects are enormous.

Nanostructured Materials

Nanostructured materials, coupled with liquid crystals and chemical receptors offer the possibility of cheap, portable biodetectors that might, for instance, be worn as a badge. Such a badge could change color in the presence of a variety of chemicals and would have applications in hazardous environments.

Nanoparticles and nanowires

Another boon to bioanalysis looks set come from the attaching of nanoparticles to molecules of interest. Nanoparticles small enough to behave as quantum dots can be made to emit light at varying frequencies. If you can get particles that emit at different frequencies to attach to different molecules, you can spectroscopically determine the presence of many different molecules at the same time in a single sample.

Several companies have been created to commercialize this and other variations on nanoparticle bioanalysis. One variation with similar applications, i.e. offering improved parallelism, uses instead nanowires that have distinctive stripes on them, like a bar code.
Others are exploiting the sensitivity of the electrical properties of nanowires (and even nanotubes) to develop highly sensitive biodetectors that could reveal the presence of a single molecule of substance. Quantum dots offer the same capability, for example by being stimulated to emit a photon in the presence of a certain molecule. Recent developments in single-photon detection and emission bear on this space too.

Nanopores and membranes

Nanomembranes also offer the ability to sort biomolecules and have already been shown capable of separating out left- and right-handed versions of molecules that come in mirror image forms. Usually only one of these is desired and the other may even be dangerous, as was the case with thalidomide.
Another intriguing application of tiny holes that is being worked on involves passing a single DNA or RNA thread through a nanosized pore, forcing it to straighten out and traverse the pore through a base at a time (a "base" being the fundamental coding element of nucleic acids). Changing electrical gradients on either side of the structure, containing the pore, or quantum tunneling current across the pore, could be used to identify the particular base that is passing through. The ability to sequence a whole genome (the sum total of genes in an organism) in a matter of hours has been proposed as a potential of this approach.

MEMS and micro fluidics

Micro technology is already making a major impact in the area of biological analysis and discovery. The basic science behind identifying the presence of a particular gene or protein has been developing for some time and is not considered nanotechnology per se, but MEMS and micro fluidics developments, such as the lab on a chip, are now offering a degree of parallelism that hasn't been seen before, the ability to detect much smaller quantities of a substance, equipment that can be taken out of the lab and carried around, increased automation by virtue of the integration of micro circuitry into the devices, and the benefits of the mass production approaches used in the semiconductor industry.

These benefits are typified by an approach to bioanalysis that takes a micro array (a standard tool for parallel biodetection using luminescence), shrinks it greatly, and then uses atomic force microscope tips to measure whether a substance has been detected. Such devices are in development now and expand the number of substances that can be easily used in array technologies because such small amounts are needed—detection using micro arrays often requires an amplification step whereby the substance to be detected is multiplied in quantity first, something that cannot be done with everything.