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Nanopore Membranes
Semiconductor Nanocrystals ("Quantum Dots")
Dendrimers
Buckyballs
Anti-Bacterial Nanotubes
Carbon Nanotubes
Leading Companies in Nanomedicine/Biology

 

NANOTECHNOLOGY AND NANOMEDICINE are not completely science fiction—but they are certainly in their infancy.

Nanotechnology’s applicability to healthcare, and the human condition in general, has been a victim of substantial hype. As with other potentially important technologies, nanotech has suffered from far-reaching claims—followed by disillusionment when those claims are not immediately realized. The “Fantastic Voyages” of nanotechnology usually cited in the press have served to create a certain degree of skepticism of the technology. It will be some time before tiny, self-replicating robots can navigate the bloodstream to blast away arterial blockages, or remove cancer tumors cell by cell. Richard Smalley, a Nobel Prize winning chemist has stated flatly that assembling such devices, atom-by-atom, may well be impossible.

Nevertheless, specific medical applications making use of nanometer-sized manufactured materials are beginning to emerge:

Nanopore Membranes

Boston University researcher Tejal Desai is using a basic form of nanotechnology to fashion replacement pancreas tissue in the treatment of diabetes. Insulin is normally produced in specialized clusters of cells within the pancreas called “islets.” When the islets become impaired, diabetes is the result.

The idea of the research is to allow pancreatic cells from one species to be implanted into other species—while preventing the body’s normal immune response from destroying those cells. Dr. Desai has shown that cells covered in a membrane filled with “nanopores”—tiny openings less than 7 nanometers across—can allow the small insulin molecules to be released into the bodies of the host--but prevent the host’s antibodies from killing the cells—as the antibodies are too large to enter the tiny pores. The membrane’s pores are created using photolithography, the same method used to etch transistors on computer chips.

To date, the technique has only been tested with rats, but diabetic rats fitted with Nanopore-membrane covered pancreases from mice—which normally would have been immediately rejected by their hosts-- have survived weeks without external insulin.

These special membranes may also be useful as specialized capsules to deliver steady doses of drugs within the bloodstream. By creating pores in the capsules that are only large enough for a single molecule of needed drug to pass through, the resulting “turnstile” effect is a slow, continuous release of the contents of the capsule, regardless of the amount remaining. Return to top

Semiconductor Nanocrystals –a.k.a.: “Quantum Dots”

Organic dyes have traditionally been used to tag organic molecules so as to monitor their actions during complex chemical reactions. These dyes however, tend to degrade and fade, and are limited in their abilities to serve as markers due to the very specific wavelengths of light which must be used to illuminate them.

Scientists are seeking to improve upon the limitations of dyes through the use of “quantum dot Nanocrystals.” At 5-10 nanometers, these crystals are composed of three layers. The core contains paired clusters of atoms, like cadmium and selenium, that form a semiconductor which, when illuminated with a broad spectrum of ultraviolet light, glows with a specific color, depending on the atoms used. This core is surrounded by a protective inorganic substance, which in turn is surrounded by an organic coating—which allows it to attach to proteins or DNA. These organic molecules, when bathed in suspensions of these crystals, can be tracked by the glow evidenced by their nanotags, and these tags do not effect their normal chemical reactions. As a result, highly complex organic reactions within cells can be observed with great accuracy, which promises, for example, to speed the creation of new, highly specialized medicines. Return to top

More information on Quantum Dots and the Quantum Dot Corporation.

Dendrimers

Researchers at University of Michigan are creating special tiny objects called dendrimers—that can carry other molecules to interact in special ways with, for example, cancer cells. Shaped like tree branches without leaves, dendrimers contain deep pockets that can contain other reactive compounds—which, because of the complex exteriors of the dendrimers, only react with other compounds that “fit” specifically to crafted contours of the nanostructure. These researchers have actually created a dendrimer that has been designed to mechanically interact with the linings of cancer cells—killing those cells with its special payloads, while leaving normal healthy cells intact. Return to top

Buckyballs

A soccer-ball shaped arrangement of 60 carbon atoms, buckminsterfullerene has been a focus of nanotechnology research since its discovery in 1985. C-Sixty, a Toronto-based firm, has finally found a potential use for this famous molecule in the fight against AIDs. By attaching dendrimers to buckyballs (or fullerenes), this deer head and antler-like assembly carries chemicals to mechanically fill the locations that the HIV virus uses to reproduce itself—similar to the function of existing anti-AIDS drugs, such as protease inhibitors. However, such drugs rely on chemical reactions, which are sensitive to mutations, while the Buckyball technique uses a mechanical process that is much less sensitive to the mutation process. Return to top

More information about fullerene drug delivery.

Anti-Bacterial Nanotubes

Reza Ghadiri, a researcher at the Scripps Research Institute in La Jolla, California has discovered a class of “nanotube” drugs that may one day be used to fight certain bacterial infections, including bacteria that have built up resistance to traditional antibiotics. The tubes are fashioned from rings of amino acids that can attach and grow on the side of cells, puncturing them so that their critical components can leak out. These nanotubes can be tweaked so that they attach and kill only specific pathogens—which often are immune to other antibiotic treatments. Nanotubes have already been used in mice to cure an infection from a lethal dose of an antibiotic-resistant strain of Staphylococcus bacteria.

Drug companies have shown an interest in this technology—but drug trials utilizing nanotubes are not expected for several years. Return to top

Carbon Nanotubes

Molecular Nanosystems, Inc., (MNI) has received two million dollars in angel investments—and licenses to several Stanford patents—to build commercial applications out of Carbon Nanotubes. These nanotube variants are very strong, flexible, and highly sensitive to chemicals, changing their electrical conductivity when exposed to certain gases. MNI plans to use this technology to create devices that can detect very small quantities of target chemicals—in as little as 2-4 years. Like many nanotech challenges—the problem lies with manufacturing: it’s very hard to create usable quantities of these materials. Structural uses of Carbon nanotubes are not expected for at least 10 years, but lesser applications of Nanotubes may arrive in as soon as a year or two. However, these diagnostic applications themselves are estimated to comprise a $4-15 billion dollar market. Return to top

More about Molecular Nanosystem’s work

 

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Leading Companies in Nanomedicine/Biology

Company	Technology Source	Strategy
Agilent Technologies (Palo Alto, CA)	Harvard University	Materials with nano-sized pores for analyzing DNA
engeneOS (Waltham, MA)	MIT	Gold nanoparticles for remote control of biological molecules
Molecular Nanosystems (Palo Alto, CA)	Stanford University	Carbon nanotubes for sensing biological molecules
Nanofluidics (Ithaca, NY)	Cornell University	Chips with nanoscale channels for analyzing DNA
NanoInk (Chicago, IL)	Northwestern University	Dip-pen nanolithography for designing biological molecules and structures
Nanosphere (Northbrook, IL)	Northwestern University	Electrode/gold nanoparticle detectors for sensing DNA and pathogens
Nanosys (Palo Alto, CA)	Harvard University	Nanowires for sensing biological molecules
SurroMed (Mountain View, CA)	Pennsylvania State University	Nanobarcodes for labeling biological molecules
U.S. Genomics (Woburn, MA)	U.S. Genomics	Nanocrystalline lattice for analyzing DNA

Chart from Technology Review

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