Nanofactories to heal you
Imagine yourself taking a pill that will detect a disease, build the remedy and deliver the drug where it's necessary to heal you. Even if it looks like science fiction, researchers at the University of Maryland are working on this, by building magnetic nanofactories to make and deliver drugs -- at least in their labs. For example, "these ingested nanofactories, using magnetism, could detect a bacterial infection, produce a medication using the body's own materials, and deliver a dose directly to the bacteria. The drug would do its work only at the infection site, and thus not cause any side effects." Even if the results of this research project are promising, these nanofactories will not be used to heal you before a while because several problems need to be solved, such as 'disguising' these nanofactories before they're attacked by your body.
Let's start with a picture describing an overview of the assembly and use of these magnetic nanofactories to locally synthesize and deliver the signaling molecule to a target cell. (Credit: William E Bentley). From left to write, you can see: "1. Synthesis of the magnetic carrier, chitosan-mag, by co-precipitation of iron salts and chitosan. 2. Attachment of pro-tagged Pfs and LuxS to chitosan-mag by 'activation' using tyrosinase to assemble magnetic nanofactories. 3. Capture of target cells by the magnetic nanofactories. 4. Recovery of captured cells using an external magnet. 5. Cell surface synthesis and delivery of AI-2 by enzymes Pfs and LuxS. 6. Uptake of AI-2 and production of cellular response (AI-2-dependent reporter)." And here is a link to a larger version.
These magnetic nanofactories have been conceived by William Bentley, professor at the Clark School of Engineering, and his research group working on metabolic engineering.
The research team is not only working on the delivery of drug molecules, but also on the manufacturing of these drugs.
Besides drug molecules, the researchers showed that the nanofactory could produce signaling molecules that communicate with the target cell or block the target cell from communicating with other, similar cells (a process called "quorum sensing") and thus prevent infection. The researchers attached the nanofactories to E. coli cells, targeting them with the help of a mixture of iron particles and chitosan, a substance derived from the shells of crustaceans like crabs and shrimp. The nanofactories then produced a signaling molecule that could render the E. coli harmless. Nanofactories could be designed to produce the needed drug molecules over an extended period of time.
This research work on magnetic nanofactories has been published by Metabolic Engineering under the title "Magnetic nanofactories: Localized synthesis and delivery of quorum-sensing signaling molecule autoinducer-2 to bacterial cell surfaces" (Volume 9, Issue 2, March 2007, Pages 228-239). Here is a link to the abstract.
Magnetic 'nanofactories', for localized manufacture and signal-guided delivery of small molecules to targeted cell surfaces, are demonstrated. They recruit nearby raw materials for synthesis, employ magnetic mobility for capture and localization of target cells, and deliver molecules to cells triggering their native phenotypic response, but with user-specified control. Our nanofactories, which synthesize and deliver the "universal" bacterial quorum-sensing signal molecule, autoinducer AI-2, to the surface of Escherichia coli, are assembled by first co-precipitating nanoparticles of iron salts and the biopolymer chitosan.
But even if the results of this research project are promising, these nanofactories will not be used to heal you before a while. "First, nanofactories must be cloaked so that the body does not react to them as a foreign substance and try to attack them. Another goal is to find a method to shut down the nanofactory once it has produced the needed substance -- a type of off-switch that could be activated from outside the body."
Sources: Clark School of Engineering, University of Maryland, February 27, 2007; and various websites
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