Bacteria Harnessed As Micro-Robot Motors

ElectricBrian writes "Researchers have found a way to propel micro-capsules by attaching bacteria (S. marcescens, the type that makes your shower curtain moldy). Scientists at Carnegie Mellon University fixed the bacteria to the micro-capsules and then used chemicals to turn on and off their motion-producing flagella. Quoting: 'In the future, such hybrid swimming micro-robots could even be used to deliver drugs inside the liquid environments of the human body, such as the urinary tract, eyeball cavity, ear, and cerebrospinal fluid...'"

Comments

Speedy little buggers

[nmb3000]

As the attached bacteria rotate their flagella, feeding on surrounding glucose, they push their bead forward at speeds of around 15 microns per second.

As interesting as this sounds, they sure aren't going anywhere very fast.

15 microns is about 0.00059 inches, so to travel one inch, it would take about 1,700 seconds, or a half an hour. IANAD, but it seems like you'd have better luck just letting the body's digestive and circulatory systems do the work for you.

As an added bonus you won't need to start spraying Lysol's Mold and Mildew Remover in your eyes, ears, and uh, other places.

Re:Speedy little buggers

[real gumby]

IANAD, but it seems like you'd have better luck just letting the body's digestive and circulatory systems do the work for you.

Actually, getting drugs past the body's first-pass metabolism is quite a big deal. The stomach, kidneys et al are pretty good at trying to keep toxins/undesirables out of the bloodstream. Getting this stuff into aqueous environments elsewhere in the body helps you skip that step.

As a side-effect, you can administer less drug. For biologics (basically: proteins) this is a big deal for stability, cost of manufacturing, and difficulty of oral administration. For small-molecule drugs those issues don't matter much, but what happens to the stuff that doesn't end up in the bloodstream? Some of it accumulates in the liver or kidneys and a lot ends up back in the water supply (there are plenty of reports now of antidepressents and hormones from contraceptives ending up in the water supply, though a few scary reports notwithstanding it's not clear if they have reached therapeutic levels yet, at least for humans).

Non-disclaimer: I've never heard of these guys and have no idea if they're brilliant, clowns, or something inbetween, nor would you want my judgement on that issue. But I am interested/working on local drug delivery.

the eyes have it

[ianchaos]

There is one good reason to work on this type of medicine delivery device and that is the eyes. The interior of the eye has NO blood flow. Delivering medicine inside the eye has some very tricky problems.

1. It needs to be perfectly clear...and/or
2. After it is injected it then needs to be able to be completely absorbed through the interior of the eye so as to not leave any residue floating around.
3. You can't go injecting a large amount of fluid into an already full fluid sac. High pressure against the retina can tear the retina wall, and can rupture the incredibly fine veins that supply the retina with blood (causing large amounts of what are known as floaters).
4. How do you get the medicine to disperse evenly throughout the fluid in the eye. If it's heavy it sinks, equal to the eye fluid it generally stays where it is, or eventually sinks, or if it's lighter then the fluid in they eye it rises to the top. Perhaps severely shaking the patient after the injection would help...

Now if you had a colony of microbes which could be directed to different areas in the eye or simply ordered to disperse and deliver the drug when it comes into contact with "x" then you would have something.

Re:any biologist around to help with definitions..

[posterlogo]

S. marcescens is a bacterium. Any and all mold are fungi, as you stated. So the summary is using the terms interchangeably, and inappropriately. It is possible that the pink stains are inaccurately referred to as mold, and that might explain the summary author's remarks.

Re:CSF

[Rob Simpson]

It allows the drugs to be more selectively delivered. Certain bacteria attack different things, same reason why people get strep instead of an upset stomach. So when you just inject them, the chemicals are taken to exactly where they need to be, something that a doctor with a needle can't do yet.

Except that isn't the case with injecting into the CSF - you just stick a needle into someone's spine (very carefully). And I can't see how these things could penetrate the CSF without damaging the blood-brain barrier, possibly worse than a single needle.